CA1231282A - Pumping means for programmable infusion system - Google Patents
Pumping means for programmable infusion systemInfo
- Publication number
- CA1231282A CA1231282A CA000486993A CA486993A CA1231282A CA 1231282 A CA1231282 A CA 1231282A CA 000486993 A CA000486993 A CA 000486993A CA 486993 A CA486993 A CA 486993A CA 1231282 A CA1231282 A CA 1231282A
- Authority
- CA
- Canada
- Prior art keywords
- medication
- flow
- pressure
- patient
- infusion
- 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.)
- Expired
Links
Landscapes
- Infusion, Injection, And Reservoir Apparatuses (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A programmable infusion system is provided herein for providing medication to a living body of a patient. The infusion system includes a medication reservoir for storing selected medication. Infusion apparatus is provided for infusing the selected medication which is stored in the medication reservoir into the living body. Such infusion apparatus has a fluid handling mechanism for delivering the selected medication and pumping means for pumping the selected medication, wherein the pumping means operates in a pulsatile mode, and the pumping means includes flow shaping means connected to its output for shaping the output flow of medication from the pumping means.
A programmable infusion system is provided herein for providing medication to a living body of a patient. The infusion system includes a medication reservoir for storing selected medication. Infusion apparatus is provided for infusing the selected medication which is stored in the medication reservoir into the living body. Such infusion apparatus has a fluid handling mechanism for delivering the selected medication and pumping means for pumping the selected medication, wherein the pumping means operates in a pulsatile mode, and the pumping means includes flow shaping means connected to its output for shaping the output flow of medication from the pumping means.
Description
~13~2~Z
This invention relates to a programmable infusion system for providing medication to a living body, and is a division of copending application Serial No.417,979 filed December 17, 1982, now allowed.
The present invention eelates to the field of dispensing medication to a living being. Although mainly intended for use by human patients requiring infusions of a deug, e.g. insulin, glucose, heparin, or any of various other chemotherapeutic agents, the invention extends to use in any - lO living body (e.g. domestic animals) and to the infusion of any liquid (e.g. blood) or colloidal suspension, or gas or granulated solid, which may provide a curative or healing effect. Although a principal use envisioned is for implantable devices, it is also envisioned that it could be ussd external to a living being for the infusion of medication.
Various techniques and devices have been suggested and are currently under study which address the problem of dispensing a drug or other medicative liquid into a living body. Of these techniques and devices, however, sufficient safety features in the environment of the flexibility achieved by programming dosage inputs are rarely contemplated.
One liquid infusion device discussed in U.S. Patent No. 4,077,405 issued March 7, 1970 to Haerton et al discloses a controllable dosing arrangement which provides for human operator interaction. syringe forces liquid through a pressuee valve into a supply reservoir and a bellows pump foeces dcug from the reservoir through a flow limiter into the body. This device fails to address various safety problems, e.g. leakage, excessive pumping, and excessive requests for drug. No provision for detecting leaks in the device, for signalling malfunctions, for restricting the number of or quantity of drug doses, or for monitoring proper operation of the device is suggested.
-la-~.2~
Like Haerton et al, U.S. Patent No. 3,692,027 issued September 10, 1972 to Ellinwood teaches an implanted, self-powered drug dispenser having a bellows pump which employs one-way valves. The Ellinwood device is not programmable and varies dosage by opening and closing portals or selecting a dose of medication fcom one of a plurality of pumes having different dosage volumes andtoc different medications stoeed therein. Safety redundancy pertaining to filling, leakage problems, patient and doctor interaction with the dispensee, and dosage input programming are not considered.
An invention of Blackshear et al (U.S. Patent No.
3,731,681 issued May 8. 1973) shows another infusion pump without appreciable safety features. Blackshear et al do not look for pressure integrity before filling the device with drug, nor teach any means for monitoring pump operation.
Richter (U.S. Patent No. 3,894,538 issued July 15, 1975) considees, in a medicine supplying device, one safety feature: an exit plug for preventing contaminants from entering the device and for limiting drug outflow. The flow ~0 from the Richter device does not provide a smooth eulsatile flow of drug which is infused over a relatively long period.
It further fails to disclose any means for reliably conteolling or varying the flow rate or for monitoring the rate of operation.
Seveeal recent publications have also underscored the need for an implantable medication infusion device. Two articles by Rhode et al ("One Year of lleparin Anticoagulation~:
Minnesota Medicine; Octobee, 1977 and protracted Parenteral ~'~3~
Drug Infusion in Ambulatory Subjects Using an Imelantable Infusion Pump"; Amecican Society for Artificial Internal Orqans Teansaction, volume XXIII, 1977) described an implantable infusion pump. No check foc pressure integrity before filling or during operation, no programming means, and no patient or doctor intecaction with the device are contemplated.
An a-rticle by Spencer ("Foe Diabetics: an electronic pancreas": IEE-Spectrum; June, 1978) discusses current trends in the implantable dcug pump field. Programming the rate of drug flow over time depending on food intake is mentioned.
efforts in the development of an implantable bellows pump are also discussed. Spencer further mentions the use of an alacm which sounds if a pump fails to provide drug in accordance with the preprogrammed rate. The Spencer article generally discussed drug dispenser teehnology but fails to address many specific problems. As in the other cited works, safety features such as an antechamber: leak detection distinctive subeutaneous stimulation to indicate various device malfunctions; safe methods of programming the deviee regardless of work, food-intake, or time schedules: and telemetering of information pertaining to the actual operation of the pump are not considered.
Finally, German Patent Application DE 31-12916-Al, published February 15, 1982, in the name of Medtronic Inc., teaches an implantable medicine dispenser which is extecnally pcogcammable. Receipt of programming commands can be verified by an acoustic signal. No means are shown or suggested or ~Z3~Z~
sensing, storing, and telemetering information pertaining to actual pump operation. As a result, only the instructions given to this aparatus can be verified and changes in the physiological response of the patient, often detrimental, are the only way to monitor pump operation.
Accordingly, an object of a broad aspect of this invention is to pLovide an improved infusion system for providing medication to a living body of a patient.
... . - , -3~-~,Z3~
By one broad aspect of this invention, a programmable infusion system is provided for providing medication to a living body of a patient, comprising an infusion apparatus including a medication reservoir for storing selected medication, infusion means for infusing the selected medication stored in the medication ~esecvoic into the living body, the infusion means having a fluid handling mechanism foc delivecing the selected medication and pumping means for pumping the selected medication, wherein the pumping means operates in a pulsatile mode, and the pumping means includes flow shaping means connected to its output for shaping the output flow of medication from the pumping means.
In one embodiment thereof, the flow shaping means comprises an output accumulator chamber for causing a fluidic capacitive effect on the flow of the selected medication, and a flow restricting element through which liquid flowing to the living body is resisted, the output accumulator chamber and the flow restricting element comprising a fluid resistive/capacitive arrangement for smoothing the pulsatile nature of the flow of the selected medication into the living body. In an alternative embodiment thereof, the flow shaping means provides an inhibiting means foc inhibiting the pumping means when pressuce in the outlet accumulator chamber exceeds a preselected pressure limit.
It is preferred that the infusion apparatus be adapted for implantation into a living body.
~3~L;28'~
In the accompanying drawings:
FIG. 1 illusteates a geneeal block diagram of the entire medication infusion system emblacing the present invention;
FIGS. 2 and 3 show a front cross-sectional and top view, respectively, of the implantable portion of a medication infusion system embracing the present invention:
FIG. 4 shows, in detail the mechanical construction of a pulsatable pump element of a medication infusion system embracing the present invention:
FIG. 5 is a block diagram showing the electronics of a medication infusion system embracing the present invention:
FIG. 6 shows a method of programming the rate of : medication infusion into a patient by the use of the maximum running integral dosage limiting technique; and FIGS. 7 and 8 are illustrative of a patient programming unit in which FIG. 7 shows a front view illustrating a sample apparatus for select'ing dosage depending on meal size and recognized body condition factors, and FIG. 8 shows a rear portion which provides information relative to the last programming of the eatient programming unit.
Generally, the medication infusion system embracing the present invention provides an antechamber which is normally willed with saline solution to act as a buffer between the medication intake point and the major medication reservoir in the device. The resecvoir may contain a fatal amount of drug 1~31~JZ
or othee medication. It is thus isolated from the body by a jilter, one-way inlet valve, the saline-containing antechamber and a septum providing a self-sealing opening to the antechamber. Further, the reservoir is at a pressure below the ambient body p{essure. Thus, even if the inlet valve and septum leak, body fluids would enter the antechamber and slowly ooze into the reservoir through the flow-impeding filter. Any other leak of medication from the reservoir or leakage of body fluid through the outer shell of the implanting device would be sensed by a fluid detector outside the reservoir. Similar safety back-ups are provided at the outlet output of the reservoir which is provided with two one-way valves and a filter.
The outlet, however, also is provided with a defocmable wall which combines with the outlet filter to yield an exponentially decaying flow of medication. This smooth flow over a long, predertermined period provides enhanced safety and flow control. The deformabie wall serves the function of an accumulator and the output filter provides the function of a flow resistor or restrictor; thus the deformable wall pLovides the "C" and the filter "R~ of an "RC" time constant for the decrease of flow after a pulse of medication has been deliveced into an outlet chamber prioe to infusion into the body via the RC network. Also at the outlet is an element foc correlating medication requests with medication dispensing, thus providing an operational indicator and safety feature.
~Z3~
Also, or saety, a filling procedure is taught which insures that medication is not injected into the device until pressure integrity at the input is determined. In the mechanical pump itself, the amount of medication pulsing it can provide is restricted in the preferred embodiment by a pressure limit intrinsic in the pump design.
