US20220193329A2 - Micropump - Google Patents
Micropump Download PDFInfo
- Publication number
- US20220193329A2 US20220193329A2 US17/011,749 US202017011749A US2022193329A2 US 20220193329 A2 US20220193329 A2 US 20220193329A2 US 202017011749 A US202017011749 A US 202017011749A US 2022193329 A2 US2022193329 A2 US 2022193329A2
- Authority
- US
- United States
- Prior art keywords
- disposable
- reusable
- component
- conduit
- bubble
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000012530 fluid Substances 0.000 claims abstract description 295
- 238000004891 communication Methods 0.000 claims abstract description 54
- 238000000034 method Methods 0.000 claims description 37
- 238000005086 pumping Methods 0.000 claims description 14
- 238000007599 discharging Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 6
- 239000000306 component Substances 0.000 description 184
- 239000012528 membrane Substances 0.000 description 64
- 239000007789 gas Substances 0.000 description 42
- 210000004369 blood Anatomy 0.000 description 23
- 239000008280 blood Substances 0.000 description 23
- 238000013461 design Methods 0.000 description 20
- 238000001802 infusion Methods 0.000 description 15
- 238000007726 management method Methods 0.000 description 13
- 238000013022 venting Methods 0.000 description 11
- 230000009471 action Effects 0.000 description 10
- 230000008030 elimination Effects 0.000 description 10
- 238000003379 elimination reaction Methods 0.000 description 10
- 230000007246 mechanism Effects 0.000 description 10
- 229940079593 drug Drugs 0.000 description 9
- 239000003814 drug Substances 0.000 description 9
- 239000007788 liquid Substances 0.000 description 9
- 238000012546 transfer Methods 0.000 description 9
- 230000035699 permeability Effects 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 6
- 230000037452 priming Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000000670 limiting effect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 238000005755 formation reaction Methods 0.000 description 3
- 238000001990 intravenous administration Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000012503 blood component Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 238000002483 medication Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000000284 resting effect Effects 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 206010001526 Air embolism Diseases 0.000 description 1
- 206010018910 Haemolysis Diseases 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000012867 bioactive agent Substances 0.000 description 1
- 239000010836 blood and blood product Substances 0.000 description 1
- 210000000601 blood cell Anatomy 0.000 description 1
- 229940125691 blood product Drugs 0.000 description 1
- 230000009172 bursting Effects 0.000 description 1
- 230000005779 cell damage Effects 0.000 description 1
- 208000037887 cell injury Diseases 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 210000003743 erythrocyte Anatomy 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000008588 hemolysis Effects 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000002372 labelling Methods 0.000 description 1
- 238000004137 mechanical activation Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- -1 plasma Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
- A61M5/1452—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons
- A61M5/1454—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons spring-actuated, e.g. by a clockwork
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/36—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests with means for eliminating or preventing injection or infusion of air into body
- A61M5/365—Air detectors
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/14212—Pumping with an aspiration and an expulsion action
- A61M5/14216—Reciprocating piston type
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16804—Flow controllers
- A61M5/16809—Flow controllers by repeated filling and emptying of an intermediate volume
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16886—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body for measuring fluid flow rate, i.e. flowmeters
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/14244—Pressure infusion, e.g. using pumps adapted to be carried by the patient, e.g. portable on the body
- A61M2005/14268—Pressure infusion, e.g. using pumps adapted to be carried by the patient, e.g. portable on the body with a reusable and a disposable component
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M2005/16863—Occlusion detection
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/50—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests having means for preventing re-use, or for indicating if defective, used, tampered with or unsterile
- A61M5/5013—Means for blocking the piston or the fluid passageway to prevent illegal refilling of a syringe
- A61M5/504—Means for blocking the piston or the fluid passageway to prevent illegal refilling of a syringe for blocking the fluid passageway
- A61M2005/5046—Means for blocking the piston or the fluid passageway to prevent illegal refilling of a syringe for blocking the fluid passageway automatically, e.g. plug actuated by the piston head, one-way valve
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/33—Controlling, regulating or measuring
- A61M2205/3331—Pressure; Flow
- A61M2205/3334—Measuring or controlling the flow rate
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/50—General characteristics of the apparatus with microprocessors or computers
- A61M2205/502—User interfaces, e.g. screens or keyboards
- A61M2205/505—Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/82—Internal energy supply devices
- A61M2205/8206—Internal energy supply devices battery-operated
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/82—Internal energy supply devices
- A61M2205/8262—Internal energy supply devices connectable to external power source, e.g. connecting to automobile battery through the cigarette lighter
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M39/00—Tubes, tube connectors, tube couplings, valves, access sites or the like, specially adapted for medical use
- A61M39/22—Valves or arrangement of valves
- A61M39/28—Clamping means for squeezing flexible tubes, e.g. roller clamps
Definitions
- the present invention relates in general to the field of infusion pumps.
- the present invention relates to an infusion pump with a disposable component and a capacity to remove gases from a fluid to be infused.
- Infusion pumps are commonly used to infuse substances such as blood and medications into patients.
- Existing infusion pumps generally require fixed power sources.
- Many existing infusion pumps also require costly and time-consuming cleaning between uses.
- many existing infusion pumps lack a capacity to detect and minimize the occurrence of gases in the fluid to be infused.
- U.S. Pat. No. 10,384,004, to Zhu which is said to disclose processes for operating an infusion pump for pumping fluid though an administration set at a constant flow rate; wherein the pump includes a pumping mechanism for pumping fluid and operates at a pulse frequency, and a controller controls the pulse frequency; wherein the pump has one or more sensors configured for measuring at least one characteristic value relating to a status of the infusion pump; wherein the controller is configured for causing the pumping mechanism to operate at a first pulse frequency, and the one or more sensors measure the characteristic value; and wherein, when the measured characteristic value meets a threshold value, the controller causes the pumping mechanism to operate at a second pulse frequency different from the first pulse frequency.
- U.S. Pat. No. 10,387,624, to Jedwab, et al. which is said to disclose an infusion pump having a control unit and a graphical user interface functionally connected to the controller, wherein the control unit is designed to receive at least two sensor signals out of the following group of sensors: cassette presence sensor, door sensor, pressure sensor, air presence sensor, motor sensor, flow rate sensor, wherein the control unit is designed to detect an error state based on the analysis of the at least two supplied sensor signals, wherein the control unit is designed to associate a degree of severity out of at least two degrees of severities based on the processing of the supplied sensor signals, and wherein the control unit is designed to control a color of the display of the graphical user interface to be displayed, wherein a different color is associated with each degree of severity as well as with a non-error state.
- the control unit is designed to receive at least two sensor signals out of the following group of sensors: cassette presence sensor, door sensor, pressure sensor, air presence sensor, motor sensor, flow rate sensor, wherein
- a pump including a disposable component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium; wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage.
- the disposable component further includes a first one-way outlet valve disposed in the first disposable conduit between the piston assembly and the disposable bubble eliminator and operable to prevent the fluid medium from flowing from the disposable bubble eliminator to the disposable piston pump assembly; a disposable flow meter positioned to measure a fluid flow through the first disposable conduit; and a second one-way outlet valve disposed in the second disposable conduit between the disposable bubble eliminator and the disposable flow meter and operable to prevent the fluid medium from flowing from the disposable flow meter to the disposable bubble eliminator; and the reusable component further includes a reusable reception tunnel configured to receive at least a portion of the first disposable conduit; a reusable inlet valve operable to close the first disposable conduit when the at least a portion of the first disposable conduit is disposed in the reusable reception tunnel; a reusable flow meter connector operable to connect to the disposable flow meter and to convey data from the disposable flow meter; and a reusable bubble detector.
- the reusable inlet valve is a one-way valve or a pinch valve.
- the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved into the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger upward in the piston barrel and the spring is disposed to move the plunger downward in the pump chamber.
- the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator.
- the disposable component further includes a disposable position measurement device to detect an alignment of the disposable component with the reusable component when assembled together.
- the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit.
- the reusable component further includes an internal electric battery or electrical connections configured to connect to an external electrical power source or both.
- the reusable component further includes an internal power management system or power management connections configured to connect to an external power management system or both.
- the reusable component further includes an integral control panel or control panel connections configured to connect to an external control panel or both.
- the reusable component further includes a screen interface or screen interface connections configured to connect to an external screen interface or both.
- the disposable component is enclosed in a disposable housing or the reusable component is disclosed in a reusable housing or both.
- a method of pumping a fluid including providing a disposable pump component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium, and wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and connecting the disposable component to a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage.
- a method of pumping a fluid medium including receiving the fluid medium from a fluid medium source into a conduit; drawing the fluid medium into a disposable piston pump assembly in the conduit, the conduit further including a disposable bubble eliminator operable to vent gas from the fluid medium within the disposable bubble eliminator; flowing the fluid medium through a disposable flow meter; measuring a flow rate of the fluid medium; discharging the fluid medium into a reusable bubble detector; detecting residual gas in the fluid medium; if less than a preselected amount of gas is detected, discharging the fluid medium from the reusable bubble detector.
- the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved from a lower end of the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger into the pump chamber and the spring is disposed to move the plunger out of the pump chamber.
- the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator.
- the method further includes detecting an alignment of the disposable component with the reusable component when assembled together.
- the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit.
- the method further includes supplying electrical power from an internal electric battery or an external electrical power source.
- the method further includes managing electrical power with an internal power management system or an external power management system.
- the method further includes supplying an integral screen interface or an external screen interface.
- a kit including a disposable component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium; wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage.
- the disposable component further includes a first one-way outlet valve disposed in the first disposable conduit between the piston assembly and the disposable bubble eliminator and operable to prevent the fluid medium from flowing from the disposable bubble eliminator to the disposable piston pump assembly; a second disposable conduit that places the disposable bubble eliminator in fluid communication with a disposable flow meter; a second one-way outlet valve disposed in the second disposable conduit between the disposable bubble eliminator and the disposable flow meter and operable to prevent the fluid medium from flowing from the disposable flow meter to the disposable bubble eliminator; and the reusable component further includes a reusable reception tunnel configured to receive at least a portion of the first disposable conduit; a reusable inlet valve operable to close the first disposable conduit when the at least a portion of the first disposable conduit is disposed in the reusable reception tunnel; a reusable flow meter connector operable to connect to the disposable flow meter and to convey data from the disposable flow meter; and a reusable bubble detector.
- the reusable inlet valve is a one-way valve or a pinch valve.
- the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved into the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger upward in the piston barrel and the spring is disposed to move the plunger downward in the pump chamber.
- the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator.
- the disposable component further includes a disposable position measurement device to detect an alignment of the disposable component with the reusable component when assembled together.
- the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit.
- the reusable component further includes an internal electric battery or electrical connections configured to connect to an external electrical power source or both.
- the reusable component further includes an internal power management system or power management connections configured to connect to an external power management system or both.
- the reusable component further includes an integral control panel or control panel connections configured to connect to an external control panel or both.
- the reusable component further includes a screen interface or screen interface connections configured to connect to an external screen interface or both.
- the disposable component is enclosed in a disposable housing or the reusable component is disclosed in a reusable housing or both.
- FIG. 1 shows the disposable component and the reusable component of the pump attached together.
- FIG. 2 shows the disposable component and the reusable component of the pump detached from each other.
- FIG. 3 shows the disposable pump assembly
- FIGS. 4A-4E show the arrangement of the disposable pump assembly at the completion of the pump stroke, mid-way through the refill stroke, at the completion of the refill stroke, mid-way through the pump stroke, and at the return to the completion of the pump stroke, respectively.
- FIGS. 5A, 5B, and 5C show the relative positions of the disposable pump assembly and the reusable movable stage during connection of the disposable component and the reusable component, when the disposable component and the reusable component are attached, and during detachment of the disposable component and the reusable component, respectively.
- FIGS. 6A and 6B show the disposable bubble eliminator during the pump stroke of the disposable pump assembly and during the refill stroke of the disposable pump assembly, respectively.
- FIGS. 7A and 7B show the bubble eliminator chamber and the approximate fluid flow lines within it, respectively.
- FIGS. 7C-7G show the disposable bubble eliminator effectively performing, with a bubble progressively becoming smaller as the bubble's air passes out through the ePTFE membrane.
- FIGS. 8A-8K show results of a study to investigate various bubble venting specifications, Examples 1-11.
- FIGS. 9A-9D schematically depict Examples 12-15, representing additional configurations tested.
- FIG. 10 shows a flowchart for a method embodiment of the present invention.
- FIG. 11 shows a flowchart for another method embodiment of the present invention.
- Infusion pumps are commonly used to infuse substances such as blood and medications into patients. They often need to be used untethered from electrical power connections, such as in ambulatory situations, where operation by internal battery power is convenient or necessary. Also, it is desirable to have a pump comprising certain disposable components which, for patient safety reasons, are discarded and replaced frequently. It is desirable that a pump have the operability to detect and minimize occurrence of gases in the fluid to be infused, to ensure correct direction of fluid flow, to prevent uncontrolled flow of fluid to be infused, and to control the rate of flow of fluid that is being infused, with accurate measurement and verification of the rate of fluid flow.
- FIG. 1 An embodiment of the present invention, a pump 100 for achieving controllable flow, is depicted in FIG. 1 .
- the invention includes a fluid flow path that is defined by multiple disposable parts and systems.
- the disposable fluid flow path comes into contact with fluids, such as intravenous delivery fluids, drug solutions, blood products, and solutions of bioactive agents.
- the disposable parts are housed by a disposable component 101 .
- the invention includes reusable parts and systems that do not come into contact with fluids.
- the reusable parts and systems are durable and function multiple times with a plurality of different disposable components.
- the reusable parts and systems are housed by a reusable component 102 .
- the parts used to achieve conversion of electrical energy, e.g., electrical energy stored in a battery 128 , to mechanical action are housed by the reusable component 102 , as are various mechanical drivers, the equipment for monitoring system performance and, the control panel 132 and the edit touch screen 134 for interfacing with a user.
- the controls to control action and speed motion of the pump are located on the reusable component. It would be wasteful and costly to dispose of these reusable parts because of their sophistication and complexity.
- the invention is intended to meet the requirements that a new disposable component 101 be easily connected to and removed from the reusable component 102 and that the disposable and reusable components 101 and 102 respectively, achieve physical, mechanical and electrical integration when attached to each other.
- FIG. 1 depicts an embodiment of the present invention, the pump 100 , including a disposable component 101 and a reusable component 102 , which are shown attached together.
- the disposable component 101 includes a disposable component inlet port 104 coupled to a first disposable conduit 106 in fluid communication with a fluid medium source (not shown).
- the first disposable conduit 106 is in fluid communication with a disposable piston pump assembly 140 and a disposable bubble eliminator 160 with bubble eliminator chamber 162 .
- the first disposable conduit 106 is in fluid communication with a disposable component outlet port 180 .
- the disposable bubble eliminator 160 is in fluid communication with a lumen (not shown) of the first disposable conduit 106 , and is operable to reduce a gas content of a fluid medium.
- the disposable piston pump assembly 140 is operable to pump the fluid medium from the disposable component inlet port 104 , through the first disposable conduit 106 and the disposable bubble eliminator 160 , to the disposable component outlet port 180 .
- the reusable component 102 includes a reusable movable stage 108 operable to compress the disposable piston pump assembly 140 and a reusable mechanical actuator 110 operable to drive the reusable movable stage 108 .
- the disposable component 101 may further include a second disposable conduit 112 in fluid communication with the disposable bubble eliminator 160 and the disposable component outlet port 180 .
- the disposable component 101 may also include a first one-way outlet valve 114 disposed in the first disposable conduit 106 between the disposable piston pump assembly 140 and the disposable bubble eliminator 160 , and operable to prevent the fluid medium from flowing from the disposable bubble eliminator 160 to the disposable piston pump assembly 140 .
- the disposable component 101 may further include a disposable flow meter 116 disposed to measure fluid flow through the second disposable conduit 112 .
- the disposable component 101 may also include a second one-way outlet valve 118 disposed between the disposable bubble eliminator 160 and the disposable flow meter 116 and operable to prevent the fluid medium from flowing from the disposable flow meter 116 to the disposable bubble eliminator 160 .
- the reusable component 102 may further include a reusable reception tunnel 120 configured to receive at least a portion of the first disposable conduit 106 .
- the reusable component 102 may also include a reusable inlet valve 122 that is operable to close the first disposable conduit 106 when the at least a portion of the first disposable conduit 106 is disposed in the reusable reception tunnel 120 .
- the reusable component 102 may also include a reusable flow meter connector 124 operable to connect to the disposable flow meter 116 and to convey data from the disposable flow meter 116 .
- the reusable component 102 may further include a reusable bubble detector 126 .
- the reusable component 102 may also include an internal electric battery or electrical connections configured to connect to an external electrical power source 128 or both.
