Title: Fail safe system for a patient triggered respirator

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Claims: I claim:

1. A fail safe system for preventing erroneous inspiratory operation of a respirator during the expiratory phase of a patient respiratory cycle comprising:

means for supplying a potential during the expiratory phase of said respiratory cycle;

sensing means coupled to said potential means for detecting an inspiratory effort of a patient during said expiratory phase;

threshold means connected to said sensing means for producing an output signal for activating said respirator in response to said sensing means detecting said inspiratory effort;

circuit means connected to said sensing means and to said threshold means for precluding the production of said output signal in response to said sensing means detecting said inspiratory effort before a predetermined portion of said expiratory phase has elapsed; and

means coupled to said threshold means and said sensing means for inhibiting production of said output signal upon said sensing means detecting an inspiratory effort at the start of said expiratory phase.

2. A system as defined in claim 1 wherein said means for supplying a potential comprises voltage source means for producing high and low level signals of equal duration corresponding to said expiratory and inspiratory phases, respectively, of said respiratory cycle.

3. A system as defined in claim 2 wherein said sensing means comprises switching means for exhibiting a high impedance in the absence of said inspiratory effort and a low impedance upon the occurrence of said inspiratory effort.

4. A system as defined in claim 3 in which said circuit means comprise a series R-C network having a resistor and a capacitor connected between said voltage source means and a reference potential.

5. A system as defined in claim 4 in which said threshold means is provided with an input terminal and said sensing means is connected between said input terminal and the junction between said resistor and capacitor.

6. A system as defined in claim 5 wherein said inhibit means comprises a further resistor connected between said input terminal and said reference potential such that said resistor and said further resistor form a voltage divider network whereby the voltage developed across said further resistor is supplied to said input terminal.

7. A system as defined in claim 6 wherein said threshold means comprises trigger means for producing said output signal in response to an input signal supplied thereto having a magnitude which exceeds a predetermined threshold value, wherein a potential developed across said further resistor of said voltage divider upon said sensing means exhibiting said low impedance at the start of said expiratory phase is supplied to said input terminal and is of a magnitude less than said predetermined value thereby inhibiting the production of said output signal by said trigger means.

8. A system as defined in claim 7 additionally including a further capacitor connected in parallel with said further resistor whereby upon occurrence of said inspiratory effort during said expiratory phase, the charge developed on said capacitor is transferred to said further capacitor such that the voltage developed across said further capacitor is supplied to said input terminal, wherein the charge transferred to said further capacitor upon said sensing means exhibiting said low impedance within the predetermined portion of said expiratory phase develops a voltage across said further capacitor having a magnitude less than said predetermined value whereby production of said output signal by said trigger means is precluded.

9. A system as defined in claim 8 wherein said trigger means comprises a unijunction transistor and said input terminal thereof comprises an emitter electrode coupled to said sensing means and to said further resistor and said further capacitor.

10. A fail safe system for preventing erroneous activation of a respirator comprising means for supplying a voltage during a period corresponding to the expiratory phase of a respiratory cycle; a series resistor-capacitor charging circuit coupled to said voltage supply means; means for sensing an attempt by a patient to inhale coupled to the junction between said resistor and capacitor; threshold means coupled to said sensing means for producing an activating signal upon the potential supplied to an input of said threshold means exceeding a predetermined value; respirator means coupled to said threshold means and adapted to be operated in response to said activating signal; and transfer means for transferring the potential of said capacitor to said input of said threshold means upon detection of said inhalative attempt with the magnitude of said transferred potential failing to exceed said predetermined threshold value until said capacitor has been charging for a predetermined initial portion of said period during which portion operation of said respirator means is to be avoided.

11. A system as defined in claim 10 additionally comprising means for inhibiting said threshold means from producing said activating upon said sensing means detecting inhalative attempt at the commencement of said period corresponding to said expiratory phase.

Other info:

Inventors: Cibulka, Anthony B. (Poynette, WI, US)

Application Number: 516567
Filing Date: 1974-10-21
Publication_date: 1976-04-27
Assignee: AIRCO, Inc. (Montvale, NJ)
Primary Class(es): 128/204.23 340/573.1
Other Classes:
US Patent Ref:

2830580	Apr, 1958	Saklad et al.	128/DIG.
3191595	Jun, 1965	Wilson	128/145.
3357428	Dec, 1967	Carlson	128/145.
3566387	Feb, 1971	Schoener et al.	128/145.
3595228	Jul, 1971	Simon	128/145.
3611178	Oct, 1971	McConnell	128/142.
3678494	Jul, 1972	Setser	340/279.

Other Refs:
Primary Examiner: Michell, Robert W.
Assistant Examiner: Cohen, Lee S.
Attorney: Rathbun; Roger M., Bopp; Edmund W., Mathews; H. Hume