In erogcamming the system embraced by the present invention, convenience and safety are again major concerns. A
flexible, maximum running integral program for limiting medication dosage inputs communicated by a patient satisfies not only a patient's need for proper amounts of medication but also satisfies a vaeiable work and eating schedule requirement ox the patient and can provide a safe, proper medication schedule even though the patient experiences time zone or work schedule changes. In addition to a programmable rate of medication input, a hardwired limit is also included. If requests exceed the limits set by the program, the hardwired limits will inhibit the pulsing of excessive medication into the patient. Finally, the system provides a histocy of medication infusion which a physician can read out through telemetry means. This telemetry means is also used to program and check the system.
Referring to FIG. 1, the varous portions of the implantable programmable medication infusion system embracing the present invention are shown. An implantable portion 2 in a patient's body can be programmed either by the medication programming system 1 or by the patients programming unit ;~;23~'~13Z
400. Commands from the medication programming system emitted from the communication head 300 are transmitted to electronies in the implantable portion 2 in order to program and effectuate the infusion of medication into the body in a save, controlled fashion. The medication programming system 1 is also capable of reading information out of the implantable portion 2 concerning the amount of medication dispensed over a specified time period and furthermore the medication programming system 1 is capable of calibrating the per pulse of medication of the imelantable portion 2. medication injection unit 7 is connected to a double hypodermic syringe which is used to provide medication to an implantable medieation reservoir 18 (shown in FIGS. 2 and 3) included within the implantable portion 2. Fill commands to the medication injection unit 7 emanate from a medication programming unit 3. A patient's programming unit 400 is eontrolled by the user to request doses of medieation. The dosage requests ace controlled by safey units embodied in fixed hardware elements and programmable elements found in the implantable portion 2. To recharge a rechargeable cell contained within the implantable portion 2, and external charging head 9 connected to a battery charging unit 11 is included. The need for the charging head 9 and battery charging unit 11 can be obviated by the inclusion in the implantable eo{tion 2 of a power supply (such as a lithium cell) which is of sufficient lifetime to negate the need for recharging. The medication programming unit 3 outputs to a paper printer 13 which provides hacd, readable output that can be readily interpreted by a physician.
~3~ 32 Reerring now to FIGS. 2 and 3, the implantable portion 2 of an implantable programmable medication infusion system embracing the present invention is shown. Medication is provided to the implantable portion 2 by means of a double hypodecmic syringe 4 which penetrates the skin 5 and a self-sealing rubber septum 6 which covers an antechamber 8 in leak-proof fashion.
Medication is introduced into the antechamber 8 through syringe 4 under pressure the level of which is controllable externally.
A reservoir chamber lO, in which the medication is stored under relatively constant pressure, is fed from the antechamber B via a ceramic filter 12 and an inlet pressure valve 14 which permits flow only from the antechamber 8 into the reservoir chamber lO when the eressure differential between them exceeds a predetermined threshold.
The inlet ceramic filter 12 performs various functions. Besides filtering contaminants from medication being fed into the reservoir chamber lO, the ceramic filter lZ
serves to limit the rate of medication flow from the antechamber 8 into the reservoir chamber lO or, conversely from the reservoir chamber 10 into antechamber 8 should the inlet pcessure valve 14 leak or malfunction. Further, should the sel~-sealing rubber septum 6 leak, the ceramic filter 12 together with the inlet pressure valve 14 prevents the inflow of body fluids into the reservoir chamber lO. Further, should the inlet pressure valve 14 and the septum 6 both leak or otherwise malfunction, the inlet ceramic filter 12 would permit only a slow flow of body fluids to enter the reservoir chamber ~z;~
10, until boy ~mbi~nt pr~a~u~e is achieved, at which time some meditation could diffuse through the ceramic filter 12 but at a cate that would not be hazardous to a tyeical patient in which the system would be implanted.
The resevoir chambec 10 comprises a liquid-vapour portion 16 which jests atop a reservoir of medication 18, the liquid vapor portion 16 and the reservoir 18 being separated by a flexible diaphragm 20. The flexible diaphragm 20 could compcise an elastomer, a moveable bellows, or other substitutive foible diaphcagm means which would separate the medication reservoir 18 crom the liquid vapor portion 16; The liquid vapor volume in the vapor portion 16 preferably comprises a saturated vapor in equilibrium with a small amount of FREON 113 (registered trade mark of a fluorocarbon refrigerant) liquid. Over normal body temperatures, FREON 113 has a linear pressure characteristic ranging from -4 psig (at 98) to approximately - 2.5 psig at 104F. Using FREON
113, the medication reservoir 18 will be maintained at a pressure below that of the human body pressure up to altitudes of 8500 feet. For patients who may live above that altitude, other fluorocacbons at lower pressure may be employed. In this way, should both the septum 6 and the inlet pressure valve 14 leak, the effect would be to cause body fluids to diffuse slowly, via the inlet ceramic filter 12, into the medication reservoir 18 rather than to have a rapid flow of medication entec into the body where it could cause harm to the patient.
Because of the pressure differential between the body and the medication .^ lC~--~231~
reservoir 18. medication will not flow from the reservoir 18 into the body. As the amount of medication in the medication reservoir 18 varies, the flexible diaphragm 20 moves up or down, with the FREON 113 being converted either prom liquid to vapor or vapor to liquid to provide an essentially constant pcessure which will always be below one atmosphere and below normal body pressure. A resecvoir chamber having a volume of approximately lOcc would be suficient for most applications.
This amount ox concentrated medication, insulin for example, could be fatal if injected over a short time. The volume of the antechamber 8 is less than 10% the size of the reservoir chamber 10. In the worst case of leakage if medication leaked from the reservoir chamber 10 into the antechamber 8 and even if the antechamber 8 leaked as well, only diluted medication would enter the body gradually passing from an area of low ; pressure to one of higher pressure. There is thus little likelihood of the dose being fatal. As readily seen in FIG.
This invention relates to a programmable infusion system for providing medication to a living body, and is a division of copending application Serial No.417,979 filed December 17, 1982, now allowed.
The present invention eelates to the field of dispensing medication to a living being. Although mainly intended for use by human patients requiring infusions of a deug, e.g. insulin, glucose, heparin, or any of various other chemotherapeutic agents, the invention extends to use in any - lO living body (e.g. domestic animals) and to the infusion of any liquid (e.g. blood) or colloidal suspension, or gas or granulated solid, which may provide a curative or healing effect. Although a principal use envisioned is for implantable devices, it is also envisioned that it could be ussd external to a living being for the infusion of medication.
Various techniques and devices have been suggested and are currently under study which address the problem of dispensing a drug or other medicative liquid into a living body. Of these techniques and devices, however, sufficient safety features in the environment of the flexibility achieved by programming dosage inputs are rarely contemplated.
One liquid infusion device discussed in U.S. Patent No. 4,077,405 issued March 7, 1970 to Haerton et al discloses a controllable dosing arrangement which provides for human operator interaction. syringe forces liquid through a pressuee valve into a supply reservoir and a bellows pump foeces dcug from the reservoir through a flow limiter into the body. This device fails to address various safety problems, e.g. leakage, excessive pumping, and excessive requests for drug. No provision for detecting leaks in the device, for signalling malfunctions, for restricting the number of or quantity of drug doses, or for monitoring proper operation of the device is suggested.
-la-~.2~
Like Haerton et al, U.S. Patent No. 3,692,027 issued September 10, 1972 to Ellinwood teaches an implanted, self-powered drug dispenser having a bellows pump which employs one-way valves. The Ellinwood device is not programmable and varies dosage by opening and closing portals or selecting a dose of medication fcom one of a plurality of pumes having different dosage volumes andtoc different medications stoeed therein. Safety redundancy pertaining to filling, leakage problems, patient and doctor interaction with the dispensee, and dosage input programming are not considered.
An invention of Blackshear et al (U.S. Patent No.
3,731,681 issued May 8. 1973) shows another infusion pump without appreciable safety features. Blackshear et al do not look for pressure integrity before filling the device with drug, nor teach any means for monitoring pump operation.
Richter (U.S. Patent No. 3,894,538 issued July 15, 1975) considees, in a medicine supplying device, one safety feature: an exit plug for preventing contaminants from entering the device and for limiting drug outflow. The flow ~0 from the Richter device does not provide a smooth eulsatile flow of drug which is infused over a relatively long period.
It further fails to disclose any means for reliably conteolling or varying the flow rate or for monitoring the rate of operation.
Seveeal recent publications have also underscored the need for an implantable medication infusion device. Two articles by Rhode et al ("One Year of lleparin Anticoagulation~:
Minnesota Medicine; Octobee, 1977 and protracted Parenteral ~'~3~
Drug Infusion in Ambulatory Subjects Using an Imelantable Infusion Pump"; Amecican Society for Artificial Internal Orqans Teansaction, volume XXIII, 1977) described an implantable infusion pump. No check foc pressure integrity before filling or during operation, no programming means, and no patient or doctor intecaction with the device are contemplated.
An a-rticle by Spencer ("Foe Diabetics: an electronic pancreas": IEE-Spectrum; June, 1978) discusses current trends in the implantable dcug pump field. Programming the rate of drug flow over time depending on food intake is mentioned.
efforts in the development of an implantable bellows pump are also discussed. Spencer further mentions the use of an alacm which sounds if a pump fails to provide drug in accordance with the preprogrammed rate. The Spencer article generally discussed drug dispenser teehnology but fails to address many specific problems. As in the other cited works, safety features such as an antechamber: leak detection distinctive subeutaneous stimulation to indicate various device malfunctions; safe methods of programming the deviee regardless of work, food-intake, or time schedules: and telemetering of information pertaining to the actual operation of the pump are not considered.
Finally, German Patent Application DE 31-12916-Al, published February 15, 1982, in the name of Medtronic Inc., teaches an implantable medicine dispenser which is extecnally pcogcammable. Receipt of programming commands can be verified by an acoustic signal. No means are shown or suggested or ~Z3~Z~
sensing, storing, and telemetering information pertaining to actual pump operation. As a result, only the instructions given to this aparatus can be verified and changes in the physiological response of the patient, often detrimental, are the only way to monitor pump operation.
