Infusion pump with direct pressure sensing

• US 4,840,542 A
• Filed: 04/10/1987
• Issued: 06/20/1989
• Est. Priority Date: 03/27/1985
• Status: Expired due to Term

• Current Assignee: General Electric Capital Corporation (General Electric Company)
• Original Assignee: Quest Medical Incorporated (Atrion Corporation)
• Inventors: Abbott, Martyn S.
• Primary Examiner(s): Smith, Leonard E.
• Application Number:
  US07/037,019
• Time in Patent Office: 802 Days
• Field of Search: 417/28, 417/63, 417/317, 417/478, 417/479, 417/9, 417/43, 417/44, 604/153, 604/152
• US Class Current: 417/9
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/128 with incorporated valves
• CPC Class Codes: A61M 5/14224 Diaphragm type

Abstract

An infusion pump incorporates a cassette formed by bonding of two substantially flat sheets. The fluid to be infused to the patient comes into contact only with the cassette. The cassette includes first and second flexible sheets which define a pumping chamber therebetween. The infusion pump is provided with a pumping member having a hub and a plurality of petal-shaped sections extending radially outward therefrom and pivotal relative thereto. A stepping motor can be operated to move the pumping member against the second flexible sheet to decrease the volume of the pumping chamber and pump fluid to the patient. A load cell monitors the force exerted by the stepping motor on the hub. An outlet restriction value is electronically controlled by a second stepping motor in response to the pressure sensed by the load cell to control pumping to a predetermined pressure. The pressure can be selectively varied which permits the use of a low pressure at low flow rates to decrease the time necessary to detect an occlusion in the output lines.

Claims

1. A pump for parenteral administration of fluid to a patient from an elevated I.V. container comprising:

tubing extending from the I.V. container to the patient;

a disposable pump chamber in line with the tubing;

a pump including means operating in discrete cycles for pressurizing the pump chamber and means for measuring the pressure during pumping cycles;

an outlet valve downstream from the pumping chamber;

means for measuring the gravity head pressure at the pump when the outlet valve is closed prior to the beginning of a pumping cycle, and establishing an operational occlusion pressure based on the measured head; and

means for stopping the pump if the measured pumping pressure exceeds the occlusion pressure during a pumping cycle.

2. An infusion pump for pumping a fluid to a patient comprising:

a disposable cassette formed of first and second flexible sheets bonded together to define a pumping chamber and a supply chamber with an inlet passage entering the supply chamber, an intermediate passage connecting the supply chamber and pumping chamber and an outlet passage from the pumping chamber;

a frame for supporting the disposable cassette having a first surface for confining motion of the first sheet, the surface confining the first sheet having a generally concave shape of constant radius;

a pump assembly mounted on the structure for contacting the outer surface of the second sheet and for urging the second sheet toward the first surface to decrease the volume of the pumping chamber and pressurize the fluid therein, the pump assembly including a hub and a plurality of wedge-shaped petal sections extending radially outward from the hub in pivotal relationship thereto, the radially outermost end of each of the petal-shaped sections being pivotally mounted on the frame, the center section and petal-shaped sections defining a surface for contacting the exterior of the second sheet;

a piston shaft mounted to the center section for linear motion in a first direction to urge the center section and petal-shaped sections against the second sheet;

a load cell mounted on the piston shaft for measuring force exerted on the hub through the piston shaft;

a stepping motor connected to the piston shaft through the load cell for exerting force on the piston shaft;

delivery valve for varying the cross section of the outlet passage between closure of the passage and the open undeformed cross section of the outlet passage;

means for operating said delivery valve in response to the force exerted on the center section through the piston shaft measured by the load cell for causing fluid to be pumped from the pressure chamber at a predetermined pump pressure;

a transfer valve for closing and opening the intermediate passage between the supply chamber and the pumping chamber;

an inlet valve for opening and closing the inlet passage to the supply chamber; and

microprocessor controlled means for electronically causing the stepping motor to move the piston assembly in the first direction with the intermediate valve and output restriction valve closing the intermediate and outlet passages for generating an alarm if the fluid pressure in the pumping chamber does not rise within a predetermined movement to indicate an instrument defect, said microprocessor controlled means upon sensing an increase in the fluid pressure continuing to direct the stepping motor to move the piston assembly in the first direction and controlling said means for operating the delivery valve to pump fluid from the pump chamber at the predetermined pump pressure to the patient with the transfer valve closed and simultaneously maintaining the inlet passage open to permit fluid to flow from the source into the supply chamber, said control means controlling the rate of fluid pumped form the infusion pump by controlling the speed of the stepping motor to deliver a predetermined rate until a predetermined volume has been pumped from the pumping chamber, said control means subsequently closing the outlet and inlet passages with the outlet restriction valve and inlet valve while opening the intermediate passage and moving the piston assembly in the direction opposite the first direction so that fluid is drawn from the supply chamber to the pumping chamber to complete the pumping cycle.