US3221734A

US3221734A - Respiration apparatus

Info

Publication number: US3221734A
Application number: US268704A
Authority: US
Inventors: Noel F Beasley
Original assignee: Bennett Respiration Products Inc
Current assignee: Bennett Respiration Products Inc
Priority date: 1963-03-28
Filing date: 1963-03-28
Publication date: 1965-12-07
Anticipated expiration: 1982-12-07

Description

Dec. 7, 1965 N. F. BEAsLEY RESPIRATION `APPARATUS Filed Maron 2a, 1963 m Sak n Nm a NL. wh .Tmmlwwmll 1| 1|! INVENTOR. /Voa F. 5545.459/ BM m@ a6/2a, ma M United States Patent O 3,221,734 RESPIRATION APPARATUS Noel F. Beasley, Santa Monica, Calif., assigner to Bennett Respiration Products, Inc., Santa Monica, Calif., a corporation of California Filed Mar. 28, 1963, Ser. No. 268,704 11 Claims. (Cl. 12S-29) This invention relates to respiration apparatus, and more particularly to improved respiration apparatus capable of use alternately as a respirator in administering intermittent positive pressure breathing therapy and as a resuscitator.

Intermittent positive pressure breathing, commonly known as IPPB, denotes a type of induced respiration or assisted breathing for patients who are breathing spontaneously. IPPB therapy has been used effectively in treating and relieving a wide variety of respiratory disorders, including cases where dyspnea, inadequate ventilation, and chronic loss of pulmonary function are present.

Physiologically, ideal IPPB therapy involves inflation of the lungs with a suitable gas or mixture of gases, which in some cases has medicament added, under a mild control pressure of, for example, -60 cm. of water. This iniiation during what is termed the inspiration phase, results in distention of the lung-thorax system slightly more than in normal inspiration and, hence, in more uniform and thorough alveolar aeration. The inspiration phase is followed by a passive or expiration phase, during which the pressure is rapidly released, preferably to ambient pressure, whereupon expiration by the patient automatically takes place by virtue of the elasticity of the lungthorax system.

IPPB therapy is intended for a patient who is spontaneously breathing at a rate and rhythm under his control and, therefore, is administered with a respirator. In the event a patient is not breathing, or is breathing erratically or at too slow a rate, it is then necessary that resuscitation be applied. For this purpose, resuscitation apparatus is used, which apparatus includes either manual or automatic means for cycling between inspiration and expiration phases. The term rate, as used herein, refers to the total number of breathing cycles in a given period 0f time. On the other hand, the term rhythm is used in referring to the regularity with which inspiration and expiration occur.

In order to be effective in administering IPPB therapy, apparatus must meet certain fundamental operational requirements which, in turn, are dictated by the standards established for ideal therapy and by the physiological requirements of the patient. One such requirement is that inflation of the lungs during the inspiration phase be in response to a slight inspiratory effort by the patient. It is desired that the eifort be sufficiently small so that no appreciable effort beyond that normally made in breathing is required. It is also preferred that the apparatus include means for adjusting the eifort required, in order that it may be used in applications where it is advantageous to force the patient to exert a greater effort.

During inspiration, an average patient has a peak ilow requirement of up to 100 liters per minute. This peak requirement exists near the start of inspiration and, thereafter, it decreases, dropping off quite rapidly to a low level near the end of inspiration. Therefore, a satisfactory system from a physiological standpoint is one which is capable of supplying at least the patients peak requirement at the preset regulator pressure.

Another important requirement, and one that is difficult to meet, is that of insuring that the inspiration phase does not terminate and the apparatus cycle into the expiration phase before the How rate to the patient is very low. This requirement stems from the fact that the lungs include a network of small passages which offer varying resistance to ow into the alveoli. For even ventilation of the alveoli, it is important that the inspiration phase be maintained until the liow requirement is very low. Specifically, the terminal ilow should be below 5 liters per minute and, to insure optimum ventilation, as low as one half liter per minute. Besides insuring proper ventilation, apparatus with a low terminal How also enables the lungs to be at least partially ventilated in the event there is a partial block or obstruction in the patients system.

It is further desired that the terminal ilow, like the eifort required to initiate inspiration, be capable of being adjusted. Such adjustability enables the apparatus to be used effectively on a patient having a leak in his system. For example, there may be a leak on the order of 10 liters per minute at the preset regulator pressure. In such a case, the terminal ilow might advantageously be adjusted to a slightly greater rate as, for example, 12 liters per minute, thereby insuring that cycling of the apparatus between inspiration and expiration phases takes place and also that the lungs are ventilated.

Most all units currently available are incapable of meeting these fundamental operational requirements. In most instances, these prior units are pressure sensitive, rather than ow sensitive, i.e. inspiration terminates when the mask pressure substantially equals the preset regulator pressure. As a consequence, inspiration terminates prematurely so that the lungs are not fully ventilated. Referring to the previous discussion, it will be recalled that the nature of the lungs is such that even when the mask pressure substantially reaches the preset regulator pressure, appreciable iiow must still take place if optimum ventilation is to be achieved. Moreover, where there is a partial block in the patients system, pressure sensitive units are completely unsatisfactory. The mask pressure quickly reaches the preset regulator pressure, and the unit rapidly cycles and even dead centers or chatters in some instances.