- the reusable component 102 may also include an internal power management system or power management connections configured to connect to an external power management system 130 or both.
- the reusable component 102 may also include an integral control panel or control panel connections configured to connect to an external control panel 132 or both.
- the reusable component 102 may also include a screen interface or screen interface connections configured to connect to an external screen interface 134 or both.
- FIG. 1 depicts the operational configuration of one embodiment of the pump 100 , where the reusable component 102 is coupled, physically, mechanically, and electrically to the disposable component 101 .
- FIG. 2 depicts the situation when the disposable and reusable components shown attached in FIG. 1 are disconnected from each other.
- the disposable component 101 includes the reciprocating disposable piston pump assembly 140 , which is of metallic or polymer construction.
- the disposable piston pump assembly 140 makes contact with a moveable stage 108 in the reusable component 102 .
- the motion of the reusable moveable stage 108 is driven by the mechanical actuator 110 , which is also in the reusable component 102 .
- the reusable mechanical actuator 110 provides the driving force for the forward stroke of the disposable piston pump assembly 140 .
- the parts needed for converting electrical energy stored in the batteries 128 into mechanical actuation are housed in the reusable component 102 , since the parts needed for electrical-to-mechanical conversion typically have significant electrical and mechanical complexity.
- the fluid path is defined by tubing and valves, consisting of a disposable component inlet port 104 , a disposable component outlet port 180 , and a piston pump chamber 144 .
- the fluid flow path is defined by tubing and connections of the type used for delivery of intravenous fluids to the body.
- the parts defining the fluid path are housed in the disposable component 101 .
- the disposable component 101 includes a disposable component inlet port 104 for receiving the fluid and a disposable component outlet port 180 for supplying the fluid to a patient.
- a controllable disposable piston pump assembly 140 incorporating the piston pump chamber 144 , is used for fluid flow from the disposable component inlet port 104 to the outlet port 180 .
- the reusable inlet valve 122 is disposed in proximity to the disposable component inlet port 104 .
- the reusable inlet valve 122 opens and closes the first disposable conduit 106 , which may be disposable IV tubing.
- the reusable inlet valve 122 uses, e.g., a pinch valve mechanism.
- a pinch valve is a component that allows the mechanical pinching of the outside of a tube, where mechanical pressure deforms the tube sufficiently to restrict or stop flow through the tube's internal diameter. Flow resumes when the mechanical pressure to the outside of the tube is released.
- the benefit of a pinch valve compared to alternatives such as a solenoid valve, is that the valve's parts and mechanisms do not come in contact with fluid.
- a pinch valve can be physically mounted, in its entirety, in the reusable component 102 , so as not to dispose of it after a single use. The fluid path through the reusable inlet valve is therefore defined by placement of the first disposable conduit 106 .
- the controllable disposable piston pump assembly 140 is disposed and operated to achieve fluid flow in the direction of the disposable component outlet port 180 .
- the one-way outlet valves V 1 114 and V 2 118 are part of the disposable component 101 .
- the fluid is pumped in only one direction because the one-way outlet valves V 1 114 and V 2 118 are normally closed but open in response to fluid pressure.
- the reusable inlet valve 122 is closed.
- the output valves V 1 114 and V 2 118 downstream are forced open, and the fluid flows towards the disposable component outlet port 180 .
- the one-way outlet valves V 1 114 and V 2 118 close, and the reusable inlet valve 122 is opened to admit more fluid.
- the two one-way outlet valves V 1 114 and V 2 118 are passive (not controlled electrically as compared to the inlet valve 122 ).
- These valves V 1 114 and V 2 118 are umbrella-type valves, allowing fluid to flow one direction but not the other.
- An umbrella valve looks like an umbrella. As the fluid travels in one direction the umbrella valve opens allowing the fluid to pass, but as the fluid tries to reverse direction, the umbrella valve closes and prevents any fluid from traveling towards the inlet.
- the embodiment shown in FIGS. 1 and 2 includes a disposable bubble eliminator 160 located between one-way outlet valves V 1 114 and V 2 118 .
- the disposable bubble eliminator 160 includes a fluid chamber 162 .
- One or more walls of the chamber 162 are formed from a gas permeable porous membrane 164 , allowing gas to vent to the external atmosphere.
- the disposable bubble eliminator 160 is placed in the fluid flow path such that positive pressure conditions are maintained within the bubble eliminator chamber 162 at all times. Operation and orientation of one-way valves V 1 114 and V 2118 working in coordination with the disposable piston pump assembly 140 , are important in managing the bubble eliminator chamber 162 fluid pressure.
- the fluid side of the disposable bubble eliminator 160 is always is at a higher pressure than atmospheric during the prime stroke as well as the forward stroke of the disposable piston pump assembly 140 .
- the embodiment shown in FIGS. 1 and 2 includes the disposable flow meter 116 positioned towards the outlet.
- the device is suitable for monitoring or measuring the activity and accuracy of the disposable piston pump assembly 140 .
- the disposable flow meter 116 is part of the disposable component 101 .
- An example disposable flow meter is the Sensiron LD 20 - 2600 B. It operates based on a thermal gradient detection, suitable for integration into the disposable component 101 .
- the disposable flow meter 116 is a direct flow measurement device used to monitor gross flow rate error, occlusion, and infiltration and to verify that the pump head is installed properly.
- the disposable flow meter 116 can measure the flow of all standard IV fluids, drugs formations, as well as blood and other high viscosity fluids.
- the flow meter may also assist in a free flow prevention algorithm.
- the disposable flow meter 116 has the additional purpose of determining correct positioning of the disposable component 101 with respect to the position of the reusable component 102 . This informs the user that correct alignment between the components 101 and 102 is achieved, to accomplish physical, mechanical, and electrical coupling prior to pump operation.
- the flow sensor operates in conjunction with a reusable flow meter connector 124 , which is part of the reusable component 102 .
- a reusable bubble detector 126 which may include an ultrasonic sensor, to detect air-in-line scenarios.
- Critical to the safety of the patient during a drug, IV fluid, or blood component infusion is the detection of air boluses in the tubing.
- An example reusable ultrasonic sensor is a Moog LifeGuard Air Bubble Detector. This reusable ultrasonic sensor is a non-wetted component. It uses ultrasonic frequencies to measure the fluid response in the tubing, alerting the operator if bubbles 50-100 uL are present. The sensor is a part of the reusable component 102 .
- Another method is to measure the movement of the piston of the disposable piston pump assembly 140 very accurately and, with electronic feedback control, use that movement to measure the volume of fluid pumped.
- the timing of the reusable inlet valve 122 and the reusable mechanical actuator 110 thus can be precisely adjusted to provide accurate fluid flow.
- the one-way outlet valves V 1 114 and V 2 118 deflection information, available through a transducer, may provide information which is substantially representative of the operational state of the disposable piston pump assembly 140 , thereby enabling control of the timing.
- the outlet flow from the piston valve may include a device that allows detection of occlusion or partial occlusion of outflow from the pump, gas trapped in the disposable piston pump assembly 140 , mechanical failure, disconnection of the line to the patient, and exhaustion of fluid supply.
- the disposable fluid lines may be packaged with the disposable component 101 in order for ease of installment and replacement.
- the disposable component 101 connects to the reusable component 102 by single action clips (not shown) to minimize effort of swapping pump heads.
- the fluid lines will also be compatible with standard IV drugs, as well as blood, plasma, water, etc.
- the touch screen 134 may give access to a drug library with preset settings that will include flow rates, bolus amounts for a given patients weight for the various drugs.
- the user has the capability to manually input the flow rate as well as volume in order for custom solutions.
- the system also has the capability to be continually updated to include or remove drugs and the parameters associated with them.
- the packaging of the pump will house all the components within either of the disposable or reusable components, 101 or 102 , respectively.
- the pump parts may have labels and markings permanently displayed consistent with regulatory agency labeling requirements. It may also have the necessary visual and audible alarms and indicators according to the IEC standard for medical pumps indicating various states (end of infusion, occlusion, air-in-line, battery, equipment failure, etc.).
- the pump 100 has the capability to be controlled and monitored via Wi-Fi/Bluetooth as well as ability to turn off those features for security purposes.
- the control board 132 for the pump may contain a processor in order to operate all electrical components.
- the reusable component 102 may also contain a Power Management System (PMS) 130 voltage balancing and monitoring, H bridges for reversing the polarity of voltage source electrically coupled to the circuitry of the pump actuation mechanism, sensors for component monitoring, and various other electrical components to operate the pump.
- PMS Power Management System
- the control board 132 also has the capability of controlling the magnitude of voltage or current applied to the individual actuators.
- the reusable piston pump assembly 140 includes a piston barrel 142 that includes the pump chamber 144 in fluid communication with the first disposable conduit 106 , a plunger 146 slidably disposed within the piston barrel 142 below the pump chamber 144 , a piston rod 148 attached to the plunger 146 opposite the pump chamber 144 , and a spring cap 150 attached to the piston rod 148 .
- the reusable piston pump assembly 140 includes a spring 152 disposed around an exterior of the piston barrel 142 and attached at an upper end of the spring 152 to the exterior of the piston barrel 142 and at a lower end of the spring 152 to the spring cap 150 .
- the spring 152 is disposed to store energy when the plunger 146 , the piston rod 148 , and the spring cap 150 are moved into the piston barrel 142 and is disposed not to store energy when the plunger 146 is at the lower end of the pump chamber 144 .
- FIG. 3 illustrates disposable piston pump assembly 140 with the spring 152 in a compressed, energy-storing state and the plunger 146 moved into the piston barrel 142 .
- the disposable piston pump assembly 140 may also include a dead volume spacer 154 disposed on the plunger 146 in the pump chamber 144 , a plunger insert 156 disposed inside the plunger 144 , and a piston hardstop 158 disposed at the bottom of the piston barrel 142 .
- the disposable piston pump assembly 140 has a flow channel in fluid communication with the disposable component inlet port 104 and the disposable component outlet port 180 via the first disposable conduit 106 .
- One end of the spring 152 is permanently affixed to the disposable piston pump assembly 140 through a permanent attachment mechanism, such as a grooved recess, a weld, solder or adhesive.
- the opposite end of the spring 152 is permanently connected to the spring cap 150 .
- the permanent attachment of spring 152 to one end of the spring cap 150 is made via a grooved recess, or alternatively by a weld, solder or adhesive.
- the movement of the plunger 146 is constrained in the forward direction by the piston pump chamber wall at the outlet side.
- the plunger 146 is constrained in the retracted position by a piston hardstop 158 .
- FIGS. 4A-4E show how fluid transfer from the disposable component inlet port 104 to the disposable component outlet port 180 is achieved, involving sequential and coordinated actions involving parts of the disposable component 101 and parts of the reusable component 102 .
- FIG. 4A shows the arrangement of the disposable piston pump assembly 140 at the completion of the forward or pump stroke.
- the plunger 146 is in the fully forward position.
- the pump chamber 144 is substantially empty of fluid.
- the spring 152 is compressed from its resting position.
- the reusable inlet valve 122 on the first disposable conduit 106 is closed. There is no more fluid flow in the direction of the disposable component outlet port 180 .
- the reusable mechanical actuator 110 of the movable stage is disengaged.
- FIG. 4B shows the arrangement mid-way during the retraction or refill stroke of the disposable piston pump assembly 140 , where the plunger 146 is partially retracted.
- the spring 152 undergoes extension which applies a force to the spring cap 150 .
- the mechanical force of the spring 152 acting on the spring cap 150 causes retraction of the plunger 146 .
- Retraction of the plunger 146 results in negative pressure (less than atmospheric) within the pump chamber 144 . Fluid flows into the pump chamber 144 from the outlet, due to negative chamber pressure.
- the refill stroke coincides with mechanical activation to open the reusable inlet valve 122 .
- one-way outlet valves V 1 114 and V 2 118 are closed, so as to prevent or restrict flow in the direction of the disposable component outlet port 180 .
- the extension of the spring 152 also applies force to the reusable movable stage 108 causing its retraction.
- the force to retract the reusable movable stage 108 is applied via the spring cap 150 , which makes physical contact with the reusable movable stage 108 via a contact surface.
- the mechanical actuator connected to the reusable movable stage 108 is disengaged, so the reusable movable stage 108 is free to move in the retraction direction.
- the disposable component 101 has an energy transfer function, where mechanical energy stored in the spring 152 is transferred to the reusable movable stage 108 , which is part of reusable component 102 .
- FIG. 4C shows the disposable piston pump assembly 140 configuration at the completion of the retraction or refill stroke.
- the plunger 146 is fully retracted.
- the disposable piston pump assembly is primed, where the spring cap 150 and the plunger 146 have moved to a stop position and the reusable movable stage has returned to a hard stop position.
- the reusable inlet valve is open but there is no flow into the pump chamber due to pressure equalization between the pump chamber and the external fluid source.
- One-way outlet valves V 1 114 and V 2 118 are closed.
- the reusable mechanical actuator 110 (not shown) which drives the reusable movable stage is disengaged.
- FIG. 4D shows an arrangement at a mid-point of the forward or pump stroke.
- the force for the forward stroke comes from activating the reusable movable stage 108 .
- the reusable mechanical actuator 110 is engaged, moving the reusable movable stage 108 in the forward direction.
- contact is made against the spring cap 150 , and the forward motion of the reusable movable stage 108 pushes against the spring cap 150 , moving the plunger 146 forward.
- Forward motion of the reusable movable stage also acts on the spring cap 150 to cause compression of the spring 152 .
- Activation of the forward stroke coincides with mechanical action to close the reusable inlet valve.
- the increased pressure in the pump chamber during the forward stroke causes fluid to exit the pump chamber under pressure (greater than atmospheric).
- the increased pressure of the fluid causes one-way outlet valves V 1 114 and V 2 118 (not shown) from closed positions to open positions.
- the reusable component 102 has a dual energy transfer function. Mechanical force exerted by the reusable movable stage 108 is transferred to the disposable component 101 to move the plunger 146 and increase fluid pressure. Also, mechanical force exerted by the reusable movable stage 108 is transferred to the disposable component 101 to compress the spring 152 , which stores mechanical energy until the refill stroke.
- FIG. 4E which duplicates FIG. 4A .
- the sequence depicted in FIGS. 4A-4E repeats itself until the desired volume of fluid is infused. The sequence is driven at a frequency corresponding to the desired rate set by the user.
- mechanical energy transfer events needed to achieve the pumping actions of the disposable piston pump assembly 140 are shared between the reusable and disposable components, 102 and 101 , respectively.
- forward motion of the reusable mechanical actuator 110 transfers energy to the disposable component 101 to move the plunger 146 and compress the spring 152 .
- Mechanical energy stored by the disposable component 101 is released during the retraction stroke, to retract the plunger 146 and reposition the reusable movable stage 108 .
- the disposable piston pump assembly 140 operates entirely without attachment mechanism or linking device between the reusable movable stage 108 and the spring cap 150 of the disposable piston pump assembly 140 . Movement in the forward direction is achieved by applying a force from the reusable component 102 via a contact surface only. Similarly, movement in the retraction direction is achieved by applying a force from the disposable component 101 via contact surfaces only. As shown in FIGS. 5A, 5B, and 5C , this arrangement allows easy and rapid insertion of the disposable component 101 , since there is no mechanical connection or disconnection step required to couple together the spring cap 150 and the reusable movable stage 108 . FIG.
- FIG. 5A shows the disposable piston pump assembly 140 being brought into contact with the reusable movable stage 108 as the disposable component 101 (not shown) is attached to the reusable component 102 (not shown).
- FIG. 5B shows the disposable piston pump assembly 140 in contact with the reusable movable stage 108 when the disposable component 101 (not shown) and the reusable component 102 (not shown) are attached together.
- FIG. 5C shows the disposable piston pump assembly 140 being removed from contact with the reusable movable stage 108 as the disposable component 101 (not shown) is detached from the reusable component 102 (not shown).
- FIGS. 6A and 6B show the disposable bubble eliminator 160 during the pump stroke of the disposable piston pump assembly 140 and during the refill stroke of the disposable piston pump assembly 140 , respectively.
- FIGS. 6A and 6B show the disposable bubble eliminator 160 , which includes a bubble eliminator chamber 162 in fluid communication with the first disposable conduit 106 and the second disposable conduit 112 ; a porous membrane 164 disposed as a wall of the bubble eliminator chamber 162 and in fluid communication with the atmosphere; and a mesh backing 166 disposed on an exterior surface of the porous membrane 164 .
- the disposable bubble eliminator 160 may also include one or more flow spacers 168 .
- the disposable bubble eliminator 160 is used to prevent or minimize the risk of injury to the patient from air embolism during delivery of fluids to the body. Dissolved gasses within the delivered fluid can form bubbles out of solution due to pressure changes, temperature changes, flow irregularities, or other factors.
