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Publication numberUS3364924 A
Publication typeGrant
Publication dateJan 23, 1968
Filing dateNov 9, 1964
Priority dateNov 9, 1964
Publication numberUS 3364924 A, US 3364924A, US-A-3364924, US3364924 A, US3364924A
InventorsClare E Barkalow
Original AssigneeMichigan Instr Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pneumatically operated closed chest cardiac compressor
US 3364924 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

1968 c. E. BARKALOW $36 PNEUMATICALLY OPERATED CLOSED CHEST CARDIAC COMPRESSOR Filed Nov. 9, 1964 4 Sheets-Sheet 1 uummmmmmu //0 IIHIIIIIIIIIIHIHIHI IHIHHHHHllllHlHi 1663 IIIHIHIIIIHIH HHH ATTORNEYS N VENTOR.

1958 c. E. BARKALOW PNEUMATICALLY OPERATED CLOSED CHEST CARDIAC COMPRESSOR 4 Sheets-Sheet 2 Filed Nov. 9, 1964 INVENTOR. (2/2/65 A. 54/6694 01d BY M? 77/72 Kszcouos/ ATTORNEYS Jan- 23, 19 c. E. BARKALOW PNEUMATICALLY OPERATED CLOSED CHEST CARDIAC COMPRESSOR Filed Nov. 9, 1964 4 Sheets-Sheet Z INVENTOR. CZAWZ i EAAAWZd/ ATTORNEYS Jan. 23, 1968 c. E. BARKALOW 4 Sheets-Sheet 4 Filed NOV. 9, 1964 NNN NNN

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- INVENTOR. 644/66 5. 545mm ATTORNEYS United States Patent Ofiice 3,364,924 Patented Jan. 23, 1968 3,364,924 PNEUMATICALLY OPERATED CLOSED CHEST CARDIAC COMPRESSOR Clare E. Barkalow, Comstock Park, Mich, assignor to Michigan Instruments, Incorporated, Cornstock Park,

Mich, a corporation of Michigan Filed Nov. 9, 1964, Ser. No. 409,634 23 Claims. (Cl. 128-53) ABSTRACT OF THE DISCLOSURE A cardiac compressor having a base with a support platform adapted to be placed under a patient and a compressor unit being rigidly attached to said base such that when in operation, it reciprocates vertically over the patient. The compressor unit is attached to a support column and with the compressor, forms a unit which snaps in place on the platform. Rigid engaging means are provided on the support platform and the supporting column for cooperative engagement. Preferably, an, overhanging flange on the platform engages a plate at the base of the column and there is provided means to snap said base into locking engagement with said column.

The compression cylinder contains a reciprocatable plunger which has thereon means to indicate the extent of external deflection.

A pressure operated system is provided to control the reciprocation cycle and the operation of the compressor. Means are further provided for controlled build-up of pressure in the compressor unit and snap action release of pressure during the return cycle of the reciprocatable plunger.

This invention relates to cardiac compressors, and more particularly to a pneumatically operated external cardiac compressor for emergency use.

A person whose heart has stopped beating normally has also stopped breathing. Cardiopulmonary resuscitation is needed within 20-30 seconds at most. This necessitates constant cyclic ventilation of the patient for oxygenation, and concomitant, constant, cyclic, forced pumping of blood from the heart for perfusion. Compression of the heart by external compression for a time period (systole) is followed by its expansion for a time period (diastole).

An external cardiac compressor must operate with a constant, cyclic force pulse to externally compress the heart by depression of the breastbone, and thereby, force blood out of the heart and through the patients system. The pulse interval sometimes is taken in response to heart signals caused by weak contractions of the heart itself, using electrical pick-offs to detect the signal. More frequently, however, the heart is compressed on an externally controlled time interval. One method of controlling this time interval is with an electrical signal generating, pulse type, power supply to activate the cardiac compressor at the controlled interval. This, however, presents difficulty in many instances, especially in ambulances where electrical power is minimal and is also erratic due to the large number of powered sirens, flashing lights, normally operated, and to the varying engine speed. To be dependent upon a small extra battery for control power supply is risky due to battery failure probabilities. Yet, control of the compressor is essential, and should be on a synchronized time basis for optimum effect. Moreover, control of the compressor should be transferable smoothly between automatic and manual control means of the power operated compressor, for dependability and continuity of treatment at all times, even during patient transfer.

A cardiac compressor, to be effective for ambulance use, must be capable of fitting into the vehicle without substantial space consumption due to the extremely limited space factor involved. Yet, in spite of its compactness, the cardiac compressor must be capable of sufiicient power and stroke to compress even the largest mans chest which might be encountered, about /5 of its thickness.