`Certain of the prior units embody sensitivity adjustment means, whereby adjustment may be made to preclude their cycling into the expiration phase before the lungs are ventilated to an acceptable degree. However, the adjustment means are constructed and arranged so that making an adjustment to reduce the terminal flow, reduces the peak ow capacity of the unit below a minimum satisfactory level.

In view of the foregoing, it is a primary object of this invention to provide an improved respiration apparatus, which obviates the problems of the prior art and meets all operational requirements of apparatus of this type.

A more specic object is to provide patient-controlled respiration apparatus adapted for use in IPPB therapy, the apparatus being flow sensitive to terminate inspiration and having a loW terminal flow so as to insure optimum ventilation of the lungs.

Another object of this invention is to provide apparatus of the type described, further characterized in that the patient-effort required to initiate the inspiration phase and the terminal llow at which the system cycles into the expiration phase may be easily adjusted and in that these adjustments may be made substantially independently of one another.

It is a further object of this invention to provide respiration apparatus, which is highly reliable in performing its intended function by virtue of being insensitive to moisture and foreign matter in the patients system.

Still another object of this invention is to provide a system of the type described, which is capable of being used eliectively not only as a respirator in administering IPPB therapy, but also as a resuscitator.

It is a still further object to provide a system, which is capable of accomplishing all of the foregoing objects, yet which includes no precision parts and, accordingly, may be manufactured at a relatively low cost.

These and other objects, features, and advantages of the invention will be better understood by referring to the following detailed description taken in conjunction with the accompanying drawing, in which the ligure is a semi-schematic view of one embodiment of the invention.

In the drawing, the basic apparatus of the invention, indicated by the reference numeral 10, includes that portion outside the phantom line enclosure 12. This basic apparatus is intended for use as the respirator, readily lending itself to advantageous use in administering IPPB therapy. The remaining portion within the enclosure 12 comprises an automatic cycling control system 11, which may be optionally activated to enable the apparatus to be used as a resuscitator.

The apparatus 10 includes a regulated source of pressurized gas 14 connected by delivery conduit means 16 to a suitable mask 18 adapted for connection to a patients respiratory system. The source, which by way of example may comprise a tank or bottle of compressed gas or room air compressed by a pump, or a combination of the two, is provided with a control element 19 for regulating or presetting the pressure of the gas delivered. In order to accommodate a wide variety of patients and therapy conditions and at the same time insure safe operation, the pressure is capable of being preset within the range of 10-60 cm. of water. In referring to the mask 18, it will be understood that it may comprise any suitable device, such as a conventional face mask, mouth piece or tracheotomy tube, which is adapted to be connected to the patients respiratory system.

Flow from the source 14 to the mask is controlled by valve means, here constituting a main diaphragm valve 20. As illustrated, the valve 20 is movable toward and away from a seated position against the end of a tube 22 to alternately block and open the flow path. When the valve 20 is pressurized, it is in an expiration or closed position and, conversely, when it is depressurized, it is in an inspiration r open position.

Expiration by the patient is through an outlet passage 24 in the conduit means 16. The passage 24 is closed during the inspiration phase by a diaphragm type exhalation valve 26, illustrated in full lines in its open position in the drawing. During operation of the apparatus l0, the opening and closing of the main diaphragm valve 20 and the exhalation valve 26 are correlated with one another. During the inspiration phase of operation, the main valve 20 is open and the exhalation valve 26 is closed, and during the expiration phase, illustrated in the drawing, the converse is true.

It is to be noted that the present invention is concerned primarily with the control means for correlating the operation of these valves and for intermittently opening and closing them, as desired. The control means includes in general a diaphragm type sensing unit 28 coupled to the conduit means 16 in operative relationship with a variable iiow restrictor 30 and operatively associated with the

valves

20 and 26. Also included as a part of the control means, is a conduit system for supplying pressure to the valves to eiiect closing of them, and embodied in this conduit system are valved bleed passages for relieving pressure in the valves to permit their opening.

Pressurization of the main valve 20 is achieved by supply conduit means 32 connecting the valve, whereby it is in constant communication with the source 14. The conduit means 32 includes an internal orifice 34 and a bleed passage 36 opening to the atmosphere. The oritice 34 and the bleed passage 36 are sized relative to one another so that when the latter is open, the pressure in the valve 20 is less than 5 cm. of water. This pressure reading is based on the condition that the pressure of the gas at the regulated source 14 is preset within the specified range of 10-60 cm. of water. The valve 20 is considered in this condition to be depressurized or in its inoperative position and flow through the delivery conduit means 16 from the source 14 of higher pressure obviously takes place. On the other hand, when the bleed passage 36 is closed, the pressure in the valve 20 is equal to the preset regulator pressure. In this condition, the valve 20 is pressurized or in its expiration position, and by virtue of the area of the valve 2t) being greater than the opening to its associated tube 22, iiow to the patient is blocked.