- the present invention includes a gas elimination device meeting these and other needs.
- the disposable bubble eliminator 160 uses the porous membrane 164 in contact with a fluid.
- the disposable bubble eliminator 160 with associated one-way valves V 1 114 and V 2 118 (shown in FIGS. 6A and 6B ), is designed to match the mechanics of the disposable piston pump assembly 140 and achieves coordination with the action of the disposable piston pump assembly 140 in a specific way.
- the disposable bubble eliminator 160 of an embodiment of the present invention is capable of exactly managing the pressure of the fluid present inside the bubble eliminator chamber 162 as the disposable piston pump assembly 140 alternates between forward and priming strokes. Management of the pressure of the fluid within the bubble eliminator chamber 162 is essential for proper function of the disposable bubble eliminator 160 and avoids disposable piston pump assembly 140 failure.
- FIGS. 6A and 6B show the disposable bubble eliminator 160 arrangement with depiction of the fluid flow path during the forward and prime stokes of the disposable piston pump assembly 140 .
- the disposable bubble eliminator 160 shown includes the bubble eliminator chamber 162 with dimensions of 0.85 in ⁇ 1.0 in ⁇ 0.004 in and an internal volume of 0.0034 in 3 .
- the porous membrane 164 which may include expanded polytetraflouroethylene (ePTFE), forms a portion of side wall of the bubble eliminator chamber 162 .
- the air permeability of the porous membrane 164 can be 0.20-0.45 ft 3 /min/ft 2 .
- the purpose of the porous membrane 164 is to allow gas to permeate through the filter via a positive pressure differential between the two sides of the porous membrane 164 .
- a mesh backing 166 provides mechanical support to the porous membrane 164 .
- the flow spacers 168 form a mechanical gas-tight seal. Representative bubbles 170 are also shown.
- the disposable bubble eliminator 160 is positioned in the fluid flow path between one-way outlet valves V 1 114 and V 2 118 .
- One-way outlet valve V 1 114 is located at the fluid entry side of the bubble eliminator chamber 162 .
- One-way outlet valve V 1 114 is a silicone umbrella-type valve allowing flow in one direction and checks flow in the opposite direction.
- One-way outlet valve V 1 114 is engineered to open under a specific cracking pressure of 0.03 psig (Minivalve UM 070.004).
- the one-way outlet valve V 2 118 is located at the fluid exit side of the bubble eliminator chamber 162 .
- the one-way outlet valve V 2 118 is an umbrella type with a cracking pressure of 2.4 psig (Minivalve UM 070.006).
- the one-way outlet valves V 1 114 and V 2 118 are passive: they are not controlled electrically.
- FIG. 6A shows the disposable bubble eliminator 160 during the forward stroke of the disposable piston pump assembly 140 , when the reusable inlet valve 122 is closed and the pump chamber 144 is being pressurized by the forward motion of the plunger 146 .
- pressure in the fluid flow path between the reusable inlet valve 122 and one-way outlet valve V 1 114 reaches values of 7-9 psig (pounds per square inch gauge).
- Gauge pressure is a measure of the fluid pressure relative to ambient atmospheric pressure. Fluid flow is towards the disposable component outlet port 180 . A decrease in fluid pressure occurs across valve one-way outlet valve V 1 114 , resulting in a fluid pressure of 5-7 psig inside the bubble eliminator chamber 162 and in the region of the porous membrane 164 .
- one-way outlet valve V 2 118 During the forward stroke, another pressure drop occurs across one-way outlet valve V 2 118 , such that the fluid pressure in the conduit between one-way outlet valve V 2 118 and the disposable component outlet port 180 is 3.5-4.5 psig.
- One-way outlet valve V 2 118 in the open position, contributes to the positive pressure of the fluid in the bubble eliminator chamber 162 versus the external vent area, causing venting of gas from the bubble eliminator chamber 162 to the outside through the porous membrane 164 . The result is that during the forward stroke of the disposable piston pump assembly 140 , bubbles are substantially eliminated from the fluid occupying the bubble eliminator chamber 162 .
- FIG. 6B represents the fluid flow path during the prime stoke, during withdrawal of the plunger 146 and when reusable inlet valve 122 opens.
- the action of the plunger 146 causes depressurization of the fluid flow path, such that fluid is drawn in from an external fluid source via reusable inlet valve 122 .
- Fluid pressure in the vicinity of the piston pump chamber 144 may be at ⁇ 2.5 psig below the ambient atmospheric pressure.
- Depressurization of the fluid flow path causes the one-way outlet valves V 1 114 and V 2 118 (not shown) to close. Closure of one-way outlet valves V 1 114 and V 2 118 during the prime stroke is vital for correct function of the disposable bubble eliminator 160 and for correct function of the overall pump 100 .
- one-way valve V 1 114 is located at the fluid entry side of the bubble eliminator chamber 162 , it mechanically and hydraulically isolates the fluid in the bubble eliminator chamber 162 from fluid depressurization caused by the withdrawal action of the plunger 146 . Thereby depressurization of the disposable bubble elimination chamber 162 is substantially avoided when one-way valve V 1 114 closes.
- one-way valve V 1 114 was not present at or near the bubble eliminator chamber 162 fluid entry point. Without isolation of the bubble eliminator chamber 162 from the disposable piston pump assembly 140 , depressurization of the bubble eliminator chamber 162 fluid would occur during the prime stroke.
- the fluid pressure within the bubble eliminator chamber 162 might equalize to the pressure of the surrounding atmosphere at the vent side of the porous membrane 164 and might fall below the pressure of the surrounding atmosphere at the vent side of the porous membrane 164 .
- These situations favor air being drawn into the disposable bubble elimination chamber 162 from the outside via the porous membrane 164 . This is undesirable. Excess air in the fluid flow path would compromise the ability of pump 100 to achieve fluid delivery to the patient in a controlled way. Fluid backflow towards the disposable component inlet port 104 would also occur, which is not desired. With continued cycling of the pump 100 , there would be opportunity for gas bubbles to flow in the direction of the patient. Further, if this were to occur, the reusable bubble detector 126 located between one-way valve V 2 118 and the patient side outlet 180 would be triggered, causing the pump to go into a patient-safe mode of operation.
- One-way outlet valve V 2 118 is located in communication with the fluid exit side of the bubble eliminator chamber 162 . When it closes during the prime stroke of the disposable piston pump assembly 140 , it mechanically and hydraulically isolates the fluid in the bubble eliminator chamber 162 from patient side disposable component outlet port 180 . Depressurization of the fluid present in the disposable bubble eliminator 160 is thus minimized or prevented.
- the fluid pressure internal to the bubble eliminator chamber 162 is maintained at or close to 2.4 psig, as in FIG. 6B .
- the pressure differential across the porous membrane 164 is sufficient to cause venting of gas from solution to the outside atmosphere.
- the one-way outlet valve V 2 118 plays an important role in managing the phenomenon of free flow.
- Free flow can occur when the vertical height of the disposable bubble eliminator 160 lies above the vertical height of the tubing or conduit connecting to the patient, such that gravity-driven flow of fluid in the direction of the patient outlet may occur.
- free flow would cause fluid pressure in the bubble eliminator chamber 162 to decrease leading to siphoning of air into the bubble eliminator chamber 162 via the porous membrane 164 .
- Having the one-way outlet valve V 2 118 in the closed position minimizes this phenomenon.
- the presence of air intake into the bubble eliminator chamber 162 is undesirable. Excess air in the fluid flow path would compromise the ability of the pump 100 to achieve fluid flow and delivery to the patient in a controlled way. There would be opportunity for gas bubbles to flow in the direction of the patient. Further, if this occurred the reusable bubble detector 126 located between the one-way outlet valve V 2 118 and the patient side outlet would be triggered, causing the pump to go into a patient-safe mode of operation.
- the one-way outlet valves V 1 114 and V 2 118 (not shown) have dual function. Under pressure during the forward disposable piston pump assembly 140 stroke, the one-way outlet valves V 1 114 and V 2118 open, but because of their orientation they only allow fluid to pass in the direction of the patient outlet. As the fluid tries to reverse direction, the one-way outlet valves V 1 114 and V 2 118 , being umbrella valves, close and prevent any fluid from traveling towards the fluid inlet.
- the disposable bubble eliminator 160 incorporates a low-cost air permeable, porous membrane 164 that is capable of venting bubbles from the fluid as it is pumped.
- Expanded Polytetraflouroethylene (ePTFE) is commonly used in fluid separation applications in medical devices due to its biocompatibility and ability to resist wetting out. Air is allowed to permeate through the filter via a positive pressure differential between the two sides of the porous membrane 164 . This means that the fluid side must always remain at a higher pressure than the atmosphere, otherwise it is possible to pull air into the fluid stream from outside the disposable bubble eliminator 160 . Therefore, the vent needs to be strategically placed in the flow such that positive pressure conditions can be maintained at all times.
- One-way outlet valve V 1 114 prevents the prime stroke from pulling a vacuum on the vent downstream, also known as backflow.
- the one-way outlet valve V 2 118 (not shown), with a suitably high cracking pressure, ensures that no air is pulled into the line by syphoning when the needle is below the disposable bubble eliminator 160 . The latter scenario is known as free-flow.
- Expanded PTFE membranes come in many different blends that vary in air permeability rates (ft 3 /min/ft 2 ), thickness, pore size ( ⁇ m), burst pressure, and hydrophobicity. Increased air permeability is an obvious advantage for bubble elimination at high flow rates, but it typically comes at the expense of burst pressure.
- a sufficiently breathable membrane must also allow several factors of safety for nominal and off-nominal pressure scenarios. As fluid pressure increases, it is typical for the membrane to deform outward into a dome shape. This not only poses a strength-of-materials risk but changes the venting criteria vital to effective air removal, as discussed herein. To mitigate this, a rigid mesh backing 166 is secured on the outside of the ePTFE membrane, which permits air breathability while maintaining the flat shape desired for venting.
- the pump 100 has a large range of flow rates at which it must facilitate this safety feature of removing gas from the fluid. These flow rates are accentuated by the duty cycle of the priming and pumping strokes: at an average flow rate of 500 mL/hr, the instantaneous flow rate in the fluid may be closer to 1,000 mL/hr. This translates to a very brief time that a fluid particle has in contact with the porous membrane 164 , called residence time. The air bubble must have a sufficient residence time to allow mass transport to occur.
- Mass transport is the movement of air molecules through the pores of the porous membrane 164 caused by the pressure differential across the ePTFE. There is an inherent time required to pass a given number of molecules through the porous membrane 164 , a value dictated by the material permeability and fluid pressure. It is desirable to maximize the bubble's exposure on the porous membrane 164 to allow all air molecules enough time to escape. Residence time can be controlled by slowing the velocity of the fluid through deliberate geometric design of the flow path: when increasing the travel length l for a given velocity, the residence must increase. Additionally, by expanding the fluid cross-sectional area to a critical dimension (thickness and width A), the velocity may be reduced to an effective value relative to other geometries for a given flow rate ⁇ dot over (m) ⁇ as understood by Equation 1:
- a liquid-gas interface creates a contact angle between the porous membrane 164 and the bubble boundary. As the bubble velocity increases, this contact angle approaches zero for which no triple point (air, membrane, liquid) exists and a stable film is formed. The film inhibits the direct exposure of air molecules to the porous membrane 164 . The bubble velocity then must be less than a critical value at which the film forms to prevent any mass transfer from occurring. This critical velocity is governed by Equation 2:
- Equation 1 y is the surface tension between gas and liquid, ⁇ is the viscosity of the gas, and ⁇ E is the contact angle of the bubble on the porous membrane 164 surface.
- the design of the disposable bubble eliminator 160 was iterated many times before reaching a suitable configuration for all fluid types.
- Initial proof of concept designs which showed effective bubble removal in water, had to be greatly re-evaluated once testing with whole blood and blood component samples such as packed red blood cells.
- blood cell damage hemolysis
- Methods that cause extreme shear stress or have excessively rough surface finishes could cause patient harm, so careful testing and analysis must be performed when designing this feature.
- the functioning design must minimize the velocity of the fluid across the membrane, thus increasing its residence time to vent all air.
- Velocity is a function of flow rate and the cross-sectional area of the flow field: increasing the area decreases the velocity at a given flow rate.
- the width will be limited by the overall size requirements of the disposable bubble eliminator 160 and the thickness will be limited by pressure drop as the fluid tries to pass through it.
- the path length may also be varied to increase residence time but must also consider size and pressure constraints.
- a membrane exhibiting superior air permeability rates could reduce the overall size required to vent the bubble, but its pore size, burst pressure, and biocompatibility will determine if its selection is appropriate in this application.
- the general design parameters of the disposable bubble eliminator 160 are shown in Table 1. These outline the variables that are combined to make for an effective disposable bubble eliminator 160 .
- the table serves as a non-limiting example for a functional embodiment of a disposable bubble eliminator 160 as it is used with the pump 100 .
- a specific set of tests were conducted which introduced regulated bubbles into a controlled stream of fluid, which was directed to flow to the bubble eliminator chamber test subject (with dimensions varied as indicated below).
- a syringe pump was used to control the rate of liquid flow.
- a 3 mL syringe was connected by an in-line three-way luer-lock valve upstream of the test subject. At the time of test, the valve was opened to allow a 0.2-1.0 mL air bubble into the free stream from the syringe.
- a 7 mL syringe downstream of the test piece collected all liquid and air pumped through the bubble eliminator chamber 162 , and the remaining air bubble was measured and compared against the input volume.
- Each disposable bubble eliminator 160 design iteration was recorded to pass or fail based on its ability to remove over 50% of air from fluid at all three distinct flow rates: 50 mL/hr, 1,000 mL/hr, and 2,000 mL/hr.
- FIGS. 7A-7G depict the bubble eliminator chamber 162 in one embodiment.
- length/ is defined by the distance from the center points of the inlet and outlet.
- Width w is defined by the distance from either wall perpendicular to the mean flow direction.
- Thickness t is defined by the spacer 168 height as shown. It is assumed that the porous membrane 164 (not sown) exists on the top plane of the depicted bubble eliminator chamber 162 , forming a hydraulic seal around the rectangular housing.
- the fluid inlet is the left-hand cylindrical borehole which is perpendicular to the plane of the bubble eliminator chamber 162 .
- the fluid outlet is the right-hand cylindrical borehole which is perpendicular to the plane of the bubble eliminator chamber 162 .
- FIG. 7B depicts the approximate flow lines for this embodiment by arrows.
- a large distribution of flow passes through the direct line between the inlet and outlet, while slower flow is pushed toward the periphery of the bubble eliminator chamber 162 .
- Computational fluid dynamic analysis shows that the highest pressure exists nearest the inlet port and gradually decreases as flow moves to the outlet port.
- FIG. 7C depicts a bubble 700 of approximately 500 uL in volume beginning to enter the bubble eliminator chamber 162 through the inlet port.
- the fluid is flowing at the highest expected flow rate of 2,000 mL/hr as controlled by a syringe pump. Not all of the bubble has entered the bubble eliminator chamber 162 .
- a relatively circular distribution of the bubble begins to form on the surface of the ePTFE.
- FIG. 7D depicts the bubble 700 of approximately 500 uL in volume continuing to fill the bubble eliminator chamber 162 . It expands in area as it enters the bubble eliminator chamber 162 , but it may or may not take the shape depicted in FIG. 7D ; the shape shown is exemplary and non-limiting.
- a significant portion of the air within the bubble is in direct contact with the ePTFE membrane and is vented with a rate defined by the air permeability and instantaneous local pressure in the bubble eliminator chamber 162 . No stable film exists between the bubble and the membrane due to the velocity with which the bubble moves across the membrane.
- FIG. 7E depicts the bubble 700 beginning to lose volume within the bubble eliminator chamber 162 . As it does so, the leading edges of the bubble reverse in on itself while more air continues to enter form the inlet port. It is common for smaller bubbles (less than 50 ⁇ L) to form as the parent bubble collapses, however it may or may not take the shape depicted in FIG. 7E ; the shape shown is exemplary and non-limiting.
- FIG. 7F depicts the bubble 700 continuing to lose volume within the bubble eliminator chamber 162 . Smaller bubbles have broken off from the original bubble but continue to vent.
- FIG. 7G depicts the last remaining air bubbles of bubble 700 within the bubble eliminator chamber 162 .
- the air in the fluid flow is significantly reduced in volume.
- Bubbles of very small size commonly move through the remainder of the bubble eliminator chamber 162 without being eliminated. This is due to the ratio of bubble volume to its dispersed area and the contact angle formed with a more spherical bubble as opposed to a flattened bubble.
- FIGS. 7C-7G depict the disposable bubble eliminator 160 effectively performing in one embodiment, with the bubble progressively becoming smaller as the bubble's air passes out through the porous membrane 164 (not shown).