One disadvantage encountered with known cardiac compressors is the great difiiculty of placing the patient between the fixed back supporting platform and the reciprocable pressure applicator. The compressor units are basically C-shaped in configuration, with the lower leg of the C being the rigid platform, and the upper leg containing the reciprocable plunger. Since the unconscious patient has to be moved directly sideways with respect to the known compressors, proper positioning of the patient with respect to the unit often becomes extremely difficult. This is particularly true with large heavy patients, and time is severely limited to a matter of seconds. If the patient is otherwise injured, the problem of sandwiching him between the operative components of the cardiac compressor becomes very crucial.

Once a cardiac compressor is in operative position relative to the patient, its safe effective operation is achieved only with exactly located and properly regulated force application to the patient. Locating the cardiac compressor on the patient is crucial. If it is too high on the sternum, it will not compress the heart adequately. If it is too low, it will damage the liver. Moreover, the pressure on the heat must be just the proper amount, i.e. sutficient to force the blood from the heart, but not too much to damage it. This is achieved with about 20% chest thickness compression. The actual amount of chest compression force varies widely with chest thickness and strength, thereby causing the pressure applied to he very important.

In addition to these factors, it has been determined that the cardiac compressor must be regulatable to not only control the time interval between stroke pulses, but also the rate of pressure application for the rate of pressure release with each timed stroke for proper pumping action from the heart.

It is one object of this invention to provide a cardiac compressor apparatus that has exactly controlled stroke timing without any dependency upon an electrical supply source. The novel device has an accurate and variable, regulated timed interval constantly controlled and dependably operated by the same pneumatic supply source that powers the compressor. The unit is subject to accurate control and operation merely by attachment of a typical oxygen cylinder supply line in an ambulance, for example, or in any other emergency treatment facilites, such as piped oxygen in the hospital.

Another object of this invention is to provide a unique, pneumatically operated cardiac compressor having a special valving system that achieves accurately controlled, pneumatic actuation of the power operation for exact time interval pulsing. It also enables manual over-riding control of the pneumatically powered operation for on timum safety. The device is attachable to a conventional oxygen supply tank in an ambulance or useable with other compressed gas supply sources as in a hospital. Yet, it uses only a small amount of gas.

Another object of this invention is to provide a pneumatically controlled, pneumatically powered cardiac compressor device employing a special valve so that the entire device is easily portable. It can thus be easily carried from place to place with the patient. The device is also very compact, thereby being useful on a stretcher as in an ambulance, or in a hospital, or any other place, while being portable with the patient on the stretcher for continuity of treatment. Yet, it has a power stroke of varying capaciy and timing suitable for persons of different size and strength, with timing intervals being regulated in accordance with the pressure to be applied to the persons chest, in spite of its lightweight and compactness.

Another object of this invention is to provide a pneumatically operated cardiac compressor that is collapsible to a storage conditionin a small space, but is capable of remounting for use in seconds.

Another object of this invention is to provide a cardiac compressor having separable components enabling convenient positioning of its rigid support under the patient while separated from the compressor plunger. It has capacity for snap-action assembly in a few seconds time for immediate usage, to enable emergency treatment to be given within less than /2 minute. Even large, heavy persons can be positioned with the plunger over the chest and the rigid support under their back with a minimum of effort, and without trying to push or drag the patient between these components. It can even be positioned, assembled and operated from a narrow stretcher, vehicle seat, bed or couch.

*Another object of this invention is to provide a cardiac compressor assembly having specially controlled rate of pressure application during cardiac compression (systole) and rate of pressure release during cardiac refilling (diastole) to achieve optium pumping action for maintaining life.

Another object of this invention is to provide a cardiac compressor that clearly indicates the amount of chest defiection with each stroke, thereby enabling immediate accurate adjustment to the necessary amount.

These and several other objects of this invention will become apparent upon studying the following specification in conjunction with the drawings in which:

FIG. 1 is a perspective view showing the novel device in a position of use on a patient;

FIG. 2 is a perspective view of the opposite side of the device from that side illustrated in FIG. 1;

FIG. 3 is a sectional view taken on plane IIIIII of FIG. 2, showing the compressor plunger;

FIG. 4 is an enlarged, plan fragmentary view of the adjustable connection between the compressor arm and support post in the apparatus of FIGS. 1 and 2;

FIG. 5 is a perspective, fragmentary, exploded view of the releaseable connection between the mounting plate of the support post and connector plate of the platform of the apparatus of FIGS. 1 and 2;

FIG. 6 is a side elevational sectional view of the apparatus in FIG. 5;

FIG. 7 is a perspective enlarged view of the pneumatically operated time control valve;

FIG. 8 is a bottom fragmentary view of the base of the unit showing the control system in place;

FIG. 9 is a schematic diagram of the pneumatic control and operational system; and

FIG. 10 is a graphical representation of a typical time versus pressure curve resulting from the novel control system of the apparatus.

Referring now specifically to the drawings, the cardiac compressor assembly 10 includes the base platform subassembly 11, the support pillar or post 14 extending upwardly from one edge of the rigid platform 12 of subassembly 11, compressor arm 16 extending out over the base plate or platform, and plunger subassembly 18 mounted to the other end of arm 16 over the platform.