For closing the exhalation valve 26, pressure is applied from the conduit means 16 through a path provided by a first auxiliary or sensing conduit 38, the sensing unit 28, and a conduit 40. It may be seen that when the main valve 20 is open and a positive pressure exists in the delivery conduit means 16, this pressure is applied through the before mentioned path to seat the exhalation valve 26 and close the outlet passage 24. Relief of pressure in the exhalation valve 26 to permit it to move back to its open position is through a bleed passage 42 in the conduit 38.

Briefly summarizing, when the bleed passage 36 is closed and the bleed passage 42 is open, the apparatus is in its expiration phase of operation. The main valve 20 is then closed and the exhalation valve 26 is open, as illustrated in the drawing. An unrestricted path is provided from the mask to the atmosphere by the outlet passage 24 through which the patient may expire. On the other hand, when the bleed passage 36 is open and the bleed passage 42 is closed, the valve positions are reversed, and flow takes place from the source 14 to the patent through the conduit means 16. The apparatus is then, of course, in its inspiration phase of operation.

Opening and closing of the bleed passages 36 and 42 to cycle the apparatus between expiration and inspiration phases is accomplished by a control valve 44. This valve has a pair of

heads

46 and 48 cooperable with the openings to the passages 36 and 42, respectively, to effect closing. The valve 44 is arranged so as to move vertically between a first or expiration operating position and second or inspiration operating position. In the tirst operating position, illustrated in the drawing, the passage 36 is closed and passage 42 is open, whereas in the second operating position the relationship is reversed.

Movement of the control valve 44 to achieve cycling of the apparatus is accomplished by the sensing unit 28 to which the valve is operatively connected. The unit 28 embodies a housing 50 defining an internal chamber. In the illustrative embodiment, the chamber is divided into an upper or first compartment 52 and a lower or second compartment 54 by a horizontal, tiexible diaphragm 56. When so mounted, the diaphragm 56 is capable of moving vertically within the chamber from an upper or iirst operating position, illustrated in full lines in the drawing, and a lower or second operating position, illustrated in phantom lines. The diaphragm is biased toward its first operating position by a light compression spring 58. For adjusting the biasing force of the spring, a threaded adjustment nut 60 is provided on the lower end of the housing.

To operatively connect the diaphragm 56 and the control valve 44, a linkage system including a connecting rod 62 and a horizontal pivotal lever 64 are provided. The rod 62 has its lower end fixed to the diaphragm 56 and its upper end projecting upwardly from the housing 50. Secured to the upper end of the rod 62 is the lever 64 which, in turn, is connected to the control valve 44. With this arrangement, it may be seen that vertical movement of the diaphragm 56 produces corresponding vertical movement of the valve 44 in the same direction. Therefore, the rst operating position of the diaphragm 56 corresponds to the first operating or expiration position of the valve 44, whereas the second operating position ofthe 5.. diaphragm corresponds to the second operating or inspiration position of the valve.

The sensing unit 2,8A is, coupledy to the delivery conduit means 16 by the rst auxiliary or sensing conduit 38 and` a second auxiliary or sensing conduit 66. The conduit 38 is coupled at its opposite ends to the conduit means 16 on the upstream side of the variable flow restrictor 30 and to the upper compartment 52 of the sensing unit. Similarly, the :second auxiliary conduit 66 is coupled at its opposite ends to the conduit means 16 on the downstream side of the restrictor 30 and to the lower compartment 54. Thus, it will be appreciated that when. the apparatus is in its inspiration phase and the main valve 20 open and the exhalation valve 26 closed, the

conduits

38 and 66 are uninterrupted and the pressures which exist in the compartments 52 and 54 are equal to thepressuresexisting in the delivery conduit means 16 on the respective sides of the restrictor 30.

It is to be noted that theopening to the conduit 38 preferably is positioned within the tube 22 with the end walls of the conduit and, tube flush with one another. It follows from this mounting arrangement that, when the main valve 20 is closed, the opening to the conduit is likewise closed. This is of importance in that when the apparatus cycles to an expiration position, the bleed passage 42 need only bleed o the volume of pressurized gas trapped within the conduit 38, the upper compartment 52 and the exhalation valve 26 and its conduit 40. Also, it insures that at the instant the valve 20 opens, pressure is applied to the compartment 5,2 and to the exhalation valve 26.

The purpose of the variable flow restrictor 30 is to create a pressure drop in the conduit means 16 in accordance with the ow therein. This result is advantageously achieved in the present case in that, unlike the units of the prior art, a drop is produced even at extremely low flow rates, yet the peak ow capacity is not impaired. In achieving this desirable end, the restrictor is provided with a tube 67 opening downwardly into an enlarged chamber 70 to aiTord an orifice 68. The orifice 68, in turn, is restricted by a closure plate 72 movable toward and away from the tube and adapted to seat on its end wall. A conical compression spring 74 yieldably urges the plate 72 into closing relationship with the orice 68, as illustrated in the drawing. With this structure, when the pressure drop across the orifice 68 is large, which is the case when the flow requirement is high, the plate 72 is urged olf its seat to permit a high rate How through the conduit means 16.