- the test case shown here would be considered a passing criterion as it properly removed >50% of a bubble of 500 ⁇ L in volume from a fluid passing at 2,000 mL/hr.
- the fluid flow path sufficiently controlled the bubble to a velocity in which no stable film formed between the air boundary and the porous membrane 164 .
- the fluid flow path sufficiently dispersed the bubble to an area conducive to vent the air quickly.
- the fluid flow path was long enough to allow the elimination of the air before it escaped the bubble eliminator chamber 162 .
- the chosen porous membrane 164 sufficiently passed air across itself under the given pressure without harm or risk of bursting.
- FIGS. 8A-8K and Table 2 illustrate results of a study to investigate various bubble venting specifications, Examples 1-11.
- FIGS. 8A-8K each depict top views and side views of the bubble eliminator chamber 162 and bubble 800 . Porous membrane 164 is also shown.
- FIG. 1 (blood) Path length 0.6 in No failures: Pass 8A Path width 0.85 in bubble Flow Field thickness 0.004 in removed >90% Velocity 9.9 in/sec Residence time 0.6 sec
- FIG. 2 (blood) Path length 0.5 in No failures: Pass 8B Path width 1.0 in bubble Flow Field thickness 0.004 in removed >90% Velocity 8.4 in/sec Residence time 0.6 sec
- FIG. 3 (blood) Path length 0.6 in No failures: Pass 8C Path width 0.85 in bubble Flow Field thickness 0.008 in removed >90% Velocity 4.9 in/sec Residence time 0.12 sec FIG.
- the spring 152 of the disposable piston pump assembly 140 was of stainless steel (Century Spring): free length 1.16 in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3 lb/in priming force 1-0.4 lb; infusing force 0.4-1.6 lb.
- the plunger 146 was a loss of resistance (LOR) lip seal type (Portex).
- FIGS. 8A and 8B were conducted using blood. Bubble elimination was achieved successfully. These examples specify a successful design in terms of the disposable bubble eliminator chamber 162 dimensions relative to flow velocity, for adequate bubble contact with the porous membrane 164 leading to bubble elimination. Confinement of the bubble 800 in the bubble eliminator chamber 162 is important. The flow field thickness was 0.004 in. We observed that the ellipse of the bubble at the liquid membrane interface was highly oblate, indicative of a “flattened” bubble geometry, favorable to rapid gas exchange.
- Example 3 ( FIG. 8C ) was less successful than Examples 1 and 2.
- the design was marginal. A lower velocity and longer residence time should benefit gas bubble venting but the expected benefit did not occur.
- We observed that the ellipse of the bubble 800 at the liquid membrane interface was more circular, less oblate, indicating the bubble 800 was less confined and closer to spherical geometry in the channel than in Examples 1 and 2.
- This design with its thicker flow field thickness ( 0 . 008 in vs 0.004 in) is less favorable to venting.
- Examples 4-6 ( FIGS. 8D-8F , respectively) involved substitution of blood for saline solution.
- the low viscous nature of Ringer's solution compared to blood improved the performance of the vent, resulting in three successful trials.
- Example 7 ( FIG. 8G ) was an ineffective design when tested with blood.
- the high flow velocity and short residence time was detrimental to bubble elimination.
- the ellipse of the bubble 800 at the liquid membrane interface tended to be circular rather than oblate (flattened) limiting the amount of bubble surface area was in contact with the porous membrane 164 . Therefore, despite possibly having no stable film developed between the air and the membrane, the bubble 800 did not have the time required to transfer air across the porous membrane 164 .
- Example 8 ( FIG. 8H ) was an ineffective design when tested with blood.
- the high flow velocity and short residence time was detrimental to bubble elimination.
- the velocity exceeded the critical value for which a stable film is formed between the air and the membrane.
- the film prevented the transfer of air across the permeable membrane, thus allowing all of the bubble 800 to escape the bubble eliminator chamber 162 .
- Example 9 ( FIG. 8I ) was an ineffective design when tested with blood.
- the flow path width was too narrow to effectively disperse the bubble for maximum contact with the porous membrane 164 .
- Example 10 ( FIG. 8J ) was an ineffective design due to its flow field thickness of 0.05 in. While the velocity was low enough to prevent the formation of a stable film between the air and membrane, the circular cross-section of the bubble resulted in a very low contact area to the membrane. Thus, air could not escape the bubble eliminator chamber 162 .
- Example 11 ( FIG. 8K ) was an ineffective design due to the excessive pressure drop experienced by the fluid. Despite the bubble being significantly dispersed and having sufficient velocity for mass transfer, the pressure losses due to the extremely narrow flow chamber put undue stress on the pump 100 . Increased pressure drop in the bubble eliminator chamber 162 is undesirable because it translates to increased power consumption by the pump.
- FIGS. 9A-9D schematically depict Examples 12-15, representing additional configurations tested.
- Each example shows the effect of modified valve configurations on the pump's function.
- the spring 152 was of stainless steel (Century Spring): free length 1.16 in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3 lb/in priming force 1-0.4 lb; infusing force 0.4-1.6 lb.
- the plunger 146 was a loss of resistance (LOR) lip seal type (Portex).
- Example 12 ( FIG. 9A ). This is a pump configuration omitting the one-way outlet valves V 1 114 and V 2 118 from the fluid flow path.
- a pump 100 of this design was set to operate at a flow rate of 500 mL per hour. The fluid was whole blood.
- valve 122 when valve 122 was open, significant air intake into the fluid flow line occurred caused by depressurization of the bubble eliminator chamber 162 . Back flow was observed. Pump 100 operation became ineffective after a few cycles.
- Fluid flow path includes one-way outlet valve V 1 114 located at or near the bubble eliminator chamber 162 fluid entry point and is oriented to allow flow only in the direction of the disposable component outlet port 180 (not shown). There is no one-way outlet valve V 2 118 in this configuration.
- the pump 100 was set to operate at 500 mL per hour flow rate using whole blood. Closure of one-way outlet valve V 1 114 during disposable piston pump assembly 140 priming isolates the bubble eliminator chamber 162 from the depressurization effect due to retraction of the plunger 146 . However, the bubble eliminator chamber 162 is not isolated from the patient disposable component outlet port 180 (not shown).
- Fluid flow path includes the one-way outlet valve V 2 118 in proximity to the fluid exit point of the disposable bubble eliminator 160 , which is oriented to allow flow only in the direction of the disposable component outlet port 180 (not shown). There is no one-way outlet valve V 1 114 in this example.
- the pump 100 was operated at 500 mL per hour flow rate using whole blood. Closure of the one-way outlet valve V 2 118 during the disposable piston pump assembly 140 prime stroke isolated the bubble eliminator chamber 162 to prevent fluid free flow in the direction of the disposable component outlet port 180 . However, the bubble eliminator chamber 162 is not isolated from the depressurization effect due to the retraction of the pump plunger 146 .
- Example 15 ( FIG. 9D ).
- the fluid flow path includes one-way outlet valves V 1 114 and V 2 118 arranged and oriented as in FIGS. 1 and 2 .
- the pump 100 was operated at 500 ml per hour using whole blood. Bubble elimination was effective. No air siphoned into the bubble eliminator chamber 162 even after extended use.
- the desired flow rate was constant at exactly at 500 mL/hr over hundreds of duty cycles of the pump.
- FIG. 10 shows a flowchart for a method embodiment of the present invention.
- Method 1000 includes in block 1005 providing a disposable pump component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium, and wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port.
- Block 1010 includes connecting the disposable component to a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage.
- FIG. 11 shows a flowchart for another method embodiment of the present invention.
- Block 1105 of method 1100 of pumping a fluid medium includes receiving the fluid medium from a fluid medium source into a conduit.
- Block 1110 includes drawing the fluid medium into a disposable piston pump assembly in the conduit, the conduit further comprising a disposable bubble eliminator operable to vent gas from the fluid medium within the disposable bubble eliminator.
- Flowing the fluid medium through a disposable flow meter is included in block 1115 .
- Measuring a flow rate of the fluid medium is included in block 1120 .
- Block 1125 includes discharging the fluid medium into a reusable bubble detector.
- Block 1130 includes detecting residual gas in the fluid medium.
- Block 1135 includes discharging the fluid medium from the reusable bubble detector if less than a preselected amount of gas is detected.
- the pump 100 may be included in a kit that also includes one or more other items commonly used when infusing liquids to a patient.
- infusion pumps will recognize that the pump 100 , the methods 1000 and 1100 and the kit disclosed herein answer the need for an infusion pump that reduces or removes gases from fluids to be infused, is less costly than using and cleaning reusable pumps, ensures correct direction of fluid flow, prevents uncontrolled flow of fluid to be infused, and controls the rate of flow of fluid that is being infused.
- the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.
- compositions and methods comprising or may be replaced with “consisting essentially of” or “consisting of” As used herein, the phrase “consisting essentially of” requires the specified integer(s) or steps as well as those that do not materially affect the character or function of the claimed invention. As used herein, the term “consisting” is used to indicate the presence of the recited integer (e.g., a feature, an element, a characteristic, a property, a method/process step, or a limitation) or group of integers (e.g., feature(s), element(s), characteristic(s), property(ies), method/process(s) steps, or limitation(s)) only.
- integers e.g., a feature, an element, a characteristic, a property, a method/process step, or a limitation
- group of integers e.g., feature(s), element(s), characteristic(s), property(ies), method/process(s) steps, or limitation(s)
- A, B, C, or combinations thereof refers to all permutations and combinations of the listed items preceding the term.
- “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.
- expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth.
- BB BB
- AAA AAA
- AB BBC
- AAABCCCCCC CBBAAA
- CABABB CABABB
- words of approximation such as, without limitation, “about,” “substantial” or “substantially” refers to a condition that when so modified is understood to not necessarily be absolute or perfect but would be considered close enough to those of ordinary skill in the art to warrant designating the condition as being present. The extent to which the description may vary will depend on how great a change can be instituted and still have one of ordinary skill in the art recognize the modified feature as still having the required characteristics and capabilities of the unmodified feature. In general, but subject to the preceding discussion, a numerical value herein that is modified by a word of approximation such as “about” may vary from the stated value by at least ⁇ 1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.
Abstract
Description
- This application claims priority to U.S. Provisional Application Ser. No. 62/895,575, filed Sep. 4, 2019, the entire contents of which are incorporated herein by reference.
- This invention was made with government support under W81XWH-16-C-0035 awarded by the US Army Medical Research and Materiel Command. The government has certain rights in the invention.
- The present invention relates in general to the field of infusion pumps. In particular, the present invention relates to an infusion pump with a disposable component and a capacity to remove gases from a fluid to be infused.
- Infusion pumps are commonly used to infuse substances such as blood and medications into patients. Existing infusion pumps generally require fixed power sources. Many existing infusion pumps also require costly and time-consuming cleaning between uses. In addition, many existing infusion pumps lack a capacity to detect and minimize the occurrence of gases in the fluid to be infused.
- The prior art includes U.S. Pat. No. 10,384,004, to Zhu, which is said to disclose processes for operating an infusion pump for pumping fluid though an administration set at a constant flow rate; wherein the pump includes a pumping mechanism for pumping fluid and operates at a pulse frequency, and a controller controls the pulse frequency; wherein the pump has one or more sensors configured for measuring at least one characteristic value relating to a status of the infusion pump; wherein the controller is configured for causing the pumping mechanism to operate at a first pulse frequency, and the one or more sensors measure the characteristic value; and wherein, when the measured characteristic value meets a threshold value, the controller causes the pumping mechanism to operate at a second pulse frequency different from the first pulse frequency.
- In addition, the prior art includes U.S. Pat. No. 10,387,624, to Jedwab, et al., which is said to disclose an infusion pump having a control unit and a graphical user interface functionally connected to the controller, wherein the control unit is designed to receive at least two sensor signals out of the following group of sensors: cassette presence sensor, door sensor, pressure sensor, air presence sensor, motor sensor, flow rate sensor, wherein the control unit is designed to detect an error state based on the analysis of the at least two supplied sensor signals, wherein the control unit is designed to associate a degree of severity out of at least two degrees of severities based on the processing of the supplied sensor signals, and wherein the control unit is designed to control a color of the display of the graphical user interface to be displayed, wherein a different color is associated with each degree of severity as well as with a non-error state.
- In some embodiments of the disclosure, a pump is disclosed as including a disposable component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium; wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage. In one aspect, the disposable component further includes a first one-way outlet valve disposed in the first disposable conduit between the piston assembly and the disposable bubble eliminator and operable to prevent the fluid medium from flowing from the disposable bubble eliminator to the disposable piston pump assembly; a disposable flow meter positioned to measure a fluid flow through the first disposable conduit; and a second one-way outlet valve disposed in the second disposable conduit between the disposable bubble eliminator and the disposable flow meter and operable to prevent the fluid medium from flowing from the disposable flow meter to the disposable bubble eliminator; and the reusable component further includes a reusable reception tunnel configured to receive at least a portion of the first disposable conduit; a reusable inlet valve operable to close the first disposable conduit when the at least a portion of the first disposable conduit is disposed in the reusable reception tunnel; a reusable flow meter connector operable to connect to the disposable flow meter and to convey data from the disposable flow meter; and a reusable bubble detector. In another aspect, the reusable inlet valve is a one-way valve or a pinch valve. In another aspect, the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved into the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger upward in the piston barrel and the spring is disposed to move the plunger downward in the pump chamber. In another aspect, the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator. In another aspect, the disposable component further includes a disposable position measurement device to detect an alignment of the disposable component with the reusable component when assembled together. In another aspect, the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit. In another aspect, the reusable component further includes an internal electric battery or electrical connections configured to connect to an external electrical power source or both. In another aspect, the reusable component further includes an internal power management system or power management connections configured to connect to an external power management system or both. In another aspect, the reusable component further includes an integral control panel or control panel connections configured to connect to an external control panel or both. In another aspect, the reusable component further includes a screen interface or screen interface connections configured to connect to an external screen interface or both. In another aspect, the disposable component is enclosed in a disposable housing or the reusable component is disclosed in a reusable housing or both.
- In some embodiments of the disclosure, a method of pumping a fluid is disclosed as including providing a disposable pump component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium, and wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and connecting the disposable component to a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage.
- In some embodiments of the disclosure, a method of pumping a fluid medium is disclosed as including receiving the fluid medium from a fluid medium source into a conduit; drawing the fluid medium into a disposable piston pump assembly in the conduit, the conduit further including a disposable bubble eliminator operable to vent gas from the fluid medium within the disposable bubble eliminator; flowing the fluid medium through a disposable flow meter; measuring a flow rate of the fluid medium; discharging the fluid medium into a reusable bubble detector; detecting residual gas in the fluid medium; if less than a preselected amount of gas is detected, discharging the fluid medium from the reusable bubble detector. In one aspect, the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved from a lower end of the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger into the pump chamber and the spring is disposed to move the plunger out of the pump chamber. In another aspect, the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator. In another aspect, the method further includes detecting an alignment of the disposable component with the reusable component when assembled together. In another aspect, the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit. In another aspect, the method further includes supplying electrical power from an internal electric battery or an external electrical power source. In another aspect, the method further includes managing electrical power with an internal power management system or an external power management system. In another aspect, the method further includes supplying an integral screen interface or an external screen interface.