Accordingly, an object of a broad aspect of this invention is to pLovide an improved infusion system for providing medication to a living body of a patient.
... . - , -3~-~,Z3~
By one broad aspect of this invention, a programmable infusion system is provided for providing medication to a living body of a patient, comprising an infusion apparatus including a medication reservoir for storing selected medication, infusion means for infusing the selected medication stored in the medication ~esecvoic into the living body, the infusion means having a fluid handling mechanism foc delivecing the selected medication and pumping means for pumping the selected medication, wherein the pumping means operates in a pulsatile mode, and the pumping means includes flow shaping means connected to its output for shaping the output flow of medication from the pumping means.
In one embodiment thereof, the flow shaping means comprises an output accumulator chamber for causing a fluidic capacitive effect on the flow of the selected medication, and a flow restricting element through which liquid flowing to the living body is resisted, the output accumulator chamber and the flow restricting element comprising a fluid resistive/capacitive arrangement for smoothing the pulsatile nature of the flow of the selected medication into the living body. In an alternative embodiment thereof, the flow shaping means provides an inhibiting means foc inhibiting the pumping means when pressuce in the outlet accumulator chamber exceeds a preselected pressure limit.
It is preferred that the infusion apparatus be adapted for implantation into a living body.
~3~L;28'~
In the accompanying drawings:
FIG. 1 illusteates a geneeal block diagram of the entire medication infusion system emblacing the present invention;
FIGS. 2 and 3 show a front cross-sectional and top view, respectively, of the implantable portion of a medication infusion system embracing the present invention:
FIG. 4 shows, in detail the mechanical construction of a pulsatable pump element of a medication infusion system embracing the present invention:
FIG. 5 is a block diagram showing the electronics of a medication infusion system embracing the present invention:
FIG. 6 shows a method of programming the rate of : medication infusion into a patient by the use of the maximum running integral dosage limiting technique; and FIGS. 7 and 8 are illustrative of a patient programming unit in which FIG. 7 shows a front view illustrating a sample apparatus for select'ing dosage depending on meal size and recognized body condition factors, and FIG. 8 shows a rear portion which provides information relative to the last programming of the eatient programming unit.
Generally, the medication infusion system embracing the present invention provides an antechamber which is normally willed with saline solution to act as a buffer between the medication intake point and the major medication reservoir in the device. The resecvoir may contain a fatal amount of drug 1~31~JZ
or othee medication. It is thus isolated from the body by a jilter, one-way inlet valve, the saline-containing antechamber and a septum providing a self-sealing opening to the antechamber. Further, the reservoir is at a pressure below the ambient body p{essure. Thus, even if the inlet valve and septum leak, body fluids would enter the antechamber and slowly ooze into the reservoir through the flow-impeding filter. Any other leak of medication from the reservoir or leakage of body fluid through the outer shell of the implanting device would be sensed by a fluid detector outside the reservoir. Similar safety back-ups are provided at the outlet output of the reservoir which is provided with two one-way valves and a filter.
The outlet, however, also is provided with a defocmable wall which combines with the outlet filter to yield an exponentially decaying flow of medication. This smooth flow over a long, predertermined period provides enhanced safety and flow control. The deformabie wall serves the function of an accumulator and the output filter provides the function of a flow resistor or restrictor; thus the deformable wall pLovides the "C" and the filter "R~ of an "RC" time constant for the decrease of flow after a pulse of medication has been deliveced into an outlet chamber prioe to infusion into the body via the RC network. Also at the outlet is an element foc correlating medication requests with medication dispensing, thus providing an operational indicator and safety feature.
~Z3~
Also, or saety, a filling procedure is taught which insures that medication is not injected into the device until pressure integrity at the input is determined. In the mechanical pump itself, the amount of medication pulsing it can provide is restricted in the preferred embodiment by a pressure limit intrinsic in the pump design.
In erogcamming the system embraced by the present invention, convenience and safety are again major concerns. A
flexible, maximum running integral program for limiting medication dosage inputs communicated by a patient satisfies not only a patient's need for proper amounts of medication but also satisfies a vaeiable work and eating schedule requirement ox the patient and can provide a safe, proper medication schedule even though the patient experiences time zone or work schedule changes. In addition to a programmable rate of medication input, a hardwired limit is also included. If requests exceed the limits set by the program, the hardwired limits will inhibit the pulsing of excessive medication into the patient. Finally, the system provides a histocy of medication infusion which a physician can read out through telemetry means. This telemetry means is also used to program and check the system.
Referring to FIG. 1, the varous portions of the implantable programmable medication infusion system embracing the present invention are shown. An implantable portion 2 in a patient's body can be programmed either by the medication programming system 1 or by the patients programming unit ;~;23~'~13Z
400. Commands from the medication programming system emitted from the communication head 300 are transmitted to electronies in the implantable portion 2 in order to program and effectuate the infusion of medication into the body in a save, controlled fashion. The medication programming system 1 is also capable of reading information out of the implantable portion 2 concerning the amount of medication dispensed over a specified time period and furthermore the medication programming system 1 is capable of calibrating the per pulse of medication of the imelantable portion 2. medication injection unit 7 is connected to a double hypodermic syringe which is used to provide medication to an implantable medieation reservoir 18 (shown in FIGS. 2 and 3) included within the implantable portion 2. Fill commands to the medication injection unit 7 emanate from a medication programming unit 3. A patient's programming unit 400 is eontrolled by the user to request doses of medieation. The dosage requests ace controlled by safey units embodied in fixed hardware elements and programmable elements found in the implantable portion 2. To recharge a rechargeable cell contained within the implantable portion 2, and external charging head 9 connected to a battery charging unit 11 is included. The need for the charging head 9 and battery charging unit 11 can be obviated by the inclusion in the implantable eo{tion 2 of a power supply (such as a lithium cell) which is of sufficient lifetime to negate the need for recharging. The medication programming unit 3 outputs to a paper printer 13 which provides hacd, readable output that can be readily interpreted by a physician.
~3~ 32 Reerring now to FIGS. 2 and 3, the implantable portion 2 of an implantable programmable medication infusion system embracing the present invention is shown. Medication is provided to the implantable portion 2 by means of a double hypodecmic syringe 4 which penetrates the skin 5 and a self-sealing rubber septum 6 which covers an antechamber 8 in leak-proof fashion.
Medication is introduced into the antechamber 8 through syringe 4 under pressure the level of which is controllable externally.
A reservoir chamber lO, in which the medication is stored under relatively constant pressure, is fed from the antechamber B via a ceramic filter 12 and an inlet pressure valve 14 which permits flow only from the antechamber 8 into the reservoir chamber lO when the eressure differential between them exceeds a predetermined threshold.
The inlet ceramic filter 12 performs various functions. Besides filtering contaminants from medication being fed into the reservoir chamber lO, the ceramic filter lZ
serves to limit the rate of medication flow from the antechamber 8 into the reservoir chamber lO or, conversely from the reservoir chamber 10 into antechamber 8 should the inlet pcessure valve 14 leak or malfunction. Further, should the sel~-sealing rubber septum 6 leak, the ceramic filter 12 together with the inlet pressure valve 14 prevents the inflow of body fluids into the reservoir chamber lO. Further, should the inlet pressure valve 14 and the septum 6 both leak or otherwise malfunction, the inlet ceramic filter 12 would permit only a slow flow of body fluids to enter the reservoir chamber ~z;~
10, until boy ~mbi~nt pr~a~u~e is achieved, at which time some meditation could diffuse through the ceramic filter 12 but at a cate that would not be hazardous to a tyeical patient in which the system would be implanted.
The resevoir chambec 10 comprises a liquid-vapour portion 16 which jests atop a reservoir of medication 18, the liquid vapor portion 16 and the reservoir 18 being separated by a flexible diaphragm 20. The flexible diaphragm 20 could compcise an elastomer, a moveable bellows, or other substitutive foible diaphcagm means which would separate the medication reservoir 18 crom the liquid vapor portion 16; The liquid vapor volume in the vapor portion 16 preferably comprises a saturated vapor in equilibrium with a small amount of FREON 113 (registered trade mark of a fluorocarbon refrigerant) liquid. Over normal body temperatures, FREON 113 has a linear pressure characteristic ranging from -4 psig (at 98) to approximately - 2.5 psig at 104F. Using FREON
113, the medication reservoir 18 will be maintained at a pressure below that of the human body pressure up to altitudes of 8500 feet. For patients who may live above that altitude, other fluorocacbons at lower pressure may be employed. In this way, should both the septum 6 and the inlet pressure valve 14 leak, the effect would be to cause body fluids to diffuse slowly, via the inlet ceramic filter 12, into the medication reservoir 18 rather than to have a rapid flow of medication entec into the body where it could cause harm to the patient.
Because of the pressure differential between the body and the medication .^ lC~--~231~
reservoir 18. medication will not flow from the reservoir 18 into the body. As the amount of medication in the medication reservoir 18 varies, the flexible diaphragm 20 moves up or down, with the FREON 113 being converted either prom liquid to vapor or vapor to liquid to provide an essentially constant pcessure which will always be below one atmosphere and below normal body pressure. A resecvoir chamber having a volume of approximately lOcc would be suficient for most applications.
This amount ox concentrated medication, insulin for example, could be fatal if injected over a short time. The volume of the antechamber 8 is less than 10% the size of the reservoir chamber 10. In the worst case of leakage if medication leaked from the reservoir chamber 10 into the antechamber 8 and even if the antechamber 8 leaked as well, only diluted medication would enter the body gradually passing from an area of low ; pressure to one of higher pressure. There is thus little likelihood of the dose being fatal. As readily seen in FIG.
