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
  • A61M5/155—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by gas introduced into the reservoir
• • 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
  • A61M5/148—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons flexible, e.g. independent bags
  • A61M5/1483—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons flexible, e.g. independent bags using flexible bags externally pressurised by fluid pressure
• • 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
  • A61M5/16877—Adjusting flow; Devices for setting a flow rate
  • A61M5/16881—Regulating valves

Definitions

• the present invention is directed toward volumetric infusion pumps, and more particularly toward a self-regulating servo valve for use with a volumetric infusion pump.
• Another similar apparatus for infusing therapeutic liquids to a patient includes a collapsible bag containing the therapeutic liquid juxtaposed with an inflatable bladder, with the bladder and the collapsible bag being contained within a rigid housing.
• the bladder is inflated, for example with compressed air, to apply pressure to the collapsible bag and thus expel therapeutic liquid from it.
• the therapeutic liquid is expelled through an outlet tube having a fixed cross-sectional area or which includes a flow restrictor of a fixed cross-sectional area. Fluid is provided to the bladder at a controlled rate with the intent that fluid is thus forced through the outlet tube at an approximate flow rate.
• the present invention is directed toward overcoming one or more of the problems discussed above.
• a first aspect of the present invention is an infusion pump including a reservoir containing a therapeutic liquid to be infused.
• the reservoir includes an outlet for the liquid.
• a volumetric air pump is operatively associated with the reservoir to pressurize the reservoir.
• a valve is operatively associated with the liquid outlet and prevents liquid flow through the liquid outlet until a select pressure is obtained in the outlet. The valve thereafter maintains an opening in the outlet that keeps the pressure in the reservoir at substantially the select pressure, whereby the volumetric flow rate of liquid through the outlet is proportional to the volumetric flow rate of air from the volumetric air pump.
• the valve varies the opening in the outlet so as to maintain the select pressure.
• the outlet may consist of a flexible conduit having a select undeformed inner cross- sectional area and the valve varies the opening in the outlet by pinching a segment of the conduit to vary the inner cross-sectional area of the segment of the conduit.
• the reservoir comprises a collapsible wall and the infusion pump further comprises an inflatable bladder juxtaposed with the collapsible wall of the reservoir.
• the volumetric air pump is in fluid communication with the bladder. The volumetric air pump provides gas to the bladder at a first rate until the select pressure is applied to the reservoir and thereafter provides gas to the bladder at a second substantially uniform rate less than the first rate.
• a second aspect of the present invention is an infusion pump including a collapsible bag defining a therapeutic liquid reservoir, the collapsible bag having a resilient tubing defining a reservoir outlet extending therefrom.
• An inflatable bladder is juxtaposed with the collapsible bag.
• a rigid housing defines a chamber receiving the collapsible bag and the inflatable bladder and includes a port receiving the resilient tubing.
• a volumetric air pump is in fluid communication with the bladder to inflate the bladder and thereby apply pressure to the collapsible bag.
• a valve is operatively associated with the resilient tubing to variably restrict the flow of liquid through the resilient tubing as a function of the pressure applied to the collapsible bag to maintain the substantially constant select pressure in the collapsible bag.
• the valve preferably prevents the flow of liquid through the resilient tubing until application of the select pressure to the collapsible bag.
• the valve may consist of a blade and anvil receiving the resilient tubing therebetween. The blade is biased toward the anvil to restrict the flow of liquid through the resilient tubing and the blade is operatively associated with the collapsible bag to bias the blade away from the anvil as pressure within the collapsible bag increases.
• the volumetric air pump preferably provides gas to the bladder at a first rate until the select pressure sufficient to overcome the biasing force on the blade so as to initially move the arm and the blade away from the anvil is applied to the reservoir and thereafter provides gas to the bladder at a second substantially uniform rate less than the first rate.