To enable the restrictor to accommodate low flow rates to produce a pressure drop, the restrictor includes a bypassage 76 around the orifice 68. The restriction to flow through the bypassage 76 is controlled by a needle valve 78. At high ow rates in the conduit means 16, some flow is through the bypassage 76, but the greater portion is through the orice 68 by virtue of a plate 72 being urged oif its seat. On the other hand, at low flow rates the plate 72 closes the orice, as in the drawing, and all tlow is through the smaller orifice in the bypassage so that the pressure drop created is determined by the adjusted position of the needle valve 78,.` For purposes of this description, the orifice means includes the passages through both the orice 68 and the bypassage 76.

Prior to use, the apparatus has the various components positioned for the expiration phase of operation, as illustrated in the drawing. The diaphragm 56 is urged to its rst operating position by the spring 58 to position a control valve 44 in its expiration position. Accordingly, the main valve is closed and the exhalation valve 26 is open. It will be seen that at this stage, ambient pressure exists in both compartments 52 and 54 of the sensing unit 28. Assuming that the pressure of the gas to be emitted from the source 14 has been preset at the desired level within the range of 10-60 cm. of water and other necessary adjustments have been made,

6 the mask 18 is connected to the patients respiratory sys. tem in preparation for administering IPPB therapy.

To commence therapy, the patient simply exerts a slight inspiration effort, as in normal breathing, causing a slight negative pressure to be drawn in the conduit means 16. This has a dualelect of drawing the exhalation valve 26 to its closed position, illustrated in phantom lines in the drawing, and of creating an unbalancing force on the diaphragm 56. As a result, the diaphragm moves downwardly toward its second operating position, illustrated in phantom lines,` against the biasing force of the spring 58. Preferably, the nut 60 is adjusted so that a negative pressure of approximately one half cm of water is suflcient to so move the diaphragm. Because of the connection of the diaphragm 56 and control valve 44, the latter is moved downwardly to open, the bleed passage 36 and close the bleed passage 42, and thereby cycle the apparatus into its inspiration phase of operation.

Responsive to shifting of the control valve 44, to open and close the bleed passages 36.and 42, respectively, the main valve 2 0 is depressurized so that the pressurized gas from the source 14 urges it off its seat. Coincidentally, pressure is applied through the conduit 38 to theupper compartment 52 of the sensing unit 28 and to the exhalation valve 26V through its conduit 40. Pressurizing the exhalation valve 26 insures that it remains in its closed positionv during the entire inspiration phase. At the start of inspiration, the flow requirement of the patient is high, being up to litersper minute, as previously noted, and, therefore, a substantial pressure differential exists on opposite sides of the flow restrictor 30. Since the lower compartment 54 of the sensing unit is coupled to the downstream side of the restrictor, a like differential is applied to the diaphragm, causing it to be maintained in its phantom line position in the drawing.

By virtue of this high oW requirement of the patient at the start of inspiration, the closure plate 72 is moved downwardly away from its seat against the action -of its spring 74 to permit the ow requirement to be met. With the plate 72 forced down 01T its seat, the pressure drop in the con-duit means 16 is, of course, reduced, however, it is more than ample to insure that the diaphragm 56 is maintained in its second operating position. The flow through the conduit means 16 decreases in accordance with the decrease in the patients requirement, and the plate 72K moves back toward its seat, so to increase the restriction to ow. This progressive decrease in the requirement during the terminal portion of the inspiration phase eventially results in the orice 68 being entirely closed, as in the drawing. However, flow still takes place through the bypassage 76, and a pressure drop is created by virtue of the restriction alforded by the needle valve 78. Depending upon the adjusted position of the valve 78, a predetermined minimum ow is reached at which the pressure drop across the restrictor 30 is insuicient to overcome the biasing force of the spring 58 acting upon the diaphragm. As set forth in the introductory discussion, it is desirable that this minimum or terminal How be as low as one half liter per minute, which is entirely possible with the present apparatus. It is signicant to note that the apparatus is flow sensitive to terminate inspiration independently of the absolute pressure in the conduit means 16. That is, even if the pressure in the conduit means 16 at the mask 18 substantially equals the preset regulator pressure, the inspiration phase will continue, provided the flow rate exceeds the predetermined minimum ow rate. Thus, optimum ventilation is assured.

The result of diaphragm movement from its second toward its rst operating position under `the influence of the spring 58 is to cycle the apparatus back to its expiration phase. The control valve 44 is shifted to its expiration position to. open 4the bleed passage 42 and close the bleed passage 36. Thus, in turn, has the effect of pressurizing the main valve 20 to preclude any further ow from the source 14. At substantially the same time, pressure in the upper compartment 52 of the sensing unit and in the exhalation valve 26 are relieved through the bleed passage 42, permitting the exhalation valve 26 to open. The patient now expires to the atmosphere through the outlet passage 24 in the conduit means 16. Such expiration continues until the patient exerts another slight inspiratory effort to initiate another breathing cycle.

