Title:
BREATHING ASSIST APPARATUS
United States Patent 3859995


Abstract:
A breathing assist device for deep sea divers and the like including a reversible jet pump powered from a breathing gas supply and controlled by a diaphragm actuated two position poppet valve which operates in response to the pressure differential occurring across the jet pump during a ventilation cycle.



Inventors:
COLSTON JOHN R
Application Number:
05/376003
Publication Date:
01/14/1975
Filing Date:
07/02/1973
Assignee:
WESTINGHOUSE ELECTRIC CORPORATION
Primary Class:
International Classes:
A62B7/04; B63C11/22; (IPC1-7): A61M16/00
Field of Search:
128/145
View Patent Images:
US Patent References:
2547458Resuscitator1951-04-03Goodner
2483698Resuscitator1949-10-04Goodner



Primary Examiner:
Gaudet, Richard A.
Assistant Examiner:
Recla, Henry J.
Attorney, Agent or Firm:
Schron D.
Claims:
I claim

1. Breathing assist apparatus in a system having a breathing input/output device coupling the respiratory system to a source of breathing gas, comprising in combination:

2. The apparatus as defined by claim 1 and additionally including another jet pump coupling said gas power source to said valve means.

3. The apparatus as defined by claim 2 wherein said another jet pump comprises a uni-directional device including a nozzle and a throat section, and

4. The apparatus as defined by claim 3 and additionally including an adjustable variable flow conduit between the last recited conduit and the output of the throat section of said another jet pump for controlling the output pressure from said supply nozzles.

5. The apparatus as defined by claim 1 wherein said source of breathing gas and said gas power source comprise a single breathable gas supply including first and second coupling means respectively coupling said supply to said input means and said valve means.

6. The invention as defined by claim 5 and additionally including a jet pump coupled between said second coupling means and said valve means.

7. The apparatus as defined by claim 1 wherein said system additionally includes a first breathing bag coupled to said output means for receiving exhaled gases, exhaled gas reconditioning means coupled to said first breathing bag, and a second breathing bag coupled between said gas reconditioning means and said input means, and

8. The apparatus as defined by claim 7 and additionally including a uni-directional jet pump coupled between said replenish gas supply and said valve means.

9. The apparatus as defined by claim 7 and additionally including pressure relief valve means coupled to said first breathing bag, and

10. The apparatus as defined by claim 9 wherein said remote gas supply is adapted to supply a helium-oxygen mixture to said breathing assist apparatus.

11. The apparatus as defined by claim 10 and additionally including a second jet pump coupled between said umbilical line and said valve means.

12. The apparatus as defined by claim 1 wherein said source of breathing gas and said gas power source comprise a common breathing gas supply situated at a remote location and additionally including a first umbilical line means coupling said common supply to said input means and said valve means, and a second umbilical line coupling said output means to said remote location for returning exhaled gases.

13. The apparatus as defined by claim 12 wherein said remote location comprises a habitat.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to ventilation, i.e., breathing apparatus, and more particularly to breathing assist apparatus for supplying breathable gas to a person's lungs, for example a diver working at great depths wherein the high flow resistance pressure drops resulting from the high density of the breathing gas must be overcome in order to receive sufficient quantities of gas in order to function efficiently.

2. Description of the Prior Art

A diver working at relatively great depths encounters increased difficulty in breathing as a function of depth due to the relatively high density of the breathing gas compared to standard air which must be used and the resulting flow restriction pressure drops which occur in the diver's air passages (mouth to lung alveoli).

Various systems are known for providing intermittent positive pressure breathing. For example, patients who are able to breathe spontaneously at a self-controlled rate but whose pulmonary function is deficient, make use of many types of ventilating machines. Hospitals and the like employ various types of systems for supplying air, gas or air-gas mixtures to a patient undergoing surgery. An example of the first is disclosed in U.S. Pat. No. 3,586,021 entitled "Fluidic Breathing Assistor" issued to James P. McGuinness, while an example of the second is disclosed in U.S. Pat. No. 3,621,842, entitled "Ventilating Machine" issued to R. E. W. Manley. Additionally, the prior art also discloses emergency breathing gas supply apparatus for use at high altitudes. Such apparatus is disclosed in U.S. Pat. No. 2,929,377 entitled "Emergency Differential Pressure Gas Applying Apparatus," issued to R. D. Cummings. The latter two patents were mentioned because they both disclose venturi type injectors. Finally, U.S. Pat. No. 3,577,988, entitled "Dual Cannister Recirculator," issued to Richard F. Jones is cited because it discloses life support apparatus for an undersea diver having a recirculating type system also including a venturi type injector for enhancing gas flow.

SUMMARY

Briefly, the subject invention is directed to breathing assist apparatus for both the inhalation and exhalation phases of a ventilation cycle and which is particularly useful but not restricted to the life support apparatus worn by undersea divers. The breathing assist apparatus according to the subject invention comprises a reversible jet pump located between a device inserted in the diver's mouth and an input valve and an output check valve, the input valve couples a source of breathing to the jet pump. The output valve acts to conduct the exhaled gas away from the pump. The reversible jet pump includes a unitary converging-diverging throat section with upper and lower supply nozzles respectively located at each end of the throat section. The supply nozzles are alternately supplied from a gas power source during exhalation and inhalation causing a gas pumping action first in one direction and then the other. Control of the nozzles is effected by valving means driven by a diaphragm operable in response to the differential pressure in the region of the supply nozzles. The pressure drop across the jet pump is sensed by the diaphragm which when the pressure drop across the jet pump exceeds a preset value, indicating a decrease in inhalation flow for example, the diaphragm causes the valving means to switch to the opposite position causing the other supply nozzle to become activated, resulting in exhalation flow pumping. This type of breathing device senses the diver's attempt to inhale and exhale and assists his normal breathing and thereby overcome the increase pressure drops due to the relatively high density of the breathing gas at increased depths. If for some reason the diver ceases to breathe on his own power, the present invention will also effect an automatic ventilation of the diver's lungs. Additionally, when desirable, another jet pump may be included between the gas power source which may comprise a replenish supply in a closed or semi-closed system and the valving means as well as a breathing assist pressure adjustment means. The additional jet pump results in quieter operation while the pressure adjustment is advantageous when a diver's work becomes harder and his breathing flow demand increases .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view illustrative of the preferred embodiment of the subject invention;

FIG. 2 is a set of performance curves illustrative of the operation of the subject invention;

FIG. 3 is a side elevational view of the subject invention incorporated in an open circuit or "Scuba" type of underwater life support apparatus;

FIG. 4 is a side elevational view of the subject invention incorporated in a closed circuit life support apparatus;

FIG. 5 is a side elevational view of the subject invention incorporated in a semi-closed life support apparatus fed from an umbilical tube coupled back to an underwater habitat, not shown; and

FIG. 6 is illustrative of the subject invention incorporated in a diving helmet fed a helium-oxygen mixture from a habitat, not shown.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and more particularly to FIG. 1, the breathing assist apparatus of the subject invention is shown comprising, inter alia, a reversible jet pump designated generally by reference numeral 10 coupled between a respirator such as a mouthpiece 12 and a pair of valves 14 and 16. The valve 14 is operable to feed a breathing gas such as air, pure oxygen or helium-oxygen mixture to the mouthpiece 12 for inhalation while the valve 16 is adapted to feed the exhaled gases away from the apparatus either to the outside atmosphere or a breathing bag, not shown. Furthermore, the valve 14 which may be referred to as the input valve is located in an input conduit 18 while the valve 16 which may be referred to as the output check valve is located in an output conduit 20. The input and output conduits 18 and 20 join together in a region 22 which is common to one diverging end of a unitary converging-diverging throat section 24, i.e., one having a common constriction or narrow portion between two flared or diverging end portions. A first aspirator type supply nozzle 26 is located in one end portion 27 which also is common to the region 22 and is directed towards the common constriction portion 28. The supply nozzle 26 and the throat portions 27 and 28 act as the first section of a reversible or bi-directional jet pump for pumping breathing gas from the conduit 18 towards the mouthpiece 12.

The mouthpiece 12 is attached to a relatively short length of conduit 30 which terminates in a bend at a region 32 which is common to the other diverging end of portion 33 of the converging-diverging throat section 24. A second aspirator type supply nozzle 34 is located in the end portion 33 and is directed toward the common constriction portion 28 and is adapted to pump the exhaled gas to the conduit 20 from the mouthpiece 12 and the conduit 30. Thus the supply nozzles 26 and 34 in combination with the respective end portions 27 and 33 and the common constriction portion 28 provides a double acting jet pump for pumping breathing gas in a first direction and then pumping the exhaled gas in the opposite direction through the throat configuration 24.

The bi-directional jet pump 10 is contained in a body 38 which additionally includes a chamber 40 located adjacent the converging-diverging throat section 24 in which is located a diaphragm 42 which separates the chamber into two parts. One part of the chamber 40 is coupled to the region 22 by means of a channel 44 while the other part of the chamber 40 is coupled to the region 32 at the opposite end of the nozzle 34 by means of the channel 46. Thus the pressure on one side of the diaphragm 42 is at the pressure in the vicinity of the region 22 while the pressure on the other side of the diaphragm is at the pressure in the vicinity of the region 32. The reason for this configuration will become evident when a description of the operation of the subject invention is set forth below.

The diaphragm 42 is connected to a double acting poppet valve 48 by means of a stem 50. The valve 48 is located in a valve chamber 52, having an input orifice in one side thereof. In a first position of the valve 48, the chamber 52 is coupled to the supply nozzle 26 by means of a fluid passage 54 while in the second position of the valve 48, the chamber 52 is coupled to the supply nozzle 34 by means of the fluid passage 56. The valve chamber 52 is fed a breathable gas for powering the jet pump 10 from a conduit 57 coupled to a suitable source, not shown, which may be for example a replenish supply in a closed or semi-closed system. The gas applied to the conduit 57 is adapted to supply the pumping power alternately to the supply nozzles 26 and 34 during inhalation and exhalation respectively, and is fed to the valve chamber 52 by means of a first stage uni-directional jet pump 58 including a supply nozzle 60 and a throat portion 62. The incoming gas supplied by means of conduit 57 is adapted to provide a pumping action of gas coupled thereto from the region 32 by means of the passage 64. At the output of the first stage jet pump 58 is a by-pass air passage 66 which couples back to the air passage 64. The amount of by-pass or bleed flow is controlled by means of a manually operated screw 68 mounted in the outer wall of the body portion 38.

The breathing assist apparatus shown in FIG. 1 constitutes a bi-stable device which senses the attempt to inhale and exhale by reason of the pressure differentials between the regions 22 and 32 to trigger the necessary pumping action to assist normal breathing. The apparatus shown in FIG. 1 operates in the following manner. Assume for purposes of illustration that exhalation has ceased and inhalation starts. At that moment the pressure in the region 32 begins to drop with respect to the pressure in region 22. The pressure differential in the passages 46 and 44 causes the diaphragm 42 to move to the position shown in FIG. 1, shutting off passage 56 from the chamber 52 while opening passage 54. The incoming gas applied to the first stage jet pump 58 by means of the conduit 57 is coupled to the passage 54 and to the supply nozzle 26, causing a pumping action from the check valve 14 and the conduit 18 by means of the venturi effect. A positive feedback action occurs via the gas flow in passage 64 causing still further pumping action due to the venturi effect and pumping action of the first stage jet pump 58. Toward the end of the inhalation stage wherein the lungs become fully charged with the breathing gas, the pressure in region 32 increases, due to the back pressure provided by the gas in the lungs. This phase of a ventilation cycle is shown for example by reference to curve 70 shown in FIG. 2 which depicts the pumping pressure existing at the mouthpiece 12 shown in FIG. 1. When the pressure in region 32 becomes greater than the pressure in region 22, the diaphragm 42 will move to the left, forcing the valve 48 to shut off passage 54 and open passage 56. The valve 48 will be held in the second position by the differential pressure across the valve in a positive manner due to the pressure differential existing between passages 56 and 54. Whereas breathing flow increased very rapidly at the beginning of the inhalation stage as shown by curve 72 shown in FIG. 2, at the end of the breath, the flow drops to zero and the pressure at the mouthpiece immediately drops as evidenced by the portion of the curve shown by reference numeral 74. The flow of the input gas to the first jet pump 58 now flows through the passage 56 and out of the supply nozzle 34, causing a low pressure high reverse flow from the mouthpiece 12 initiating and/or aiding exhalation of the gases from the lungs toward the output conduit 20 and check valve 16. The pressure at the mouthpiece 12 now exhibits a characteristic as shown by the curve 76 in FIG. 2 while the flow out of the lungs appears as shown by the curve 78 shown in FIG. 2, until, where for example at the end of the three second period exhalation flow ceases and the inhalation action again is triggered.

The apparatus as shown in FIG. 1 is particularly adapted to overcome the pressure drop increase with depth experienced with relatively high density breathing gases (helium-oxygen) utilized in underwater life support apparatus. The configuration as disclosed in FIG. 1 is operable to sense a diver's attempt to inhale and exhale and assist his normal breathing of these relatively high density breathing gases. If for some reason the diver ceases to breathe on his own power, the present invention will cause automatic ventilation of the diver's lungs. In this sense it also becomes a life sensing device.

The first stage jet pump 58 shown in FIG. 1 acts to convert high pressure low flow gas in the conduit 57 into a medium pressure medium flow output into the valve chamber 52 and the by-pass or bleed passage 66. The first stage jet pump results in a quieter operating device. Adjustment of the screw 68 adjusts the pressure occurring at the output of the supply nozzles 26 and 34, which is advantageous, for example, when a diver increases his work output requiring a greater breath flow demand.

Since jet pumps are momentum conserving devices, much of the energy in the gas energy applied to the first stage jet pump 58 from the conduit 57 is dissipated in the form of turbulence and noise. A second reason for the desirability of the first stage jet pump 58 is to reduce the length of the converging-diverging nozzle 24 of the reversible jet pump 10. The first stage jet pump results in larger areas and lower velocities in the supply nozzles 26 and 34. This in turn results in a shorter distance for the velocity to become reasonably uniform in the throat section 24 of the reversible jet pump 10.

It has been pointed out above that the apparatus shown in FIG. 1 has particular utility for diving life support systems. FIGS. 3 through 6, inclusively, disclose various combinations of life support systems which the subject invention can be used in conjunction therewith. FIG. 3, for example, is illustrative of an open circuit system which might, for example, comprise a "Scuba" diving rig wherein a tank 80 containing oxygen or air is coupled to an input demand valve 14' by means of a flexible hose 82 and to the conduit 57 by means of another hose 84 branching off of the hose 82. The gas supplied through the hose 84 acts simply as a power source for operating the apparatus. On inhalation, gas is drawn from the bottle 80 through the demand valve 14' and out of the mouthpiece 12. During the exhalation phase, the exhaled gases including carbon dioxide CO2 is fed back through the mouthpiece 12 where it is pumped out of the output check valve 16 to the surrounding water environment.

FIG. 4, on the other hand, discloses a closed circuit breathing apparatus whereupon the oxygen bottle 80 is coupled by means of a flow regulating valve 81 to the conduit 57 by means of a flexible tube 86 to act as a make up or replenish source and power the supply nozzles 26 and 34. In this instance the exhaled gases are fed from the output check valve 16 into a first breathing bag 88 which feeds into a canister 90, which removes the carbon dioxide from the exhaled air. The output of the canister 90 comprises CO2 -free breathing gas which is fed to a second breathing bag 92 where it can then be fed back to the input valve 14 so that the breathing gas is recirculated. Oxygen consumed by breathing is replenished by gas from the oxygen bottle 80.

The configuration shown in FIG. 5 constitutes a semi-closed system which is adapted to replenish and power the breathing assist mechanism shown in FIG. 1 and is particularly useful in connection with deep diving apparatus where a helium-oxygen mixture is coupled to the apparatus shown in FIG. 1 from a habitat not shown, by means of an umbilical line 94. Such a system using a He-O2 mixture normally requires a relief valve such as shown by reference numeral 96 at the input to the exhalation breathing bag 88. Such a relief valve feeds to the surrounding atmosphere and acts to relieve the pressure build up in the exhalation breathing bag 88.

FIG. 6 is intended to illustrate, for example, the apparatus as depicted in FIG. 1, incorporated in a diving helmet shown in phantom section by reference numeral 98. Also instead of a single umbilical line 94 feeding the breathing assist apparatus, a second umbilical line 100 is utilized to feed the exhaust gases, including helium, oxygen and carbon dioxide back to an underwater habitat, not shown.

The curves shown in FIG. 2 and the values associated therewith are based on calculations provided in an analysis for a diver at the depth of 1,000 feet of sea water, breathing 4% O2 -96%He gas mixture with the breathing assist pressure adjusted to a maximum value of 15cm H2 O for no flow. The peak instantaneous breathing flow is assumed to be 2.5 meters per second. The value of 15cm H2 O is shown as the maximum pumping pressure because values greater than this could result in air being forced into a diver's stomach.

Thus what has been shown is an improved means of overcoming the pressure drop increase as a function of depth utilizing a reversible jet pump operated in a bi-stable mode in response to differential pressure changes occurring during a breathing cycle. Such apparatus acts to overcome the restrictive pressure drops of relatively high density breathing gases encountered at depths wherein unassisted breathing becomes increasingly difficult.

Having shown and described what is at present considered to be the preferred embodiment of the subject invention,