The base plate or platform 12 is of rigid metal construction, normally of aluminum. It has a generally fiat upper surface to receive the back of a patient. It provides a rigid, non-flexing support when the patients chest is compressed. It tapers from its thinner outer end to the opposite thicker end 20 of enlarged height. This latter end has a hollow underside to receive the pneumatic control system 22 mounted to the underside of the unit (FIG. 8), and communicating to the compressor through port connections to be described.

Aflixed to the upper surface of this enlarged end portion 20 of platform 12 is a rigid mounting plate 26 having one end extending out over the edge of the platform. This mounting and port connector plate (FIG. 5) has an air line inlet fitting 30 mounted thereon and communicating with a passageway from the fitting to control assembly 22 in a manner to be described. It also has a port 32 extending through the plate and surrounded by an O-ring 34 received in a groove to form a positive seal with the under surface of the column base plate 36 when Pressed together. Port 32 communicates with a port 38 communicant with the inside of the hollow enclosed column or post 14. This post acts as a reservoir for the gas, in a manner to be described hereinafter.

Another port 40 in plate 26 is surrounded by a sealing O-ring 42 adapted to contact and seal against the under surface of column plate 36, and communicating with port 46, to flexible hose 48 that extends to plunger subassembly 18 (FIGS. land 2).

Another opening 50 extends through plate 26 at the outer end of the plate. This orifice is intersected transversely by a blade latch 54 having a handle 56 on one end and a pivot mount 58 to plate 26 on the other end. This blade latch fits within a slot 60 in the outer extending end of plate 26. It is normally retained by spring 62 in a position to intersect the diameter of the through opening 50, as illustrated in FIG. 6.

The base 36 of support column 14 releasably interfits with mounting plate 26 by having its inner edge 36' slidablyreceived beneath the overlying flange 66. This flange is part of a support block that is affixed to plate 26 along its inner edge. It extends upwardly and out over the edge of plate 36. Alignment of plate 36 with plate 26 is facilitated adjacent flange 66 by a pair of straddling alignment pins 65. Attached to the opposite end of column base plate 36 is a tapered catch 70 having a narrow neck portion 72 between the enlarged head thereof and plate 36, into which latch blade 54 is biased to retain the assembly in tightly fitting condition once it is assembled. This catch is mounted to plate 36 by a suitable stud and nut 74 connection. The support cylinder can be readily connected or disconnected, with the gas line connections being automatically completed with latching of the unit. Operational forces will not be applied to the latch, but only to the retention flange 66 which is rigid and securely attached.

Secured to support column 14 is the compression arm 16, which extends radially therefrom. This compression arm includes a peripheral collar that surrounds the column 14. This collar is rotatable on the post 14 and is vertically slidable when locking means 82 is loosened.

This locking means includes a pair of generally cylindrical.

abutting elements 84 and 86 on threaded stud 88. A knurled knob 90 is attached to one end of this stud for manual loosening and tightening. Elements 84 and 86 have tapered faces 92 and 94 respectively, adjacent to and abutting the periphery of post 14 to bind the assembly. The passage in element 86 is unthreaded and forms a slip fit with stud 88. Passage in element 84 is threaded to receive threaded stud 88. To bind the assembly, knob is rotated so that collar 91 presses element 86 toward post 14 while threaded stud 88 simultaneously draws element 84 toward the opposite side of post 14 to bind on it. Once this binding connection is made, compression arm 16 is fixed vertically and rotationally with respect to the support column. This adjustment feature is important for reasons to be described hereinafter.

Mounted to the outerradial end of compression arm 16 is plunger subassembly 18. This includes a basic cylinder housing (FIG. 3). having a gas line fitting connection 102, into which fitting 104 from hose 48 interfits, to supply the upper end of the cylinder with compressed gas. The lower portion of the cylinder includes a cylindrical bushing 108. The bushing is integrally attached to an annular plate 114 abutting the bottom face of cylinder 100 (FIG. 3). This plate as well as the retaining cup 110 and a lubricating wiper 116 are secured to the bottom annular face of cylinder 100 by suitable screws 112.

The plunger element 120 is preferably basically hollow in configuration, having an enclosing upper end cap 122 inside cylinder 100. This end cap has a peripheral edge which extends out beyond plunger 120 to abut with the upper edge of bushing 108 and limit the downward stroke of the assembly. The lower end of plunger 120 includes a chest contacting resilient pad 128 which is adapted to abut the lower portion of the patients sternum in a manner to be described hereinafter.

Inscribed around and into the periphery of plunger 120 are spaced rings 121 of small indicia marks arranged in annuli. These are clearly visible to the operator as the plunger reciprocates vertically. The small vertical dimension of the small marks prevents the mark from being entirely concealed inside the cylinder when the plunger stops at the particular mark ring. The alignment of any one mark with the bottom face of cylinder 160 is indicative of piston extension and, therefore, of the depth of compression of the patients chest. Normally, these markings are placed approximately at one-half inch intervals, so that heavier rings 121' and 121" are at intervals of one and one-half inches. This is the normal deflection required for the average adult chest. The stroke length of the plunger can be regulated accurately by watching these indicia as the regulatory valve knob 140 (FIG. 2) is rotated and during operation, as explained more specifically hereinafter.