It will be appreciated that the apparatus 10 is highly exible in its mode of operation. For example, in the event that there is an unavoidable leak in the patients system of 10 liters per minute, then it might be desirable to adjust the terminal ow to approximately l2 liters per minute. This would insure that the apparatus cycles properly, rather than stays continuously in its inspiration phase. In this situation, the actual terminal ow to the patients system would be 2 liters per minute which is within the desirable range. To increase the terminal ow, it is simply necessary to adjust the needle valve 78 to decrease the resistance to flow through the bypassage 76. It is to be noted in connection with such adjustment of the terminal flow that it is independent of the preset pressure of the source 14. That is, the preset pressure of the source may be varied within the specied range without appreciably effecting the terminal flow. Also, the terminal ow adjustment may be made substantially independently of the adjustment of the negative pressure required to initiate inspiration. This follows from the fact that even though the biasing force of the spring 58 actually shifts the diaphragm 56 to terminate inspiration, adjustments of the spring force which are normally made are insufficient to appreciably effect terminal flow.

The above ydescription and explanation have been concerned with respirator operation of the basic apparatus 10. Should the patient require resuscitation, this may be accomplished manually by intermittently moving the lever 64 up and down to shift the control valve 44 between its inspiration and expiration positions to cycle the apparatus. In this instance, the rate and rhythm of breathing are under the control of the operator, assuming the patient is not breathing spontaneously. Alternately, it may be desired to provide means for automatically cycling the apparatus. As noted above, a control system for this purpose is shown within the phantom line enclosure 12. The control system shown by way of illustration in the drawing is a pneumatic one. However, it will be understood that various other types of automatic cycling control systems may be used effectively with the basic apparatus 10.

In order to automatically initiate the inspiration phase, a conduit 32a with a bleed passage 82 is provided, this conduit being a branch of the valve supply conduit 32 connected to the main valve 20. The bleed passage 82 is normally closed by a valve element 84 secured to a lever 85. It will be seen that opening the bleed passage 82 serves to depressurize the main valve 20 and thereby initiate inspiration. To achieve this, a first diaphragm type accumulator 86 is arranged so that when it is fully inflated or expanded, it pivots the lever 8S carrying the valve element 84 to open the passage 82. Pressure for inating the accumulator 86 is supplied from a fixed pressure source 88 through a conduit 90 having a needle valve 92 and a bleed passage 94 therein.

The expiration phase is initiated in the present system by virtue of a second diaphragm type accumulator 96 acting on the lever 64 to shift the control valve 44. This latter accumulator is likewise supplied with pressure from the source 88, in this case through a conduit 98 provided with a needle valve 100 and a bleed passage 102.

In order to insure that the inspiration and expiration phases occur in timed sequence to one another, a control valve 104, similar to the control valve 44, is provided for alternately opening and closing the bleed passages 94 and 102. Movement of the valve 104 is effected by a third accumulator 106 acting on a lever 108 connected to the valve. This third accumulator is coupled to the upper compartment 52 of the sensing unit by a branch 40a of the conduit 40. By virtue of this coupling, the pressure in the accumulator is equal to that in the cornpartment 52.

Prior to actuation of the automatic cycling control system 11, all three accumulators 86, 96, and 106 are deliated and the bleed passage 82 is closed. Assuming the apparatus 10 is in its expiration phase of operation, the bleed passages 102 and 94 are open and closed, respectively. The system is actuated by rst opening the needle valve 92 to permit the ow of gas from the source 88 to the accumulator 86. After a sufficient time period, dependent upon the rate of gas flow and, hence, the needle valve setting, the accumulator inflates sufliciently to open the bleed passage 82. This depressurizes the main valve 20 and permits flow to take place through the conduit means 16 to the patient. Likewise, pressurized gas from the source 14 flows through the conduit 38 to the upper compartment 52 of the sensing unit 28, and then through the conduit 40 to the exhalation valve 26 to close the valve even though the bleed passage 42 is initially open. By virtue of the high flow requirement of the patient at the start of inspiration, a substantial pressure differential exits across the flow restrictor 30. As a result, the diaphragm 56 quickly moves to its second operating position, shifting the control valve 44 to its inspiration position to open the bleed passage 36 and close the bleed passage 42.

Upon pressure being applied to the upper compartment 52, the accumulator 106 immediately inates to shift the control valve 104 and thereby open the bleed passage 94 (and close the bleed passage 102) to deate the accumulator 86. The bleed passage 82 is therefore closed, however, the inspiration phase of the cycle continues in that the bleed passage 36 is now open, as previously noted. Such inspiration phase continues provided the pressure differential produced by the variable ow restrictor is sufficient to maintain the diaphragm in its second operation.

The next step of the automatic cycling mode of operation involves opening the needle valve to commence inflation of the accumulator 96. The latter accumulator similarly ini'lates at a rate dependent upon the setting of the valve 100. It eventually becomes sutliciently inated to shift the control valve 44 to its expiration position. This action, in turn, cycles the apparatus into its expiration phase to open the bleed passage 42 and close the bleed passage 36. With the passage 36 closed, the main valve 20 is pressurized to block flow through the conduit means 16 and conduit 38. Moreover, the passage 42 serves to bleed off the small volume of gas within the conduits 38 and 40, compartment 52 and valve 26, thereby permitting the latter to open.