2, decreasing or expanding the size of the reservoir chamber 10 would be a simple modificiation because of the arrangement of elements in the system. Included in the reservoir chamber 10 is a dual pressure switch which can comprise a reservoir fill switch 23 for indicating when the pressure in the reservoir chamber 10 reaches a predetermined level e.g. -2 esig and a second switch 25 for indicating when the pressure reaches -1 psig. Fill switch 23 is used during the filling procedure to indicate (by a telemetry system to be described later) when the level ox medication in the reservoir chamber 10 has reached a
3 2 specific value. Should body fluids leak into the medication reservoir 18 ~oc any reason, an increase in pres6ure would result that would activate the second pressure switch 2~. For example, when body fluids entering reservoir 18 reach a pressure ox -1 psig, this would set off a subcutaneous electrical stimulation alarm system. By having the fill switch 23 set at a lower pressure than the body fluid leak detection pressure switch 25, the filling of the reservoir 18 can be accomplished without setting off an alarm signal.
In order to fill the reservoir chamber 10 with medication, a sequence of steps is followed. The antechamber 8 is normally filled with a saline or other innocuous solution which povides a buffer between the body and the reservoir chamber 10 and which if the septum failed would cause no harm to the patient. it the time of filling, a double hypodermic syringe 4 is directed into the antechamber 8 and saline is intcoduced into the antechamber 8 through one needle and exits through the other in order to flush the antechamber 8 with more saline. Once flushed, the antechamber 8 is checked for pressure integrity with saline introduced under a pressure which is less than that cequired to open the inlet pressure valve 14. When pressure integrity is determined, the antechambec 8 is flushed with the desiced medication (e.g.
insulin). Medication is then forced into the antechamber 8 at a pressure greater than that required to open inlet pressure valve 14. The insulin fills the medication reservoir 18 ox the reservoir chamber 10 until the flexible membrane 20 ~'~331L~
contacts the dual pressure switch Z2, ~occing the reser~roir Jill switch 23, to generate a signal (e.g. at -2 psig~ which indicates that the filling has been completed. The amount of medication required to fill the medication reservoir 18 is noted and then the antechamber 8 is slushed once again with innocuous saline solution. The entire reservoir chamber lO is surrounded by a wall 24 and is isolated from the other elements of the system by means of the inlet pressuee valve 14 and an interface pressure valve 26 which connects the reservoir to a pulsatile pup 23 which is shown in FIG. 4. The remaining elements of the implanted portion 2 are also shown in FIG. 2:
an electronics section 30 with a battecy subsection 32. As is already seen in FIG. 2, a hermetically sealed enclosure 34 surrounds the reservoir chamber lO as well as the pulsatile pump 28 (see FIG. 4) and the electronics section 30 with the battery subsection 32. To provide an enhanced safety feature, a fluid detector 35 is pLovided between the wall 24 and the hermetically sealed enclosuee 34. Should either the outer hermetic enclosuee 34 leak or should the reservoie chamber lO
leak, the 1uid detector 35 is placed at a location where the leaking body 1uids or medication would be detected. The fluid detector 35 could be a very high resistance resistor (e.g. lO megohms) whose resistance drops significantly in the presence of fluids. A malfunction signal to warn the patient if such a leak is detected, is provided. Similaely, a medication leakage detector 37 in the liquid-vapor volume 16 would indicate when medication was leaking into that chamber ~L~3~
l This detector may also be a resistoc whose value will be significantly altered by the presence of the medication. The medication leakage detector 37 when actuated would set off a distinct subcutaneous electcical stimulation alarm signal that can be detected by the patient FIG. 4 illustrates the pulsatile pump 28 shown in the top vi.ew o the implanted poetion 2 shown in FIG. 3. The interface pressure valve 26 shows where medication enters the pulsatile pump 28 when the diferential in pressuce between the reservoir chamber 10 and a medication storing means 200 (inside the eulsatile pume 28) reaches a level sufficient to open the inlet pressure valve 26. In the preferred embodiment shown in FIG. 4, this differential in pressure is caused by the expansion of a spring bellows 202 in response to an electrical pulse introduced to a pulsing coil 204 which surrounds a plate 206 which is attached to the spcing bellows 202. When a pulse passes through the pulsing coil Z04, plate 206 is driven to a forward stop 208. This action of expanding the storing means 200 causes the interface pcessure valve 26 to open, thereby allowing medication from the reservoir chamber 10 to fill the medication storing means 200. The plate 206 is a permanent magnet (or, possibly, a magnetizable material) which moves in response to a curcent induced magnetic force. When current in the pulsing coil 204 ceases, the spring focce of the bellows 202 cetucns the plate 206 to a position against a backstop member 210. The amount of tcavel of plate 206 is thus fixed, rendering the stcoke volume of the pulsatile pump 2~ constant 3~
and independent of the electrical pulse current oe pulse width into the pulsing coil 20~ as long as certain minimum currents and pulse width is provided. The maximum pressure that can be exerted by the pulsatile pump 28 is dependent on the spring force that can be exerted by the bellows 202 as well as the cross section area of plate 206 which is in contact with the medication in the storing means 200. More simply, PmaX=F/A
where Pmax is the maximum pressure that can be created by the spring force of the bellows within the medication storing means 200, F is the spring force of bellows 202, and A is the portion of surface of plate 206 which is in contact with the medication in the medication storing means 200 which extends into the bellows 202. Should a malfunction occur in the electronics and a continuous sequence of rapid pulses be introduced to the pulsing coil 204, causing the plate 206 to reciprocate, the return of the plate 206 to its original position against the backstop member 210 would be inhibited once the pressure in the stoing means 200 exceeded PmaX. The pressure builds up rapidly because of the output flow resistance caused by the ceramic filter 218. The possibility of introducing drugs or other medication at an unsafe high pressure or high rate is thus essentially eliminated.
An outlet pressure valve 212 connects the storing means 200 in the pulsatile pump 208 with an outlet chamber 214. In operation, when the plate 206 returns toward its original position against backstop 210 after being reciprocated by the action of the pulsing coil 204 and the bellows 202, an 3~
increase in pressure in the stoeing means 200 results. When the pressure differential between the peessure in the storing means 200 and the pressure in outlet chamber 214 exceeds that required to open outlet pressure valve 212, medication flows into outlet chamber 214 from the medication storing means 200. To prevent lacge spurts or pulses of medication from entering the body over a short period of time, an elastic wall 216 and an output ceramic filter 218 are provided a the entrance to the outlet 220 of outlet chamber 214. The output ceramic filter 218 serves to resist the flow of medication from the outlet chamber 214 into the living body. The elastic wall 216 acts as a type of capacitance to flow, deforming when a pulse of medication is fed ino the outlet chamber 214, the elastic wall 216 thus serving as a fluid accumulator. The combination of the elastic wall 216 and the output ceramic filtec 218 comprises a fluid or mechanical RC network that provides medication into the body within an initial rise followed by a decaying flow. The time constant which is fairly long, is determined by the elasticity of the elastic wall 216 and the resistance of the output ceramic filter 218.
In addition, the output ceramic filter 218 disallows medication from being diffused into the body at a high rate, should both the interface pressure valve 26 and the outlet eressure valve 212 fail to seal.
Should valve 212, leak, there would be a slow diffusion of rnedication through the cecamic filter 218 until the pressure in the stocing means 200 is essentially equal to ~23~Z13;~ , ambient body pressure. However, since the volume means 200 is very small and since the medication fluid i5 essentially incompressible, very little medication can diffuse out and that amount only at a slow rate. Should both valve 26 and 212 leak, body fluids would then diffuse into the ressrvoir 18 because it is at a pressure below body ambient pressure. A
rise in pressure in the medication reseevoir 18 relative to that of the ambient body pressuce would cause the -1 psig switch to be activated setting off an alarm. Further, the medication then could not difuse through the outlet ceramic filter 218 at an unsafe eate because there is no pressure differential across the flow resistance of the ceramic filter 218.
Safety of the output is best understood by considering the various eressure levels in the pulsatile pump 28. With a bellows sering force which gives a maximum pressure, Pmax~ f 15 psig and with an outlet pressure valve droe of 5 esi, it is possible for the pulsatile pump 28 to provide a pressure as high as 10 psig in the outlet chamber 214. The pressure in the outlet chamber 214 is significantly greater than the body ambient pressure of approximately 0 psig or the diastolic blood pressure which is approximately 2 psig. The resistance of the output ceramic filter 218 is selected to limit the drug flow to a given safe level, for example less than 50% the maximum pumping flow at which the pulsatile pump 28 is designed to operate. As with the inlet ceramic jilter 12 (of FIG.2) the outlet ceramic filter 218 also filters out contaminants moving ~L~31~Z
in either direction, feom the outlet chamber 21~ into the body or from the body into the outlet chamber 21q. Also included in the pulsatile pump 28 is a pressure transducer 222 which is shown located in the outlet chamber 214 but could be located wherevec it could detect and respond to a pressure change corresponding to medication being pumped from the pump 28.
The pressure transducer 222 produces an electrical outeut when a pressure pulse ox medication enters the outlet chamber 214.
The pressure transducer ~Z2, in other words, detects the pressure pulses which are provided each time the spring bellows 202 returns the plate 206 to its original position against backstop 210. By comparing the pulsing from pulsing coil 204 with the pulsing generated by pressure transducer 222, an indication is given as to whether an absence or insufficient number of pulses or medication have been provided to the body. An indication of extra pulses of medication compared to the number of electrical eulses may also be provided.