Assembly 22 (FIGS. 8 and 9) allows pneumatic control of the pneumatically powered operation of the cardiac compressor. This system is supplied by pressurized gas, for example from the pressurized oxygen tank (not shown) in a conventional ambulance. It is supplied through a hose 144 (FIG. 1) that connects to the releasable coupling 30. The pnuematic supply and control system that supplies gas supply hose 144 communicates through ports 32 and 38 (FIG. to reservoir 14 inside column 14- through branch line 144 (FIGS. 6 and 9), and then separates into pressure lines 152 and 169. Line 152 includes manually adjustable actuating pressure regulator 154 operated by knob 140 (FIG. 2). This line 152 communicates with the basic control valve 150 through an inlet port 156. The second branch conduit 160 from the supply line communicates through a control pressure regulator 162 and through a controlled constriction 164 such as an orifice plate, through branched conduit 169, to inlet port 168 of valve 150, and also to inlet port 170 of the automatic on-off pneumatic switch 172. This pneumatic switch includes a valve spool 174 inside housing 176, operable by extending suitable manual knob 178 which may have a push-pnll rigid connection (FIG. 9) or a toggle connection like that shown at 178 mounted to housing base 20 in FIG. 2.

Control valve 150 includes a basic housing construction 180 having a valve spool 182 inside the valve body. Magnetically responsive pistons 134 and 186 are attached to opposite ends of the spool and are located in piston chambers 188 and 190, respectively.

These piston chambers are closed by suitable end cap assemblies 192 and 194 illustrated graphically in FIG. 9 and structurally in FIG. 7. The portion of chamber 190 adjacent the inner face of piston 186 communicates through a port 200 and a conduit 202 to a small gas reservori chamber 204 which may be simply a hollow cylindrical vessel, for example. This reservoir also communicates through conduit 206 to another port 208 in valve body 180. Both of these ports are interconnected pneumatically through an annular recess passage 212 around spool 182 when the spool is at the far right position illustrated in FIG. 9. At the left position of the spool (relative to the drawing) port 168 is communicant with passage 216 in the valve spool body, which is in communica- 6 tion through conduit 218 to a second reservoir chamber 220. This reservoir chamber also communicates through another conduit 222 back to spool 174 of manual switch 172, and specifically with annular recess 226 therearound.

In one position of this spool 174, it therefore is in operative communication with conduit 230 that communicates with the side of chamber adjacent the outer face of piston 186. In the other position of spool 174, conduit 230 is in operative communication with conduit 169 which communicates with port 168 in the valve body 180.

Spool 132 also includes an annular recess 236 intermediate its ends, communicating with an exhaust outlet port 238 in the valve body, and also with a branch passage 216 interconnecting with passage 216. In another position, recess 236 interconnects exhaust port 238 to passage 208' branched from passage 208 in the valve body.

A third annular recess 244 in valve spool 182 is communicable in its first position to the right (FIG. 9) with port 248 and output pressure conduit 246, and also exhaust port 250 to allow flow therebetween. In its second position to the left, it interconnects port 156 of conduit 152 with outlet port 248 to conduit 246. This outlet conduit 246 interconnects with ports 40 and 46 (FIG. 5) to supply pressurized gas on a controlled basis to hose 48 to the top end of the plunger cylinder.

As noted previously, pistons 184 and 186 are magnetically responsive. Mounted adjacent the pistons is a pair of magnets 260 and 268 for the respective pistons 184 and 186. By positioning these magnets at a controlled distance with respect to the outer faces of the pistons, the bias necessary to overcome the magnetic attraction of each piston to its own magnet and shift the spool in the opposite direction, is controlled. This enables adjustment of the pressure necessary to build up in the alternate reservoir capacitor chambers 204 and 220 to shift the valve spool in one direction or the other. This controls the time interval of valve shifting, as will be described more specifically hereinafter. Mounting of the magnets to the end of valve 150 can be by extending end caps 192 and 194 to surround the magnets and overlap the ends thereof. Spacing of the magnets to the pistons can be achieved by suitable spacers 193 and/or by threadably engaging the outer attached sleeve 195 around the magnet (e.g. magnet 260) with the surrounding end cap retainer 192 such as at 192. Preferably, this timing adjustment is determined and fixed at the factory, to have a particular controlled time relationship to the pressure applied.

A fixed rod extension 270 is attached to piston 184 and extends through one magnet 260 out of the housing to terminate in a manual knob 272. This manual knob (FIG. 9) extends from the end of base 20 (FIG. 2) to be manually operable for actuating the valve manually.