Simultaneous with cycling into the expiration phase, the third accumulator 106 is deflated, whereby the valve 104 moves the bleed passage 102 to deflate its associated accumulator 96 and close the bleed passage 94. With the passage 94 closed, low takes place to the accumulator 86 to begin filling it for the purpose of again cycling the apparatus to its inspiration phase.

The rate of breathing and the ratio of the inspiration phase to the expiration phase depend upon the settings of the

needle valves

92 and 100. An important feature of the present control system is that a patient may override 1t at any time. The sensing unit is operable, as durmg respirator operation, to sense a slight inspiratory effort by the patient to initiate inspiration and to the predetermined minimum or terminal flow in the conduit means 16 to terminate inspiration. The shifting of the valve 104 to open and close the bleed passages 94 and 102 insures that the patient can maintain full control 1n the event he commences proper spontaneous breathing.

Advantageous use may be made of the automatic cycling control system in a case where a patient is breathing spontaneously but erratically. Such use involves setting of the

needle valves

92 and 100 so that inspiration and expiration phases establishedv by the system 11 are slightly longer than the normal phases of the patient. Thus, as long as the patient breathes properly, the accumulator 106 operates to move the control valve 104 and thereby nullify the operation` of the system. However, should the patient suddenly begin breathing too slow or stop altogether, the system 1I takes over.

While the illustrated apparatus has been described in considerable detail, it will be understood that various changes in the constructions and arrangements of the parts may be made without departing from the scope andY spirit ofthe invention.

lclaim:

1. Respiration apparatus, comprising:

a` regulated source of pressurized gas, the pressure of said gas beingI adapted to be` preset;

a mask adapted to beiv connected to a patients respiratory system;

delivery conduit means coupled. at one end to said source and at the otherend to said mask;

valve means in said conduit means adapted to be cycled between an inspiration position, wherein fiow of gas takes place through saidy conduit means from said source tosaid mask,4 and an expiration position wherein such flow is blocked;

a variable iiow restrictor in said delivery conduit means including. orifice means in said deli-very conduit means and closure means` cooperable with said orifice means and mova-ble relative thereto to vary the size thereof, said closure means being biased toward a position wherein said orifice is of a minimum size;

diaphragm type sens-ing means operatively connected to.` said valve means and to said conduit means, said sensing means being responsive to` a predetermined negative pressure at said mask for cycling said valve means to its inspiration position and to a predetermined minimum fiow independent of absolute pressures in said conduit means for cycling said valve means to its expiration position;

first adjustment means for adjustably establishing the predetermined negative pressure at which said sensing means cycles said valve means to its inspiration position;

and second adjustment means substantially independent of said first adjustment means for adjustably establishing the predetermined minimum fiow at which sensing means cycles said valve means to its expiration position.

2. Respiration apparatus, comprising:

a source of pressurized gas;

a mask adapted to be connected to a patients respiratory system;

delivery conduitvmeans coupled at one end to said source and at the other end to said mask;

valve means in said conduit means adapted to be cycled between an inspiration position, wherein fiow of gas takes place through said conduit means from said source to said mask, and an expiration position wherein such flow is blocked;

a variable flow restrictor in said delivery conduit means including orifice means in said delivery conduit means and closure means cooperable with said orifice means and movable relative thereto to vary the size thereof, said closure means being biased toward a position wherein said orifice is of a minimum size;

a diaphragm type `sensing unit including a chamber separated into first and second compartments by a diaphragm which is movable between first and second operating positions;

a first auxiliary conduit coupled at its opposite ends to said conduit means on the upstream side of said restrictor and to said first compartment;

a second auxiliary conduit coupled at its opposite ends to said conduit means on the downstream side of said restrictor and to said second compartment;

mea-ns operatively connecting said diaphragm tok said valve means, whereby said valve means is in its inspiration position when said diaphragm is in its first operating position and inits expiration position when said valve means is in its second operating position;

means biasing said diaphragm toward its first operating position, said diaphragm being responsive to a -slight negative pressure applied at said mask to overcome the action of said biasing means and move from its first toward its second operating position and being movable from its sec-ond operating position toward its first operating posi-tion solely in response to pressures in said conduit means which are transmitted uninterruptedly through said first and second auxiliary conduits.

3. Respiration apparatus, comprising:

a regulated source of pressurized gas, the pressure of 4said being adapted to be preset within the range of 10-60 cm. of water;

a mask adapted to be connected to a patients respiratory system;

delivery conduit means coupled at one end to said source and at the other end to said mask;

a' valve seat in said conduit means adjacent the end thereof coupled to said source;

a main diaphragm valve cooperable with said valve seat in a pressurized condition to block iiow from said source to said mask and in a depressurized condition to permit such iiow;

valve supply conduit means coupled to said source and said diaphragm valve, said valve supply conduit means having an internal orifice and a bleed passage which are sized rela-tive to one another so that when the latter is open, said diaphragm valve is in its depressurized condition, said diaphragm valve being in its pressurized condition when said bleed passage is closed;

a flow restrictor in said conduit means intermediate said valve means and said mask for creating a pressure drop in said conduit means in accordance with the rate of flow therein;

a diaphragm type sensing unit including a chamber separated into first and second compartments by a diaphragm which is movable between first and second operating positions;

