Medical infusion pump with sensors

• US 4,856,339 A
• Filed: 04/06/1988
• Issued: 08/15/1989
• Est. Priority Date: 11/17/1986
• Status: Expired due to Fees

• Current Assignee: Centaur Sciences, Inc.
• Original Assignee: Centaur Sciences, Inc.
• Inventors: Williams, David R.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US07/178,277
• Time in Patent Office: 496 Days
• Field of Search: 73/714, 73/719, 73/722, 73/725, 73/728, 338/32 H, 128/672, 128/675, 128/D12, 128/D13, 604/153, 604/118, 604/123, 604/34
• US Class Current: 73/714
• CPC Class Codes: A61M 2205/3375 Acoustical, e.g. ultrasonic, measuring means
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/14232 Roller pumps
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A medical infusion pump includes a housing (10), a pump assembly (30), a bubble sensor assembly (120), a pressure sensor assembly (140) and a flow control assembly (180). The pump assembly includes a ring (26) with teeth (44) and a wheel (46) mounted for eccentric rotation within the ring. The pumping action is developed by the rotation of the wheel which continuously closes a portion of tubing (36) against one or two teeth as it goes through the pumping cycle. The bubble sensor includes a pair of sensor blocks (124) defining a generally V-shaped trough for cradling a portion of the tubing. The pressure sensor assembly detects pressure variations by movement of a diaphragm (168) coupled to a magnet (162) which is operatively coupled to a Hall effect circuit (160). The flow control assembly includes a thumb wheel (196) having a cam groove (197) interacting with a valve stem (199) for controlling the fluid flow through an orifice and associated valve seat (194).

Claims

1. In a medical infusion pump apparatus, a system for measuring the pressure of the pumped fluid comprising:

a cassette including at least a first fluid inlet port adapted to be connected to the pump and at least a first fluid outlet port, a chamber interposed between and in fluid communication with said inlet and outlet ports, said chamber being defined in part by a first flexible diaphragm having a flexure response compatible with the range of pressure to be measured in said chamber; and

a fluid transducer assembly including a Hall effect device supported in spaced relationship with respect to said cassette, a magnet supported adjacent to said device for movement relative thereto, and reciprocally moveable support means for coupling said magnet to said first diaphragm, whereby flexure of the first diaphragm produces a commensurate displacement of the magnet, thereby causing said device to generate a signal indicative of the pressure of the fluid in said chamber.

2. The pressure measuring system of claim 1 wherein said means for coupling said magnet to said first diaphragm includes a second diaphragm in contact with said first diaphragm, means for positioning said second diaphragm against the first diaphragm and wherein said coupling means is rigid and is interposed between said second diaphragm and said magnet for translating the motion of said first diaphragm into motion of said magnet.

3. The pressure measuring system of claim 2 wherein said first diaphragm has a concave profile and said second diaphragm has a complementary convex profile.

4. The pressure measuring system of claim 2 wherein said cassette includes a second inlet port and a second outlet port, said infusion pump being connected between said second outlet port and said first inlet port whereby said cassette defines separate transducer assemblies for measuring fluid pressure upstream and downstream of the infusion pump, wherein the first diaphragm senses an increase in fluid pressure and has a concave profile mating with a convex profile on said second diaphragm and wherein said cassette includes a second chamber interposed between said second inlet and second outlet ports, said second chamber being defined in part by a third flexible diaphragm, said third diaphragm sensing a decrease in fluid pressure and having a convex profile mating with a concave profile on a fourth diaphragm.

5. The pressure sensing system of claim 4 wherein said first and third diaphragms are integral.

6. The pressure sensing system of claim 5 wherein said second and fourth diaphragms are integral.

7. A pressure sensor for use in medical infusion pump apparatus comprising:

a disposable cassette, said cassette having first and second fluid inlet ports and first and second fluid outlet ports, said cassette defining a pair of chambers, fluid communication being established via respective of said chambers between said first inlet and outlet ports and said second inlet and outlet ports, said first and second chambers being in part respectively defined by first and second shaped flexible diaphragms;

means fluidically coupling said first outlet port to said second inlet port, said coupling means being insertable in an infusion pump apparatus whereby said first outlet port will be fluidically upstream of the pump and said second inlet port will be fluidically downstream of the pump;

first and second pressure transducer means, said transducer means being respectively associated with said first and second diaphragms, said transducer means each including a magnet field responsive device for generating an output signal and a variable position magnet, said magnets being coupled to respective of said diaphragms whereby deflection of said diaphragms is translated into movement of said magnets relative to said field responsive devices.

8. The pressure sensor of claim 7 wherein the first of said diaphragms presents a reaction surface to the interior of said first chamber and the second of said diaphragms presents a reaction surface to the interior of the second of said chambers.

9. The pressure sensor of claim 8 wherein said transducer means each include a diaphragm having a contour which is complementary to the shape of the exposed surface of the diaphragm of its associated cassette chamber, said transducer means diaphragms being in intimate contact with respective of said chamber defining diaphragms.

10. The pressure sensor of claim 9 wherein said reaction surface of said first diaphragm has a generally convex shape and the reaction surface of said second diaphragm has a generally concave shape.