• a detector may be operatively associated with the arm and the volumetric air pump with the detector detecting the initial movement of the arm and sending a first signal to the volumetric air pump.
• the sensor may further detect if the blade moves more than a select distance from the anvil, at which point a second signal is sent to the volumetric air pump.
• a third aspect of the present invention is a method of infusing therapeutic liquid to a patient.
• the method includes providing a reservoir containing a therapeutic liquid and having a liquid outlet, providing a volumetric air pump in operative association with the reservoir to pressurize the reservoir and maintaining the select pressure in the reservoir so that liquid through the liquid outlet is proportional to the volumetric flow rate of the volumetric air pump.
• the liquid outlet may comprise a resilient tube and the method may further comprise applying a pinching force to a segment of the resilient tube and decreasing the pinching force as the pressure in the reservoir increases to increase an effective inner cross-sectional area of the segment of the resilient tube.
• the method may further comprise pressurizing the reservoir by providing a bladder juxtaposed with the reservoir in fluid communication with the volumetric air pump and preventing flow of liquid through the liquid outlet if the pressure in the reservoir is less than the select pressure.
• the method may further include inflating the bladder at a first rate until the select pressure is reached in the reservoir and thereafter inflating the bladder at a second substantially constant rate less than the first rate.
• a select pressure at the outlet can be accurately maintained, thereby insuring a substantially constant flow rate by keeping the liquid volumetric flow rate proportional to the volumetric rate of air provided by the volumetric air pump. If the pressure in a line to a patient increases, for example, due to lowering of the pump relative to the point of infusion, pressure will build within the bag which will thereby cause the valve to open further, allowing for a gradually increasing flow rate until the pressure in the bag returns to the select pressure. In this manner, the pump is self regulating. If the valve opens beyond a select amount, indicating a downstream occlusion, the volumetric air pump stops operating, preventing an excessive pressure build up.
• Fig 1 is a schematic cross-sectional, elevational representation of the volumetric infusion with servo valve control of the present invention.
• a volumetric infusion pump 10 including a servo valve 12 of the present invention is illustrated schematically in Fig. 1.
• the volumetric infusion pump 10 consists of a housing 14 defining a chamber 16 of a fixed volume. Within the chamber 16 is a collapsible bag 18 defining a reservoir for a therapeutic liquid. Also within the chamber 16 juxtaposed with the collapsible bag 18 is an inflatable bladder 20 in fluid communication by conduit 22 with a volumetric gas source 24.
• the volumetric gas source 24 consists of a volumetric air pump 26 driven by an encoded electric motor 27.
• the encoded electric motor 27 is coupled to a control circuit or microprocessor 28 by a connector 29.
• the microprocessor 28 may be preprogrammed or alternatively reprogramable through input station 30.
• the microprocessor 28 and electric motor 27 are preferably powered from a single power supply 31 which distributes power via lines 32 and 33.
• the power supply 31 may be an internal battery which can be replaceable, rechargeable or disposable along with the entire infusion pump 10. Alternatively, the power supply can be external to the pump 10. such as a common household current.
• a resilient outlet tube 36 having a select undefo ⁇ ned inner cross-sectional area extends from the collapsible bag 18 and a port 38 in the housing 14 and is in fluid communication with a patient administration set (not shown) to deliver therapeutic liquid from the collapsible bag 18 to a patient.
• liquid flows from the resilient outlet tube 36 by application of pressure from the inflatable bladder 20 upon the collapsible bag 18 within the chamber 16 of fixed volume.
• the servo valve 12 consists of an anvil 40 and a blade 42 which receive a segment of the resilient outlet tube 36 therebetween.
• the anvil 40 consists of a portion of the wall of the housing 14 which defines the port 38 for the resilient outlet tube 36.
• the blade 42 is on the distal end 46 of an arm 48.
• the proximal end 50 of the arm 48 is pivotally attached to the housing 14.