a first auxiliary conduit coupled at its opposite ends -to said delivery conduit means on the upstream side of said restrictor and to said first compartment;

a second auxiliary conduit coupled at its opposti-te ends to said delivery conduit means on the downstream yside of said restrictor and to said second compartment;

means forming a ybleed passage from said first com partment;

control valve means movable between a iirst operating position, wherein said valve bleed passage is closed and said compartment bleed passage is open, and a second operating posit-ion, wherein said valve bleed passage is open and said compartment bleed passage is closed;

means operatively connecting said control valve means and said diaphragm, said control valve means being in its first and second operating positions when said diaphragm is in its first and second operating positions, respectively;

and means biasing said diaphragm toward its first operating position, said ,diaphragm being responsive to a slight unegative pres-sure applied at said mask to overcome the act-ion of said biasing means and move from its first to its second operating position.

4. The subject matter of claim 3 further including:

first automatic cycling control means selectively operable responsive to said main valve being in its pressurized condition for a predetermined expiration time period for depressurizing said last mentioned valve;

second automatic cycling control means selectively operable responsive to said main valve being in a depressurized condition for a predetermined inspiration time period for moving said control valve means from its second to its first operating position;

and means operatively associated with said first and second automatic cycling control means for providing for sequential operation thereof.

5. The subject matter of claim 4 further characterized in that:

said first automatic cycling control means includes means for adjustably establishing the predetermined expiration time period;

and said second automatic cycling control means includes means for adjustably establishing the predetermined inspiration time period.

6. Respiration apparatus, comprising:

a regulated source of pressurized gas, the pressure of said gas being adapted to be preset within the range of -60 cm. of water;

a mask adapted to be connected to the patients respiratory system;

valve means in said conduit means adapted to be cycled between an inspiration position, wherein flow of gas takes place through said conduit means from said source to said mask, and an expiration position, wherein such llow is blocked;

a variable ow restrictor in said conduit means intermediate said valve means and said mask for creating a pressure drop in said conduit means in accordance with the rate of ow therein, the extent of the restriction decreasing in response to an increase in flow therethrough, said restrictor being constructed and arranged to create a pressure drop while permitting ow at fiow rates below 5 liters per minute and to permit ow rates up to 100 liters per minute when the pressure of the gas at said source is preset within said range;

land a diaphragm type sensing unit divided by a movable diaphragm into compartments connected to said conduit means on the upstream and downstream sides, respectively of said flow restrictor, and operatively connected to said valve means, said unit being responsive to a predetermined negative pressure in said conduit means at said mask for cycling said valve means to its inspiration position and to a predetermined minimum flow independent of absolute pressures in said conduit means through said variable iiow restrictor of less than 5 liters per minute for cycling said valve means to its expiration position.

7. In apparatus including a source of pressurized gas,

a delivery unit, and conduit means having an inlet end coupled to said source and an outlet end coupled to said delivery unit, means for controlling the flow of gas through said -conduit means from said source to said delivery unit, comprising:

valve means in said conduit means adapted to be cycled between an open position, wherein ow of gas takes place through said conduit means from said source to said delivery unit and a closed position, wherein such flow is blocked;

-a variable fiow restrictor in said conduit means including means forming an orifice in said conduit means, closure means movable into and out of closing relationship with said orifice to variably restrict flow therethrough, said closure means being biased tow-ard its closing relationship and being responsive to high rates of ow through said conduit means to move out of such relationship, and means forming a restricted bypassage around said orifice of a size substantially smaller than said orifice, valve means in said bypassage for adjustably restricting iiow therethrough;

CFI

and control means including a sensing unit coupled to the upstream and downstream sides of said restrictor and operatively connected to said valve means, said unit being responsive to a predetermined negative pressure in said conduit means adjacent said delivery unit for opening said valve means and to a predetermined minimum pressure drop in said conduit means across said restrictor for closing said valve means.

8. In apparatus including a source of pressurized gas,

a delivery unit, and a conduit means having an inlet end coupled to said source and an outlet end coupled to said delivery unit, means for controlling the flow of gas through said conduit means from said source to said delivery unit, comprising:

means forming an orifice in said conduit means;

a closure member movable toward and away from closing relationship with said means forming said orifice, the effective area of said orifice being increased as said closure member moves away therefrom, said closure member being maintained toward its said open position in response to fiow in said conduit means toward said outlet end;

means biasing said closure member toward said closing relationship;

means forming a by-passage around said orifice;

valve means in said by-passage for adjustably restricting ow therethrough; and

control means coupled to said conduit means and operatively connected to said valve means, said control means being responsive to a predetermined negative pressure in said conduit means adjacent said delivery unit for cycling said valve means to its open position and to a predetermined minimum f'low independent of absolute pressures in said conduit means for cycling said valve means to its closed position.