Operation Because of the compactness of the novel device, and its relatively lightweight and small size, it can be readily adapted for use in ambulances, on the back seat of a police car, in hospitals, at business establishments or manufacturing facilities for industrial safety purposes, in the home, or in a variety of other places.

The device, due to its particular features, is convenient to use. It may be placed by one person in the proper operative position with respect to the patient.

Assuming for example, that the patient P (FIG. 1) requires cardiac compressive treatment on an emergency basis, he is placed into the operative relation illustrated in FIG. 1 when the device is disassembled. That is, to detach the upper end of the unit, column 14 of the unit is grasped, and knob 56 is pulled to release the latch when blade 54 is removed to the phantom position illustrated in FIG. 5 against the bias of spring 62. This enables the column to be tilted forwardly to the position illustrated in FIG. 5 and FIG. 6, so that edge 36' of plate 36 can he slid backwardly, out from beneath hold down flange 66. The column, compressive arm, and plunger are then laid aside for a moment while the base platform is inserted under the patient. The patient is first tilted by grasping his shoulder and rolling him part way onto his side, so that base platform 12 can be slide beneath his back. He is then rolled back to be flat on the platform. The column is replaced by inserting edge 36 again under flange 66, tilting the column vertically up to upright position so that knob 70 is inserted in opening 50 to catch beneath blade 54. This not only latches the assembly together, but also seals the passage connections at the ports illustrated in FIG. due to the pressure of the O-rings against the underside of plate 36.

The plunger pad 128 is adjusted relative to the patient to lie over the lower part of his breastbone, i.e. sternum. The exact position is achieved by loosening knob 90 and rotating arm 16 to assume its proper location. This is important for reasons stated previously.

Simultaneously, while arm 16 is still movable on col+ umn 14, the arm is slid down until pad 128 contacts the chest when the pad and plunger are in the raised position (FIG. 1).

Then, gas supply hose 144, as from a conventional oxygen tank, is then connected by coupling 30 to the system, to supply pressurized gas. This is done when knob 140 (FIG. 2) is in closed position to prevent premature presusne flow. No pressure then registers on gauge 141. The pressurized gas, when applied, wil lact as (l) the actuating means for the plunger, and (2) to operate the timing controller for the plunger. Plunger 120 is initially not pressurized, therefore, and can be held up in its upper, retracted position illustrated in FIG. 1. Normally, its weight allows it to slide to its lowered position (FIG. 2), but it can be easily pushed up.

Air flow through line 144 (FIG. 9) will build up in reservoir chamber 14- column 14 to act as a buffer and provide a constant, fairly steady pressure supply, even though the oxygen is supplied through a small hose from its nk.-

This air supply is allowed to pass from reservoir 14 with controlled opening of regulator 154 \by turning knob 149. This air will apply operating pressure, controlled by regulator 154 through knob 140 (FIG. 2) through conduit 152 and restriction 157 to port 156 in the valve body. When the spool of the valve assembly 156 is in the position to the right as illustrated in FIG. 9, conduit line 246 (which supplies pressurized gas to hose 4S and to the top of the compressor cylinder) is open to exhaust port 256 to the atmosphere.

The gas flowing through conduit 160 and regulator 162, which is previously adjusted for a particular time interval, fiows through constriction 164 to manual switch 172, and to port 168 of the control valve. Switch 172 may be placed in the position illustrated in FIG. 9 for its automatic cycling control, and will be placed in its second position to cause communication between conduits 230 and 169 if valve 150 is to be operated manually.

' Assuming that it is to be operated automatically, and that it is in the position illustrated in FIG. 9, gas passing through conduit 169, port 168, recess 212 in valve spool 132, port 298, conduit 206 to reservoir chamber 204, causes a steadily increasing pressure in chamber 204. Pressure increase is gradual due to restriction 164. At the same time, chamber 220 is exhausted to atmosphere by flow through conduits 218 and 216, recess 236 and port 238. As soon as the pressure in chamber 204 reaches a predetermined amount to apply a sufiicient pressure to piston 186 to overcome the magnetic attraction between magnet 260 and piston 184, it will shift piston 186 to the left from that illustrated in FIG. 9, toward magnet 262. When it does this, conduit 152, port 156 and recess 244 will allow fiow of pressurized actuating gas from conduit 152, through cavity 244 and spool 182, through port 248 and conduit 246, and thence, through ports 40 and 46 (FIG. 5) to hose 43, and thus to the upper end of the compressor cylinder. This exerts downward pressure on the plunger cap 122 (FIG. 3) to force the plunger downwardly. By turning and thereby controlling pressure knob (FIG. 2) to regulator 154 (FIG. 9), the amount that the plunger is forced down against the breastbone to compress the chest and squeeze the heart is determined. This will vary with the particular size and physical condition of the patient.

If a man having a thick rigid chest is to be the patient, the amount of pressure needed will be greater to compress his chest 20% of its thickness, than if a smaller person of more fragile nature is treated. If, for example, a small baby is being treated, the amount of presusre will be very small to bend his breastbone and compress the heart, due to the relatively small amount of plunger movement needed, and to the relative flexibility of his breastbone. By watching indicia 121 on the plunger (FIG. 3), the movement can be accurately seen.

