US3537449A - Respirator using pure fluid amplifier - Google Patents

Description

United States Patent Leo G. Foxwell Longmeadow, Massachusetts; James E. Smith, Avon; Hermann Ziermann, Cheshire, Connecticut 715,344

March 22, 1968 Nov. 3, 1970 United Aircraft Corporation East Hartford, Connecticut a corporation of Delaware Inventors Filed Patented Assignee RESPIRATOR USING PURE FLUID AMPLIFIER 11 Claims, 4 Drawing Figs.

U.S. Cl 128/1455, l37/8l.5

Int. Cl A62b 7/02 Field of Search l28/(Fluid Amplifier Digest), 145.5; 137/815 [56] References Cited UNITED STATES PATENTS 3,068,856 12/1962 Bird et al. 128/1455 3,368,555 2/1968 Beasley 128/1455 Primary Examiner-Richard A. Gaudet Assistant Examiner-G. F. Dunne Attorney-Norman Friedland ABSTRACT: Pure fluid amplifiers of a respirator switch valves on and off for directing pressurized fluid to and from a mouthpiece for assisting inhalation and exhalation while minimizing pressure drop. The output channel of a second fluid amplifier is connected to the control port of the first fluid amplifier for assisting the switching thereof during the negative pressure regimes.

Patented Nov. 3, 1970 3,537,449

l/A I 76. z 55%;; g5 07 XX W RESPIRATOR USING PURE FLUID AMPLIFIER BACKGROUND OF THE INVENTION This invention relates to intermittent positive pressure breathing (IPPB) apparatus utilizing a pure fluid amplifier and more particularly for automatically opening and closing valve means at predetermined inspiration and expiration.

IPPB apparatus normally employs the following basic components and functions:

1. Ejector To create high peak flows at the initial inspiration effort and low flows at the termination of inspiration. Also when operating from an oxygen supply, the ejector provides an oxygen/air mix normally in the ratio of 40/60 percent.

'2. Positive pressure control Pressure controlled respirators are switched from inspiration to expiration at a preset positive pressure. The flow created by the ejector will inflate the lungs and will develop a pressure due to the elasticity of the lungs. The pressure to which the lungs is inflated is preset and when the pressure is reached the in spiratory flow is terminated. The normal pressure range is to 40 H O positive pressure.

. Sensitivity Control The expiration phase of the respiration cycle is normally passive and with pressure controlled respirators is terminated by a conscious inspiratory effort. This effort usually involves a slight suction or negative pressure (sensitively) on the order of 1 to 5 cm. H O pressure below ambient.

4. Expiratory Valve This valve is maintained closed during the inspiration phase. During expiration the valve is open providing rapid exhalation while there is positive pressure in the airway passages. When the pressure in the airway is depleted, the valve closes and remains closed to minimize the sensitivity control effort.

5. Nebulizer The nebulizer injects atomized medication into the inhaled air during the inspiratory effort.

The state of the art of IPPB devices normally controls and regulates their functions by complex mechanisms usually involving magnetic clutches, large diaphragm actuators and/or jeweled counterweighted drum controllers.

US. Pat. application Ser. No. 467,838 filed on June 27, 1965, and assigned to the same assignee, discloses and claims an IPPB device which performs the basic control mechanisms (without moving parts) utilizing a pure fluid amplifier. The fluid amplifier directs the output of one leg directly to the lungs of the patient. Intermittant breathing is accomplished by picking up the pressure in the output channel of the fluid amplifier for controlling the switching functions.

The above fluid amplifier apparatus is beneficial for IPPB apparatus which are compressor driven and where pressure head available is not a critical factor. However, when developing a lightweight IPPB system which is easily portable by severely infirmed individuals, the pressure head and flow requirements for the above fluid amplifier system require a compressor which is not easily portable. Further, the system is not adaptive to oxygen use. The fluid amplifier operates continuously at reasonable high flows. With the expiratory phase of respiration generally twice that of inspiration, two-thirds of the oxygen consumed is wasted and discharged overboard.

We have found that we can obviate the problems of excessive oxygen comsumption and high pressure and flow requirements by driving a movable valve which will limit flow to the inspiratory effort with the use of a small fluid amplifier utilizing only a small insignificant control flow, thus retaining the features of simplicity inherent in fluid amplifiers.

Secondly, it has heretofore been extremely difficult to achieve adjustment in controls without interaction either with positive pressure switching flow and sensitivity switching. Also particularly with fluid amplifiers, the positive switching pressure required to switch the amplifier is the same as the negative pressure. It has heretofore been difficult to achieve switching from positive and negative sequel whose levels differ by as much as 30 to l.

SUMMARY OF INVENTION The primary object of this invention is an intermittant positive pressure breathing apparatus and particularly an improved respirator.

A further object of this invention is to provide timed valve sequence in response to fluid amplifier control.

A still further object of this invention is to provide an additional fluid amplifier to drive the first amplifier during relative low pressure operating regimes.

A still further object of this invention is to include means for driving a nebulizer in time sequence with the inspiration cycle at a high pressure level relative to the source pressure occasioned by a small pressure drop from the respiratory control elements. I

Other features and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a schematic illustration of this invention.

FIG. 2 is a partial schematic illustrating a modification to FIG. 1.

FIG. 3 is a partial schematic illustrating an additional modification to FIG. 1.

FIG. 4 is a partial schematic illustrating an additional modification to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the major component of the respirator comprises the fluid amplifiers 16 and I8, and valves 10, I2 and 14. The source of compressed gas is schematically illustrated by black box 26. This source may be a small, portable air compressor or a regulated oxygen supply. Flow from the compressor or oxygen supply flows to amplifiers I6 and 18 via valve 80 and line 30 and valve 78 and line 32 respectively. Valves 78 and 80 control the flow to the fluid amplifiers. Flow is also directed to valve 10. Flow through valve 10 is controlled by actuator 38 which is actuated by the output flow of amplifier 16 through either output 34 and line 40 or output 62 and line 66. Flow through valve 10, when it is actuated, is directed to the venturi 48 via the valve 82 and primary nozzle 46. Flow also is directed to the nebulizer via valve 84. Valve 82 and 84 control flow through their respective lines.

Flow through the primary nozzle 46 will draw ambient air along with it through the venturi 48 increasing the total flow in the venturi. During flow, valve 12 will be open transmitting air or air and oxygen through 28 to the mouthpiece 50. Valve 14 is connected to 28 via line 76. The actuator 42 is controlled by the output of amplifier 16, output port 34 via 40 and 44.

The pressure in line 28 is sensed in line 56 and distributed via 58 and 60 to the control port 52 of amplifier 16 and to control port 54 via valve which opens or closes control port 54 of amplifier 18. Valve 75 may take any suitable form that serves to block off passage 54 and is shown as an inflatable flexible bag. The output leg 64 of amplifier 18 is connected to control port 37 of amplifier 16.

DESCRIPTION OF OPERATION The following discussion will describe the operation of a compressor driven respirator. However, the operation is identical when the compressed gas is regulated oxygen. Compressed air from the compressor is discharged through line 28 to valve 10 and through valves 78 and 80 and lines 32 and 30 to amplifiers l6 and 18. Amplifier 18 normally has a preferred orientation for channel 64. However, with control port 54 closed by valve 75, the orientation will be out through port 36. During exhalation port 54 is closed and flow through amplifier 18 is directed through the power jet 24 and deflected through port 36 and discharged overboard. Flow through amplifier 16 will be directed through power jet 20 and deflected through output 62. The flow will be directed through line 66 to actuator 38 keeping valve 10 closed and making the venturi 48 and the nebulizer 70 inoperative. In addition, flow from output port 62 of amplifier 16 is directed through line to controller 43 closing valve 12.

Line 44 from the output leg 34 of amplifier id is unpres surized and the controller 42 is inoperative. When the patient is exhaling, air is exhausted through the mouthpiece 54D, channel 76 and overboard through valve 14. When exhalation through valve 14 is complete, valve 14 will close but will still permit exhaust if the patient were to make a forced exhalation. At the termination of exhalation, the plumbing downstream of valve 12 may be considered as a closed cavity encompassing a portion of line 28, line 74, and line '76 since valves 12 and 14 are now in the closed position. Hence, when a very small inspiration effort is made, the volume of air in 28 is reduced creating a negative pressure. This subamibent pressure (as low as l cm. H O) is sensed by line 56, 53 and 60. The reduced pressure resulting at control port 52 of amplifier 16 is insufficient to cause a change in the operation of this amplifier at this time. However, the negative pressure moves valve 75 opening port 54 of amplifier 18 causing flow to be directed through power jet 24 and to the preferred orientation output port 64. The flow through port 64 is directed to port 37 and causes amplifier 16 to switch its output from port 62 to port 34.

When the air is diverted to port 34, pressure is lost in lines 68 and 66. The pressure created in line 40 and 44 actuates actuator 42 and will hold valve 14 closed during the remainder of the inspiration cycle. This pressure also actuates actuator 38 opening valve 10. Flow from 28 now is directed through valve 82 to the ejector nozzle 46 and through valve 84 to the nebulizer 70. Immediately medication is atomized into the cavity 74 and 28. Simultaneously, the flow through 46 will suck ambient air into the venturi 48 opening valve i2 and flowing through 12 and mouthpiece 50 to the patient.

As the lungs are inflated pressure is created in 28 and flow diminishes through the venturi 48. The pressure is sensed by lines 56 and 58 and 60. When the pressure rises to approximately -l-l3 cm. H O, the control flow through port 52 is small compared to the larger flow opposing it through 37. However, the pressure is sufficient to move 75 and close port 54. With port 54 closed a vacuum is created in control port 54 causing amplifier 18 to divert its output to port 36 and overboard. It will remain this way as long as positive pressure or atmospheric pressure remains in line 60. As the pressure increases in 28, no further action alters the position of amplifier 18. However, as the pressure rises a pressure is reached where the control flow through 58 and 54 is sufficient to deflect the flow to port 62. At this point the inspiration phase is terminated.

Flow through 62 depletes pressure in line 40 and 44 and the back pressure bias on controller 42. As a result the pressure in 28 and 76 opens 14 and exhausts to atmosphere. The flow through 62 is transmitted through 66 and 63, actuating actuators 38 and 43, closing valves 12 and 19. Flow through 46 and 48 is terminated as is the medicated atomization through 70. Exhalation will prevail at this point, and the cycle is repeated.

The amount of medication atomized in 70 is controlled by opening and closing valve 84 controlling the flow to 70.

The inspiratory flow is controlled by valve 82 by regulating the pressure at 46. Opening valve 82 increases pressure and flow at 46 and increases total inspiratory flow in venturi 43. This also increases the ultimate pressure that can be created in the lungs. Closing valve 82 decreases flow and available pres sure for lung inflation.

The positive pressure for switching from inhalation can be regulated by adjusting valve 89. Opening valve 80 increases flow through power jet 20 and requires a higher sequel at 52. Closing valve 80 decreases flow through 24) and lowers the control pressure required at 52.

Valve 78 is adjusted to trim the flow through power jet 24 to the desired flow. It is not adjusted further.

The desired system affords a respirator which has independence of control features so essential to lPPB devices. Specifically, this is independence of adjustment and noninteraction of nebulization, flow, positive pressure control and stable sensitivity switchover.

An alternate embodiment exemplifying this invention is shown in FIG.'2 where the actuator 42 is actuated by the pressure just immediately upstream of valve 82 via line 90. This eliminates the connection between the output channel 34 of amplifier 16 and actuator 42.

This system can be further modified so as to eliminate valve 12 and replacing it by one-way check valve 13 as shown in FIG. 3. This check valve 13 is closed during the exhalation cycle and automatically opens during the inhalation cycle.

An alternate embodiment is schematically shown in FIG. 4. The amplifier 18 shown in FIG. 1 may also be a bistable amplifier as schematically shown in FIG. 4. The light suction pressure in line 60 will pull the output of flow through amplifier 18 to output 64 and switch amplifier 16 initialing inspiration. At the first presence of positive pressure (+1 to +5 cm. H O), the positive pressure signal will reset the output of amplifier 18 to output 36. The amount of sensitivity pressure (-1 to 5 cm. H O) can be controlled by valve 78. Opening 78 increases flow through power jet 24 increasing sensitivity. Closing will minimize sensitivity required to initiate inspiration.

It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit or scope of this novel concept as defined by the following claims.

We claim:

1. A respirator adapted to assist in breathing comprising, in combination:

a. a source of fluid under pressure;

b. at least one fluid amplifier having a pair of output channels and a power jet connected to said source;

c. a mouthpiece;

d. connection means interconnecting said mouthpiece with said source;

e. first valve means controlled to an opened and closed position by said fluid amplifier in said connection means for blocking off flow of fluid therein during the exhalation cycle;

. second valve means including a bleed connection connecting said connection means at a point upstream of said first valve means for connecting the mouthpiece to atmosphere; and

g. additional connecting means connected to the output channels of said fluid amplifier for sequentially opening and closing said first and second valve means as a function of the inhalation and exhalation cycle of the breathing.

2. A respirator as claimed in claim 1 wherein said first valve means is opened and said second valve means is closed by said fluid amplifier during the inhalation cycle and said first valve means is closed and said second valve means is opened by said fluid amplifier during the exhalation cycle.

3. A respirator adapted to assist in breathing comprising, in combination:

. a. A source of fluid under pressure;

b. a first fluid amplifier having a pair of output channels, a

control port and a power jet connected to said source;

c. a mouthpiece;

d. connection means interconnecting said mouthpiece with said source;

e. first valve means controlled by said first fluid amplifier in said connection means for blocking off flow of fluid therein;

f. second valve means including a bleed connection connecting said connection means at a point upstream of said first valve means; I

g. additional connecting means connected to the output channels of said fluid amplifier for sequentially opening and closing said first and second valve means as a function of the inhalation and exhalation cycle of the breathing;

h. a second fluid amplifier having a pair of output channels and a power jet connected to said source;

i. a fluid line connecting one of said output channels of said second fluid amplifier to said control port; and

j. means responsive to a pressure in said connection means for switching the flow of fluid from said power jet to either one or the other output channels in both said first and second fluid amplifiers.

4. The combination as claimed in claim 3 including third valve means in said connection means synchronized with and disposed downstream of said first valve means so that said third valve means opens and closes together with said first valve means.

5. A respirator as claimed in claim 3 including means in said connection means for increasing the flow of fluid above the flow capacity of said pressure source.

6. The combination as claimed in claim 4 including an ejector in said connection means disposed between said first valve means and said third valve means.

7. The combination as claimed in claim 6 including an ejector having a power jet and a passage communicating with said power jet and said connection means so as to inject medication therein and another passage interconnecting said power jet and said connection means at a point intermediate said first valve means and said third valve means.

8. The combination as claimed in claim 3 wherein one of said output channels of said second fluid amplifier communicates with ambient.

9. The combination as claimed in claim 3 wherein said second fluid amplifier switches the flow stream from one of said channels to the other of said channels therein at a pressure lower than the pressure to switch the flow stream from one of said channels to the other of said channels in said first fluid amplifier.

10. A respirator adapted to assist in breathing comprising,

in combination:

a. a source of fluid under pressure;

b. a first fluid amplifier having a pair of output channels, a

control port and a power jet connected to said source;

c. a mouthpiece;

d. a main passage interconnecting said mouthpiece with said source;

e. first valve means controlled by said fluid amplifier in said main passage for blocking off flow of fluid therein;

f. second valve means including a bleed connection connecting said main passage at a point ilpstream of said first valve means;

g. connecting means connected to the output channel of said first fluid amplifier for sequentially opening and closing said first valve means as a function of the inhalation and exhalation cycle of the breathing;

h. a second fluid amplifier having a pair of output channels and a power jet connected to said source;

i. a fluid line connecting one of said output channels of said second fluid amplifier to said control port;

j. means responsive to a pressure in said main passage for switching the flow of fluid from said power jet to either one or the other output channels in both said first and second fluid amplifiers;

k. third valve means in said main passage spaced downstream from said first valve means and normally positioned in a closed position and pressure actuated to the opened position when the flow in the main passage flows toward the mouthpiece; and

1. means responsive to the pressure between said first valve means and said third valve means for opening and closing said second valve means.

11. The combination as claimed in claim 10 wherein said third valve means is a one-way check valve.

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