The pulsing signal to eulsing coil 20~ as well as the pulse output from the pressure transducer 222 are better understood with reverence to FIG. 5 a block diagram of the electronics section 30 shown in FIGS. 2 and 3. As seen in FIG. 5, the electronics section 30 communicates with a communication head 300 which is external to the body, communicating through skin 5 by means of radio signals which includes an alternating magnetic field. The communications head 300 provides both power inputs and commands, including programmable inputs, to the electronics section 30. Power is 123~8Z
erovided by jeans of an alternating field, e.g., a magnetic field, which is communicated to a pickue coil 304 which is implanted together with the rest of the electronics section 30 in the body. The pickup coil 30~ receives an AC power signal from communications head 300 and passes it on to a full wave rectifier 306. One cectified output from the full wave reactifier 306 enters a battery charge control 308 which provides a fixed DC charging signal to a power cell 310. The power cell 310 can be a nickel-cadmium cell which is readily - lO cechargeable of a rectified signal at a typical frequency of 20 kHz. Altecnatively, a lithium-type solid state battery can be used instead of the nickel-cadmium cell in which case the charging circuity would be elimiated, the lithium-type battery providing sufficient power over a long term, thereby obviating the need for cecharging. The power cell 310 provides a biasing voltage to a transistor switch 312, the output of which enters the pulsing coil 204 previously described in the context of the eulsatile pump 28. In addition to providing power to the power cell 310, rectified power is also introduced to a DC
to DC converter 314 the purpose of which is to provide power at the proper levels to the various loads in the system. In addition to the AC power signal. pickue coil 304 also receives a train of serial digital bits from the communication head 300. The digital bits comprise commands for programmable inputs which are conveyed. via the pickup coil 304 to a command receiveL 316. The signals from the command receiver 316 enter a command decoder 318 which determines it the digital bits are lZ3îf~87~
in a p~opec sequence and, if so, what action in the syfitem the commands dictate. It should be noted that the full wave recti~ie~ 306, the battecy charge controller 308, the command -receiver 316, and the comand decoder 318 are powered only when an AC signal is picked up by the pickup coil 304. this, of course, erevents the possibility of detecting stray signals as commands and provides power savings. To be sure, the power savings achieved cou]d make eossible the use of the afocementioned lithium cell which would not required recharging. From the command decoder 318, programmable inputs and other commands can be provided to a number of elements. A
erogrammable base rate is entered into a base late memory unit 320 which stores a value indicating the number of pulses of medication which are requested to be provided to a patient during a normal preselected eeriod of time. A second programmable input is provided, namely, a patient controlled rate memory unit 322 which stores a value indicating a number of eulses of medication that are requested to be intLoduced into the body over a given period of time during which the patient eats a meal or otherwise alters the chemical balance of the body was by exercising). Associated with the base rate memory unit 320 is a hardwired base rate limit control 324 which sets a maximum rate that can override requests of the base rate memory unit 320 which are excessive. Similarly, a hardwired patient controlled rate limit control 326 provides a fixed maximum number ox pulses which can be provided at a time after a meal or at other times and under otheL conditions. AS
long as the ~23~
base cate and the patient controlled cate values stored in memory units 320 and 322 respectively, do not exceed the hacdwired values fixed within limit controls 324 and 326, respectively, an output pulse is provided to the input of transistor switch 312 to stimulate a pulse output from pulsing coil 204. Should the rate of either memory unit 320 or 322 exceed the hardwired limits in the limit contcol element6 324 or 326 respectively, a "rate request exceeds limit" signal is fed from the limit control element 324 or 326 into a programmable alaem generator 328 which provides an electrical signal to be stimulation electrode 330 implanted subcutaneously. By the stimulation electrode 330, the patient is informed by means of subcutaneous stimulation that one of the memocy units 320 or 322 is requesting more than the maximum allowable number of pulses.
It should be noted that the signal to the stimulation electrode 330 can serve the dual function of not only providing the patient with a subcutaneous electrical stimulation but may also be the source of a signal detected by the communication head 300 communicated to the patient or his physician either or both.that a failure has occuered. As shown in FIG. 5, the electrode 330 will be isolated and should be insulated from the outside of the hermetically sealed enlosure 34 of the implanted portion 2.
A particularly significant feature of the infusion system embracing the p[esent invention resides in the programmability of the alarm generator 328 based on input ;
8'~
commands from the command decode 31a. The alarm generator 328 can be switched on oc off and the voltage pcoduced by the genecator and hence the electrode 330 can be varied in response to signals emanating from the communication head 300 and channeled through the command receiver 316 to the command decoder 318. In addition, to check the proper operation of the system, the command decoder 31B can receive test signals which can simulate actual occurcances to determine whether the circuitry in the electronic section 30 is operating properly.
For example, extra pulses from trhe command decoder 318 can be entered into the hardwired limit control elements 324 and 326. These extra pulses can be added to the pulses pcovided by the base rate and the patient controlled rate memory units in order to exceed the hardwired base rate and the hardwired patient-controlled rate, respectively. When the rates are exceeded, the alarm generator 328 will provide a signal. In this way, the alarm generator 328 can be used to check the operation of the limit control elements 324 and 326 and also familiarize the patent with the corresponding subcutaneous emitted by the tickle electrode 330. The programmable alarm generator 328 also receives inputs from the pressure switch 22 and the fluid detector 35 both shown in FIG. 2. If body fluids leak into the resecvoir 18, the pressure switch 25 will be activated, indicating this fault condition to the patient by means of the activation of the alarm generator 328 and the electrode 330. If the patient was unconscious, voltage levels on the patients skin at the site of the inplanted portion 2 ~23~
could be used by the phsyician to indicate if a malfunction has occurred and which malfunction it was. Fuether, as previously desc{ibed, should fluid leak out of the reservoir chamber 10 and onto the lining of the enclosure 3~ or, alternatively, if body fluid should leak in through the enclosure 34, the fluid detector 35 would sense such leakage and, as shown in FIG. 5, would provide ineut to the alarm geneeator 328. Still another input to the alarm generator 320 comes from the power cell 310 associated with transistoc switch 312. The voltage level of the powee cell 310 is communicated to the alarm generator 328,.
a tickle or subcutaneous stimulation being generated when the voltage is below a predeteLmined level. Finally, referring back to the pulsatile pump 28 of FIG. 4, the electrical pressure transducer 222 provides a signal which is compared to a programmed "insufficient rate" value emanating from the command decoder 318. If the number of pulses sensed by the pressure transducer 222 over a specified period of time are less than the number of pulses associated with the "insufficient cate" command input, a pulse rate detector 332 will pLovide an output indicating that an insufficient amount of medication is being provided to the patient over the specified time. The output of pulse rate detector 332 (FIG.
5) also enters the tickle generator 328 to provide a subcutaneous tickle detectable by the patient. It should be noted that the various mentioned failures in the system result in subcutaneous stimulations each of which may be different in stimulation magnitude, duration, or eeriodicity. For example, ;~3~
the stimulation may range between one to your volts and may vary in frequency above and below 20 pulses per second and most importantly. a variety of pulse patteens may be used each unique to a particular malfunction or warning. Additional warnings that might be used are: (1) medication has leaked into the liquid-vapor volume, ~2) only 10~ of the medication remains in the reservoir, (3) only 5 days medication remains.
In addition to eulsing the pump coil 20~, the outputs of the limit control elements 324 and 326 also provide input to a pulse cecorder 334. Pulse recorder 334 maintains a running history of how many electrical pulses have been provided to the pulsatile eump 28 since the last refill of the reservoir 18 (in FIG. 1). An "interrogate" signal from the command decoder 318 instructs the pulse recorder 334 to provide the history to a telemetcy transmitter 336 which communicates the pulse history to a telemetry coil 338. The pulse recorder 334 would record both the number of pulses delivered to the pumping coil 204 and the number of eulses detected by the pressure transducer 222 and/or the diffecence between these two numbers. The telemetry coil 338, in turn, provides its output through radio frequency signals to a telemetry receiving antenna in the communication head 300. In addition to the eulse history the telemetry tansmitter 336 also receives, during programming, inputs prom the base rate memocy unit 320 and patient controlled rate memocy unit 322 which are transmitted back to the communcation head 300 indicating that the desired base rate - and patient controlled rate, respectively, have been programmed ~ILZ3~
in the corcesponding memory unit 32 oc 322. Similarly, othec key parameters 337 o the system are also conveyed by means of the telemetry tcansmitter 336 back to the communication head 300. Foc example, the exact pcessure tcansducer output wavefocm would be telemetered. Of course, the pressure waveform signal would be transmitted when the telemetry system is powered. Similarly, the ceservoir fill switeh 23 elaced in the reservoir chamber 10 to indicate when it has ceached a predetermined fill level is also connected via the telemetcy transmitter 336 and telemetry coil 338 to the communication head 300 to indicate when the reservoir 18 has been filled with medieation. Finally, a simulated low battery voltage signal can be eonveyed from the command decoder 318 to the telemetry transmitter 336 to check that portion of the status circuitry. As with the full wave cectifiec 306, battery eharge contLol 308, command receiver 316, and command decoder 31a, the telemetcy tcansmittec 336 is powered only ducing pcogramming, interrogation, testing with simulation signals, and power cell charging.
Reference is now made to FIG. 6 which shows a method of erogramming the patient controlled memory untit 322. The significance of the method lies in the act that it provides two maximum running integral dose limits in response Jo requests for medication. Two maximum integral number of pulses for two different time periods are provided. Both are independent o the time of day and therefore would be effective regardless of the patients eating or working schedule, which schedule change might be a result of the patient changing time zones. In the sample graph ox FIG. 6, a maximum of eight pulses for a four hour period and twenty-four pulses for any ~wenty-our hour period are imposed as maximum running integral dose limits. These rate settings can, of course, be altered depending on patient needs and medication to be administered and time periods other than four hours or Z4 hours could be used. In FIG. 6, the number of pulses is shown as function of time.
In Fig. 6, at midnight, the number of pulses that are allowed in the four hour period is eight. Shortly after 8 A.M. five pulses are requested diminishing the number of additional pulses allowed to three pulses. Prior to noon, within the four hour time period, a five pulse request is entered. In accordance with the maximum running integral four hour restraint, only three pulses are permitted but the remaining two pulses in the request are stored in the memory unit 322 (FIG. 5) to be executed at the end of the four hour period beginning immediately after four hours past the delivery time for the after breakfast pulsing. Shortly after noon, when the four hours are over the two pulses are executed. It should be noted that shortly after noon the three pulses provided just before noon were subtracted from the eight pulse allowance. The dispensing of three pulses prior to noon is not eradicated until four hours thereafter, or shortly before 4 P.M. Shortly before 4 P.M. the three pulse allowance is automatically raised to six pulses, accounting for the three 1~3~
pulses executed just before noon. Shortly after 4 P.M., the allowance automatically rises to eight pulses thereby accounting for the two pulses executed shortly after noon. At approximately 6 P.M. the patient has dinner requiring five pulses and the allowance diminishes to three pulses. Shortly before 10 P.M. the patient has a snack which requices two pulses of medication diminishing the allowance to one pulse.