- In some embodiments of the disclosure, a kit is disclosed as including a disposable component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium; wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port; and a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage. In one aspect, the disposable component further includes a first one-way outlet valve disposed in the first disposable conduit between the piston assembly and the disposable bubble eliminator and operable to prevent the fluid medium from flowing from the disposable bubble eliminator to the disposable piston pump assembly; a second disposable conduit that places the disposable bubble eliminator in fluid communication with a disposable flow meter; a second one-way outlet valve disposed in the second disposable conduit between the disposable bubble eliminator and the disposable flow meter and operable to prevent the fluid medium from flowing from the disposable flow meter to the disposable bubble eliminator; and the reusable component further includes a reusable reception tunnel configured to receive at least a portion of the first disposable conduit; a reusable inlet valve operable to close the first disposable conduit when the at least a portion of the first disposable conduit is disposed in the reusable reception tunnel; a reusable flow meter connector operable to connect to the disposable flow meter and to convey data from the disposable flow meter; and a reusable bubble detector. In another aspect, the reusable inlet valve is a one-way valve or a pinch valve. In another aspect, the disposable piston pump assembly includes a piston barrel including a pump chamber in fluid communication with the first disposable conduit; a plunger slidably disposed within the piston barrel below the pump chamber; a piston rod attached to the plunger opposite the pump chamber; a spring cap attached to the piston rod; and a spring disposed around an exterior of the piston barrel and attached at an upper end of the spring to the exterior of the piston barrel and at a lower end of the spring to the spring cap, wherein the spring is disposed to store energy when the plunger, the piston rod, and the spring cap are moved into the piston barrel and is disposed not to store energy when the plunger is at the lower end of the pump chamber; wherein the reusable movable stage is disposed to move the plunger upward in the piston barrel and the spring is disposed to move the plunger downward in the pump chamber. In another aspect, the disposable bubble eliminator is in fluid communication with the disposable piston pump assembly and the disposable flow meter and includes a vent through which gas in the fluid medium may escape the disposable bubble eliminator to the atmosphere when pressure higher than atmospheric pressure is maintained in the disposable bubble eliminator. In another aspect, the disposable component further includes a disposable position measurement device to detect an alignment of the disposable component with the reusable component when assembled together. In another aspect, the reusable bubble detector includes a reusable bubble detector conduit in fluid communication with the disposable component outlet port when the disposable component and the reusable component are assembled together; and a reusable ultrasonic sensor to detect gas in the fluid medium, disposed outside the reusable bubble detector conduit. In another aspect, the reusable component further includes an internal electric battery or electrical connections configured to connect to an external electrical power source or both. In another aspect, the reusable component further includes an internal power management system or power management connections configured to connect to an external power management system or both. In another aspect, the reusable component further includes an integral control panel or control panel connections configured to connect to an external control panel or both. In another aspect, the reusable component further includes a screen interface or screen interface connections configured to connect to an external screen interface or both. In another aspect, the disposable component is enclosed in a disposable housing or the reusable component is disclosed in a reusable housing or both.
- For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures, in which:
-
FIG. 1 shows the disposable component and the reusable component of the pump attached together. -
FIG. 2 shows the disposable component and the reusable component of the pump detached from each other. -
FIG. 3 shows the disposable pump assembly. -
FIGS. 4A-4E show the arrangement of the disposable pump assembly at the completion of the pump stroke, mid-way through the refill stroke, at the completion of the refill stroke, mid-way through the pump stroke, and at the return to the completion of the pump stroke, respectively. -
FIGS. 5A, 5B, and 5C show the relative positions of the disposable pump assembly and the reusable movable stage during connection of the disposable component and the reusable component, when the disposable component and the reusable component are attached, and during detachment of the disposable component and the reusable component, respectively. -
FIGS. 6A and 6B show the disposable bubble eliminator during the pump stroke of the disposable pump assembly and during the refill stroke of the disposable pump assembly, respectively. -
FIGS. 7A and 7B show the bubble eliminator chamber and the approximate fluid flow lines within it, respectively.FIGS. 7C-7G show the disposable bubble eliminator effectively performing, with a bubble progressively becoming smaller as the bubble's air passes out through the ePTFE membrane. -
FIGS. 8A-8K show results of a study to investigate various bubble venting specifications, Examples 1-11. -
FIGS. 9A-9D schematically depict Examples 12-15, representing additional configurations tested. -
FIG. 10 shows a flowchart for a method embodiment of the present invention. -
FIG. 11 shows a flowchart for another method embodiment of the present invention. - Illustrative embodiments of the system of the present application are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
- In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction.
- Infusion pumps are commonly used to infuse substances such as blood and medications into patients. They often need to be used untethered from electrical power connections, such as in ambulatory situations, where operation by internal battery power is convenient or necessary. Also, it is desirable to have a pump comprising certain disposable components which, for patient safety reasons, are discarded and replaced frequently. It is desirable that a pump have the operability to detect and minimize occurrence of gases in the fluid to be infused, to ensure correct direction of fluid flow, to prevent uncontrolled flow of fluid to be infused, and to control the rate of flow of fluid that is being infused, with accurate measurement and verification of the rate of fluid flow.
- An embodiment of the present invention, a
pump 100 for achieving controllable flow, is depicted inFIG. 1 . The invention includes a fluid flow path that is defined by multiple disposable parts and systems. The disposable fluid flow path comes into contact with fluids, such as intravenous delivery fluids, drug solutions, blood products, and solutions of bioactive agents. The disposable parts are housed by adisposable component 101. - The invention includes reusable parts and systems that do not come into contact with fluids. The reusable parts and systems are durable and function multiple times with a plurality of different disposable components. In one embodiment, the reusable parts and systems are housed by a
reusable component 102. In some embodiments, the parts used to achieve conversion of electrical energy, e.g., electrical energy stored in abattery 128, to mechanical action are housed by thereusable component 102, as are various mechanical drivers, the equipment for monitoring system performance and, thecontrol panel 132 and theedit touch screen 134 for interfacing with a user. The controls to control action and speed motion of the pump are located on the reusable component. It would be wasteful and costly to dispose of these reusable parts because of their sophistication and complexity. - The invention is intended to meet the requirements that a new
disposable component 101 be easily connected to and removed from thereusable component 102 and that the disposable andreusable components -
FIG. 1 depicts an embodiment of the present invention, thepump 100, including adisposable component 101 and areusable component 102, which are shown attached together. Thedisposable component 101 includes a disposablecomponent inlet port 104 coupled to a firstdisposable conduit 106 in fluid communication with a fluid medium source (not shown). The firstdisposable conduit 106 is in fluid communication with a disposablepiston pump assembly 140 and adisposable bubble eliminator 160 withbubble eliminator chamber 162. The firstdisposable conduit 106 is in fluid communication with a disposablecomponent outlet port 180. Thedisposable bubble eliminator 160 is in fluid communication with a lumen (not shown) of the firstdisposable conduit 106, and is operable to reduce a gas content of a fluid medium. The disposablepiston pump assembly 140 is operable to pump the fluid medium from the disposablecomponent inlet port 104, through the firstdisposable conduit 106 and thedisposable bubble eliminator 160, to the disposablecomponent outlet port 180. Thereusable component 102 includes a reusablemovable stage 108 operable to compress the disposablepiston pump assembly 140 and a reusablemechanical actuator 110 operable to drive the reusablemovable stage 108. - The
disposable component 101 may further include a seconddisposable conduit 112 in fluid communication with thedisposable bubble eliminator 160 and the disposablecomponent outlet port 180. Thedisposable component 101 may also include a first one-way outlet valve 114 disposed in the firstdisposable conduit 106 between the disposablepiston pump assembly 140 and thedisposable bubble eliminator 160, and operable to prevent the fluid medium from flowing from thedisposable bubble eliminator 160 to the disposablepiston pump assembly 140. Thedisposable component 101 may further include adisposable flow meter 116 disposed to measure fluid flow through the seconddisposable conduit 112. Thedisposable component 101 may also include a second one-way outlet valve 118 disposed between thedisposable bubble eliminator 160 and thedisposable flow meter 116 and operable to prevent the fluid medium from flowing from thedisposable flow meter 116 to thedisposable bubble eliminator 160. - The
reusable component 102 may further include areusable reception tunnel 120 configured to receive at least a portion of the firstdisposable conduit 106. Thereusable component 102 may also include areusable inlet valve 122 that is operable to close the firstdisposable conduit 106 when the at least a portion of the firstdisposable conduit 106 is disposed in thereusable reception tunnel 120. Thereusable component 102 may also include a reusableflow meter connector 124 operable to connect to thedisposable flow meter 116 and to convey data from thedisposable flow meter 116. Thereusable component 102 may further include areusable bubble detector 126. Thereusable component 102 may also include an internal electric battery or electrical connections configured to connect to an externalelectrical power source 128 or both. Thereusable component 102 may also include an internal power management system or power management connections configured to connect to an externalpower management system 130 or both. Thereusable component 102 may also include an integral control panel or control panel connections configured to connect to anexternal control panel 132 or both. Thereusable component 102 may also include a screen interface or screen interface connections configured to connect to anexternal screen interface 134 or both. -
FIG. 1 depicts the operational configuration of one embodiment of thepump 100, where thereusable component 102 is coupled, physically, mechanically, and electrically to thedisposable component 101.FIG. 2 depicts the situation when the disposable and reusable components shown attached inFIG. 1 are disconnected from each other. - The
disposable component 101 includes the reciprocating disposablepiston pump assembly 140, which is of metallic or polymer construction. The disposablepiston pump assembly 140 makes contact with amoveable stage 108 in thereusable component 102. The motion of the reusablemoveable stage 108 is driven by themechanical actuator 110, which is also in thereusable component 102. The reusablemechanical actuator 110 provides the driving force for the forward stroke of the disposablepiston pump assembly 140. The parts needed for converting electrical energy stored in thebatteries 128 into mechanical actuation are housed in thereusable component 102, since the parts needed for electrical-to-mechanical conversion typically have significant electrical and mechanical complexity. - In the embodiment shown in
FIGS. 1 and 2 , the fluid path is defined by tubing and valves, consisting of a disposablecomponent inlet port 104, a disposablecomponent outlet port 180, and apiston pump chamber 144. The fluid flow path is defined by tubing and connections of the type used for delivery of intravenous fluids to the body. The parts defining the fluid path are housed in thedisposable component 101. Thedisposable component 101 includes a disposablecomponent inlet port 104 for receiving the fluid and a disposablecomponent outlet port 180 for supplying the fluid to a patient. A controllable disposablepiston pump assembly 140, incorporating thepiston pump chamber 144, is used for fluid flow from the disposablecomponent inlet port 104 to theoutlet port 180. Thereusable inlet valve 122 is disposed in proximity to the disposablecomponent inlet port 104. Thereusable inlet valve 122 opens and closes the firstdisposable conduit 106, which may be disposable IV tubing. In the embodiment illustrated, thereusable inlet valve 122 uses, e.g., a pinch valve mechanism. A pinch valve is a component that allows the mechanical pinching of the outside of a tube, where mechanical pressure deforms the tube sufficiently to restrict or stop flow through the tube's internal diameter. Flow resumes when the mechanical pressure to the outside of the tube is released. The benefit of a pinch valve, compared to alternatives such as a solenoid valve, is that the valve's parts and mechanisms do not come in contact with fluid. A pinch valve can be physically mounted, in its entirety, in thereusable component 102, so as not to dispose of it after a single use. The fluid path through the reusable inlet valve is therefore defined by placement of the firstdisposable conduit 106. - The controllable disposable
piston pump assembly 140 is disposed and operated to achieve fluid flow in the direction of the disposablecomponent outlet port 180. In addition to thereusable inlet valve 122 and the disposablepiston pump assembly 140, there are two one-way outlet valves (V1 and V2), 114 and 118, respectively, disposed between the disposable piston pump assembly and the disposable component outlet port. The one-wayoutlet valves V1 114 andV2 118 are part of thedisposable component 101. The fluid is pumped in only one direction because the one-wayoutlet valves V1 114 andV2 118 are normally closed but open in response to fluid pressure. In the embodiment shown inFIG. 1 , after fluid is introduced into thepump chamber 144, thereusable inlet valve 122 is closed. As the piston increases the pressure in thepump chamber 144, theoutput valves V1 114 andV2 118 downstream are forced open, and the fluid flows towards the disposablecomponent outlet port 180. When the pressure drops sufficiently during the retraction stroke, the one-wayoutlet valves V1 114 andV2 118 close, and thereusable inlet valve 122 is opened to admit more fluid. The two one-wayoutlet valves V1 114 andV2 118 are passive (not controlled electrically as compared to the inlet valve 122). Thesevalves V1 114 andV2 118 are umbrella-type valves, allowing fluid to flow one direction but not the other. An umbrella valve looks like an umbrella. As the fluid travels in one direction the umbrella valve opens allowing the fluid to pass, but as the fluid tries to reverse direction, the umbrella valve closes and prevents any fluid from traveling towards the inlet. - The embodiment shown in
FIGS. 1 and 2 includes adisposable bubble eliminator 160 located between one-wayoutlet valves V1 114 andV2 118. Thedisposable bubble eliminator 160 includes afluid chamber 162. One or more walls of thechamber 162 are formed from a gas permeableporous membrane 164, allowing gas to vent to the external atmosphere. Thedisposable bubble eliminator 160 is placed in the fluid flow path such that positive pressure conditions are maintained within thebubble eliminator chamber 162 at all times. Operation and orientation of one-way valves V1 114 and V2118 working in coordination with the disposablepiston pump assembly 140, are important in managing thebubble eliminator chamber 162 fluid pressure. The fluid side of thedisposable bubble eliminator 160 is always is at a higher pressure than atmospheric during the prime stroke as well as the forward stroke of the disposablepiston pump assembly 140. - The embodiment shown in
FIGS. 1 and 2 includes thedisposable flow meter 116 positioned towards the outlet. The device is suitable for monitoring or measuring the activity and accuracy of the disposablepiston pump assembly 140. Thedisposable flow meter 116 is part of thedisposable component 101. An example disposable flow meter is the Sensiron LD 20-2600B. It operates based on a thermal gradient detection, suitable for integration into thedisposable component 101. Thedisposable flow meter 116 is a direct flow measurement device used to monitor gross flow rate error, occlusion, and infiltration and to verify that the pump head is installed properly. Thedisposable flow meter 116 can measure the flow of all standard IV fluids, drugs formations, as well as blood and other high viscosity fluids. The flow meter may also assist in a free flow prevention algorithm. - In the embodiment shown in
FIGS. 1 and 2 thedisposable flow meter 116 has the additional purpose of determining correct positioning of thedisposable component 101 with respect to the position of thereusable component 102. This informs the user that correct alignment between thecomponents flow meter connector 124, which is part of thereusable component 102. - The embodiment shown in
FIGS. 1 and 2 incorporates areusable bubble detector 126, which may include an ultrasonic sensor, to detect air-in-line scenarios. Critical to the safety of the patient during a drug, IV fluid, or blood component infusion is the detection of air boluses in the tubing. An example reusable ultrasonic sensor is a Moog LifeGuard Air Bubble Detector. This reusable ultrasonic sensor is a non-wetted component. It uses ultrasonic frequencies to measure the fluid response in the tubing, alerting the operator if bubbles 50-100 uL are present. The sensor is a part of thereusable component 102. - For fluid flow metering, another method is to measure the movement of the piston of the disposable
