Flow fault sensing system

• US 4,431,425 A
• Filed: 04/28/1981
• Issued: 02/14/1984
• Est. Priority Date: 04/28/1981
• Status: Expired due to Fees

• Current Assignee: General Electric Capital Corporation (General Electric Company)
• Original Assignee: Quest Medical Incorporated (Atrion Corporation)
• Inventors: Thompson, Thomas C., Abbott, Martyn S., Easley, Robert L.
• Primary Examiner(s): Truluck, Dalton L.
• Application Number:
  US06/258,362
• Time in Patent Office: 1,022 Days
• Field of Search: 128/214 R, 128/214 E, 128/214 F, 128/214.2, 128/DIG. 12, 128/DIG. 13, 128/634, 137/486, 137/487.5, 73/269-271, 340/556, 340/611, 340/626, 340/621, 340/606, 340/686, 604/65-67, 604/245, 604/246
• US Class Current: 604/246
• CPC Class Codes: A61M 5/16809 by repeated filling and emptying of an intermediate volume pressure infusion using positive displacement pumps A61M5/142
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: G01P 13/0066 by using differences of pressure in the fluid
• CPC Class Codes: G01P 13/0086 with photo-electric detection
• CPC Class Codes: Y10S 128/13 Infusion monitoring
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

A system for sensing flow faults in a membrane system for intravenous fluid introduction is provided. A scanner is pulsed to generate reflected energy signals representative of the position of a membrane within a chamber. The scanner is pulsed both before and after the membrane is commanded to move within the chamber. The signals are then compared by an electronic circuit to determine the difference between them. If there exists a sufficiently large difference between the signals, this indicates that the membrane is moving in response to the command signals and the system is functioning properly. If there exists little or no difference between the signals, this indicates that there is a flow fault in the system, and an alarm is sounded.

Claims

1. A volumetric metering device for controlling the flow of fluid in a fluid path extending from a fluid supply to a patient which automatically and non-invasively senses flow faults comprising:

(a) a metering chamber of predetermined volume much smaller than the volume of fluid to be delivered to the patient, divided into first and second compartments by a membrane, said first and second compartments each having an inlet and and outlet;

(b) valve means settable into a first state in which the inlet to the first compartment and the outlet from the second compartment are open and the outlet from the first compartment and the inlet from the second compartment are closed; and

a second state in which the inlet to the second compartment and the outlet from the first compartment are open and the inlet to the first compartment and the outlet from the second compartment are closed, whereby a small discrete volume of fluid equal to the volume of the chamber is delivered upon each alternate switching into the first or second state of the valve means;

(c) control means for cycling the valve means by setting the time lapse between each successive setting of the valve means into such states; and

(d) non-invasive flow fault sensing means external to the metering chamber for generating discrete signals the magnitude of which is directly determined by the position of the membrane during preselected portions of the cycling established by the control means, and for comparing such signals with each other to determine movement of the membrane.

2. A volumetric metering device for controlling the flow of intravenous fluid in a fluid path extending from a fluid supply to a patient which automatically and non-invasively senses a flow fault comprising:

(a) a metering chamber divided into first and second compartments by a flexible membrane, said first and second compartments each having an inlet and an outlet;

(b) valve means settable into a first state in which the inlet to the first compartment and the outlet from the second compartment are open and the outlet from the first compartment and the inlet from second compartment are closed; and

a second state in which the inlet to the second compartment and the outlet from the first compartment are open and the inlet to the first compartment and the outlet from the second compartment are closed, whereby a discrete volume of fluid equal to the volume of the metering chamber is delivered to the patient upon switching into each such state of the valve means;

(c) control means for causing delivery of fluid at a selected overall volumetric rate of fluid flow to the patient, although not an instantaneous flow rate, comprising means for switching the valve means into such states alternately at a predetermined constant time interval; and

(d) non-invasive sensing and alarm means external to the metering chamber for generating reflected energy signals representative of the position of the membrane during preselected portions of the operation of the control means, and comparing such signals with each other to determine membrane movement.

3. A volumetric metering device for delivering an intravenous fluid to a patient through a fluid line in discrete increments, which automatically and noninvasively senses a flow fault, comprising:

(a) a metering chamber having a small predetermined volume divided into first and second compartments by a membrane, said chamber having valved inlet and outlet means;

(b) control means for switching the valve inlet and outlet means to cause the membrane to move and discrete increments of fluid to be delivered to the patient, each increment equal to the chamber volume;

(c) means external to the chamber for generating a first signal representative of membrane position prior to switching by the control means and a second signal representative of membrane position after such switching;

(d) comparator means for comparing the first and second signals; and

(e) alarm means for producing a perceptible alarm in the event that the comparator means indicates that the membrane is not moving in response to the control means.

4. In a membrane system for intravenous fluid delivery employing a metering chamber separated into two compartments by a movable membrane, a flow fault sensing system comprising:

(a) means for producing reflected energy signals representative of the position of the membrane comprising a scanner which detects energy reflected from membrane; and

(b) means for processing said signals to determine whether the membrane has moved in response to a command signal comprising means for comparing said reflected energy signals from said scanner.

5. The flow fault sensing system of claim 4 wherein said scanner is pulsed to generate a first reflected energy signal before the command signal and a second reflected energy signal after the command signal, said first and second reflected energy signals being compared by said means for comparing to determine the difference between said first and second signals.

6. An apparatus for intravenous introduction comprising:

a membrane enclosed by a body;

means for moving the membrane with respect to the body in accordance with cycle established by a control intelligence;

a transmitter of energy signals directed toward the membrane;

a receiver of energy signals reflected from the membrane;

means for pulsing the transmitter and receiver during selected portions of the cycle established by the control intelligence such that at least first and second reflected energy signals representative of the positions of the membrane at different times are received;

means for holding and interpreting a plurality of reflected energy signals to determine whether the membrane has moved in accordance with the control intelligence; and

alarm means for producing a perceptible alarm in the event that the membrane has not moved in accordance with the control intelligence.

7. The apparatus of claim 6 wherein said means for holding and interpreting the signals includes means for determining the difference between the first and second reflected energy signals and means for comparing the difference to a reference to ascertain whether the membrane has moved.

8. The apparatus of claim 7 including a first storage member adapted to hold a first voltage representing the first energy signal, a second storage member adapted to hold a second voltage representing the second energy signal, means for ascertaining the difference between the first and second voltages;

means for comparing the difference with a reference voltage;

said alarm means being activated should the difference between the first and second voltages be insufficient to indicate that the membrane has moved.