At appeoximately 10 P.M. the five pulses provided at dinner are no longer of impoct and the allowance is raised by those five pulses to a six pulse level allowance. The importance of FIG.
5 i8 readily apparent when one considers the various time zones or work schedules a patient may go through fcom time to time in the course of his life. The program in FIG. 6 provides sufficient safety and flexibility for a wide variety of patients.
Referring now to FIG. 7, the front view of a patient programming unit 400 is shown. In the center of the unit is a dial 402 which can be rotated to indicate,the size of a meal eaten by the patient or the amount of exercise he had undergone, in ordec to provide inputs indicating the amount of medication needed. Output from the patient programming unit 400 is detected by the pickup coil 304 of FIG. 5 as commands.
Whether oc not the request is valid is determined in the electronic section 30 and is conveyed back to the patient programming unit 400 by telemetry. A signal by the patient pcogcamming unit 400 to the patient indicates whether his request has been satisfied. The patient programming unit 400 ~3~
will be provided both with audio and visual outputs cendering it particulacly useful for those patients having either visual or heacing handicaps.
In FIG. 8 is the rear view of the patient programming unit 400. The cear side of the patient p~oyramming unit 400 will provide in~ocmation indicating the number of pulses sent a the last cequest 403; the time of the last cequest 404: and possibly (but is not shown) the number of pulses which can be sent within the program restraints. By programming ROMS (not shown) in the patient programming unit 400 in accordance with the running integral programs shown in FIG. 5 an "OK" or "TOO
MUCH REQUESTED" video and/or audible output can be provided.
The audio output would emanate from the loudspeaker 405. When the request leads to the dispensing of a pulse oe pulses of medication into the outlet chambert, a "MEDICATION SENT" signal from the implanted poction 2 i6 relayed to the patient programming unit 400 to actuate an audio indication by loudspeaker 405 or by visual means.
It should be undecstood that alternative embodiments are contemplated for the infusion system embraeing the present invention. Foc example, the antechamber 8 can compcise a vitreous carbon insert in the skull, oc other suitable, accessible place on the body, coupled with a tube direeted to the reservoic chamber 10 which may be located in the torso.
The filling pcocedure and elements ox antechambec 8 (e.g., the septum 6) would cemain the same with the vitceous cacbon insect. The inlet pressuce valve 14 and ~iltec 12 would still lZ3~
separate the insert and tube fcom the reservoir chamber 10.
Similarly, in addition to the patient progcamming unit 500, a physician's unit may be provided which indicates: when the medication reservoir lB (of FIG. 1) has been filled, the pulse history from the pulse recorder 334, and other signals from the telemetry transmitter 336 of FIG. 4. Such a physician'6 unit would be connected to the telemetry portion of the communication head 300.
,,
In order to fill the reservoir chamber 10 with medication, a sequence of steps is followed. The antechamber 8 is normally filled with a saline or other innocuous solution which povides a buffer between the body and the reservoir chamber 10 and which if the septum failed would cause no harm to the patient. it the time of filling, a double hypodermic syringe 4 is directed into the antechamber 8 and saline is intcoduced into the antechamber 8 through one needle and exits through the other in order to flush the antechamber 8 with more saline. Once flushed, the antechamber 8 is checked for pressure integrity with saline introduced under a pressure which is less than that cequired to open the inlet pressure valve 14. When pressure integrity is determined, the antechambec 8 is flushed with the desiced medication (e.g.
insulin). Medication is then forced into the antechamber 8 at a pressure greater than that required to open inlet pressure valve 14. The insulin fills the medication reservoir 18 ox the reservoir chamber 10 until the flexible membrane 20 ~'~331L~
contacts the dual pressure switch Z2, ~occing the reser~roir Jill switch 23, to generate a signal (e.g. at -2 psig~ which indicates that the filling has been completed. The amount of medication required to fill the medication reservoir 18 is noted and then the antechamber 8 is slushed once again with innocuous saline solution. The entire reservoir chamber lO is surrounded by a wall 24 and is isolated from the other elements of the system by means of the inlet pressuee valve 14 and an interface pressure valve 26 which connects the reservoir to a pulsatile pup 23 which is shown in FIG. 4. The remaining elements of the implanted portion 2 are also shown in FIG. 2:
an electronics section 30 with a battecy subsection 32. As is already seen in FIG. 2, a hermetically sealed enclosure 34 surrounds the reservoir chamber lO as well as the pulsatile pump 28 (see FIG. 4) and the electronics section 30 with the battery subsection 32. To provide an enhanced safety feature, a fluid detector 35 is pLovided between the wall 24 and the hermetically sealed enclosuee 34. Should either the outer hermetic enclosuee 34 leak or should the reservoie chamber lO
leak, the 1uid detector 35 is placed at a location where the leaking body 1uids or medication would be detected. The fluid detector 35 could be a very high resistance resistor (e.g. lO megohms) whose resistance drops significantly in the presence of fluids. A malfunction signal to warn the patient if such a leak is detected, is provided. Similaely, a medication leakage detector 37 in the liquid-vapor volume 16 would indicate when medication was leaking into that chamber ~L~3~
l This detector may also be a resistoc whose value will be significantly altered by the presence of the medication. The medication leakage detector 37 when actuated would set off a distinct subcutaneous electcical stimulation alarm signal that can be detected by the patient FIG. 4 illustrates the pulsatile pump 28 shown in the top vi.ew o the implanted poetion 2 shown in FIG. 3. The interface pressure valve 26 shows where medication enters the pulsatile pump 28 when the diferential in pressuce between the reservoir chamber 10 and a medication storing means 200 (inside the eulsatile pume 28) reaches a level sufficient to open the inlet pressure valve 26. In the preferred embodiment shown in FIG. 4, this differential in pressure is caused by the expansion of a spring bellows 202 in response to an electrical pulse introduced to a pulsing coil 204 which surrounds a plate 206 which is attached to the spcing bellows 202. When a pulse passes through the pulsing coil Z04, plate 206 is driven to a forward stop 208. This action of expanding the storing means 200 causes the interface pcessure valve 26 to open, thereby allowing medication from the reservoir chamber 10 to fill the medication storing means 200. The plate 206 is a permanent magnet (or, possibly, a magnetizable material) which moves in response to a curcent induced magnetic force. When current in the pulsing coil 204 ceases, the spring focce of the bellows 202 cetucns the plate 206 to a position against a backstop member 210. The amount of tcavel of plate 206 is thus fixed, rendering the stcoke volume of the pulsatile pump 2~ constant 3~
and independent of the electrical pulse current oe pulse width into the pulsing coil 20~ as long as certain minimum currents and pulse width is provided. The maximum pressure that can be exerted by the pulsatile pump 28 is dependent on the spring force that can be exerted by the bellows 202 as well as the cross section area of plate 206 which is in contact with the medication in the storing means 200. More simply, PmaX=F/A
where Pmax is the maximum pressure that can be created by the spring force of the bellows within the medication storing means 200, F is the spring force of bellows 202, and A is the portion of surface of plate 206 which is in contact with the medication in the medication storing means 200 which extends into the bellows 202. Should a malfunction occur in the electronics and a continuous sequence of rapid pulses be introduced to the pulsing coil 204, causing the plate 206 to reciprocate, the return of the plate 206 to its original position against the backstop member 210 would be inhibited once the pressure in the stoing means 200 exceeded PmaX. The pressure builds up rapidly because of the output flow resistance caused by the ceramic filter 218. The possibility of introducing drugs or other medication at an unsafe high pressure or high rate is thus essentially eliminated.
An outlet pressure valve 212 connects the storing means 200 in the pulsatile pump 208 with an outlet chamber 214. In operation, when the plate 206 returns toward its original position against backstop 210 after being reciprocated by the action of the pulsing coil 204 and the bellows 202, an 3~
increase in pressure in the stoeing means 200 results. When the pressure differential between the peessure in the storing means 200 and the pressure in outlet chamber 214 exceeds that required to open outlet pressure valve 212, medication flows into outlet chamber 214 from the medication storing means 200. To prevent lacge spurts or pulses of medication from entering the body over a short period of time, an elastic wall 216 and an output ceramic filter 218 are provided a the entrance to the outlet 220 of outlet chamber 214. The output ceramic filter 218 serves to resist the flow of medication from the outlet chamber 214 into the living body. The elastic wall 216 acts as a type of capacitance to flow, deforming when a pulse of medication is fed ino the outlet chamber 214, the elastic wall 216 thus serving as a fluid accumulator. The combination of the elastic wall 216 and the output ceramic filtec 218 comprises a fluid or mechanical RC network that provides medication into the body within an initial rise followed by a decaying flow. The time constant which is fairly long, is determined by the elasticity of the elastic wall 216 and the resistance of the output ceramic filter 218.
In addition, the output ceramic filter 218 disallows medication from being diffused into the body at a high rate, should both the interface pressure valve 26 and the outlet eressure valve 212 fail to seal.
Should valve 212, leak, there would be a slow diffusion of rnedication through the cecamic filter 218 until the pressure in the stocing means 200 is essentially equal to ~23~Z13;~ , ambient body pressure. However, since the volume means 200 is very small and since the medication fluid i5 essentially incompressible, very little medication can diffuse out and that amount only at a slow rate. Should both valve 26 and 212 leak, body fluids would then diffuse into the ressrvoir 18 because it is at a pressure below body ambient pressure. A
rise in pressure in the medication reseevoir 18 relative to that of the ambient body pressuce would cause the -1 psig switch to be activated setting off an alarm. Further, the medication then could not difuse through the outlet ceramic filter 218 at an unsafe eate because there is no pressure differential across the flow resistance of the ceramic filter 218.