piston pump assembly 140 very accurately and, with electronic feedback control, use that movement to measure the volume of fluid pumped. The timing of thereusable inlet valve 122 and the reusablemechanical actuator 110 thus can be precisely adjusted to provide accurate fluid flow. The one-wayoutlet valves V1 114 andV2 118 deflection information, available through a transducer, may provide information which is substantially representative of the operational state of the disposablepiston pump assembly 140, thereby enabling control of the timing. In addition to control of timing, the outlet flow from the piston valve may include a device that allows detection of occlusion or partial occlusion of outflow from the pump, gas trapped in the disposablepiston pump assembly 140, mechanical failure, disconnection of the line to the patient, and exhaustion of fluid supply. - The disposable fluid lines may be packaged with the
disposable component 101 in order for ease of installment and replacement. Thedisposable component 101 connects to thereusable component 102 by single action clips (not shown) to minimize effort of swapping pump heads. The fluid lines will also be compatible with standard IV drugs, as well as blood, plasma, water, etc. - To operate the
pump 100, a user interacts with thetouch screen 134. Thetouch screen 134 may give access to a drug library with preset settings that will include flow rates, bolus amounts for a given patients weight for the various drugs. The user has the capability to manually input the flow rate as well as volume in order for custom solutions. The system also has the capability to be continually updated to include or remove drugs and the parameters associated with them. - The packaging of the pump will house all the components within either of the disposable or reusable components, 101 or 102, respectively. The pump parts may have labels and markings permanently displayed consistent with regulatory agency labeling requirements. It may also have the necessary visual and audible alarms and indicators according to the IEC standard for medical pumps indicating various states (end of infusion, occlusion, air-in-line, battery, equipment failure, etc.). The
pump 100 has the capability to be controlled and monitored via Wi-Fi/Bluetooth as well as ability to turn off those features for security purposes. - The
control board 132 for the pump may contain a processor in order to operate all electrical components. Thereusable component 102 may also contain a Power Management System (PMS) 130 voltage balancing and monitoring, H bridges for reversing the polarity of voltage source electrically coupled to the circuitry of the pump actuation mechanism, sensors for component monitoring, and various other electrical components to operate the pump. Thecontrol board 132 also has the capability of controlling the magnitude of voltage or current applied to the individual actuators. - Pumping Mechanism. In the embodiment shown in
FIGS. 1 and 2 , the parts of the pump that contact the fluids that form the fluid flow path are located on thedisposable component 101, including the disposablepiston pump assembly 140, shown in detail inFIG. 3 . The reusablepiston pump assembly 140 includes apiston barrel 142 that includes thepump chamber 144 in fluid communication with the firstdisposable conduit 106, aplunger 146 slidably disposed within thepiston barrel 142 below thepump chamber 144, apiston rod 148 attached to theplunger 146 opposite thepump chamber 144, and aspring cap 150 attached to thepiston rod 148. Further, the reusablepiston pump assembly 140 includes aspring 152 disposed around an exterior of thepiston barrel 142 and attached at an upper end of thespring 152 to the exterior of thepiston barrel 142 and at a lower end of thespring 152 to thespring cap 150. Thespring 152 is disposed to store energy when theplunger 146, thepiston rod 148, and thespring cap 150 are moved into thepiston barrel 142 and is disposed not to store energy when theplunger 146 is at the lower end of thepump chamber 144.FIG. 3 illustrates disposablepiston pump assembly 140 with thespring 152 in a compressed, energy-storing state and theplunger 146 moved into thepiston barrel 142. The disposablepiston pump assembly 140 may also include adead volume spacer 154 disposed on theplunger 146 in thepump chamber 144, aplunger insert 156 disposed inside theplunger 144, and apiston hardstop 158 disposed at the bottom of thepiston barrel 142. - The disposable
piston pump assembly 140 has a flow channel in fluid communication with the disposablecomponent inlet port 104 and the disposablecomponent outlet port 180 via the firstdisposable conduit 106. One end of thespring 152 is permanently affixed to the disposablepiston pump assembly 140 through a permanent attachment mechanism, such as a grooved recess, a weld, solder or adhesive. The opposite end of thespring 152 is permanently connected to thespring cap 150. The permanent attachment ofspring 152 to one end of thespring cap 150 is made via a grooved recess, or alternatively by a weld, solder or adhesive. The movement of theplunger 146 is constrained in the forward direction by the piston pump chamber wall at the outlet side. Theplunger 146 is constrained in the retracted position by apiston hardstop 158. - Forward movement of the
plunger 146 occurs until it reaches a stop point. The disposable piston pump assembly's 140 forward stroke results in the delivery of media from thepiston chamber 144. Return or retraction of theplunger 146 occurs under the force of aspring 152, causing the pressure in thepiston chamber 144 to fall. The reduced pressure in thepiston chamber 144 causes media to flow from theinlet portion 104 through an opening in the piston chamber to refill thepiston chamber 144, thus equalizing the pressure between the fluid source and thepiston chamber 144. This can be referred to as the retraction, refill, or prime stroke, which prepares the disposablepiston pump assembly 140 for its next forward or delivery stroke. -
FIGS. 4A-4E show how fluid transfer from the disposablecomponent inlet port 104 to the disposablecomponent outlet port 180 is achieved, involving sequential and coordinated actions involving parts of thedisposable component 101 and parts of thereusable component 102.FIGS. 4A-4E depict disposablepiston pump assembly 140 including thepump chamber 144, theplunger 146, thespring cap 150, thespring 152, and, in addition, the firstdisposable conduit 108, the reusablemovable stage 108, and thereusable inlet valve 122. -
FIG. 4A shows the arrangement of the disposablepiston pump assembly 140 at the completion of the forward or pump stroke. Theplunger 146 is in the fully forward position. Thepump chamber 144 is substantially empty of fluid. Thespring 152 is compressed from its resting position. Thereusable inlet valve 122 on the firstdisposable conduit 106 is closed. There is no more fluid flow in the direction of the disposablecomponent outlet port 180. The reusablemechanical actuator 110 of the movable stage is disengaged. -
FIG. 4B shows the arrangement mid-way during the retraction or refill stroke of the disposablepiston pump assembly 140, where theplunger 146 is partially retracted. During the retraction stroke, thespring 152 undergoes extension which applies a force to thespring cap 150. The mechanical force of thespring 152 acting on thespring cap 150 causes retraction of theplunger 146. Retraction of theplunger 146 results in negative pressure (less than atmospheric) within thepump chamber 144. Fluid flows into thepump chamber 144 from the outlet, due to negative chamber pressure. The refill stroke coincides with mechanical activation to open thereusable inlet valve 122. Due to negative pressure in the pump chamber, one-wayoutlet valves V1 114 and V2 118 (not shown) are closed, so as to prevent or restrict flow in the direction of the disposablecomponent outlet port 180. In addition to the extension of thespring 152 providing force forplunger 146 retraction, the extension of thespring 152 also applies force to the reusablemovable stage 108 causing its retraction. The force to retract the reusablemovable stage 108 is applied via thespring cap 150, which makes physical contact with the reusablemovable stage 108 via a contact surface. During the retraction stroke, the mechanical actuator connected to the reusablemovable stage 108 is disengaged, so the reusablemovable stage 108 is free to move in the retraction direction. Thus, during the refill stroke, thedisposable component 101 has an energy transfer function, where mechanical energy stored in thespring 152 is transferred to the reusablemovable stage 108, which is part ofreusable component 102. -
FIG. 4C shows the disposablepiston pump assembly 140 configuration at the completion of the retraction or refill stroke. Theplunger 146 is fully retracted. The disposable piston pump assembly is primed, where thespring cap 150 and theplunger 146 have moved to a stop position and the reusable movable stage has returned to a hard stop position. The reusable inlet valve is open but there is no flow into the pump chamber due to pressure equalization between the pump chamber and the external fluid source. One-wayoutlet valves V1 114 andV2 118 are closed. The reusable mechanical actuator 110 (not shown) which drives the reusable movable stage is disengaged. -
FIG. 4D shows an arrangement at a mid-point of the forward or pump stroke. The force for the forward stroke comes from activating the reusablemovable stage 108. During the forward stroke, the reusablemechanical actuator 110 is engaged, moving the reusablemovable stage 108 in the forward direction. At the same time, contact is made against thespring cap 150, and the forward motion of the reusablemovable stage 108 pushes against thespring cap 150, moving theplunger 146 forward. Forward motion of the reusable movable stage also acts on thespring cap 150 to cause compression of thespring 152. Activation of the forward stroke coincides with mechanical action to close the reusable inlet valve. The increased pressure in the pump chamber during the forward stroke causes fluid to exit the pump chamber under pressure (greater than atmospheric). The increased pressure of the fluid causes one-wayoutlet valves V1 114 and V2 118 (not shown) from closed positions to open positions. During the pump stroke, thereusable component 102 has a dual energy transfer function. Mechanical force exerted by the reusablemovable stage 108 is transferred to thedisposable component 101 to move theplunger 146 and increase fluid pressure. Also, mechanical force exerted by the reusablemovable stage 108 is transferred to thedisposable component 101 to compress thespring 152, which stores mechanical energy until the refill stroke. - At the completion of the forward stroke the
plunger 146 is in the forward position. Thepump chamber 144 is substantially empty of fluid. Thespring 152 is compressed from its resting position. Mechanical energy is stored in thespring 152. This situation is as depicted inFIG. 4E , which duplicatesFIG. 4A . The sequence depicted inFIGS. 4A-4E repeats itself until the desired volume of fluid is infused. The sequence is driven at a frequency corresponding to the desired rate set by the user. - To summarize, mechanical energy transfer events needed to achieve the pumping actions of the disposable
piston pump assembly 140 are shared between the reusable and disposable components, 102 and 101, respectively. During the pump stroke, forward motion of the reusablemechanical actuator 110 transfers energy to thedisposable component 101 to move theplunger 146 and compress thespring 152. Mechanical energy stored by thedisposable component 101 is released during the retraction stroke, to retract theplunger 146 and reposition the reusablemovable stage 108. - The disposable
piston pump assembly 140 operates entirely without attachment mechanism or linking device between the reusablemovable stage 108 and thespring cap 150 of the disposablepiston pump assembly 140. Movement in the forward direction is achieved by applying a force from thereusable component 102 via a contact surface only. Similarly, movement in the retraction direction is achieved by applying a force from thedisposable component 101 via contact surfaces only. As shown inFIGS. 5A, 5B, and 5C , this arrangement allows easy and rapid insertion of thedisposable component 101, since there is no mechanical connection or disconnection step required to couple together thespring cap 150 and the reusablemovable stage 108.FIG. 5A shows the disposablepiston pump assembly 140 being brought into contact with the reusablemovable stage 108 as the disposable component 101 (not shown) is attached to the reusable component 102 (not shown).FIG. 5B shows the disposablepiston pump assembly 140 in contact with the reusablemovable stage 108 when the disposable component 101 (not shown) and the reusable component 102 (not shown) are attached together.FIG. 5C shows the disposablepiston pump assembly 140 being removed from contact with the reusablemovable stage 108 as the disposable component 101 (not shown) is detached from the reusable component 102 (not shown). - Disposable Bubble Eliminator.
FIGS. 6A and 6B show thedisposable bubble eliminator 160 during the pump stroke of the disposablepiston pump assembly 140 and during the refill stroke of the disposablepiston pump assembly 140, respectively.FIGS. 6A and 6B show thedisposable bubble eliminator 160, which includes abubble eliminator chamber 162 in fluid communication with the firstdisposable conduit 106 and the seconddisposable conduit 112; aporous membrane 164 disposed as a wall of thebubble eliminator chamber 162 and in fluid communication with the atmosphere; and amesh backing 166 disposed on an exterior surface of theporous membrane 164. Thedisposable bubble eliminator 160 may also include one ormore flow spacers 168. - The
disposable bubble eliminator 160 is used to prevent or minimize the risk of injury to the patient from air embolism during delivery of fluids to the body. Dissolved gasses within the delivered fluid can form bubbles out of solution due to pressure changes, temperature changes, flow irregularities, or other factors. A need exists for a device that removes gas bubbles and/or dissolved gas from fluids delivered to a patient via the intravenous route during a medical procedure. A need also exists for such a device that can be located at a point in the fluid delivery line near the patient, to minimize the potential for bubble formation between the device and the patient. The present invention includes a gas elimination device meeting these and other needs. Thedisposable bubble eliminator 160 uses theporous membrane 164 in contact with a fluid. Gas passes from the fluid and into the surrounding atmosphere due to a pressure differential. Thedisposable bubble eliminator 160, with associated one-way valves V1 114 and V2 118 (shown inFIGS. 6A and 6B ), is designed to match the mechanics of the disposablepiston pump assembly 140 and achieves coordination with the action of the disposablepiston pump assembly 140 in a specific way. Thedisposable bubble eliminator 160 of an embodiment of the present invention is capable of exactly managing the pressure of the fluid present inside thebubble eliminator chamber 162 as the disposablepiston pump assembly 140 alternates between forward and priming strokes. Management of the pressure of the fluid within thebubble eliminator chamber 162 is essential for proper function of thedisposable bubble eliminator 160 and avoids disposablepiston pump assembly 140 failure. - Coordinated Action with the Disposable
Piston Pump Assembly 140.FIGS. 6A and 6B show thedisposable bubble eliminator 160 arrangement with depiction of the fluid flow path during the forward and prime stokes of the disposablepiston pump assembly 140. Thedisposable bubble eliminator 160 shown includes thebubble eliminator chamber 162 with dimensions of 0.85 in×1.0 in×0.004 in and an internal volume of 0.0034 in3. Theporous membrane 164, which may include expanded polytetraflouroethylene (ePTFE), forms a portion of side wall of thebubble eliminator chamber 162. The air permeability of theporous membrane 164 can be 0.20-0.45 ft3/min/ft2. The purpose of theporous membrane 164 is to allow gas to permeate through the filter via a positive pressure differential between the two sides of theporous membrane 164. Amesh backing 166 provides mechanical support to theporous membrane 164. The flow spacers 168 form a mechanical gas-tight seal. Representative bubbles 170 are also shown. Thedisposable bubble eliminator 160 is positioned in the fluid flow path between one-wayoutlet valves V1 114 andV2 118. One-wayoutlet valve V1 114 is located at the fluid entry side of thebubble eliminator chamber 162. One-wayoutlet valve V1 114 is a silicone umbrella-type valve allowing flow in one direction and checks flow in the opposite direction. One-wayoutlet valve V1 114 is engineered to open under a specific cracking pressure of 0.03 psig (Minivalve UM 070.004). The one-wayoutlet valve V2 118 is located at the fluid exit side of thebubble eliminator chamber 162. The one-wayoutlet valve V2 118 is an umbrella type with a cracking pressure of 2.4 psig (Minivalve UM 070.006). The one-wayoutlet valves V1 114 andV2 118 are passive: they are not controlled electrically.FIG. 6A shows thedisposable bubble eliminator 160 during the forward stroke of the disposablepiston pump assembly 140, when thereusable inlet valve 122 is closed and thepump chamber 144 is being pressurized by the forward motion of theplunger 146. During the forward stoke, pressure in the fluid flow path between thereusable inlet valve 122 and one-wayoutlet valve V1 114 reaches values of 7-9 psig (pounds per square inch gauge). Gauge pressure is a measure of the fluid pressure relative to ambient atmospheric pressure. Fluid flow is towards the disposablecomponent outlet port 180. A decrease in fluid pressure occurs across valve one-wayoutlet valve V1 114, resulting in a fluid pressure of 5-7 psig inside thebubble eliminator chamber 162 and in the region of theporous membrane 164. Thus, there is a positive pressure differential between thebubble eliminator chamber 162 internal fluid and the external vent area, causing venting of gas from solution to the outside through theporous membrane 164. During the forward stroke, another pressure drop occurs across one-wayoutlet valve V2 118, such that the fluid pressure in the conduit between one-wayoutlet valve V2 118 and the disposablecomponent outlet port 180 is 3.5-4.5 psig. One-wayoutlet valve V2 118, in the open position, contributes to the positive pressure of the fluid in thebubble eliminator chamber 162 versus the external vent area, causing venting of gas from thebubble eliminator chamber 162 to the outside through theporous membrane 164. The result is that during the forward stroke of the disposablepiston pump assembly 140, bubbles are substantially eliminated from the fluid occupying thebubble eliminator chamber 162. -
FIG. 6B represents the fluid flow path during the prime stoke, during withdrawal of theplunger 146 and whenreusable inlet valve 122 opens. The action of theplunger 146 causes depressurization of the fluid flow path, such that fluid is drawn in from an external fluid source viareusable inlet valve 122. Fluid pressure in the vicinity of thepiston pump chamber 144 may be at −2.5 psig below the ambient atmospheric pressure. Depressurization of the fluid flow path causes the one-wayoutlet valves V1 114 and V2 118 (not shown) to close. Closure of one-wayoutlet valves V1 114 andV2 118 during the prime stroke is vital for correct function of thedisposable bubble eliminator 160 and for correct function of theoverall pump 100. Because one-way valve V1 114 is located at the fluid entry side of thebubble eliminator chamber 162, it mechanically and hydraulically isolates the fluid in thebubble eliminator chamber 162 from fluid depressurization caused by the withdrawal action of theplunger 146. Thereby depressurization of the disposablebubble elimination chamber 162 is substantially avoided when one-way valve V1 114 closes. Consider if one-way valve V1 114 was not present at or near thebubble eliminator chamber 162 fluid entry point. Without isolation of thebubble eliminator chamber 162 from the disposablepiston pump assembly 140, depressurization of thebubble eliminator chamber 162 fluid would occur during the prime stroke. In that case, the fluid pressure within thebubble eliminator chamber 162 might equalize to the pressure of the surrounding atmosphere at the vent side of theporous membrane 164 and might fall below the pressure of the surrounding atmosphere at the vent side of theporous membrane 164. These situations favor air being drawn into the disposablebubble elimination chamber 162 from the outside via theporous membrane 164. This is undesirable. Excess air in the fluid flow path would compromise the ability ofpump 100 to achieve fluid delivery to the patient in a controlled way. Fluid backflow towards the disposablecomponent inlet port 104 would also occur, which is not desired. With continued cycling of thepump 100, there would be opportunity for gas bubbles to flow in the direction of the patient. Further, if this were to occur, thereusable bubble detector 126 located between one-way valve V2 118 and thepatient side outlet 180 would be triggered, causing the pump to go into a patient-safe mode of operation. - One-way
