Logic-controlled occlusive cuff system

• US 4,294,261 A
• Filed: 06/01/1976
• Issued: 10/13/1981
• Est. Priority Date: 06/01/1976
• Status: Expired due to Term

• Current Assignee: The United States Of America As Represented By The National Aeronautics And Space Administration
• Original Assignee: United States Administrator of National Aeronautics and Space Administration
• Inventors: Hursta, William N., Hoffler, George W., Baker, Joseph T.
• Primary Examiner(s): Thaler, Michael H.
• Application Number:
  US05/691,647
• Time in Patent Office: 1,960 Days
• Field of Search: 128/2.05 A, 128/2.05 M, 128/2.05 C, 128/327, 128/2.05 G, 128/691, 128/686
• US Class Current: 600/504
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval

Abstract

The occlusive cuff system of this invention comprises a pressure cuff and a source of regulated compressed gas feeding the cuff through an electrically-operated fill valve. An electrically-operated vent valve vents the cuff to the ambient pressure. The fill valve is normally closed and the vent valve is normally open. In response to an external start signal, a logic network opens the fill valve and closes the vent valve, thereby starting the pressurization cycle and a timer. A pressure transducer continuously monitors the pressure in the cuff. When the transducer'"'"'s output equals a selected reference voltage, a comparator causes the logic network to close the fill valve. The timer, after a selected time delay, opens the vent valve to the ambient pressure, thereby ending the pressurization cycle.

Claims

1. A cuff system for occulding venous return from a limb, comprising:

a pressure cuff;

a source of pressurized gas;

means including a solenoid-operated fill valve for selectively coupling said gas source with said cuff, said fill valve being opened in response to a high level energizing electrical fill signal which energizes the solenoid associated with said fill valve and being closed in response to the application of a low level electrical signal to said solenoid-operated fill valve;

regulator means for controlling the pressure and volume of gas flowing from said source when coupled to said cuff;

means including a solenoid-operated vent valve for venting said cuff to the ambient atmosphere, said vent valve being closed in response to application of a low level electrical signal which deenergizes the solenoid associated with said vent valve and said vent valve being opened in response to application of a high level electrical signal which energizes the vent solenoid;

means for supplying a high level energizing electrical fill signal to said solenoid-operated fill valve to open said fill valve and maintain the fill valve in open condition whereby the cuff receives gas from said pressurized source;

means including a timer means instantly operative in response to said fill signal for producing a low level deenergizing close vent signal for a predetermined period of time and applying said low level close vent signal to said vent valve to close said vent valve through said time period;

a pressure transducer fluidly coupled with said cuff, said transducer measuring the fluid pressure in said cuff and generating a transducer output electrical voltage signal proportional to said pressure;

a source of reference voltage;

means operatively associated with said pressure transducer and said reference voltage source for terminating said high level energizing electrical fill signal and applying a second low level electrical signal to said solenoid-operated fill valve to close said fill valve when the ratio between said transducer electrical output voltage signal and said reference voltage signal reaches a predetermined value whereby said cuff is in a pressure holding condition while the vent remains closed; and

means responsive to the termination of said low level deenergizing close vent signal at the end of said time period to energize said solenoid-operated vent valve to open condition and thereby depressurize said cuff;

said system further comprising;

an AND gate,

a pressure latch,

a start latch,

each one of said latches having a set, reset, and output terminals, the output of said pressure latch being coupled to one input of said AND gate, the output of said start latch being coupled to the other input of said AND gate,

means coupling the output of said start latch to the input of said timer and to the reset terminal of said pressure latch,

means coupling the output of said timer to the reset terminal of said start latch,

means coupling the output of said AND gate to said fill valve; and

said system adapted to start a pressurization cycle upon the application of a start signal to the set terminal of said start latch.

2. The system of claim 1 and further comprising:

means coupling an external signal to said set terminal of said start latch.

3. The system of claim 2 and further including an electrocardiogram trigger circuit for providing said external signal, said trigger circuit comprising:

a filter means receiving an ECG signal,

a detector coupled to the output of said filter means, and

a time delay network coupled to the output of said detector.

4. The system of claim 3 wherein said filter means comprises a high-pass filter in tandem with a low-pass filter, said ECG signal being applied to said high-pass filter.