IV Pump with back pressure control

• US 4,322,201 A
• Filed: 09/21/1979
• Issued: 03/30/1982
• Est. Priority Date: 03/09/1979
• Status: Expired due to Term

• Current Assignee: Graseby Medical Limited (ICU Medical Incorporated)
• Original Assignee: AVI Inc.
• Inventors: Archibald, G. Kent
• Primary Examiner(s): Freeh, William L.
• Application Number:
  US06/077,620
• Time in Patent Office: 921 Days
• Field of Search: 128/214 E, 128/214 F, 417/279, 417/507, 417/540, 417/542
• US Class Current: 417/279
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/168 Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body flow control in general G05D7/00
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: F04B 43/021 the plate-like flexible member is pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the plane of the plate-like flexible member and each having its own driving mechanism
• CPC Class Codes: F04B 43/082 the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism
• CPC Class Codes: F04B 7/00 Piston machines or pumps characterised by having positively-driven valving
• CPC Class Codes: F04B 9/042 the means being cams

Abstract

A volumetric infusion pump of the type having a rolling diaphragm pumping chamber includes a back pressure sensor between the rolling diaphragm pumping chamber and the pump outlet for sensing back pressure. A valve is positioned between the back pressure sensor and the pump outlet for controlling fluid flow to the pump outlet in order to control back pressure supplied to the rolling diaphragm pumping chamber. Back pressure is maintained within the rolling diaphragm pump chamber so that the rolling diaphragm maintains close contact with the piston even in the event of a negative head pressure at the pump outlet. The valve and the back pressure sensor are preferably linked so that the valve restricts fluid flow to the pump outlet only when the sensed back pressure is less than a predetermined level.

Claims

1. A volumetric infusion pump for pumping fluid from a reservoir to a patient, the volumetric infusion pump comprising:

a pump inlet for connection to the reservoir;

a pump outlet for connection to the patient;

rolling diaphragm pumping chamber means connected between the pump inlet and the pump outlet;

pressure sensing means connected between the rolling diaphragm pumping chamber means and the pump outlet for sensing pressure;

wherein the pressure sensing means comprises;

a cylinder;

a piston movable in the cylinder;

flexible diaphragm means between the cylinder and the piston defining a pressure sensing chamber; and

spring bias means for applying a force urging the piston in a direction which reduces the volume of the pressure sensing chamber, and wherein pressure in the pressure sensing chamber applies a force urging the piston in a direction which increases the volume of the pressure sensing chamber; and

valve means between the pressure sensing means and the pump outlet for controlling fluid pressure in the rolling diaphragm pumping chamber means wherein the valve means restricts a flow passage between the pumping chamber means and the pump outlet to increase pressure in the rolling diaphragm pumping chamber means if the pressure sensed by the pressure sensing means is less than a predetermined level, and wherein the valve means does not restrict the flow passage if the pressure sensed is greater than the predetermined level.

2. The volumetric infusion pump of claim 1 and further comprising:

linkage means for linking the valve means and the piston when the pressure is less than the predetermined level.

3. The volumetric infusion pump of claim 2 wherein the linkage means comprises:

a longitduinal slot in the piston; and

arm means fixedly connected to the valve means and having a free end extending into the slot, wherein the arm engages one end of the slot and imparts force from the spring bias means to the valve means when pressure in the pressure sensing chamber is less than the predetermined level, and where a pressure in the pressure sensing chamber of greater than the predetermined level causes the piston to move to a position in which the end of the arm means is not engaging an end of the slot, thereby disconnecting the spring bias means and the valve means.

4. A volumetric infusion pump for pumping fluid from a reservoir to a patient, the volumetric infusion pump comprising:

a pump inlet for connection to the reservoir;

a pump outlet for connection to the patient;

pumping chamber means connected between the pump inlet and the pump outlet; and

pressure sensing and regulating means connected between the pumping chamber means and the pump outlet for sensing a pressure indicative of fluid pressure in the pumping chamber means and controlling the fluid pressure in the pumping chamber means as a function of the sensed pressure to maintain the fluid pressure in the pumping chamber means at least at a predetermined level even if pressure at the pump outlet is less than the predetermined level;

wherein the pressure sensing and regulating means allows the fluid pressure in the pumping chamber means to equal the pressure at the pump outlet if the pressure at the pump outlet exceeds the predetermined level; and

wherein the pressure sensing and regulating means comprises;

a cylinder;

a piston movable in the cylinder;

flexible diaphragm means between the cylinder and the piston defining a pressure sensing chamber;

valve means for occluding an outlet of the pressure sensing chamber as a function of the position of the piston.

5. The volumetric infusion pump of claim 4 wherein the pumping chamber means includes at least one rolling diaphragm pumping chamber.

6. The volumetric infusion pump of claim 4 and further comprising:

linkage means for linking the valve means and the piston when the sensed pressure is less than the predetermined level.

7. The volumetric infusion pump of claim 6 wherein the linkage means comprises:

a longitudinal slot in the piston; and

arm means fixedly connected to the valve means and having a free end extending into the slot, wherein the arm engages one end of the slot and imparts force from the spring bias means to the valve means when pressure in the pressure sensing chamber is less than the predetermined level, and wherein a pressure in the pressure sensing chamber of greater than the predetermined level causes the piston to move to a position in which the end of the arm means is not engaging an end of the slot, thereby disconnecting the spring bias means and the valve means.

8. A volumetric infusion pump for pumping fluid from a reservoir to a patient, the volumetric infusion pump comprising:

a pump inlet for connection to the reservoir;

a pump outlet for connection to the patient;

pumping chamber means connected in a fluid flow path between the pump inlet and the pump outlet;

a pressure sensing chamber connected in the fluid flow path between the pumping chamber means and the pump outlet for receiving fluid from the pumping chamber means and including a cylinder and a piston movable in the cylinder as a function of fluid pressure of the fluid contained in the pressure sensing chamber, the fluid pressure of the fluid in the pressure sensing chamber being a function of the fluid pressure in the pumping chamber means;

spring bias means for applying a force urging the piston in a direction which reduces the volume of the pressure sensing chamber, and wherein fluid pressure of the fluid contained in the pressure sensing chamber applies a force urging the piston in a direction which increases the volume of the pressure sensing chamber; and

valve means positioned along the fluid flow path between the pressure sensing chamber and the pump outlet for occluding an outlet of the pressure sensing chamber as a function of the position of the piston to maintain the fluid pressure in the pumping chamber at least at a predetermined level even if pressure at the pump outlet is less than the predetermined level; and

wherein the valve means allows the fluid pressure in the pumping chamber means to equal the pressure at the pump outlet if the pressure at the pump outlet exceeds the predetermined level.