• arm 48 is rigid and the pivotal attachment is by a hinge 52.
• the housing and arm 14 could be integrally made of a suitable thermoplastic and the pivotal attachment could be a living hinge.
• a pressure pad 54 intermediate the proximal 50 and distal 46 ends of the arm 48 extends through an orifice 56 in the housing 14.
• the face of the pressure pad 54 has a defined surface area which is in contact with the collapsible bag 18.
• a spring 58 is located at the distal end of the arm 48 and biases the blade toward the anvil 40 so as to collapse and therefore to close the interior of the resilient outlet tube 36 by applying a select force. As an alternative to the spring 58, if the pump is maintained in the orientation illustrated in Fig. 1, the weight of the arm can apply the select force.
• a sensor 60 is operatively associated with the arm 48 to detect movement of the arm 48, and thus the blade 42. The sensor 60 is connected by connector 62 to the microprocessor 30. In operation, the inflatable bladder 20 is inflated by air delivered from the volumetric air pump 26 through the conduit 22 to the bladder 20.
• a threshold pressure preferably 9 psi
• the surface area of the pressure pad 54 is selected so that the select force is overcome when a desired threshold pressure is achieved in the collapsible bag 18.
• gas is supplied to the inflatable bladder 20 at a substantially constant rate sufficient to provide a desired rate of flow to the patient through the resilient outlet tube. Assuming a 9 psi threshold pressure, the flow of air to the inflatable bladder 20 necessary to sustain a desired flow rate can be calculated as follows:
• the microprocessor Upon entry of the desired flow rate by a user, through the input station 30, the microprocessor calculates the required air flow in accordance with this equation. In application, depending on how smooth flow rate from the air pump is, the valve tends to "float" in a position which maintains an equilibrium.
• the volumetric air pump 26 is operated at a maximum rate to inflate the bladder until sufficient pressure develops within the collapsible bag 18 that the arm 48 and therefore the blade 42 are caused to lift relative to the anvil 40.
• the initial movement of the arm is detected by the sensor 60 which sends a signal to the microprocessor 28 which in turn sends a signal to the encoded electric motor drive 27 which slows the encoded electronic motor to slow the delivery of gas to the bladder to the necessary rate calculated to provide the desired flow rate entered in the input station 30 through the resilient outlet tube.
• the pump works similarly to a pressure regulator in which the valve 12 opens and closes to maintain a desired pressure at the outlet tube 36.
• the blade 42 will move further away from the anvil 40, thereby temporarily increasing the effective inner cross-sectional area of the resilient tube 36 to allow more flow until the system pressure returns to the desired pressure at the outlet tube and the flow rate returns to the desired flow rate.
• the pump is self regulated. If an obstruction occurs in the patient administration set or blood vessel of the patient such that pressure builds on the system above a select maximum, the sensor 60 will detect corresponding movement of the arm 48 and send a signal to the microprocessor which in turn will stop the electric motor 27 and sound an alarm.

Landscapes

• Health & Medical Sciences (AREA)
• Hematology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biomedical Technology (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• Anesthesiology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
• Control Of Positive-Displacement Pumps (AREA)

Priority Applications (6)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26315750

Family Applications (1)

Country Status (9)

Cited By (9)

Families Citing this family (3)

Citations (4)

• 2000
  • 2000-06-15 CA CA002341745A patent/CA2341745A1/en not_active Abandoned
  • 2000-06-15 KR KR1020017003117A patent/KR20010075031A/ko not_active Application Discontinuation
  • 2000-06-15 CN CN00801303A patent/CN1315876A/zh active Pending
  • 2000-06-15 BR BR0006913-2A patent/BR0006913A/pt not_active IP Right Cessation
  • 2000-06-15 WO PCT/US2000/016394 patent/WO2001003758A1/en not_active Application Discontinuation
  • 2000-06-15 EP EP00942820A patent/EP1112100A1/en not_active Withdrawn
  • 2000-06-15 AU AU57390/00A patent/AU5739000A/en not_active Abandoned
  • 2000-06-15 JP JP2001509230A patent/JP2003504125A/ja not_active Withdrawn
  • 2000-07-10 AR ARP000103535A patent/AR024698A1/es unknown

Patent Citations (4)

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