Safety of the output is best understood by considering the various eressure levels in the pulsatile pump 28. With a bellows sering force which gives a maximum pressure, Pmax~ f 15 psig and with an outlet pressure valve droe of 5 esi, it is possible for the pulsatile pump 28 to provide a pressure as high as 10 psig in the outlet chamber 214. The pressure in the outlet chamber 214 is significantly greater than the body ambient pressure of approximately 0 psig or the diastolic blood pressure which is approximately 2 psig. The resistance of the output ceramic filter 218 is selected to limit the drug flow to a given safe level, for example less than 50% the maximum pumping flow at which the pulsatile pump 28 is designed to operate. As with the inlet ceramic jilter 12 (of FIG.2) the outlet ceramic filter 218 also filters out contaminants moving ~L~31~Z
in either direction, feom the outlet chamber 21~ into the body or from the body into the outlet chamber 21q. Also included in the pulsatile pump 28 is a pressure transducer 222 which is shown located in the outlet chamber 214 but could be located wherevec it could detect and respond to a pressure change corresponding to medication being pumped from the pump 28.
The pressure transducer 222 produces an electrical outeut when a pressure pulse ox medication enters the outlet chamber 214.
The pressure transducer ~Z2, in other words, detects the pressure pulses which are provided each time the spring bellows 202 returns the plate 206 to its original position against backstop 210. By comparing the pulsing from pulsing coil 204 with the pulsing generated by pressure transducer 222, an indication is given as to whether an absence or insufficient number of pulses or medication have been provided to the body. An indication of extra pulses of medication compared to the number of electrical eulses may also be provided.
The pulsing signal to eulsing coil 20~ as well as the pulse output from the pressure transducer 222 are better understood with reverence to FIG. 5 a block diagram of the electronics section 30 shown in FIGS. 2 and 3. As seen in FIG. 5, the electronics section 30 communicates with a communication head 300 which is external to the body, communicating through skin 5 by means of radio signals which includes an alternating magnetic field. The communications head 300 provides both power inputs and commands, including programmable inputs, to the electronics section 30. Power is 123~8Z
erovided by jeans of an alternating field, e.g., a magnetic field, which is communicated to a pickue coil 304 which is implanted together with the rest of the electronics section 30 in the body. The pickup coil 30~ receives an AC power signal from communications head 300 and passes it on to a full wave rectifier 306. One cectified output from the full wave reactifier 306 enters a battery charge control 308 which provides a fixed DC charging signal to a power cell 310. The power cell 310 can be a nickel-cadmium cell which is readily - lO cechargeable of a rectified signal at a typical frequency of 20 kHz. Altecnatively, a lithium-type solid state battery can be used instead of the nickel-cadmium cell in which case the charging circuity would be elimiated, the lithium-type battery providing sufficient power over a long term, thereby obviating the need for cecharging. The power cell 310 provides a biasing voltage to a transistor switch 312, the output of which enters the pulsing coil 204 previously described in the context of the eulsatile pump 28. In addition to providing power to the power cell 310, rectified power is also introduced to a DC
to DC converter 314 the purpose of which is to provide power at the proper levels to the various loads in the system. In addition to the AC power signal. pickue coil 304 also receives a train of serial digital bits from the communication head 300. The digital bits comprise commands for programmable inputs which are conveyed. via the pickup coil 304 to a command receiveL 316. The signals from the command receiver 316 enter a command decoder 318 which determines it the digital bits are lZ3îf~87~
in a p~opec sequence and, if so, what action in the syfitem the commands dictate. It should be noted that the full wave recti~ie~ 306, the battecy charge controller 308, the command -receiver 316, and the comand decoder 318 are powered only when an AC signal is picked up by the pickup coil 304. this, of course, erevents the possibility of detecting stray signals as commands and provides power savings. To be sure, the power savings achieved cou]d make eossible the use of the afocementioned lithium cell which would not required recharging. From the command decoder 318, programmable inputs and other commands can be provided to a number of elements. A
erogrammable base rate is entered into a base late memory unit 320 which stores a value indicating the number of pulses of medication which are requested to be provided to a patient during a normal preselected eeriod of time. A second programmable input is provided, namely, a patient controlled rate memory unit 322 which stores a value indicating a number of eulses of medication that are requested to be intLoduced into the body over a given period of time during which the patient eats a meal or otherwise alters the chemical balance of the body was by exercising). Associated with the base rate memory unit 320 is a hardwired base rate limit control 324 which sets a maximum rate that can override requests of the base rate memory unit 320 which are excessive. Similarly, a hardwired patient controlled rate limit control 326 provides a fixed maximum number ox pulses which can be provided at a time after a meal or at other times and under otheL conditions. AS
long as the ~23~
base cate and the patient controlled cate values stored in memory units 320 and 322 respectively, do not exceed the hacdwired values fixed within limit controls 324 and 326, respectively, an output pulse is provided to the input of transistor switch 312 to stimulate a pulse output from pulsing coil 204. Should the rate of either memory unit 320 or 322 exceed the hardwired limits in the limit contcol element6 324 or 326 respectively, a "rate request exceeds limit" signal is fed from the limit control element 324 or 326 into a programmable alaem generator 328 which provides an electrical signal to be stimulation electrode 330 implanted subcutaneously. By the stimulation electrode 330, the patient is informed by means of subcutaneous stimulation that one of the memocy units 320 or 322 is requesting more than the maximum allowable number of pulses.
It should be noted that the signal to the stimulation electrode 330 can serve the dual function of not only providing the patient with a subcutaneous electrical stimulation but may also be the source of a signal detected by the communication head 300 communicated to the patient or his physician either or both.that a failure has occuered. As shown in FIG. 5, the electrode 330 will be isolated and should be insulated from the outside of the hermetically sealed enlosure 34 of the implanted portion 2.
A particularly significant feature of the infusion system embracing the p[esent invention resides in the programmability of the alarm generator 328 based on input ;
8'~
commands from the command decode 31a. The alarm generator 328 can be switched on oc off and the voltage pcoduced by the genecator and hence the electrode 330 can be varied in response to signals emanating from the communication head 300 and channeled through the command receiver 316 to the command decoder 318. In addition, to check the proper operation of the system, the command decoder 31B can receive test signals which can simulate actual occurcances to determine whether the circuitry in the electronic section 30 is operating properly.
For example, extra pulses from trhe command decoder 318 can be entered into the hardwired limit control elements 324 and 326. These extra pulses can be added to the pulses pcovided by the base rate and the patient controlled rate memory units in order to exceed the hardwired base rate and the hardwired patient-controlled rate, respectively. When the rates are exceeded, the alarm generator 328 will provide a signal. In this way, the alarm generator 328 can be used to check the operation of the limit control elements 324 and 326 and also familiarize the patent with the corresponding subcutaneous emitted by the tickle electrode 330. The programmable alarm generator 328 also receives inputs from the pressure switch 22 and the fluid detector 35 both shown in FIG. 2. If body fluids leak into the resecvoir 18, the pressure switch 25 will be activated, indicating this fault condition to the patient by means of the activation of the alarm generator 328 and the electrode 330. If the patient was unconscious, voltage levels on the patients skin at the site of the inplanted portion 2 ~23~
could be used by the phsyician to indicate if a malfunction has occurred and which malfunction it was. Fuether, as previously desc{ibed, should fluid leak out of the reservoir chamber 10 and onto the lining of the enclosure 3~ or, alternatively, if body fluid should leak in through the enclosure 34, the fluid detector 35 would sense such leakage and, as shown in FIG. 5, would provide ineut to the alarm geneeator 328. Still another input to the alarm generator 320 comes from the power cell 310 associated with transistoc switch 312. The voltage level of the powee cell 310 is communicated to the alarm generator 328,.
a tickle or subcutaneous stimulation being generated when the voltage is below a predeteLmined level. Finally, referring back to the pulsatile pump 28 of FIG. 4, the electrical pressure transducer 222 provides a signal which is compared to a programmed "insufficient rate" value emanating from the command decoder 318. If the number of pulses sensed by the pressure transducer 222 over a specified period of time are less than the number of pulses associated with the "insufficient cate" command input, a pulse rate detector 332 will pLovide an output indicating that an insufficient amount of medication is being provided to the patient over the specified time. The output of pulse rate detector 332 (FIG.
5) also enters the tickle generator 328 to provide a subcutaneous tickle detectable by the patient. It should be noted that the various mentioned failures in the system result in subcutaneous stimulations each of which may be different in stimulation magnitude, duration, or eeriodicity. For example, ;~3~
the stimulation may range between one to your volts and may vary in frequency above and below 20 pulses per second and most importantly. a variety of pulse patteens may be used each unique to a particular malfunction or warning. Additional warnings that might be used are: (1) medication has leaked into the liquid-vapor volume, ~2) only 10~ of the medication remains in the reservoir, (3) only 5 days medication remains.
In addition to eulsing the pump coil 20~, the outputs of the limit control elements 324 and 326 also provide input to a pulse cecorder 334. Pulse recorder 334 maintains a running history of how many electrical pulses have been provided to the pulsatile eump 28 since the last refill of the reservoir 18 (in FIG. 1). An "interrogate" signal from the command decoder 318 instructs the pulse recorder 334 to provide the history to a telemetcy transmitter 336 which communicates the pulse history to a telemetry coil 338. The pulse recorder 334 would record both the number of pulses delivered to the pumping coil 204 and the number of eulses detected by the pressure transducer 222 and/or the diffecence between these two numbers. The telemetry coil 338, in turn, provides its output through radio frequency signals to a telemetry receiving antenna in the communication head 300. In addition to the eulse history the telemetry tansmitter 336 also receives, during programming, inputs prom the base rate memocy unit 320 and patient controlled rate memocy unit 322 which are transmitted back to the communcation head 300 indicating that the desired base rate - and patient controlled rate, respectively, have been programmed ~ILZ3~
in the corcesponding memory unit 32 oc 322. Similarly, othec key parameters 337 o the system are also conveyed by means of the telemetry tcansmitter 336 back to the communication head 300. Foc example, the exact pcessure tcansducer output wavefocm would be telemetered. Of course, the pressure waveform signal would be transmitted when the telemetry system is powered. Similarly, the ceservoir fill switeh 23 elaced in the reservoir chamber 10 to indicate when it has ceached a predetermined fill level is also connected via the telemetcy transmitter 336 and telemetry coil 338 to the communication head 300 to indicate when the reservoir 18 has been filled with medieation. Finally, a simulated low battery voltage signal can be eonveyed from the command decoder 318 to the telemetry transmitter 336 to check that portion of the status circuitry. As with the full wave cectifiec 306, battery eharge contLol 308, command receiver 316, and command decoder 31a, the telemetcy tcansmittec 336 is powered only ducing pcogramming, interrogation, testing with simulation signals, and power cell charging.
Reference is now made to FIG. 6 which shows a method of erogramming the patient controlled memory untit 322. The significance of the method lies in the act that it provides two maximum running integral dose limits in response Jo requests for medication. Two maximum integral number of pulses for two different time periods are provided. Both are independent o the time of day and therefore would be effective regardless of the patients eating or working schedule, which schedule change might be a result of the patient changing time zones. In the sample graph ox FIG. 6, a maximum of eight pulses for a four hour period and twenty-four pulses for any ~wenty-our hour period are imposed as maximum running integral dose limits. These rate settings can, of course, be altered depending on patient needs and medication to be administered and time periods other than four hours or Z4 hours could be used. In FIG. 6, the number of pulses is shown as function of time.
In Fig. 6, at midnight, the number of pulses that are allowed in the four hour period is eight. Shortly after 8 A.M. five pulses are requested diminishing the number of additional pulses allowed to three pulses. Prior to noon, within the four hour time period, a five pulse request is entered. In accordance with the maximum running integral four hour restraint, only three pulses are permitted but the remaining two pulses in the request are stored in the memory unit 322 (FIG. 5) to be executed at the end of the four hour period beginning immediately after four hours past the delivery time for the after breakfast pulsing. Shortly after noon, when the four hours are over the two pulses are executed. It should be noted that shortly after noon the three pulses provided just before noon were subtracted from the eight pulse allowance. The dispensing of three pulses prior to noon is not eradicated until four hours thereafter, or shortly before 4 P.M. Shortly before 4 P.M. the three pulse allowance is automatically raised to six pulses, accounting for the three 1~3~
pulses executed just before noon. Shortly after 4 P.M., the allowance automatically rises to eight pulses thereby accounting for the two pulses executed shortly after noon. At approximately 6 P.M. the patient has dinner requiring five pulses and the allowance diminishes to three pulses. Shortly before 10 P.M. the patient has a snack which requices two pulses of medication diminishing the allowance to one pulse.
At appeoximately 10 P.M. the five pulses provided at dinner are no longer of impoct and the allowance is raised by those five pulses to a six pulse level allowance. The importance of FIG.
5 i8 readily apparent when one considers the various time zones or work schedules a patient may go through fcom time to time in the course of his life. The program in FIG. 6 provides sufficient safety and flexibility for a wide variety of patients.
Referring now to FIG. 7, the front view of a patient programming unit 400 is shown. In the center of the unit is a dial 402 which can be rotated to indicate,the size of a meal eaten by the patient or the amount of exercise he had undergone, in ordec to provide inputs indicating the amount of medication needed. Output from the patient programming unit 400 is detected by the pickup coil 304 of FIG. 5 as commands.
Whether oc not the request is valid is determined in the electronic section 30 and is conveyed back to the patient programming unit 400 by telemetry. A signal by the patient pcogcamming unit 400 to the patient indicates whether his request has been satisfied. The patient programming unit 400 ~3~
will be provided both with audio and visual outputs cendering it particulacly useful for those patients having either visual or heacing handicaps.
In FIG. 8 is the rear view of the patient programming unit 400. The cear side of the patient p~oyramming unit 400 will provide in~ocmation indicating the number of pulses sent a the last cequest 403; the time of the last cequest 404: and possibly (but is not shown) the number of pulses which can be sent within the program restraints. By programming ROMS (not shown) in the patient programming unit 400 in accordance with the running integral programs shown in FIG. 5 an "OK" or "TOO
MUCH REQUESTED" video and/or audible output can be provided.
The audio output would emanate from the loudspeaker 405. When the request leads to the dispensing of a pulse oe pulses of medication into the outlet chambert, a "MEDICATION SENT" signal from the implanted poction 2 i6 relayed to the patient programming unit 400 to actuate an audio indication by loudspeaker 405 or by visual means.
It should be undecstood that alternative embodiments are contemplated for the infusion system embraeing the present invention. Foc example, the antechamber 8 can compcise a vitreous carbon insert in the skull, oc other suitable, accessible place on the body, coupled with a tube direeted to the reservoic chamber 10 which may be located in the torso.
The filling pcocedure and elements ox antechambec 8 (e.g., the septum 6) would cemain the same with the vitceous cacbon insect. The inlet pressuce valve 14 and ~iltec 12 would still lZ3~
separate the insert and tube fcom the reservoir chamber 10.
Similarly, in addition to the patient progcamming unit 500, a physician's unit may be provided which indicates: when the medication reservoir lB (of FIG. 1) has been filled, the pulse history from the pulse recorder 334, and other signals from the telemetry transmitter 336 of FIG. 4. Such a physician'6 unit would be connected to the telemetry portion of the communication head 300.
,,
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. A programmable infusion system for providing medication to a living body of a patient, comprising an infusion apparatus including a medication reservoir for storing selected medication, infusion means for infusing said selected medication stored in said resevoir into said living body, said infusion means having a fluid handling mechanism for delivering said selected medication and pumping means for pumping said selected medication, wherein said pumping means operates in a pulsatile mode, and said pumping means includes flow shaping means connected to its output for shaping the output flow of medication from said pumping means.
2. system according to Claim 1, wherein said flow shaping means comprises an output accumulator chamber for causing a fluidic capacitive effect on the flow of said selected medication, and a flow restricting element through which liquid flowing to the said living body is resisted, said output accumulator chamber and said flow restricting element comprising a fluid resistive/capacitive arrangement for smoothing the pulsatile nature of the flow of said selected medication into said living body.
3. A system in accordance with Claims 1 or 2, wherein said flow shaping means provides an inhibiting means for inhibiting said pumping means when pressure in said outlet accumulator chamber exceeds a preselected pressure limit.
4. A system in accordance with Claims 1 or 2, wherein said infusion apparatus is adapted for implantation in said living body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000486993A CA1231282A (en) | 1982-12-17 | 1985-07-17 | Pumping means for programmable infusion system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000417979A CA1193934A (en) | 1982-12-17 | 1982-12-17 | Implantable programmable medication infusion system |
| CA000486993A CA1231282A (en) | 1982-12-17 | 1985-07-17 | Pumping means for programmable infusion system |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000417979A Division CA1193934A (en) | 1982-12-17 | 1982-12-17 | Implantable programmable medication infusion system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1231282A true CA1231282A (en) | 1988-01-12 |
Family
ID=4124170
Family Applications (4)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000417979A Expired CA1193934A (en) | 1982-12-17 | 1982-12-17 | Implantable programmable medication infusion system |
| CA000486976A Expired CA1231281A (en) | 1982-12-17 | 1985-07-17 | Inhibiting means for programmable infusion system |
| CA000486993A Expired CA1231282A (en) | 1982-12-17 | 1985-07-17 | Pumping means for programmable infusion system |
| CA000486992A Expired CA1206832A (en) | 1982-12-17 | 1985-07-17 | Alarm means for programmable infusion system |
Family Applications Before (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000417979A Expired CA1193934A (en) | 1982-12-17 | 1982-12-17 | Implantable programmable medication infusion system |
| CA000486976A Expired CA1231281A (en) | 1982-12-17 | 1985-07-17 | Inhibiting means for programmable infusion system |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000486992A Expired CA1206832A (en) | 1982-12-17 | 1985-07-17 | Alarm means for programmable infusion system |
Country Status (1)
| Country | Link |
|---|---|
| CA (4) | CA1193934A (en) |
-
1982
- 1982-12-17 CA CA000417979A patent/CA1193934A/en not_active Expired
-
1985
- 1985-07-17 CA CA000486976A patent/CA1231281A/en not_active Expired
- 1985-07-17 CA CA000486993A patent/CA1231282A/en not_active Expired
- 1985-07-17 CA CA000486992A patent/CA1206832A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CA1231281A (en) | 1988-01-12 |
| CA1206832A (en) | 1986-07-02 |
| CA1193934A (en) | 1985-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4373527A (en) | Implantable, programmable medication infusion system | |
| EP0124546B1 (en) | Medication infusion system | |
| US4784645A (en) | Apparatus for detecting a condition of a medication infusion system and providing an informational signal in response thereto | |
| US8491547B2 (en) | Septum monitoring system and method for an implantable therapeutic substance delivery device | |
| US4360019A (en) | Implantable infusion device | |
| EP0387439B1 (en) | Implantable infusion device | |
| US6635049B1 (en) | Drug bolus delivery system | |
| US7887505B2 (en) | Flow condition sensor assembly for patient infusion device | |
| EP1649884B1 (en) | Implantable pump with detection of the placement of a refill instrument | |
| US6830558B2 (en) | Flow condition sensor assembly for patient infusion device | |
| US4871351A (en) | Implantable medication infusion system | |
| US7018360B2 (en) | Flow restriction system and method for patient infusion device | |
| EP3643343A1 (en) | Needle insertion responsive system | |
| GB2174218A (en) | Programmable infusion system for medication | |
| CA1231282A (en) | Pumping means for programmable infusion system | |
| JPS59115049A (en) | Administration program system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |