FLUIDIC BREATHING ASSISTOR

• US 3,586,021 A
• Filed: 11/26/1968
• Issued: 06/22/1971
• Est. Priority Date: 11/26/1968
• Status: Expired due to Term

• Current Assignee: James P. Mcguinness
• Original Assignee: James P. Mcguinness
• Inventors: Mcguinness, James P.
• Application Number:
  US04/778,926
• Time in Patent Office: 938 Days
• US Class Current: 128/204.24
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: Y10T 137/2234 And feedback passage[s] or path[s]

Abstract

A fluidic breathing assistor comprises a bistable fluidic amplifier of the wall-attachment type which selectively supplies a power stream of breathable gas to a patient'"'"''"'"'s lungs via an outlet channel, or dumps the power stream into an exhaust channel along with exhaled air entrained by the power stream from the outlet channel. Means are provided to switch the power stream from the outlet channel to the exhaust channel when the lungs are inflated to a predetermined adjustable pressure, the power stream remaining so switched until the patient begins to inhale. A downstream vent passage communicating between ambient air and the outlet channel serves four functions during four respective operating modes: (1) during inhalation, substantial ambient air is entrained by the power stream via the downstream vent to increase the air flow to the lungs; (2) toward the end of inhalation, the downstream vent begins to bleed power stream gas providing a gradual, rather than sudden decrease of flow to the lungs; (3) during exhalation, the downstream vent bleeds substantial exhaled air from the outlet channel to minimize resistance to exhalation; and (4) after exhalation sufficient ambient air is provided to the outlet channel via the downstream vent to prevent further evacuation of the lung by the exhausting power stream.

Claims

1. An improved fluidic breathing assistor of the type in which pressurized breathable gas is supplied to a patient via a bistable fluidic element and in which said bistable fluidic element includes a power nozzle responsive to application of said pressurized breathable gas thereto for issuing a power stream, a respiratory receiver channel for conducting said power stream to said patient during the inhalation mode of said breathing assistor, an exhaust receiver channel for conducting said power stream to ambient and receiving entrained exhaled air from said respiratory channel during the exhalation mode of said breathing assistor, means for switching said power stream from said respiratory receiver channel to said exhaust receiver channel when the static pressure in said respiratory receiver channel reaches a predetermined level and means for switching said power stream from said exhaust receiver channel to said respiratory receiver channel upon initiation of inhalation by said patient, the improvement comprising downstream vent means communicating between ambient air and said respiratory receiver channel and responsive to below-ambient pressure in said respiratory receiver channel for supplying substantial inflow of ambient air to said respiratory receiver channel.

2. The fluidic breathing assistor according to claim 1 further comprising only one fluid feedback passage, said feedback passage being disposed to conduct fluid above a predetermined pressure from the downstream end of said respiratory channel into interaction with said power stream to switch the latter to said exhaust channel.

3. The fluidic breathing assistor according to claim 1, wherein said downstream vent means is further responsive to above-ambient pressure in said respiratory receiver channel for bleeding fluid from said receiver channel to ambient.

4. The fluidic breathing assistor according to claim 3 wherein said means for switching said power stream from said respiratory receiver channel comprises a feedback passage having an ingress opening proximate the downstream end of said respiratory receiver channel and arranged to issue feedback fluid in deflecting relationship with said power stream to deflect the latter into said exhaust receiver channel, said breathing assistor being devoid of means for feeding back fluid flowing doWnstream in said exhaust receiver channel.

5. A fluidic breathing assistor for supplying breathable gas to a patient via a respiratory channel upon initiation of inhalation by the patient and for exhausting gas exhaled by the patient into said respiratory channel, said fluidic breathing assistor including a fluidic element comprising:

an interaction region;

a power nozzle responsive to application of pressurized breathable gas thereto for issuing a power stream of said breathable gas into said interaction region;

first and second opposed sidewalls defining respective sides of said interaction region, each sidewall disposed to permit attachment of said power stream thereto;

a flow splitter having an apex disposed at the downstream end of said interaction and defining said respiratory channel in receiving relation to said power stream between said first sidewall and said flow splitter, and defining an exhaust channel in receiving relation to said power stream between said second sidewall and said flow splitter, said exhaust channel being vented to ambient at its downstream end;

negative feedback means responsive to a predetermined static pressure at said downstream portion of said respiratory channel for deflecting said power stream from said respiratory channel to said exhaust channel;

downstream vent means communicating between ambient pressure and a specified portion of said respiratory channel between said flow splitter apex and said downstream portion of said respiratory channel, said downstream vent means being responsive to below-ambient static pressure at said specified portion of said respiratory channel for supplying ambient air to said respiratory channel, and responsive to above-ambient static pressure at said specified portion of said respiratory channel for bleeding fluid from said respiratory channel.

6. The combination according to claim 5 wherein said exhaust channel is devoid of negative feedback means for feeding back fluid from said exhaust channel to said interaction region.

7. The fluidic breathing assistor according to claim 5, further comprising upstream vent means communicating between ambient air and said interaction region through said second sidewall for supplying ambient air for entrainment by said power stream.

8. The fluidic breathing assistor according to claim 7, further comprising control means for selectively varying the flow rate of said power stream.

9. The fluidic breathing assistor according to claim 7, wherein said power nozzle has a width W, the distance between said power nozzle and the apex of said flow splitter is approximately 11W, and the width of said downstream vent means at its narrowest point is between 2W and 2.5W.

10. The fluidic breathing assistor according to claim 7, wherein said negative feedback means comprises:

a control nozzle defined through said first sidewall at the upstream end of said interaction region;

a pressure sensing port defined through said first sidewall at said downstream portion of said respiratory channel; and

a fluid passage interconnecting said pressure sensing port and said control nozzle.

11. The fluidic breathing assistor according to claim 10, further comprising feedback adjustment means for selectively adjusting said predetermined static pressure, said feedback adjustment means comprising a control valve disposed in said fluid passage.

12. The fluidic breathing assistor according to claim 7, further comprising:

a second control nozzle defined through said second sidewall at the upstream end of said interaction region; and

a fluid passage interconnecting said second control nozzle to ambient air.

13. The fluidic breathing assistor according to claim 12 further comprising sensitivity control means for selectively adjusting the inspiratory effort required of said patient in order to switch said power stream from said exhaust channel to said respiratory channel, said sensitivity control mEans comprising an adjustable valve disposed in said fluid passage.

14. The fluidic breathing assistor according to claim 13, wherein said negative feedback means comprises:

a further control nozzle defined through said first sidewall at the upstream end of said interaction region;

a pressure sensing port defined through said first sidewall at said downstream portion of said respiratory channel;

a fluid passage interconnecting said pressure sensing port and said further control nozzle; and

feedback adjustment means disposed in said last-mentioned fluid passage for selectively adjusting said predetermined static pressure.

15. The fluidic breathing assistor according to claim 14, further comprising control means for selectively varying the flow rate of said power stream.

16. The fluidic breathing assistor according to claim 14, wherein said power nozzle has a width W, the distance between said power nozzle and the apex of said flow splitter is approximately 11W, and the width of said downstream vent means at its narrowest point is between 2W and 2.5W.