The actual time of piston extension, i.e. the interval between the down stroke and its release for retraction is determined by filling of the second reservoir chamber 220 (FIG. 9).

As soon as valve spool 182 is shifted to the second position from that illustrated in FIG. 9, gas passes from conduit 169, through port 168, recess 212, port 216, conduit 218, to fill reservoir chamber 220. Pressure in chamber 220 is also exerted on the outer face of piston 186, due to the connection through conduits 222 and 236 through the selector switch valve 172. Therefore, as soon as the pressure in this chamber has built up sufiiciently to overcome the magnetic attraction of magnet 262 to piston 186, the valve shifts back to the opposite direction. Meanwhile, pressure in chamber 204 will be bled to atmosphere through conduits 2G6 and 208', recess 236 and port 238. Once valve is back in its initial position, the time interval for shifting it again for another compressive movement is the same as that already described.

When the valve shifts back to its initial position, pressurized air exerted on plunger 120 is released by communication of conduit 246 to exhaust port 250 (FIG. 9) through annular concavity 244. This release of pressure on the plunger, and thus on the breastbone allows the natural resilience of the chest to expand it, thereby allowing the heart to expand and refill with blood (diastole). The valve spool repeatedly reciprocates back and forth at these time intervals which are preset in dependence upon the location of magnets 260 and 262, the opening of re strictor 164, and the volume of chambers 204 and 220. After each shift, one pressure chamber begins building up in pressure while the other is exhausted to atmosphere.

Often it is desirable to have spool 182 of valve 150 remain at one end of the valve body for a longer time interval than at the other end. This enables time control of both the non-compression interval and compression interval, to allow optimum operation. 7

Exhaust port 12 is purposely quite large to cause an almost immediate exhaust of fluid pressure from the plunger. On the other hand, the application of actuating pressure through conduit 152 and port 156, hence, down through cavity 244, port 248, conduit 246, and thence through hose 48 to the top of the compressor cylinder is on a regulated, gradual basis. The plunger does not shift all at once, therefore, with applied pressure.

It is advisable medically to depress the breastbone and heart on a controlled gradual basis of a particular nature, rather than having an immediate thrust. An instant thrust may damage the heart and other anatomy and does not produce optimum pumping action. It has been found with extensive experimentation that a pressure application curve of the type illustrated in FIG. 10 is that which should be followed. Consequently, a restrictor or restriction valve 157 is located (FIG. 9) in conduit 152 to regulate the rate of gaseous flow to the plunger.

Since the pressure build up on the plunger is exponential, the most convenient manner of expressing the rate of pressure build up is by a time constant. It has been determined that the time constant for pressure build up on the plunger, for most effective pumping action from the heart, and for safety to the heart, should be at least 0.15 second to increase pressure to within (1/e)th of the total constant pressure to be applied wherein e is the Napierian logarithm base. The restrictor valve 157 allows throttling of gas inlet to achieve this time constant. The time constant can be somewhat greater than this also.

Pressure release from the unit is also of course exponential in nature, but by providing a substantially large exhaust outlet 25%, release is very rapid. It has been found to be desirable to have release as close to instantaneous as possible, for best heart refill action. This allows the rib cage to spring back rapidly. A time constant of about 0.05 second for pressure drop to within (1/e)th of the total pressure drop is satisfactory. If possible, even a smaller time constant should be obtained.

If for some reason it is necessary to operate the control valve 159 manually, switch valve 172 is shifted manually by pushing spool 174 to the left position, so that conduit 236 communicates with conduit 169. Byso doing, pressurized gas from conduit 169 flows directly through line 230 to piston chamber 1%). Chamber 188 is either open to atmospheric (with spool at extreme left position) or filled at control pressure (with spool at right position). In the first position, full differential pressure will be exerted on piston-armature 186 to move the spool to the extreme right position, at which time an equal pressure will develop on the opposite side of the piston. Due, however, to a differential area on opposite sides of the piston (produced by the inside face being covered by the end of the spool) there still remains a small net differential force to assure full return of the armature to the extreme right position, where it is held rimarily by the differential magnetic coercive force. In this position, the total holding force is much less than if full differential control pressure were applied to the piston. Thus, the manual knob 272 may be easily depressed to supply output pressure to the plunger. Upon releasing knob 272, the ditferential pressure built up after the preset delay time will return the spool to the extreme right (exhaust position). It will stay there until the manual knob is depressed again. Thus, by depressing manual knob 272 of valve 156 repeatedly, the compressor will intermittently compress the patients breastbone and heart in a similar fashion to that automatically done previously.

As mentioned previously, the amount of chest deflection is preferably 20% of the patients chest thickness. Since the amount of pressure necessary to depress different patients chests 20% varies greatly, e.g. from about 60 p.s.i. to about 80 p.s.i., the control knob 14% will be adjusted slowly from pressure up to the desired amount. This is determined easily by Watching the amount of extension of plunger 120 with each stroke. This is clearly indicated from the relationship of indicia 121 with respect to the bottom of cylinder 1&0.

It will be apparent after studying this disclosure that the unique device is an extremely desirable emergency unit that is useable in any of a variety of locations and situations. Indeed, actual use of the device presently in emergency efforts have proven this to be true. It is not only lightweight and compact, it is convenient to use, even on a vehicle seat or on a stretcher, is easily inserted beneath the patient, and is readily operated by a person with only a small amount of training. Furthermore, its controlled time operation is dependable, as well as variable and controllable. It is completely independent of any electrical control systems, being controlled, as Well as operated, from the same pneumatic supply attached to it, and available in any ambulance, hospital, or other emergency facility.

The complete assembly can be manufactured and sold relatively inexpensively, to serve as an important emergency adjunct to equipment now available.

Several additional advantages will probably occur to those in the art upon studying the foregoing description of the preferred device. Also, it is conceivable that certain minor details of structure could be changed Within the concept presented, without departing from the invention as taught. Therefore, the invention is to be limited only by the scope of the appended claims and the reasonably equivalent structures to those defined therein.

I claim:

1. A cardiac compressor comprising a base having a support platform; a support column rigidly attached to said base at the bottom portion thereof and extending upwardly therefrom at an end of said support platform; a compressor arm rigidly attached to an upper portion of said support column and extending laterally therefrom; and a vertically reciprocatable compressor rigidly attached to said arm; said arm and compressor constituting a subassembly removable as a unit from said base; said column having an attachment element and an engagable projection on its lower end; said base having a receiving and retention means for said attachment element, said receiving and retention means comprising a flange engagable with said attachment element near said platform and including releasable latch means spaced from said flange and aligned with said engagable projection enabling separation of said column arm and compressor from said base, for insertion of said platform under a patient, and rapid reassembly thereof for cardiac compression with regard to the patient.

2. A cardiac compressor comprising; a base having a support platform; a support column rigidly attached to said base at the bottom portion thereof and extending upwardly therefrom at an end of said support platform; a compressor arm rigidly attached to an upper portion of said support column and extending laterally therefrom; and a vertically reciprocatable compressor rigidly attached to said arm; said column, arm, and compressor constituting one assembly removable as a unit from said base; said column having an attachment plate on its lower end extending substantially perpendicular to said column; said base having a generally horizontal surface to engage said plate; a plate retention flange projecting up from the end of said surface closest said platform, and extending out over said surface, said flange being so shaped as to interfit one end of said plate nearest said platform when said plate is positioned therebeneath; and releasable latch means between said base and the opposite end of said plate to retain said column upright and retain said one plate end under said flange during cardiac compression.

3. A cardiac compressor comprising: a base including a support platform for a patients back; a support column extending vertically from one end of said base; a compressor arm mounted to said column, extending radially therefrom and terminating in a fluid cylinder over said platform; a piston plunger reciprocatable in said cylinder toward and away from said platform; said column having a mounting plate on its bottom end; said base including plate receiving and retention means to retain one end of said mounting place; and means on said base to restrain another end of said plate whereby said plate is rigidly attached to said base, and rotational movement of said column is prevented.

4. The compressor in claim 2 wherein said latch means includes an opening in said base, a slotted vertically adjustable projection extending down from said plate to be received by said opening; and a latch blade pivotally attached near one end to said base, and movable and biased transversely of said projection into its slot to retain said assembly until released.

5. A cardiac compressor comprising: a base forming a patients back supporting platform; one end of said base being hollow; a support column extending vertically up from said one end; a compressor arm extending radially out from said column and terminating in a fluid cylinder; a piston plunger in said cylinder, reciprocable toward and away from said platform and having a sternum contact pad on its lower end; a mounting plate on the bottom of said column; plate receiving and retention means on said one end of said base; releasable latch means between said plate and said retention means; said column being hollow and comprising a gas storage and bufler chamber; a main gas line connection to said base; pneumatic pulse timing valving control means mounted in said hollow base; gas conduit passageway means between said gas line connection, said chamber, said control means and said cylinder including coincident ports in said base and said plate; and said ports including compression seals between said base and plate, automatically sealing around said ports with connection of said plate to said receiving and retention means.

6. A cardiac compressor comprising: a base forming a back supporting platform; a support column extending vertically up from one end of said base; a compressor arm extending radially from said column above said platform, and terminating in a fluid cylinder; a piston plunger in said cylinder, reciprocable toward and away from said platform and having a contact pad on its lower end; a mounting plate on the bottom of said column; plate receiving and retention means on said one end of said base; releasable latch means between said plate and said retention means; said column being hollow and comprising a gas storage and buffer chamber; a main gas line connection to said base; passageway means between said gas line connection, said chamber, and said cylinder, including connecting ports between said base and said plate; and said ports including compression seals automatically engaged with connection of said plate to said receiving and retention means.