outlet valve V2 118 is located in communication with the fluid exit side of thebubble eliminator chamber 162. When it closes during the prime stroke of the disposablepiston pump assembly 140, it mechanically and hydraulically isolates the fluid in thebubble eliminator chamber 162 from patient side disposablecomponent outlet port 180. Depressurization of the fluid present in thedisposable bubble eliminator 160 is thus minimized or prevented. The fluid pressure internal to thebubble eliminator chamber 162 is maintained at or close to 2.4 psig, as inFIG. 6B . Thus, during the prime stroke, the pressure differential across theporous membrane 164 is sufficient to cause venting of gas from solution to the outside atmosphere. The one-wayoutlet valve V2 118 plays an important role in managing the phenomenon of free flow. Free flow can occur when the vertical height of thedisposable bubble eliminator 160 lies above the vertical height of the tubing or conduit connecting to the patient, such that gravity-driven flow of fluid in the direction of the patient outlet may occur. In the absence of the one-wayoutlet valve V2 118, free flow would cause fluid pressure in thebubble eliminator chamber 162 to decrease leading to siphoning of air into thebubble eliminator chamber 162 via theporous membrane 164. Having the one-wayoutlet valve V2 118 in the closed position minimizes this phenomenon. The presence of air intake into thebubble eliminator chamber 162 is undesirable. Excess air in the fluid flow path would compromise the ability of thepump 100 to achieve fluid flow and delivery to the patient in a controlled way. There would be opportunity for gas bubbles to flow in the direction of the patient. Further, if this occurred thereusable bubble detector 126 located between the one-wayoutlet valve V2 118 and the patient side outlet would be triggered, causing the pump to go into a patient-safe mode of operation. - The one-way
outlet valves V1 114 and V2 118 (not shown) have dual function. Under pressure during the forward disposablepiston pump assembly 140 stroke, the one-wayoutlet valves V1 114 and V2118 open, but because of their orientation they only allow fluid to pass in the direction of the patient outlet. As the fluid tries to reverse direction, the one-wayoutlet valves V1 114 andV2 118, being umbrella valves, close and prevent any fluid from traveling towards the fluid inlet. -
Disposable Bubble Eliminator 160 Design Details. Thedisposable bubble eliminator 160 incorporates a low-cost air permeable,porous membrane 164 that is capable of venting bubbles from the fluid as it is pumped. Expanded Polytetraflouroethylene (ePTFE) is commonly used in fluid separation applications in medical devices due to its biocompatibility and ability to resist wetting out. Air is allowed to permeate through the filter via a positive pressure differential between the two sides of theporous membrane 164. This means that the fluid side must always remain at a higher pressure than the atmosphere, otherwise it is possible to pull air into the fluid stream from outside thedisposable bubble eliminator 160. Therefore, the vent needs to be strategically placed in the flow such that positive pressure conditions can be maintained at all times. By placing the ePTFE vent on the patient side of the disposablepiston pump assembly 140, the fluid pressure is maintained to be at least atmospheric throughout operation. One-way outlet valve V1 114 (not shown) prevents the prime stroke from pulling a vacuum on the vent downstream, also known as backflow. The one-way outlet valve V2 118 (not shown), with a suitably high cracking pressure, ensures that no air is pulled into the line by syphoning when the needle is below thedisposable bubble eliminator 160. The latter scenario is known as free-flow. - Expanded PTFE membranes come in many different blends that vary in air permeability rates (ft3/min/ft2), thickness, pore size (μm), burst pressure, and hydrophobicity. Increased air permeability is an obvious advantage for bubble elimination at high flow rates, but it typically comes at the expense of burst pressure. A sufficiently breathable membrane must also allow several factors of safety for nominal and off-nominal pressure scenarios. As fluid pressure increases, it is typical for the membrane to deform outward into a dome shape. This not only poses a strength-of-materials risk but changes the venting criteria vital to effective air removal, as discussed herein. To mitigate this, a
rigid mesh backing 166 is secured on the outside of the ePTFE membrane, which permits air breathability while maintaining the flat shape desired for venting. - Several factors determine the efficacy of the
porous membrane 164 during pumping: bubble length, travel time, velocity, and pressure difference. To start, thepump 100 has a large range of flow rates at which it must facilitate this safety feature of removing gas from the fluid. These flow rates are accentuated by the duty cycle of the priming and pumping strokes: at an average flow rate of 500 mL/hr, the instantaneous flow rate in the fluid may be closer to 1,000 mL/hr. This translates to a very brief time that a fluid particle has in contact with theporous membrane 164, called residence time. The air bubble must have a sufficient residence time to allow mass transport to occur. Mass transport is the movement of air molecules through the pores of theporous membrane 164 caused by the pressure differential across the ePTFE. There is an inherent time required to pass a given number of molecules through theporous membrane 164, a value dictated by the material permeability and fluid pressure. It is desirable to maximize the bubble's exposure on theporous membrane 164 to allow all air molecules enough time to escape. Residence time can be controlled by slowing the velocity of the fluid through deliberate geometric design of the flow path: when increasing the travel length l for a given velocity, the residence must increase. Additionally, by expanding the fluid cross-sectional area to a critical dimension (thickness and width A), the velocity may be reduced to an effective value relative to other geometries for a given flow rate {dot over (m)} as understood by Equation 1: -
- A liquid-gas interface creates a contact angle between the
porous membrane 164 and the bubble boundary. As the bubble velocity increases, this contact angle approaches zero for which no triple point (air, membrane, liquid) exists and a stable film is formed. The film inhibits the direct exposure of air molecules to theporous membrane 164. The bubble velocity then must be less than a critical value at which the film forms to prevent any mass transfer from occurring. This critical velocity is governed by Equation 2: -
- In Equation 1, y is the surface tension between gas and liquid, μ is the viscosity of the gas, and θE is the contact angle of the bubble on the
porous membrane 164 surface. - Regarding cross-sectional area, there is an optimal value to which
porous membrane 164 performance and pump 100 capability must be found. It is favorable to spread the bubble as wide and thin as possible so as to expose a greater area of air to theporous membrane 164 and thus vent in a shorter amount of time. One obvious limitation isdisposable bubble eliminator 160 space. However, perhaps more important is the effect of pressure losses through the disposablebubble eliminator chamber 162. A variation in flow field thickness impacts the pressure by a power of two. Increased pressure during the infusion stroke translates to a higher effective power required by the pump actuation mechanisms. Thus, an improperly designed bubble vent will cost the system valuable battery life to perform its normal function, or otherwise not effectively disperse a bubble to an area conducive for complete mass transport. Thedisposable bubble eliminator 160 design presented by the present invention provides a unique solution to the problems identified above. - The design of the
disposable bubble eliminator 160 was iterated many times before reaching a suitable configuration for all fluid types. Initial proof of concept designs, which showed effective bubble removal in water, had to be greatly re-evaluated once testing with whole blood and blood component samples such as packed red blood cells. The complex multi-component makeup, along with altered fluid characteristics, meant that bubbles could not effectively be removed even at low flow rates. Additionally, blood cell damage (hemolysis) must be considered when designing thedisposable bubble eliminator 160. Methods that cause extreme shear stress or have excessively rough surface finishes could cause patient harm, so careful testing and analysis must be performed when designing this feature. - The functioning design must minimize the velocity of the fluid across the membrane, thus increasing its residence time to vent all air. Velocity is a function of flow rate and the cross-sectional area of the flow field: increasing the area decreases the velocity at a given flow rate. However, the width will be limited by the overall size requirements of the
disposable bubble eliminator 160 and the thickness will be limited by pressure drop as the fluid tries to pass through it. The path length may also be varied to increase residence time but must also consider size and pressure constraints. A membrane exhibiting superior air permeability rates could reduce the overall size required to vent the bubble, but its pore size, burst pressure, and biocompatibility will determine if its selection is appropriate in this application. - The general design parameters of the
disposable bubble eliminator 160 are shown in Table 1. These outline the variables that are combined to make for an effectivedisposable bubble eliminator 160. The table serves as a non-limiting example for a functional embodiment of adisposable bubble eliminator 160 as it is used with thepump 100. -
TABLE 1 of Variables for Disposable Bubble Eliminator 160# Variable Range Requirements 1 Flow Rate 0.1-999 mL/hr System Requirement Threshold 2 Bubble Volume 50-100 uL System Requirement Threshold 3 Compact Size 0.005-0.15 in3 System Requirement Threshold 4 Pressure 0.1-10 PSIG Atmospheric < P < Burst Pressure 5 Membrane Air 0.20-0.45 ft3/ Permeability should not Permeability min/ft2 @ 125 Pa drastically minimize burst pressure rating 6 Path Length 0.6-0.7 in L >> H 7 Path Width 0.85-1.0 in Maximize bubble area 8 Flow Field 0.004-0.007 in Pressure drop should not be Thickness excessive 9 Velocity 5-15 in/s V < VCritical 10 Residence 0.06-0.17 s TResidence < Time required to Time air vent all - To reach a suitable design of the
disposable bubble eliminator 160, a specific set of tests were conducted which introduced regulated bubbles into a controlled stream of fluid, which was directed to flow to the bubble eliminator chamber test subject (with dimensions varied as indicated below). A syringe pump was used to control the rate of liquid flow. A 3 mL syringe was connected by an in-line three-way luer-lock valve upstream of the test subject. At the time of test, the valve was opened to allow a 0.2-1.0 mL air bubble into the free stream from the syringe. A 7 mL syringe downstream of the test piece collected all liquid and air pumped through thebubble eliminator chamber 162, and the remaining air bubble was measured and compared against the input volume. Eachdisposable bubble eliminator 160 design iteration was recorded to pass or fail based on its ability to remove over 50% of air from fluid at all three distinct flow rates: 50 mL/hr, 1,000 mL/hr, and 2,000 mL/hr. -
FIGS. 7A-7G depict thebubble eliminator chamber 162 in one embodiment. InFIG. 7A , length/is defined by the distance from the center points of the inlet and outlet. Width w is defined by the distance from either wall perpendicular to the mean flow direction. Thickness t is defined by thespacer 168 height as shown. It is assumed that the porous membrane 164 (not sown) exists on the top plane of the depictedbubble eliminator chamber 162, forming a hydraulic seal around the rectangular housing. The fluid inlet is the left-hand cylindrical borehole which is perpendicular to the plane of thebubble eliminator chamber 162. The fluid outlet is the right-hand cylindrical borehole which is perpendicular to the plane of thebubble eliminator chamber 162.FIG. 7B depicts the approximate flow lines for this embodiment by arrows. A large distribution of flow passes through the direct line between the inlet and outlet, while slower flow is pushed toward the periphery of thebubble eliminator chamber 162. Computational fluid dynamic analysis shows that the highest pressure exists nearest the inlet port and gradually decreases as flow moves to the outlet port. -
FIG. 7C depicts abubble 700 of approximately 500 uL in volume beginning to enter thebubble eliminator chamber 162 through the inlet port. The fluid is flowing at the highest expected flow rate of 2,000 mL/hr as controlled by a syringe pump. Not all of the bubble has entered thebubble eliminator chamber 162. A relatively circular distribution of the bubble begins to form on the surface of the ePTFE. -
FIG. 7D depicts thebubble 700 of approximately 500 uL in volume continuing to fill thebubble eliminator chamber 162. It expands in area as it enters thebubble eliminator chamber 162, but it may or may not take the shape depicted inFIG. 7D ; the shape shown is exemplary and non-limiting. A significant portion of the air within the bubble is in direct contact with the ePTFE membrane and is vented with a rate defined by the air permeability and instantaneous local pressure in thebubble eliminator chamber 162. No stable film exists between the bubble and the membrane due to the velocity with which the bubble moves across the membrane. -
FIG. 7E depicts thebubble 700 beginning to lose volume within thebubble eliminator chamber 162. As it does so, the leading edges of the bubble reverse in on itself while more air continues to enter form the inlet port. It is common for smaller bubbles (less than 50 μL) to form as the parent bubble collapses, however it may or may not take the shape depicted inFIG. 7E ; the shape shown is exemplary and non-limiting. -
FIG. 7F depicts thebubble 700 continuing to lose volume within thebubble eliminator chamber 162. Smaller bubbles have broken off from the original bubble but continue to vent. -
FIG. 7G depicts the last remaining air bubbles ofbubble 700 within thebubble eliminator chamber 162. At this point, the air in the fluid flow is significantly reduced in volume. Bubbles of very small size (less than 20 μL) commonly move through the remainder of thebubble eliminator chamber 162 without being eliminated. This is due to the ratio of bubble volume to its dispersed area and the contact angle formed with a more spherical bubble as opposed to a flattened bubble. -
FIGS. 7C-7G depict thedisposable bubble eliminator 160 effectively performing in one embodiment, with the bubble progressively becoming smaller as the bubble's air passes out through the porous membrane 164 (not shown). The test case shown here would be considered a passing criterion as it properly removed >50% of a bubble of 500 μL in volume from a fluid passing at 2,000 mL/hr. The fluid flow path sufficiently controlled the bubble to a velocity in which no stable film formed between the air boundary and theporous membrane 164. The fluid flow path sufficiently dispersed the bubble to an area conducive to vent the air quickly. The fluid flow path was long enough to allow the elimination of the air before it escaped thebubble eliminator chamber 162. The chosenporous membrane 164 sufficiently passed air across itself under the given pressure without harm or risk of bursting. -
FIGS. 8A-8K and Table 2 illustrate results of a study to investigate various bubble venting specifications, Examples 1-11.FIGS. 8A-8K each depict top views and side views of thebubble eliminator chamber 162 andbubble 800.Porous membrane 164 is also shown. -
TABLE 2 Results of a study to investigate various bubble venting specifications for Examples 1-11. Pass/ FIG. Example Design Observation Fail FIG. 1 (blood) Path length 0.6 in No failures: Pass 8A Path width 0.85 in bubble Flow Field thickness 0.004 in removed >90% Velocity 9.9 in/sec Residence time 0.6 sec FIG. 2 (blood) Path length 0.5 in No failures: Pass 8B Path width 1.0 in bubble Flow Field thickness 0.004 in removed >90% Velocity 8.4 in/sec Residence time 0.6 sec FIG. 3 (blood) Path length 0.6 in No failures: Pass 8C Path width 0.85 in bubble Flow Field thickness 0.008 in removed >90% Velocity 4.9 in/sec Residence time 0.12 sec FIG. 4 (saline) Path length 0.6 in No failures: Pass 8D Path width 0.85 in bubble Flow Field thickness 0.004 in removed >90% Velocity 9.9 in/sec Residence time 0.06 sec FIG. 5 (saline) Path length 0.6 in No failures: Pass 8E Path width 0.85 in bubble Flow Field thickness 0.008 in removed >90% Velocity 4.9 in/sec Residence time 0.12 sec FIG. 6 (saline) Path length 0.6 in No failures: Pass 8F Path width 0.85 in bubble Flow Field thickness 0.008 in removed >90% Velocity 4.9 in/sec Residence time 0.12 sec FIG. 7 (blood) Path length 0.5 in Bubble Fail 8G Path width 0.5 in breakthrough: Flow Field thickness 0.004 in insufficient Velocity 16.9 in/sec contact Residence time 0.03 sec area and residence time FIG. 8 (blood) Path length 1.0 in Bubble Fail 8H Path width 0.42 in breakthrough: Flow Field thickness 0.004 in insufficient Velocity 19.7 in/sec contact area Residence time 0.03 sec and residence time FIG. 9 (blood) Path length 1.0 in Bubble Fail 8I Path width 0.42 in breakthrough: Flow Field thickness 0.008 in insufficient Velocity 9.8 in/sec contact area Residence time 0.06 sec and residence time FIG. 10 (blood) Path length 1.2 in Bubble Fail 8J Path width 0.25 in breakthrough: Flow Field thickness 0.05 in insufficient Velocity 2.7 in/sec contact area Residence time 0.44 sec and residence time FIG. 11 (blood) Path length 0.6 in Excessive Fail 8K Path width 1.5 in pressure drop; Flow Field thickness 0.002 in pump loses Velocity 11.1 in/sec performance Residence time 0.05 sec - These values make assumptions about the fluid's viscosity, Reynolds number, and flow rate. In each example, the disposable
piston pump assembly 140 specifications were: stroke volume=0.7 mL;piston chamber 144 ID 0.59 in; stroke length 0.156 in. Thespring 152 of the disposablepiston pump assembly 140 was of stainless steel (Century Spring): free length 1.16 in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3 lb/in priming force 1-0.4 lb; infusing force 0.4-1.6 lb. Theplunger 146 was a loss of resistance (LOR) lip seal type (Portex). Theporous membrane 164 material was ePTFE (Sterlitech): thickness=0.008-0012 in. Repeated forward motion of theplunger 146 was achieved using an Admet mechanical actuator. - Examples 1 and 2 (