9. In apparatus including a source of pressurized gas, a delivery unit, and conduit means having an inlet end coupled to said source and an outlet end coupled to said delivery unit, means for controlling the flow of gas through said conduit means from said source to said delivery unit, comprising:

valve means in said conduit means adapted to be cycled between an open position, wherein fiow of gas takes place through said conduit means from said source to said delivery unit and a closed position, wherein such flow is blocked;

a variable flow restrictor in said conduit means including orifice means in said conduit means and closure means cooperable with said orifice means and movable relative thereto to vary the size thereof, said closure means being biased toward a position wherein said orifice means is of minimum size; and

control means coupled to said conduit means and operatively associated with said restrictor and said valve means, said control means being responsive to a predetermined negative pressure in said conduit means adjacent said delivery unit for opening said valve means and to a predetermined minimum fiow independent of absolute pressures in said conduit means through said variable flow restrictor for closing said valve means.

10. The subject matter of claims 16 further characterized in that said control means includes first adjustment means for adjustably establishing said predetermined negative pressure, and said variable fiow restrictor includes second adjustment means substantially independent of said first adjustment means for varying the minimum size of said orifice means and thereby adjustably establishing said predetermined minimum fiow.

11. In apparatus including a source of pressurized gas, a delivery unit, and conduit means having an inlet end coupled to said source and an outlet end coupled to said delivery unit, means for controlling the flow of gas through said conduit means from said source to said delivery unit, 5 comprising:

valve means in said conduit means adapted to be cycled between an open position, wherein ow of gas takes place through said conduit means from said source means, said control means being responsive to a patient-effort for opening said valve means and to said predetermined minimum flow independent of absolute pressures in said conduit means through said orifice means when it is of minimum size for closing said valve means.

References Cited by the Examiner UNITED STATES PATENTS to said delivery unit and a closed position, wherein l0 2 867 210 1/1959 Bennet 128 29 Suh ow 1S blocked; 2,881,757 4/1959 Haveriand 128-29 a varrable ow restrictor 1n sald condult means lnclud- 2 929 377 3/1960 Cummins 128 144 ing variable orifice means in said conduit means, 3073298 1/1963 Stanton 128 29 said oriiice means normally being of minimum size 3083721 4/1963 MattheWgTe-t-l" 13,7 63 and increasing in size in response to ow there- 15 3111946 11/1963 Galeazzi "128 142 through at a rate greater than a predetermined mini- 3138152 6/1964 Wilson 128 29 mum; and

control means coupled to said conduit means and oper- 4atlvely associated with said restrictor and said valvel RICHARD A. GAUDET, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,221,734 December 7, 1965 Noel F. Beasley It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column l0, line 18, after "said" insert gas column l2, line 68, for "claims 16" read claim 9 Signed and sealed this 18th day of October 1966.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD I. BRENNER Commissioner of Patents

Claims

1. RESPIRATION APPARATUS, COMPRISING: A REGULATED SOURCE OF PRESSURIZED GAS, THE PRESSURE OF SAID GAS BEING ADAPTED TO BE PRESET; A MASK ADAPTED TO BE CONNECTED TO A PATIENT''S RESPIRATORY SYSTEM; DELIVERY CONDUIT MEANS COUPLED AT ONE END TO SAID SOURCE AND AT THE OTHER END TO SAID MASK; VALVE MEANS IN SAID CONDUIT MEANS ADAPTED TO BE CYCLED BETWEEN AN INSPIRATION POSITION, WHEREIN FLOW OF GAS TAKES PLACE THROUGH SAID CONDUIT MEANS FROM SAID SOURCE TO SAID MASK, AND AN EXPIRATION POSITION WHEREIN SUCH FLOW IS BLOCKED; A VARIABLE FLOW RESTRICTOR IN SAID DELIVERY CONDUIT MEANS INCLUDING ORIFICE MEANS IN SAID DELIVERY CONDUIT MEANS AND CLOSURE MEANS COOPERABLE WITH SAID ORIFICE MEANS AND MOVABLE RELATIVE THERETO TO VARY THE SIZE THEREOF, SAID CLOSURE MEANS BEING BIASED TOWARD A POSITION WHEREIN SAID ORIFICE IS OF A MINIMUM SIZE; DIAPHRAGM TYPE SENSING MEANS OPERATIVELY CONNECTED TO SAID VALVE MEANS AND TO SAID CONDUIT MEANS, SAID SENSING MEANS BEING RESPONSIVE TO A PREDETERMINED NEGATIVE PRESSURE AT SAID MASK FOR CYCLING SAID VALVE MEANS TO ITS INSPIRATION POSITION AND TO A PREDETERMINED MINIMUM FLOW INDEPENDENT OF ABSOLUTE PRESSURES IN SAID CONDUIT MEANS FOR CYCLING SAID VALVE MEANS TO ITS EXPIRATION POSITION; FIRST ADJUSTMENT MEANS FOR ADJUSTABLY ESTABLISHING THE PREDETERMINED NEGATIVE PRESSURE AT WHICH SAID SENSING MEANS CYCLES SAID VALVE MEANS TO ITS INSPIRATION POSITION; AND SECOND ADJUSTMENT MEANS SUBSTANTIALLY INDEPENDENT OF SAID FIRST ADJUSTMENT MEANS FOR ADJUSTABLY ESTABLISHING THE PREDETERMINED MINIMUM FLOW AT WHICH SENSING MEANS CYCLES SAID VALVE MEANS TO ITS EXPIRATION POSITION.