GB2164568A - Self-contained portable single patient ventilator/resuscitator - Google Patents

Abstract

A self-contained portable single patient ventilator/resuscitator of the type which has a timed cycle of operation, but which a patient can override in response to his physiological needs. The ventilator/resuscitator has a power source in the form of a chemical oxygen generator (18 or 132), fluid operated delivery means associated with the oxygen source, and control means. The delivery means includes pump means (28 or 122) associated with an ambient air filter (32 or 120), a two position valve shiftable between inspiratory and expiratory modes, an output tube (42 or 130) and a mask (10 or 110) and head harness (12 or 112). When the delivery means is in the inspiratory mode at least a portion of the oxygen output is delivered to the patient (14 or 114) and when the delivery means is in the expiratory mode at least a portion of the oxygen output is delivered to an accumulator (54 or 124). The control means (24 or 186, 188, 190, 192) will cause the valve means (22 or 128) to cycle between its inspiratory and expiratory positions in a timed cycle established by timing modules (88, 89 or 188, 190). The control means additionally includes pressure sensing devices (90, 92 or 202) which are capable of causing the valve means to be shifted to an inspiratory mode when the patient initiates an inspiratory effort, and which are also capable of causing the valve means to be shifted to an expiratory mode when the pressure to the patient exceeds its set peak pressure. <IMAGE>

Description

SPECIFICATION Self-contained portable single patient ventilator/ resuscitator Field of the Invention The present invention relates generally to respiratory apparatus, and more particularly to a self-contained portable respiratory device which can be used with a single patient either as a ventilator or as a resuscitator for a limited period of time.

Background of the Invention Various types of respiratory devices are well known in the art, and the present invention deals with that class of devices generally referred to as either resuscitators and/orventilators, depending upon their primary intended usage. As used in this application, a resuscitator is defined as an apparatus utilized for initiating respiration in a person whose breathing has stopped. Similarly, a ventilator is defined as a positive pressure apparatus, other than a resuscitator, utilized to assist in pulmonary ventilation. Most types of known prior art have been developed for use in hospitals and are adapted to be powered by electrical current received from the hospital, and are also adapted to utilize the hospital oxygen supply system.

While some portable resuscitators have been known in the past, these devices typically used bottled oxygen, which has an adverse weight to oxygen supply ratio. In addition such devices which rely on bottled oxygen typically have a relatively short shelf life when compared to devices which rely on chemical oxygen generators. Therefore, it is desirable that a portable resuscitator be developed that has an acceptable weight to oxygen supply ratio and a relatively long shelf life.

Known portable resuscitators have operated only in a timed cycle mode wherein a volume of an air oxygen mixture is forced into a patient's lungs for a period of time and then the air oxygen mixture is permitted to expire for another period of time, the periods of time being selected to approximate a normal breathing cycle. Known portable ventilators could be operated in a demand cycle wherein each inspiratory phase of ventilation is triggered by the inspiratory effect of the patient's breathing. Demand mode ventilators are not suitable for use as resuscitators, as the patient is incapable of triggering their operation. Similarly, timed cycle resuscitators are not desirable for use as ventilators or with patients who start breathing on their own, as a mismatch of the breathing cycle to the physiological needs of the patient could be traumatic.Therefore, it is desirable that a portable unit be developed which can operate either as a ventilator or a resuscitator, such a portable unit normally operating in a timed cycle mode, the timed cycle being capable of being overridden by a patient's inspiratory or expiratory efforts.

Objects and Summary of the Invention It is an object of the present invention to provide a portable ventilator/resuscitator which overcomes the disadvantages of the known prior art devices.

More specifically, it is an object of the present invention to provide a self-contained portable single patient ventilator/resuscitator of the type having a chemical oxygen generator, the ventilator/ resuscitator further including an accumulator adapted to receive oxygen from the chemical oxygen generator during exhalation, and also being adapted to supplement the oxygen provided by the chemical oxygen generator during inhalation, such a ventilator/resuscitator having an extended shelf life and a satisfactory operational duty cycle.

It is a further object of the present invention to provide a self-contained portable single patient ventilator/resuscitator of the type set forth above wherein the ventilator/resuscitator is provided with a venturi pump and a filter, the unit being capable of entraining filtered air into the output of the oxygen generator to further extend its operational duty time, such a unit having an acceptable weight to oxygen supply ratio.

It is another object of the present invention to provide a self-contained portable single patient ventilator/resuscitator of the type which has a primary timed cycle of operation, the ventilator/ resuscitator initially being capable of delivering an air oxygen mixture to a patient for a first limited timed period and subsequently being capable of permitting the patient's respiratory cavity to expire the air oxygen mixture for a second limited timed period, and wherein the patient, through his own breathing cycle, may override either the inspiratory or the expiratory cycle.

The foregoing objects and other objects and advantages of this invention will become more apparent from a consideration of the following detailed description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings Figure 1 is a somewhat schematic fluid circuit system diagram illustrating one form of the present invention.

Figure 2 is a simulated pressure-time curve showing a normal timed inspiratory/exhalation cycle of 2 seconds inspiratory time and 4 seconds expiratory time and also patient triggered shortened inspiratory and exhalation cycles wherein the patient has overridden the normal cycle to satisfy his physiological needs.

Figure 3 is a somewhat schematic fluid system circuit diagram, similar to Figure 1, illustrating another form of the present invention of Figure 1.

Description of the Embodiment of Figure 1 Referring now to Figure 1, a single patient ventilator/resuscitator is shown in a system diagram. The ventilator/resuscitator includes a mask 10 which is adapted to be secured to a patient through a head harness 12, the patient in part being indicated by the respiratory cavity 14 and the patient's air passages 16. The ventilator/resuscitator further includes a source of oxygen 18, delivery means, indicated generally at 20 and fluid operated control means. The delivery means includes, in addition to the mask 10 and head harness 12, valving-means or distributor valve 22 shiftable between inspiratory and expiratory positions and other fluid components disposed between the source of oxygen 18 and the mask 10. The fluid operated control means is indicated generally at 24.

An optional oxygen supply line is indicated at 25.

The valve 22 acts as a two position flow directing means.

The source of oxygen 18, which also acts as a power supply, includes a chemical oxygen generator which is preferably a chlorate candle.

Chlorate candles are well known in the art and one such candle is disclosed in U.S. patent 2,507,450.

The chlorate candle when in operation discharges oxygen thyrough an outlet line 26. Disposed immediately downstream of the outlet 26 is a venturi pump means which includes a venturi 28, the output of the chlorate candle being directed through a jet orifice 27 and then through venturi 28.

In accordance with well known principles, as the oxygen flows through the narrow portion of the venturi its pressure will drop. This drop in pressure is utilized to introduce ambient air, indicated by arrow 30, into the suction portion 33 of the pump means 28, the air passing through an activated charcoal filterorthe like, indicated at 32, and through the inlet or suction portion 33 of the venturi.

The purpose of the filter is to remove toxic or harmful contaminants from the ambient air. The filter has a filter inlet open to ambient air, and a filter outlet connected to the suction portion of the pump.

A check valve may be associated with the inlet to permit air only to flow in the direction indicated by the arrow 30. The filtered ambient air will be mixed with the oxygen downstream of the jet orifice 27, and the filtered air and oxygen will be discharged through the discharge portion 33a of the pump means 28. A pressure or flow regulating valve, indicated at 34, is disposed downstream of the pump means for insuring that a relatively constant output is provided to the valve 22.

The filter 32, pump means, control means 24 and oxygen generator are all mounted within a housing, indicated by the dot dash line 8. The distributor valve 22 is basically a two position three port directional control valve which is normally held in the inspiratory position illustrated in Figure 1 by the action of a spring 35, but which is shiftable to an expiratory position under the influence of pilot line pressure in pilot line 36. When the valve is in the inspiratory position illustrated in the figure the flow from the oxygen generator will be through the valve 22, line 38, check valve 40, outline 42, check valve 44, and line 46 into the mask 10 and then through the patient's air passage 16 into the respiratory cavity 14. This flow will continue until the valve 22 is shifted to its expiratory position by the influence of pilot line 36.When the valve 22 is in its expiratory position flow from the oxygen generator 18 will be through the valve 22, line 48, check valve 50, line 52 and into accumulator 54. If the pressure in accumulator 54 should exceed its design level, the additional pressure may be vented to atmosphere through pressure relief valve 56. The line 52 is connected with line 38 by a further line 58 provided with a compensated check valve 60. The valve 60 is compensated by means of a pilot line 62 which has associated therewith a bleed to atmosphere 64.

Other fluid components in the oxygen delivery system are the positive end expiratory pressure (PEEP) valve which is in the form of a pressure compensated relief valve 66 which is connected to line 42 through line 67 and pilot line 68 and line 58 through pilot line 69 which is also provided with a bleed to atmosphere line 70. In Figure 2 PEEP pressure is illustrated at 0 cm H2O. Finally, a compensated exhalation valve in the form of a pressure compensated check valve 72 is provided.

The valve 72 is compensated by the pilot line 74 which extends from line 42. The check valve 44 and pressure compensated check valve 72 form a compensated inhalation/exhalation valve typically mounted on mask at the end of the outlet tube 42.

The control means 24 as illustrated is penumatically operated and includes a fluidicflip- flop 76 whose input is connected with the source of oxygen through line 78. One such suitable flipflop is the Norgren module 4FF-202.000. The output of the flip-flop can be through either line 80 or line 82, both of which are bled to atmosphere through restrictors 81 and 83, respectively. However, it should be noted that pilot line 36 extends from line 82 to control valve 22, the pilot line 36 being connected upstream of the restrictor 83. Input control lines 84 and 86 are also provided for the flipflop. As is well known in the art, when the bistable flip-flop is subjected to pressure in control line 84 its output will be diverted from line 80 to line 82.

Similarly, when the flip-flop 76 is subjected to pressure in line 86 its output will be diverted from line 82 to line 80. Each of these lines 84 and 86 are connected with an associated output line 80 or 82, respectively, by suitable valving. One such valve may be a timing module 88 and 89, and fluidic timing modules are well known in the art, one being the Norgren time delay module 5TD0214~000 which combines a fluidic resistance capacitance network with a Schmitt trigger, the module being provided with variable restrictor inputs. Afluidic timing module operates essentially by having a flow of control fluid pass through a variable orifice 88 until certain predetermined volume 89 has entered the module, at which point an output flow is then triggered. Thus, the adjustable orifice 88 disposed between lines 80 and 84 may be adjusted to cause the output flow to be triggered after two seconds.

Similarly, the adjustable orifice 88 associated with lines 82 and 86 can be adjusted to cause the output flow to be triggered after four seconds. By utilizing such timing modules the operation of the control valve 22 can be controlled. However, as has been previously noted the patient's physiological needs may differfrom the preset times established by the timing modules. Accordingly, additional controls are provided. One such control would normally block flow from line 80 to line 84 but would open when the pressure exceeded a predetermined limit, this control being indicated at 90. This control 90 will permit the timing module to be overriden under certain situations which are described below.

Additional controls may be provided between line 82 and line 86, one such control 92 being opened when the pressure in the mask drops below that value established by valve 66, which would happen when the patient initiates an inhalation effort.

Pilot operated two position two port directional control valves are illustrated. Valve 90 is normally spring biased to a closed position, but will open when the pressure in pilot line 94 exceeds the value determined by the adjustable spring. Valve 92 is normally spring biased to a closed position, but when the patient initiates an inspiratory effort the pressure in the mask will drop below that determined by the PEEP valve, and these conditions will be sensed by pilot lines 96 and 98 causing the valve 92 to shift to its open position. While two position directional control devices are illustrated, it should be obvious that other control devices may be used, as for example, monostable flip-flops associated with suitable pressure relief valves. In addition, air logic control systems may be substituted for the various controls 76, 88, 89, 90 and 92.

In operation, let-us assume that the operation of the chlorate candle 18 has just been initiated and that the output ofthefluidic module is in line 80. The distributor valve 22 will be biased to the position illustrated in the drawing by the spring 35. Flow from the generator 18 will be through the venturi pump 28 where it picks up air 30 which has passed through filter 32. The pressure of the output of the venturi is regulated by regulating valve 34. In Figure 2 the regulated pressure is such that a peak pressure of 35 cm H20 is delivered to a patient. However, higher pressures may be desirable. Flow from valve 34 now passes through valve 22 into line 38, check valve 40, and on to the mask 10 and into the patient 14.This flow will continue until eitherthetiming module between lines 80 and 84 times out or until the control 90 is shifted to permit flow from line 80 to 84. The normal timed inspiratory period is indicated at I in Figure 2. Similarly, a normal or timed expiratory period indicated at F in Figure 2, and a complete normal timed cycle is indicated at TC. The pressure to which valve 90 responds can be adjusted as indicated in Fig. 1, but it would normally respond in one of two situations, namely when the patient is trying to exhale or when the patient's respiratory cavity has been filled to the set pressure.

In either event the flow of oxygen and air through line 38 and check valve 40 has nowhere to go except to build up pressure in the pilot line 94 which extends between line 42 and control 90 causing the control to permit the flow of fluid from 80 to line 84 thereby shifting# the output of the fluidic flip-flop 76 to line 82. This increase in pressure is indicated at 95 in Figure 2. After this event occurs several things happen. First, the valve 22 is shifted by the pressure in line 36 from the indicated position to that position where the output of the source of oxygen 18 is passed from valve 22 into line 48 and then into the accumulator 54. This will cause a shortened inspiratory period SI and a shortened cycle SC.It should be noted at this point that the output of the chlorate candle is substantially constant over a given period of time and if it is not being used by the patient it must either be stored or be wasted. The accumulator provides a means whereby the output of the candle may be stored for subsequent use by the patient. When the valve is in the expiratory position the output of the candle will, in normal operation, go merely into the accumulator to discharge its accumulated oxygen and air when line 48 is pressurized as the valve 60 is compensated by line 62. At the same time the pressure in lines 38, 58, and pilot line 64 are bled to atmosphere through bleed 70. This permits the pressure compensated relief valve or PEEP valve 66 to lower the pressure in pilot line 74 which compensates the exhalation valve 72.Meanwhile the patient will expire air through valve 72 until the PEEP pressure is obtained, which pressure is determined by the adjustable PEEP valve 66, and which may vary the pressure setting between 0 and 20 centimeters of water. When this pressure is attained, additional air will not be exhausted through valve 72.

Customarily, exhalation occurs rapidly (within 1 second), and the remaining exhalation time (for example 3 seconds) is just a pause until inhalation occurs. Inhalation may be initiated by the timing module 88,89, which is disposed between lines 82 and 86, having timed out causing fluid to be introduced into line 86 shifting the output of the fluidic module to line 80 thus ending the expiratory cycle. Alternatively, if the patient should attempt to inhale indicated by the drop in pressure at 97 in Figure 2, this would also cause the control 92 to open. Thus, when the pressure in pilot line 96 drops below the pressure in pilot line 98 which would happen when the patient attempts to inhale, the valve 92 will be shifted to its open position causing a shortened expiratory cycle SE.When the output is again cycled back to line 80 the valve 22 will be shifted to the position indicated in Figure 1.

Additional oxygen and air will now flow into the mask from the venturi 28 and also from the accumulator which will unseat the check valve 60 as it is no longer being compensated through line 62, this line having bled out through bleed 64. The pressure in line 38, 58, and 69 will also cause the PEEP valve to be biased to a closed position preventing fluid from being exhausted through this valve.

By allowing the patient's natural physiological needs to sequence the inspiratory/expiratory cycle it will permit the attending person to address other needs. Prior art portable and/or pneumatically controlled ventilator/resuscitators will not allow a timed inspiratory/expiratory cycle to lengthen or shorten automatically as needed but must be adjusted manually to match the needs of the patient.

It should be noted that one of the advantages of the device described above is that the control means is operated solely by the output of the oxygen source. It has been found in practice that chlorate candles have an extremely long and reliable shelf life, for example 10 years or more. Thus, by using its output to control the cycling of the unit as well as its pressure compensation, a highly reliable ventilator/ resuscitator is providded which additionaly has a long shelf life.

While one form of the present invention is illustrated in Figure 1 and has been described above, another form is shown in Figure 3. While there are many differences between the two forms illustrated in Figure 1 and Figure 3, two distinctions should be initially noted. The first of these distinctions is thatthe form shown in Figure 1 relies upon fluidic circuits in the control means 24 whereas in the design shown in Figure 3 air logic control elements are utilised. The other disticntion relates to the location of the valving means. Thus, in Figure 1, the two position valve means is downstream of the venturi pump whereas in the design shown in Figure 3 the valve means is located upstream of the venturi pump.

Description of the Embodiment of Figure 3 Referring now to Figure 3 in greater detail, the housing which contains various of the components of the single patient venti lato rlresuscitato r is indicated by the dot dash line 108. Disposed to the exterior of the housing is a mask 110 which is adapted to be secured to a patient through a head harness 112, the patient in part being indicated by the respiratory cavity 114 and the patient's air passages 116.

Mounted within the housing are various components, and the primary components include a power supply indicated generally at 118, and ambient air filter indicated generally at 120, pump means indicated generally at 122, an accumulator 124 having an inlet/outlet line 126, two position flow directing means indicated generally at 128, and varioius line means interconnecting the above components, which line means will be described in greater detail below. Also mounted within the housing are primary control means (which will be described in detail below) for shifting the valve means between its first and second positions in accordance with predetermined timed intervals, and patient override control means which permit the patient to override the primary control means through his inspiratory or expiratory efforts. Outlet tubing 130 extends from the pump means 122 to the mask 110.

The power for operating the ventilator/ resuscitator of this invention when used as a portable unit is derived solely from the source of oxygen which is a chemical oxygen generator 132, preferably a chlorate candle. Extending away from the oxygen generator, and forming part of the powersupply, are a checkvalve 134, a gas supply filter 135, and an oxygen delivery line 136 which terminates at junction J1 in the design illustrated in Figure 3.As in the design illustrated in Figure 1, provision is made for connecting the outlet line or delivery line from the oxygen generator to any external source of air/oxygen of suitable pressure when desired, and to this end, a fitting 138 is provided which extends to the outside of the housing 108, the fitting in turn being conencted to the oxygen delivery line 136 at junction J2 through line 140 which is also provided with a check valve 142. The purpose of the check valves 134 and 142 are to prevent reverse flow through either the oxygen generator or the fitting 138.

The two position valve means 128 is provided with nine ports indicated at P11, P12, P13, P21, P22, P23, P31, P32, and P33. When the valve spool 129 of the valve 128 is in its normal position illustrated in Figure 1, ports P12 and P13 are connected, P22 and P23 are connected and P32 and P33 are connected.

Ports 11, P21 and P31 are blocked by the valve spool. No lines are connected to ports P11, P23 and P31, and these ports are therefore open to ambient.

When the valve is shifted to its second position, port P1 2 will be connected to port P11 and therefore to ambient, port P21 will be conencted to port P22, and port P32 will be connected to port P31 and also to ambient. Ports P13, P23, and P33 will be blocked internally, through port P23 will open to ambient.

Referring now in greater detail to the pump means 122, the pump means is a venturi pump which, as illustrated, includes a hollow structure 144 in which is mounted a venturi 146. Mounted upstream of the venturi 146 is a jet orifice 148 which is surrounded by suction portion 150 of the pump means. Downstream of the venturi is discharge portion 152 of the pump, the discharge portion including a check valve 154 and a flow control valve 156. The purpose of the check valve 154 is to prevent reverse flow through the pump, and the purpose of the control valve 156 is to adjust the rate of flow through the pump. Finally, the pump means is provided with a number of ports, P1-P7 various lines being connected to the various ports, as for example, the outlet tubing 130 being connected to port P1.

The ambient air filter 120 is schematically illustrated in the drawings but may be of a canister or cartridge containing activated charcoal and/or other components capable of filtering out harmful ingredients from the air. Such a filtertypically has an outlet which may be screwed into or otherwise secured to a port, in this case port P4 of the pump means. In addition, the filter has an inlet 160 typically provided with a check valve 162 capable of preventing reverse flow through the filter. The filter is mounted in the housing with its inlet 160, 162 disposed adjacent a perforated wall in the housing so that when suction is applied to the outlet 158 ambient air will be drawn into the filter.

Line means are provided which interconnect the power supply 118, the accumulator 124, 126, the valve means 128, and the pump 122. To this end, a first supply line 164 extends from junction J1 to port P13 on the valve means 128, and from port P12 to port P2 on the pump means 122, port P2 in turn being disposed upstream of the jet orifice 148. Thus, the first supply line 164 connects the power supply 118 to the pump means 122 when the valve 128 is in the position shown. When the valve 128 is in its other position a second supply line 166 extends from junction J1 through port P21 in valve 128 and then from port P22 to the accumulator terminating at junction J3. Thus, it can be seen that the second supply line connects the power supply 118 to the accumulator 124, 126. A check valve 168 is provided in line 166to prevent flow from the accumulator 124 through the line 166 to port P22. When the valve 128 is in the position shown a third supply line 170 extends from the accumulator, and specifically junction J3, to the port P33 of valve 128, and then from Port P32 to port P3 of the pump means 122, the port P3 being, in turn operatively connected to the suction portion 150. A pressure control valve may be disposed in the third supply line for the purpose of regulating the output pressure of the accumulator so that the pressure delivered to the pump from the accumulator does not exceed a certain value. In addition, a relief valve may also be interconnected with the accumulator through junction J3 to insure that the accumulator does not accumulate oxygen above a safe pressure.

As can be seen, the two position valve means 128 will block the second supply line 166 when its valve spool 129 is in its first position. When the valve spool is shifted to its second position, it will then block the first and third supp#ly lines 164,170. It should be noted that the valve spool is normally spring biased to its first position but is shiftable to its second position in response to pilot line pressure above a first predetermined level. After this first predetermined level has been achieved, the valve spool is shifted back to its first position when the pilot line pressure falls below a second predetermined level, the second predetermined level being less than the first predetermined level.

To this end, the valve spool is provided with an extension 176 provided with a pair of spaced apart annular grooves, schematically illustrated by the V shaped notches 178. A spring biased detent assembly 180 is adapted to be received in either of the grooves 178. Assuming that the spring force of spring 182 is equivalent to 1.75 kilo./sq.cm. and assuming that it is necessary to apply a force equivalent to 0.75 kilo./sq.cm. to cause the detent 180 to be shifted out of the groove 178, it can be seen that it is necessary to apply a force in the direction indicated by the arrow equivalent to 1.75+0.75 in order to shift the valve to the second position. Thus, it is necessary to apply a force through pilot line 186 at a first predetermined level which is the sum of the spring force 182 and the force required to lift the detent 180.Similarly, to cause the valve to shift from its second position to its first position, it is necessary that the pressure in line 186 be less than a second predetermined pressure level, the second predetermined pressure level being the pressure of the spring 182 less the pressure of the force required to lift the detent 180 out of groove 178. The pilot line 186, which extends from junction J4 in line 164 to valve 128 is part of a primary control means. Associated with the pilot line are first and second time delay assemblies 188 and 190, respectively. A volume chamber is associated with each of the time delay assemblies, and, as illustrated in the drawings, a common volume chamber 192 may be utilized.The function ofthefirsttime delay 188 isto insure that the pressure slowly builds up within the pilot line 186 between the time delay device and the valve 128 until it attains the first predetermined pressure level.