FIGS. 8A and 8B , respectively) were conducted using blood. Bubble elimination was achieved successfully. These examples specify a successful design in terms of the disposablebubble eliminator chamber 162 dimensions relative to flow velocity, for adequate bubble contact with theporous membrane 164 leading to bubble elimination. Confinement of thebubble 800 in thebubble eliminator chamber 162 is important. The flow field thickness was 0.004 in. We observed that the ellipse of the bubble at the liquid membrane interface was highly oblate, indicative of a “flattened” bubble geometry, favorable to rapid gas exchange. - Example 3 (
FIG. 8C ) was less successful than Examples 1 and 2. The design was marginal. A lower velocity and longer residence time should benefit gas bubble venting but the expected benefit did not occur. We observed that the ellipse of thebubble 800 at the liquid membrane interface was more circular, less oblate, indicating thebubble 800 was less confined and closer to spherical geometry in the channel than in Examples 1 and 2. This design with its thicker flow field thickness (0.008 in vs 0.004 in) is less favorable to venting. - Examples 4-6 (
FIGS. 8D-8F , respectively) involved substitution of blood for saline solution. The low viscous nature of Ringer's solution compared to blood improved the performance of the vent, resulting in three successful trials. - Example 7 (
FIG. 8G ) was an ineffective design when tested with blood. The high flow velocity and short residence time was detrimental to bubble elimination. We observed that the ellipse of thebubble 800 at the liquid membrane interface tended to be circular rather than oblate (flattened) limiting the amount of bubble surface area was in contact with theporous membrane 164. Therefore, despite possibly having no stable film developed between the air and the membrane, thebubble 800 did not have the time required to transfer air across theporous membrane 164. - Example 8 (
FIG. 8H ) was an ineffective design when tested with blood. The high flow velocity and short residence time was detrimental to bubble elimination. The velocity exceeded the critical value for which a stable film is formed between the air and the membrane. Despite the increased travel length, the film prevented the transfer of air across the permeable membrane, thus allowing all of thebubble 800 to escape thebubble eliminator chamber 162. - Example 9 (
FIG. 8I ) was an ineffective design when tested with blood. We observed that the ellipse of the bubble at the liquid membrane interface tended to be circular rather than oblate (flattened) which limited the amount of bubble surface area was in contact with theporous membrane 164. The flow path width was too narrow to effectively disperse the bubble for maximum contact with theporous membrane 164. - Example 10 (
FIG. 8J ) was an ineffective design due to its flow field thickness of 0.05 in. While the velocity was low enough to prevent the formation of a stable film between the air and membrane, the circular cross-section of the bubble resulted in a very low contact area to the membrane. Thus, air could not escape thebubble eliminator chamber 162. - Example 11 (
FIG. 8K ) was an ineffective design due to the excessive pressure drop experienced by the fluid. Despite the bubble being significantly dispersed and having sufficient velocity for mass transfer, the pressure losses due to the extremely narrow flow chamber put undue stress on thepump 100. Increased pressure drop in thebubble eliminator chamber 162 is undesirable because it translates to increased power consumption by the pump. -
FIGS. 9A-9D schematically depict Examples 12-15, representing additional configurations tested. Each example shows the effect of modified valve configurations on the pump's function. In each example, the specifications of the disposablepiston pump assembly 140 were: stroke volume=0.7 mL;piston chamber 144 ID 0.59 in; stroke length 0.156 in. Thespring 152 was of stainless steel (Century Spring): free length 1.16 in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3 lb/in priming force 1-0.4 lb; infusing force 0.4-1.6 lb. Theplunger 146 was a loss of resistance (LOR) lip seal type (Portex). Theporous membrane 164 material was ePTFE (Sterlitech): thickness=0.008-0.0012 in. - Example 12 (
FIG. 9A ). This is a pump configuration omitting the one-wayoutlet valves V1 114 andV2 118 from the fluid flow path. Apump 100 of this design was set to operate at a flow rate of 500 mL per hour. The fluid was whole blood. During the priming stroke, whenvalve 122 was open, significant air intake into the fluid flow line occurred caused by depressurization of thebubble eliminator chamber 162. Back flow was observed. Pump 100 operation became ineffective after a few cycles. - Example 13 (
FIG. 9B ). Fluid flow path includes one-wayoutlet valve V1 114 located at or near thebubble eliminator chamber 162 fluid entry point and is oriented to allow flow only in the direction of the disposable component outlet port 180 (not shown). There is no one-wayoutlet valve V2 118 in this configuration. Thepump 100 was set to operate at 500 mL per hour flow rate using whole blood. Closure of one-wayoutlet valve V1 114 during disposablepiston pump assembly 140 priming isolates thebubble eliminator chamber 162 from the depressurization effect due to retraction of theplunger 146. However, thebubble eliminator chamber 162 is not isolated from the patient disposable component outlet port 180 (not shown). Lower conduit height versus the height of thebubble eliminator chamber 162 caused fluid free flow in the direction of the disposablecomponent outlet port 180. Concurrently, air siphoned into thebubble eliminator chamber 162 from the outside atmosphere via the gas permeableporous membrane 164. Pump 100 operation was ineffective after a few cycles due to excess air in the fluid flow path and inability to control the rate of fluid flow to the disposablecomponent outlet port 180. - Example 14 (
FIG. 9C ). Fluid flow path includes the one-wayoutlet valve V2 118 in proximity to the fluid exit point of thedisposable bubble eliminator 160, which is oriented to allow flow only in the direction of the disposable component outlet port 180 (not shown). There is no one-wayoutlet valve V1 114 in this example. Thepump 100 was operated at 500 mL per hour flow rate using whole blood. Closure of the one-wayoutlet valve V2 118 during the disposablepiston pump assembly 140 prime stroke isolated thebubble eliminator chamber 162 to prevent fluid free flow in the direction of the disposablecomponent outlet port 180. However, thebubble eliminator chamber 162 is not isolated from the depressurization effect due to the retraction of thepump plunger 146. When the disposablepiston pump assembly 140 was operated, air siphoned into the flow system across the gas permeableporous membrane 164 and fluid backflow was observed occurring from thebubble eliminator chamber 162 towards the disposablepiston pump assembly 140. Pump 100 operation was ineffective after 10 cycles due to excess air in the fluid flow path and inability to control the rate of fluid flow to the disposablecomponent outlet port 180. - Example 15 (
FIG. 9D ). The fluid flow path includes one-wayoutlet valves V1 114 andV2 118 arranged and oriented as inFIGS. 1 and 2 . Thepump 100 was operated at 500 ml per hour using whole blood. Bubble elimination was effective. No air siphoned into thebubble eliminator chamber 162 even after extended use. The desired flow rate was constant at exactly at 500 mL/hr over hundreds of duty cycles of the pump. -
FIG. 10 shows a flowchart for a method embodiment of the present invention.Method 1000 includes inblock 1005 providing a disposable pump component including a disposable component inlet port coupled to a first disposable conduit in fluid communication with a fluid medium source, wherein the first disposable conduit includes a disposable piston pump assembly and a disposable bubble eliminator, and the first disposable conduit is in fluid communication with a disposable component outlet port, wherein the disposable bubble eliminator is in fluid communication with a lumen of the first disposable conduit and is operable to reduce a gas content of a fluid medium, and wherein the disposable piston pump assembly is operable to pump the fluid medium from the disposable component inlet port, through the first disposable conduit and the disposable bubble eliminator, to the disposable component outlet port.Block 1010 includes connecting the disposable component to a reusable component including a reusable movable stage operable to compress the disposable piston pump assembly; and a reusable mechanical actuator operable to drive the movable stage. -
FIG. 11 shows a flowchart for another method embodiment of the present invention.Block 1105 ofmethod 1100 of pumping a fluid medium includes receiving the fluid medium from a fluid medium source into a conduit.Block 1110 includes drawing the fluid medium into a disposable piston pump assembly in the conduit, the conduit further comprising a disposable bubble eliminator operable to vent gas from the fluid medium within the disposable bubble eliminator. Flowing the fluid medium through a disposable flow meter is included inblock 1115. Measuring a flow rate of the fluid medium is included inblock 1120.Block 1125 includes discharging the fluid medium into a reusable bubble detector.Block 1130 includes detecting residual gas in the fluid medium.Block 1135 includes discharging the fluid medium from the reusable bubble detector if less than a preselected amount of gas is detected. - The
pump 100 may be included in a kit that also includes one or more other items commonly used when infusing liquids to a patient. - Those skilled in the art of infusion pumps will recognize that the
pump 100, themethods - It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.
- All publications and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
- The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.
- As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. In embodiments of any of the compositions and methods provided herein, “comprising” may be replaced with “consisting essentially of” or “consisting of” As used herein, the phrase “consisting essentially of” requires the specified integer(s) or steps as well as those that do not materially affect the character or function of the claimed invention. As used herein, the term “consisting” is used to indicate the presence of the recited integer (e.g., a feature, an element, a characteristic, a property, a method/process step, or a limitation) or group of integers (e.g., feature(s), element(s), characteristic(s), property(ies), method/process(s) steps, or limitation(s)) only.
- The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.
- As used herein, words of approximation such as, without limitation, “about,” “substantial” or “substantially” refers to a condition that when so modified is understood to not necessarily be absolute or perfect but would be considered close enough to those of ordinary skill in the art to warrant designating the condition as being present. The extent to which the description may vary will depend on how great a change can be instituted and still have one of ordinary skill in the art recognize the modified feature as still having the required characteristics and capabilities of the unmodified feature. In general, but subject to the preceding discussion, a numerical value herein that is modified by a word of approximation such as “about” may vary from the stated value by at least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.
- All of the devices and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the devices and/or methods of this invention have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the invention as defined by the appended claims.
- Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the disclosure. Accordingly, the protection sought herein is as set forth in the claims below.
- Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order.
- To aid the Patent Office, and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims to invoke 35 U.S.C. § 112(f) as it exists on the date of filing hereof unless the words “means for” or “step for” are explicitly used in the particular claim.
Claims (23)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17/011,749 US11779699B2 (en) | 2019-09-04 | 2020-09-03 | Micropump |
US18/473,958 US20240017002A1 (en) | 2019-09-04 | 2023-09-25 | Micropump |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201962895575P | 2019-09-04 | 2019-09-04 | |
US17/011,749 US11779699B2 (en) | 2019-09-04 | 2020-09-03 | Micropump |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/473,958 Continuation US20240017002A1 (en) | 2019-09-04 | 2023-09-25 | Micropump |
Publications (4)
Publication Number | Publication Date |
---|---|
US20210060237A1 US20210060237A1 (en) | 2021-03-04 |
US20220080111A2 US20220080111A2 (en) | 2022-03-17 |
US20220193329A2 true US20220193329A2 (en) | 2022-06-23 |
US11779699B2 US11779699B2 (en) | 2023-10-10 |
Family
ID=74680712
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/011,749 Active 2041-10-01 US11779699B2 (en) | 2019-09-04 | 2020-09-03 | Micropump |
US18/473,958 Pending US20240017002A1 (en) | 2019-09-04 | 2023-09-25 | Micropump |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/473,958 Pending US20240017002A1 (en) | 2019-09-04 | 2023-09-25 | Micropump |
Country Status (1)
Country | Link |
---|---|
US (2) | US11779699B2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10994871B2 (en) * | 2013-07-03 | 2021-05-04 | Deka Products Limited Partnership | Apparatus, system and method for fluid delivery |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020169439A1 (en) * | 2001-02-22 | 2002-11-14 | Flaherty J. Christopher | Modular infusion device and method |
US20110218516A1 (en) * | 2008-09-15 | 2011-09-08 | Leonid Grigorov | Methods and Devices for Programmable Delivery of Microdoses of Liquid Drugs |
US20120004602A1 (en) * | 2009-12-30 | 2012-01-05 | Medtronic Minimed, Inc. | Connection and alignment detection systems and methods |
US20120172800A1 (en) * | 2010-12-29 | 2012-07-05 | Baxter Healthcare S.A. | Intravenous pumping air management systems and methods |
US20190275241A1 (en) * | 2018-03-09 | 2019-09-12 | Amgen Inc. | Backflow prevention mechanism for drug delivery device |
Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3993061A (en) | 1975-02-28 | 1976-11-23 | Ivac Corporation | Syringe pump drive system and disposable syringe cartridge |
US4424720A (en) | 1980-12-15 | 1984-01-10 | Ivac Corporation | Mechanism for screw drive and syringe plunger engagement/disengagement |
US4515591A (en) | 1982-09-28 | 1985-05-07 | Ivac Corporation | Disposable syringe cartridge for fluid delivery apparatus |
US4838860A (en) | 1987-06-26 | 1989-06-13 | Pump Controller Corporation | Infusion pump |
US5006050A (en) | 1988-12-09 | 1991-04-09 | James E. Cooke | High accuracy disposable cassette infusion pump |
US7201746B2 (en) | 2001-04-10 | 2007-04-10 | Medtronic, Inc. | Implantable therapeutic substance delivery device having a piston pump with an anti-cavitation valve |
EP1527792A1 (en) | 2003-10-27 | 2005-05-04 | Novo Nordisk A/S | Medical injection device mountable to the skin |
US20060173418A1 (en) | 2004-12-13 | 2006-08-03 | Arrow International, Inc. | Loss of resistance syringe |
EP1957794B1 (en) | 2005-11-23 | 2014-07-02 | Eksigent Technologies, LLC | Electrokinetic pump designs and drug delivery systems |
US20080287874A1 (en) | 2007-05-18 | 2008-11-20 | Medtronic, Inc. | Controlling dead volume of a piston pump using an adjustment screw |
NO329730B1 (en) | 2007-10-17 | 2010-12-13 | Tts Sense Mud As | Piston Pump |
US8231608B2 (en) | 2008-05-08 | 2012-07-31 | Minipumps, Llc | Drug-delivery pumps and methods of manufacture |
US9968733B2 (en) | 2008-12-15 | 2018-05-15 | Medtronic, Inc. | Air tolerant implantable piston pump |
US20110275987A1 (en) | 2010-04-20 | 2011-11-10 | Minipumps, Llc | Piston-driven drug pump devices |
US9308320B2 (en) | 2010-09-24 | 2016-04-12 | Perqflo, Llc | Infusion pumps |
EP2830499B8 (en) | 2012-03-30 | 2019-04-03 | Insulet Corporation | Fluid delivery device with transcutaneous access tool, insertion mechansim and blood glucose monitoring for use therewith |
US10293102B2 (en) | 2014-12-01 | 2019-05-21 | Carefusion 2200, Inc. | Pump cassettes with piston and infusion pump systems |
-
2020
- 2020-09-03 US US17/011,749 patent/US11779699B2/en active Active
-
2023
- 2023-09-25 US US18/473,958 patent/US20240017002A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020169439A1 (en) * | 2001-02-22 | 2002-11-14 | Flaherty J. Christopher | Modular infusion device and method |
US20110218516A1 (en) * | 2008-09-15 | 2011-09-08 | Leonid Grigorov | Methods and Devices for Programmable Delivery of Microdoses of Liquid Drugs |
US20120004602A1 (en) * | 2009-12-30 | 2012-01-05 | Medtronic Minimed, Inc. | Connection and alignment detection systems and methods |
US20120172800A1 (en) * | 2010-12-29 | 2012-07-05 | Baxter Healthcare S.A. | Intravenous pumping air management systems and methods |
US20190275241A1 (en) * | 2018-03-09 | 2019-09-12 | Amgen Inc. | Backflow prevention mechanism for drug delivery device |
Also Published As
Publication number | Publication date |
---|---|
US20220080111A2 (en) | 2022-03-17 |
US11779699B2 (en) | 2023-10-10 |
US20210060237A1 (en) | 2021-03-04 |
US20240017002A1 (en) | 2024-01-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20240017002A1 (en) | Micropump | |
AU2015289999B2 (en) | Systems and methods for improved performance of fluidic and microfluidic systems | |
US9593678B2 (en) | System, method, and apparatus for utilizing a pumping cassette | |
US6485263B1 (en) | Systems for determining the volume of a volumetric chamber and pumping a fluid with a pump chamber | |
US6416293B1 (en) | Pumping cartridge including a bypass valve and method for directing flow in a pumping cartridge | |
US6663359B2 (en) | Pump chamber having at least one spacer for inhibiting the pumping of a gas | |
US6604908B1 (en) | Methods and systems for pulsed delivery of fluids from a pump | |
US6302653B1 (en) | Methods and systems for detecting the presence of a gas in a pump and preventing a gas from being pumped from a pump | |
US6905479B1 (en) | Pumping cartridge having an integrated filter and method for filtering a fluid with the cartridge | |
JP2006223871A (en) | Pressure activated intravascular set with drip chamber access | |
US10926895B2 (en) | Methods and systems for controlling the flow rate in a pneumatic syringe | |
CN211272846U (en) | Portable infusion device | |
US20230126860A1 (en) | Pressure-assisted air elimination | |
EP4339459A1 (en) | Passive pressure wave dampener systems | |
WO2023152008A1 (en) | Infusion system for administering a fluid to a patient | |
WO2011153697A1 (en) | Medical infusion device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FEPP | Fee payment procedure |
Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY |
|
FEPP | Fee payment procedure |
Free format text: ENTITY STATUS SET TO SMALL (ORIGINAL EVENT CODE: SMAL); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY |
|
AS | Assignment |
Owner name: LYNNTECH, INC., TEXAS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PEDRONI, JESSE;VARUGHESE, JIBI;RIDGE, GRAYSON;AND OTHERS;SIGNING DATES FROM 20200109 TO 20200203;REEL/FRAME:053808/0097 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: FINAL REJECTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE AFTER FINAL ACTION FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: PUBLICATIONS -- ISSUE FEE PAYMENT VERIFIED |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |