INFUSION SYSTEM

• US 3,731,679 A
• Filed: 10/19/1970
• Issued: 05/08/1973
• Est. Priority Date: 10/19/1970
• Status: Expired due to Term

• Current Assignee: Sherwood Medical Company (Medtronic Plc)
• Original Assignee: Jack L. Wilhelmson, Theodore E. Weichselbaum, Vernon F. Braun
• Inventors: Wilhelmson, Jack L., Weichselbaum, Theodore E., Braun, Vernon F.
• Primary Examiner(s): Truluck, Dalton L.
• Application Number:
  US05/081,926
• Time in Patent Office: 932 Days
• Field of Search: 128/213,214R,214E,214F,214B,214.2,218R,218A,230,234,273,DIG.1,DIG.12 417/45,411
• US Class Current: 604/121
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: F04B 17/03 driven by electric motors
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: F04B 9/02 the means being mechanical
• CPC Class Codes: H02P 7/2913 whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value
• CPC Class Codes: Y10S 128/01 Motorized syringe
• CPC Class Codes: Y10S 128/12 Pressure infusion
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A portable infusion system uses a disposable piston type syringe as a positive displacement pump. The syringe piston is reciprocally driven by a bidirectional DC motor under control of a battery powered circuit. Different selectable rates of pumping are maintained by controlling the width of bidirectional DC pulses coupled to the DC motor and by monitoring the motor back EMF during the off-time of the pulses. A disposable two-way valve connects the syringe pump with a fluid source and a catheter. Safety circuits protect against deleterious conditions such as the passage of an air bubble or an over-pressure condition.

Claims

1. In a portable infusion system for transferring fluid from a fluid source to a catheter, a positive displacement pumping system having disposable parts, comprising:

a self-contained source of DC power;

disposable syringe means having a barrel and a piston movable in said barrel along a path to move fluid within the barrel, said barrel having a fluid passage opening;

disposable valve means having a pump port in fluid communication with said passage opening, input port means connected with said fluid source for passing fluid to said barrel, and output port means for connection with said catheter for passing fluid to said catheter;

base means removably holding said syringe means and said valve means to allow disposal after use with a patient;

a holding member removably connected to said piston and mounted on said base for reciprocal movement along said path;

motor means energized by said DC power source for reciprocating said holding member and said piston, said motor means including gear means connected to said holding member to effect reciprocal movement of said holding member in response to rotation of said gear means, and a DC motor for rotating said gear means, means for selecting one of a plurality of rates of pumping including generator means for generating DC drive pulses having different duty cycles selectable to effect different rates of pumping, circuit means for coupling said DC drive pulses to said DC motor, and voltage variation compensation means including means responSive to decreasing voltage from said DC power source for increasing the duty cycle of at least some of said DC drive pulses.

2. The system of claim 1 wherein said DC motor is a bidirectional DC motor having an armature shaft rotatable in opposite directions when opposite polarity current is coupled to the DC motor, said gear means converting rotational movement of said armature shaft into translational movement which drives said holding member, and circuit means for periodically reversing the polarity of current passed from said DC power source to said DC motor.

3. The system of claim 1 wherein said valve means includes sensing means for detecting the presence of an air bubble, and safety means responsive to detection of an air bubble for terminating the operation of said motor means.

4. The system of claim 1 including over-pressure means for detecting when the pressure of fluid passed to said catheter exceeds a predetermined maximum, and indicator means actuated when said predetermined maximum is exceeded for providing an alarm indication.

5. In an infusion system for transferring fluid to catheter means, a pumping system comprising a source of fluid capable of passing electricity, a valve assembly having a fluid channel with an outlet adapted for connection with the catheter means for directing the flow of said fluid to the catheter means, fluid pump means including a chamber connected in fluid communication with said fluid source and said fluid channel, and drive means in said chamber actuable to effect movement of fluid from said fluid source and pump fluid through said fluid channel to the catheter means, unidirectional valve means connected in fluid communication with said fluid channel to permit fluid flow from said fluid channel to the catheter and prevent fluid flow from the catheter to said fluid channel, said fluid channel including a fluid passageway having a fluid opening contiguous with said fluid channel for admitting fluid into said passageway a distance determined by the pressure of the fluid in said fluid channel, and a pair of electrode means located within said fluid channel and having extensions connectable with an external circuit, at least one of said pair of electrode means being located in said passageway a predetermined distance from said fluid opening so that the presence of fluid at said last named electrode means indicates a predetermined fluid pressure condition.

6. The pumping system of claim 5 further including third electrode means in said channel adjacent the other of said pair of electrodes, and circuit means responsive to the presence of an air bubble between said third and other electrode means to provide a signal indicative thereof.

7. The pumping system of claim 5 wherein said fluid passageway has a closed end opposite said fluid opening for trapping a compressible gas between said closed end and the fluid admitted trough said fluid opening, said last named electrode means being surrounded by said compressible gas when the pressure of fluid in said fluid channel means is less than said predetermined pressure condition.

8. In an infusion system for transferring fluid to catheter means, a pumping system comprising a source of fluid capable of conducting electricity, a syringe having a barrel and a reciprocal plunger slidable in said barrel for moving fluid into and out of said barrel, a valve assembly having a fluid source inlet connected to said source of fluid, a pressure fluid inlet connected to said syringe barrel and in fluid communication with said fluid source inlet, and a channel connected in fluid communication with said pressure fluid inlet and having an outlet connectable with the catheter, first valve means connected in fluid communication with said source of fluid to permit fluid flow from said source to said syringe barrel and to prevent return fluid flow from said syringe barrel to said fluid source, second valve means connected in fluid communication with said channel to permit fluId flow from said channel to the catheter and prevent return fluid flow from the catheter to said channel, and means for reciprocating said plunger to draw fluid from said source into said barrel through said pressure fluid inlet during movement thereof in one direction and supply pressurized fluid to said channel from said barrel during movement thereof in the opposite direction to transfer the fluid to the catheter, said valve assembly including a pressure chamber connected at one end in fluid communication with said channel and closed at the opposite end thereof, an electrode within said chamber, gas disposed in said chamber normally between said electrode and said one end to prevent contact between said fluid and said electrode, said gas being compressible to permit said fluid to contact said electrode upon the occurrence of fluid pressure in said channel of a predetermined value, and circuit means connected with said electrode for detecting the contact between the fluid and said electrode.

9. The infusion system of claim 8 wherein said circuit means includes a second electrode disposed in said channel in contact with the fluid therein.

10. The infusion system of claim 8 further including a pair of closely spaced electrodes in said channel and normally bridged by the fluid to normally provide a predetermined value of impedance between said pair of electrodes, and circuit means connected to said pair of electrodes and responsive to a change in said value of impedance upon the occurrence of the presence of an air bubble between said electrodes to interrupt the reciprocation of said plunger.