The time which this takes can be set by varying the adjustable restriction within the time delay assembly. Similarly, the time delay device 190 regulates the length of time it takes to vent to atmosphere the pressure within the pilot line 186 between valve 128 and time delay assembly 190 when the valve 128 is in its second position. The operation of the primary control means will be explained in somewhat greater detail below.

While the primary control means establishes timed inhalation and exhalation cycles once the supply of power has been initiated, it may be desirable for the patient to override the primary control means. To this end, patient override control means are provided, which patient override control means include a dump valve indicated generally at 194, a switch valve assembly which is indicated generally at 196. The valve 196 is a three position three port directional control valve having ports P8, P9 and P10. A pressure line 198 extends from junction J5 in the oxygen delivery line 136 to port P8 and also from port P9 to junction J6 in the pilot line 186.In addition, a pilot line 200 and sensor mechanism are provided for operating the valve 196, the pilot line extending from port P5, which is located downstream of the check valve 154 in the pump 122, to the sensor mechanism 202. Afurther pilot line 204 extends from port P10 of the valve assembly 196 to the dump valve 194. This line is provided with a bleed orifice 206. The switch valve 196 is normally spring biased to the centered position, shown. When a reduction in pressure in the discharge portion of the pump is sensed by sensor 202 via pilot line 200, valve 196 will be shifted to the left to put the power supply 118 in communication with pilot line 204.Similarly, when the sensor mechanism 202 senses an increase in pressure in the discharge portion of the pump through pilot line 200, it will shift the valve to the right hand position, unblocking line 198 and putting the oxygen delivery line 136 in communication with pilot line 186 via line 198.

The ventilator/resuscitator described above further includes a positive and expiratory pressure (PEEP) valve assembly indicated generally at 208. As such valve assemblies are well known in the art, it will not be described herein except to note that it is connected with the discharge portion of the pump means to either side of the check valve 154 through a discharge line 210 extending from port P6 to valve assembly 208, and also by means of a pilot line 212 extending from port P7 to the valve assembly 208.

The mask assembly is provided with a pressure compensated combined inhalation/exhalation valve indicated generally at 214. Such valves are also well known in the art and they are customarily mounted directly on the mask which is to be worn by a patient, the inlet side of the valve 214 being connected directly to the outlet line 130.

The unit shown in Fig. 3 operates in the following manner: To start up the unit, the chemical oxygen generator is caused to be ignited (typically done by pulling a lanyard which operates a firing pin mechanism). Once the operation of the chemical oxygen generator 132 has been initiated, it will start putting out oxygen up to a pressure of 50 PSI. At start up, the valves 128, 194 and 196 will be in their normal position, shown in this figure. The output from the oxygen generator 132 will flow through line 136 and line 164 into the jet orifice 148 and then through the venturi 146. The reduction in the pressure of the oxygen as it flows through the venturi will cause the pressure to be- reduced in the suction portion 150 of the pump.This reduced pressure will cause ambient air to be drawn in through the filter 120, to be mixed with the oxygen within the pump 122, and the oxygen enriched air discharged from the pump then passing to the mask 110 through the compensated inhalation/exhalation valve 214. However, if there has been a previous expiratory cycle, the accumulator will be charged up to a pressure established by is relief valve 174, and the accumulator will also discharge through its pressure control valve 172, and line 170 into the suction side 150 of the pump 122 through port P3.

As the pressure is relatively constant on either side of the PEEP valve, it will be in the position indicated and there will be no discharge to ambient. The pressure in the pilot line 200 for the sensor mechanism 202 is at pump discharge pressure and is not sufficient to cause the sensor 202 to switch the valve 196 away from its centered position. Oxygen is also flowing through pilot line 186 from junction J4 bypassing time delay 190 and pressing through the variable restriction in time delay 188, and slowly increasing the pressure within the volume chamber 192 and slowly increasing the pressure in pilot line 186. When the pressure in this pilot line 186 exceeds a first predetermined level, for example 2.5 kilo./ sq.cm.,the valve 128 will be shifted to its second position.The restrictor in time delay 188 is set in such a manner that it will normallytake approximately two seconds to achieve switch over pressure. However, by varying the restrictor in time delay 188, the time can be varied. During this time, any pressure in the pilot line 204 to the dump valve will be bled through orifice 206. The cycle just described can be described as a timed inhalation cycle.

During the timed exhalation cycle, the valve spool in valve 128 will be in its second position.

Immediately after the valve has switched, the flow from the oxygen generator will be through line 166 into the accumulator. The relief valve 174 is set at preferably 0.14 kilo./sq.cm. to prevent too much pressure from being available in the circuit as the accumulator will feed the venturi in a nonrestricted (no pressure drop) circuit. The discharge from the accumulator is blocked by the spool as port P33 is now blocked. At this time, line 164, extending from port P12 to port P2, will be placed in communication with atmosphere through port P11 thereby dropping the pressure in the downstream portion of line 164 as well as in the line 186 between the time delay 190 and junction J4.The discharge side of the pump is maintained at that pressure which is established by the PEEP valve since the PEEP valve is free to discharge through its variable restrictor 216 in accordance with the pressure upstream of the check valve 154 and the valve established by the variable spring 218 in the PEEP valve. It should be noted that, as the pressure in the discharge side of the pump quickly drops below that value established during the inhalation cycle, the compensated exhalation valve 214 will be permitted to discharge to ambient.

Meanwhile, the pressure in pilot line 200 is not sufficient to cause the sensor 202 to move the valve 196 out of its centered position. Therefore, the dump valve 194 will be maintained in the position shown.

This will permit the pressure in the pilot line 186 and volume chamber 192 to slowly discharge through the time delay 190. By varying the orifice size in time delay 190, the timed exhalation cycle can be established at approximately four seconds or whatever figure is desired. When the pressure in the volume chamber 192 drops to approximately 1 kilo./ sq.cm., the spring 182 acting on the spool of valve 128 will shift it back to the position illustrated.

During a timed inhalation cycle, if a patient attempts to override by exhaling, the gases delivered to the discharge end 152 of the pump 122 cannot be discharged as the valve 214 in the pressure compensated inhalation/exhalation valve will be closed. This will cause pressure to build up within the pilot line 200 to the sensor 202 causing the valve 196 to be shifted to place the discharge of the oxygen generator 132 directly in communication with the volume chamber 192 through line 198 as it extends from junction J5 to junction J6. This will quickly increase the pressure in the volume chamber 192 and pilot line 186 to a pressure sufficient to shift the spool 129 withi#n the valve 128 to its second position.Once the valve spool 129 is switched to its second position, the gasses in line 164 between port P12 and port P3 can bleed through the valve 128 and through port P11 to ambient thereby reducing the pressure in line 164 to ambient. As the pressure drops in the pump on the upstream side of the check valve 154, the PEEP valve will permit the pressure in the discharge chamber 152 on the downstream side of the check valve to discharge to ambient thus reducing the pressure in pilot line 200 to the sensor 202 permitting the switch valve 196 to be returned to its normal position. At this point in time, the volume chamber can now start to discharge as it would during a normal timed exhalation cycle.

Finally, in a timed exhalation cycle, if a patient attempts to override by inhalating, the discharge portion 152 of the pump 122 will drop below ambient. This will in turn cause the sensor 202 to shift the valve to the left to permit the pilot line 204 to the dump valve to be interconnected with the oxygen under pressure through line 198. This will now cause the dump valve to move to its other position dumping the pressure in the pilot line 186 betwen the dump valve and the two position valve 128 to atmosphere thereby permitting the valve spool 129 in valve 128 to switch to the other position thus initiating a timed inhalation cycle. Once such a cycle is resumed, pressure will build up in the discharge side 152 of the pump 122 which will then permit the valve 196 to return to its normal centered position. Pressure in line 204 bleeds to ambient through restrictor 206 allowing valve 194 to return to its normal position as shown.

While various control devices are shown entirely within the housing, it should be apparent that such controls, such as the PEEP pressure controller 218 and the manual operator 222 for the dump valve 194, could extend to the exterior of the housing 108.

Claims (17)

CLAIMS 1. A self-contained portable single patient ventilator/resuscitator capable of operating without attention in a normal mode during operation of a power supply to cyclically force filtered air and oxygen into a patient's respiratory cavity during an inspiratory mode and to then permit the patient's respiratory cavity to expire during an expiratory mode; said ventilator/resuscitator comprising: a power supply in the form of a chemical oxygen generator of the type which, when in operation, is capable of discharging oxygen over a period of time at a pressure sufficiently great to force oxygen into a patient's lungs; a filter capable of filtering out toxic and harmful contaminants from ambient air, the filter having a filter inlet open to ambient air and a filter outlet; pump means having a suction portion operatively interconnected with said filter outlet and a discharge portion, the pump means being capable of being operated when powered by said oxygen generator to cause ambient air to be drawn through said filter and into said pump means through said suction portion, the filtered air to be mixed with said oxygen within said pump means, and the filtered air and oxygen to be discharged through said discharge portion;; an accumulator adapted to receive oxygen from the chemical oxygen generator during exhalation and also being adapted to deliver accumulated oxygen to the pump during inhalation; line means extending between said oxygen generator, said pump means, and said accumulator; two position valve means operatively interconnected with said line means and capable, when in a first position, of preventing the flow of oxygen from said oxygen generator to said accumulator, and when in a second position, being capable of preventing the flow of oxygen from said oxygen generator to said pump means;; primary control means normally operated by the oxygen discharged by said generator, and during operation of said power supply being capable either of disposing said two position valve means in said first position for a first limited timed period dying an inspiratory mode or of disposing said valve means in said second position for a second limited timed period during an expiratory mode; and outlet tubing having one end portion connected to the discharge portion of said pump means, and another end portion adapted to be interconnected to a patient. 2. The self-contained portable single patient ventilator/resuscitator as set forth in claim 1 wherein said control means includes two shiftable valves, one valve being shifted during an exhalation effort by the patient and the other valve being shifted during an inhalation effort. 3. The self-contained portable single patient ventilator/resuscitator as set forth in claim 2 wherein the control means further includes a fluidic flip-flop whose input is connected with the source of oxygen. 4. The self-contained portable ventilator/ resuscitator as set forth in claim 2 wherein said pump means is provided with a check valve within said discharge portion, said check valve presenting reverse flowthrough said pump means, and further characterized by the provision of a positive and expiratory pressure (PEEP) valve means, a portion of the PEEP valve means being connected to the discharge portion of the pump means downstream of said check valve and another portion being connected to the pump means upstream of said check valve. 5. The self-contained portable single patient ventilator/resuscitator as set forth in claim 1 wherein said ventilator/resuscitatorfurther includes a housing, the power supply, filter, pump means, accumulator, line means, two position valve means, and primary control means all being mounted within said housing. 6. The self-contained portable single patient ventilator/resuscitator as set forth in claim 3 further characterized by the provision of a pressure compensated combination inhalation/exhalation valve assembly, said valve assembly being associated with said mask outside of said housing. 7. The self-contained portable single patient ventilator/resuscitator as set forth in claim 1 wherein said line means includes first, second and third supply lines, the first supply line extending from said power supply to said pump means, the second supply line extending from said power supply to said accumulator, and the third supply line extending from said accumulator to said pump means; and wherein said two position valve means is connected to said first, second and third supply lines and is capable, when in the first position, of blocking the second supply line, and additionally is capable, when in the second position, of blocking the first and third supply lines. 8. The self-contained portable single patient ventilator/resuscitator as set forth in claim 7 further characterized by the provision of a pilot line extending to said valve means from the first supply line downstream of said valve means, and wherein the two position valve means is normally spring biased to a first position but is movable to a second position in response to pilot line pressure above a first predetermined value. 9. The self-contained portable single patient ventilator/resuscitator as set forth in claim 8 further characterized by the provision of a first time delay assembly in said pilot line which operates to prevent the movement of the two position valve means from its first position to its second position until after a predetermined length of time after the first supply line pressure has obtained the first predetermined value. 10. The self-contained portable single patient ventilator/resuscitator as set forth in claim 8 wherein the two position valve is shiftable by spring bias from its second position to its first position only after pilot line pressure has dropped below a second predetermined value, said second predetermined value being less than said first predetermined value. 11. The self-contained portable single patient ventilator/resuscitator as set forth in claim 10 wherein first and second time delay assemblies are disposed within first and second said pilot line and are operable to delay the switching of the two position valve means from one position to another for a predetermined length of time after a predetermined pressure value has been obtained in the first supply line. 12. The self-contained portable single patient ventilator/resuscitator as set forth in claim 7 wherein the two position valve means is shiftable between its first and second positions in response to changes in pressure in the first supply line downstream of said valve means, and further characterized by the provision offirst and second time delay assemblies in said pilot line and operable to prevent the two position valve from shifting its positions until-after predetermined variable timed periods. 13. The self-contained portable single patient ventilator/resuscitator as set forth in claim 12 further characterized by the provision of patient override control means extending between the power supply, the discharge portion of the pump means, and the pilot line and operable, in response to an increase in pressure in the discharge portion of the pump means due to a patient's exhalation effort of causing said valve means to substantially switch from its first position to its second position. 14. The self-contained portable single patient ventilator/resuscitator as set forth in claim 13 further characterized by the provision of a dump valve in said pilot line, said dump valve being capable of dumping fluid in said pilot line to atmosphere, and wherein the patient override control means also extends to said dump valve, said patient override control means further being capable of causing said dump valve to be shifted to its dump position in response to a negative pressure in the discharge portion of said pump means due to a patient's inspiratory effort thereby shifting the two position valve means to its first position. 15. A self-contained portable single patient ventilator/resuscitator capable of operating without attention in a normal mode during operation of a power supply to cyclically force filtered air and oxygen into a patient's respiratory cavity during an inspiratory mode and to then permit the patient's respiratory cavity to expire during an expiratory mode; said ventilator/resuscitator comprising: a power supply in the form of a chemical oxygen generator of the type which, when in operation, is capable of discharging oxygen over a period of time at a pressure sufficiently great to force oxygen into a patient's lungs; a filter capable of filtering out toxic and harmful contaminants from ambient air, the filter having a filter inlet open to ambient air and a filter outlet;; pump means powered by and which receives oxygen from said power supply, said pump means having a suction portion operatively interconnected with said filter outlet and a discharge portion, the pump means being capable of being operated when powered by said power supply to cause ambient air to be drawn through said filter and into said pump means through said suction portion, the filtered air to be mixed with said oxygen within said pump means, and the filtered air and oxygen to be discharged through said discharge portion; an accumulator adapted to receive oxygen from the chemical oxygen generator during an expiratory mode and also being adapted to supplement the oxygen provided by the chemical oxygen generator during an inspiratory mode;; outlet tubing having one end portion interconnectiblewith said discharge portion of said pump means and another end portion adapted to be interconnected to a patient; two position flow directing means operatively interconnected with said pump means and said accumulator, and capable when in a first mode of directing oxygen to a patient and capable when in a second mode of directing oxygen to said accumulator; control means normally operated by the oxygen discharged by said generator and capable, during operation of said power supply, either of disposing said flow directing means in said first mode for a first limited timed period during an inspiratory mode or of disposing said flow directing means in said second mode for a second limited timed period during an expiratory mode;; said control means including two shiftable valves, one valve being shifted during an exhalation effort by the patient and the other valve being shifted during an inhalation effort. Amendments to the claims have been filed, and have the following effect:~ *(a) Claims 1 to 15 above have been deleted. *(b) New claims have been filed as follows:~ CLAIMS

1. A self-contained portable single patient ventilator/resuscitator capable of operating without attention in a normal mode during operation of a power supply to cyclically force air and oxygen into a patient's respiratory cavity (114) during an inspiratory mode and to then permit the patient's respiratory cavity to expire during an expiratory mode; said ventilator/resuscitator comprising: a power supply (132) of the type which, when in operation, is capable of discharging oxygen over a period of time at a pressure sufficiently great to force oxygen into a patient's lungs (114); pump means (122) having a suction portion (150) and a discharge portion (152), the pump means being capable of being operated when powered by said power supply to cause ambient air to be drawn into said pump means through said suction portion, the air to be mxied with said oxygen within said pump means, and the air and oxygen to be discharged through said discharge portion; an accumulator (124) adapted to receive oxygen from the power supply during exhalation and also being adapted to deliver accumulated oxygen to the pump means during inhalation;; line means(164, 166 and 170) extending between said power supply (132), said pump means (122), and said accumulator (124); two position valve means (128) operatively interconnected with said-line means and, when in a first position, being capable of permitting the flow of oxygen from said power supply (132) to said pump means (122), and when in a second position, being capable of preventing the flow of oxygen from said power supply (132) to said pump means (122);; primary control means (186, 188, 190 and 192) normally operated by the oxygen discharge by said power supply (132) and during operation of said power supply capable of causing said two position valve means (128) to be disposed either in said first position for a first limited timed period during an inspiratory mode or to be disposed in said second position for a second limited timed period during an expiratory mode; and outlet tubing (130) having one end portion connected to the discharge portion of said pump means (122), and another end portion adapted to be interconnected to a patient whereby air and oxygen may be delivered to the patient.

2. A self-contained portable ventilator/resuscitator as claimed in claim 1 wherein said pump means (122) is provided with a check valve (154) within said discharge portion (152), said check valve presenting reverse flow through said pump means (122), and further characterized by the provision of a positive and expiratory pressure (PEEP) valve means (208), a portion of the PEEP valve means being connected to the discharge portion of the pump means upstream of said check valve.

3. A self-contained portable single patient ventilator/resuscitator as claimed in claim 1 or claim 2 wherein said ventilato'r/resuscitatorfurther includes a housing (108), the power supply (132), pump means, accumulator, line means, two position valve means (120), and primary control means (186, 190 and 192) all being mounted within said housing (108).

4. A self-contained portable single patient ventilator/resuscitator as claimed in claim 3 further characterized bythe provision of a mask (110) connected to said another end of said outlet tubing, and a pressure compensated combination inhalation/exhalation valve assembly (214), said valve assembly being associated with said mask outside of said housing (108).

5. A self-contained portable single patient ventilator/resuscitator as claimed in any preceding claim wherein said line means includes first (164), second (166) and third (170) supply lines, the first supply line (164) extending from said power supply (132) to said pump means (122), the second supply line (166) extending from said power supply (132) to said accumulator (124), and third supply line (170) extending from said accumulator (124) to said pump means (122); and wherein said two position valve means (128) is connected to said first, second and third supply lines(164, 166 and 170) and is capable, when in the first position, of blocking the second supply line (166), and additionally is capable, when in the second position, of blocking the first and third supply lines (164 and 170).

6. A self-contained portable single patient ventilator/resuscitator as claimed in claim 5 wherein the primary control means includes a pilot line (186) extending to said valve means (128) from the first supply line (164) downstream of said valve means, and wherein the two position valve means (128) is normally spring biased by a first position but is movable to a second position in response to pilot line pressure above a first predetermined value.

7. A self-contained portable single patient ventilator/resuscitator as claimed in claim 6 wherein said primary control means includes a first time delay assembly (188) in said pilot line (186) which operates to prevent the movement of the two position valve means (128) from its first position to its second position until after a predetermined length of time after the first supply line pressure has obtained the first predetermined value.

8. A self-contained portable single patient ventilator/resuscitator as claimed in claim 6 wherein the two position valve means (128) is shiftable by spring bias from its second position to its first position only after pilot line pressure has dropped below a second predetermined value, said second predetermined value being less than said first predetermined value.

9. A self-contained portable single patient ventilator/resuscitator as claimed in claim 8 wherein the primary control means further includes first and second time delay assemblies (188, 190) disposed within said pilot line (186) and operable to delay the switching of the two position valve means (128) from one position to another for a predetermined length of time after a predetermined pressure value has been obtained in the first supply line (164).

10. A self-contained portable single patient ventilator/resuscitator as claimed in claim 5 wherein the two position valve means (128) is shiftable between its first and second positions in response to changes in pressure in the first supply line (164) downstream of said valve means, and wherein the primary control means includes first and second time delay assemblies (188,190) in said pilot line (186) and operable to prevent the two position valve means (128) from shifting its positions until after predetermined variable timed periods.

11. A self-contained portable single patient ventilator/resuscitator as claimed in claim 10 further characterized by the provision of patient override control means(194, 196) extending between the discharge portion of the pump means and the pilot line and capable, in response to an increase in pressure in the discharge portion of the pump means due to a patient's exhalation effort, of causing said valve means (128) to substantially switch from its first position to its second position.

12. A self-contained portable single patient ventilator/resuscitator as claimed in claim 11 wherein the patient override control means includes a dump valve (194) in said pilot line (186), said dump valve being capable of dumping fluid in said pilot line (186) to atmosphere in response to a negative pressure in the discharge portion of said pump means (122) due to a patient's inspiratory effort thereby causing the two position valve means (128) to be shifted to its first position.

13. A self-contained portable single patient ventilator/resuscitator as claimed in any preceding claim, further including: a afilter (120) capable of filtering out toxic and harmful contaminants from ambient air, the filter having a filter inlet (160) open to ambient air and a filter outlet (158) operatively interconnected with said suction portion (150) of said pump means (122).

14. A self-contained portable single patient ventilator/resuscitator as claimed in any preceding claim, wherein said power supply (132) is a chemical oxygen generator.

15. Aself-contained portable single patient ventilator/resuscitator capable of operating without attention in a normal mode during operation of a power supply to cyclically force air and oxygen into a patient's respiratory cavity (114) during an inspiratory m-ode and to then permit the patient's respiratory cavity to expire during an expiratory mode; said ventilator/resuscitator comprising: a power supply in the form of a chemical oxygen generator of the type which, when in operation, is capable of discharging oxygen over a period of time at a pressure sufficiently great to force oxygen into a patient's lungs; a filter capable of filtering out toxic and harmful contaminants from ambient air, the filter having a filter inlet open to ambient air and a filter outlet;; pump means powered by and which receives oxygen from said power supply, said pump means having a suction portion operatively interconnected with said filter outlet and a discharge portion, the pump means being capable of being operated when powered by said power supply to cause ambient air to be drawn through said filter and into said pump means through said suction portion, the filtered air to be mixed with said oxygen within said pump means, and the filtered air and oxygen to be discharged through said discharge portion; an accumulator adapted to receive oxygen from the chemical oxygen generator during an expiratory mode and also being adapted to supplement the oxygen provided by the chemical oxygen generator during an inspiratory mode;; outlet tubing having one end portion interconnectible with said discharge portion of said pump means and another end portion adapted to be interconnected to a patient; two position flow directing means operatively interconnected with said pump means and said accumulator, and capable when in a first mode of directing oxygen to a patient and capable when in a second mode of directing oxygen to said accumulator; and control means normally operated by the oxygen discharged by said generator and capable, during operation of said power supply, either of disposing said flow direction means in said first mode for a first limited timed period during an inspiratory mode or of disposing said flow direction means in said second mode for a second limited timed period during an expiratory mode, said control means including two shiftable valves, one valve being shifted during an exhalation effort by the patient and the other valve being shifted during an inhalation effort.

16. A self-contained portable single patient ventilator/resuscitator as claimed in claim 15 wherein the control means further includes a fluidic flip-flop whose input is connected with the source of oxygen.

17. A self-contained portable single patient ventilator/resuscitator, constructed, arranged and adapted to operate substantially as described with reference to, and as shown in, Figure 1 or Figure 3 of the accompanying drawings.