7. A pneumatic operated, pneumatically controlled cardiac compressor, comprising: a base including a back supporting platform; means to support a cylinder above said platform; piston plunger means in said cylinder, reciprocable toward said platform under pressure, and releasable to be pushed away from said platform by a patients rib cage expansion; a pneumatically operated timing control valve; gas supply means to said valve; controlled gas conduit means through said valve to said cylinder; said valve including a valve element shiftable between a first position allowing gaseous flow from said supply connection means to said cylinder, to a second position allowing exhaust from said cylinder to the atmosphere; piston means contained in a piston chamber and connected to said element, being responsive to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either end of said chamber, the reciprocation of said valve causing alternate flow to either end of said chamber in its alternate positions with shifting thereof; and pressure build up regulating means in said gas passage means allowing time control of pressure build up suflicient to shift said piston means and valve element.

8. A pneumatically operated, pneumatically controlled cardiac compressor, comprising: a base including a back supporting platform; means to support a cylinder above said platform; piston plunger means in said cylinder, reciprocable toward said platform under pressure, and releasable from the pressure to be pushed away from said platform by a patients rib cage expansion; a pneumatically operated timing control valve; gas supply connection means to said valve; controlled gas conduit means from said valve to said cylinder; said valve including a valving element shiftable between a first position allowing gaseous flow from said supply connection means to said cylinder, to a second position allowing exhaust from said cylinder to the atmosphere; a pair of pistons contained in piston chambers and connected to said element in opposition to each other, at least one of said pistons being responsive to gaseous pressure from said supply to shift said element between said positions; said piston means being magnetically responsive; magnetic attraction means adjacent the pistons, alternately biasing them and said valve element in each of the shifted positions, to obtain. a snap action of said element upon the occurrence of a pressure increase on one of the pistons greater than the biasing force caused by the magnetic attraction; gas passage means from said supply connection means through said valve to either end of said chamber containing said one piston, the reciprocation of said valve causing alternate flow to either end of said chamber with shifting thereof; and pressure build up regulating means in said passage means allowing time control of pressure build up sufficient to shift said piston means and valve element, thereby allowing control of pressure pulse applications and releases.

9. The apparatus in claim 8 including means for adjust ing the magnetic attraction of said magnetic attraction means for said pistons to vary the time of pause of said valve element at each position.

10. A pneumatically operated, pneumatically controlled cardiac compressor, comprising: a base including a back supporting platform; means to support a cylinder above said platform; piston plunger means in said cylinder, reciprocable toward said platform under pressure, and releasable to be pushed away from said platform by a patients rib cage expansion; a pneumatically operated timing control valve; gas supply connection means to said valve; controlled gas conduit means from said valve to said cylinder; and said valve including a valving element shiftable between a first position allowing gaseous flow from said supply connection means to said cylinder, to a second position allowing exhaust from said cylinder to the atmosphere; piston means contained in piston chambers and connected to said element, at least one of said pistons being responsive. to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either side of said cylinder containing said one piston, the reciprocation of said valve causing alternate flow to either end of said chamber with shifting thereof; pressure build up regulating means in said gas passage means allowing time control of pressure build up suflicient to shift said piston means and valve element; said controlled gas conduit means including restriction control means to increase the time constant of pressure increase in said cylinder to at least about 0.15 second for build up to within (l/e)th of stable pressure wherein e is the Napierian logarithm base; and said valve including exhaust means to the atmosphere allowing cylinder pressure exhaust with a time constant of at least about 0.015 second for pressure decrease to within (1/e)th of atmospheric pressure.

11. A cardiac compressor, comprising: a base having a support platform; a cylinder; a plunger reciprocable in said cylinder toward said platform under fluid pressure; said plunger capable of extending down from said cylinder and having a resilient contact pad on its lower end; means to rigidly attach said cylinder to said base such that said plunger is vertically reciprocatable and indicator markings at vertical intervals on said plunger, enabling its degree of extension from said cylinder to be readily seen as it reciprocates, thereby enabling the compressor operator to accurately visually determine the depth of chest compression.

12. A cardiac compressor, comprising: a base having a support platform; a support column mounted vertically upright on one end of said base; a compressor arm extending radially from said column and having a cylinder at the outer end; a plunger reciprocable in said cylinder toward said platform; pneumatic time pulse control valve means to extend said plunger repeatedly toward said platform and including valve operating inlet port means and inlet port means for cylinder actuating gas; gas passage 13 means from said pneumatic time pulse control means to said cylinder; and gas supply connector means and branched conduit means communicant with both said inlet port means to supply both from the same supply each of said branches containing a pressure regulator.

13. A pneumatically operated, pneumatically controlled cardiac compressor, comprising: a base including a back supporting platform; means to support a cylinder above said platform; piston plunger means in said cylinder, reciprocable toward said platform under pressure, and releasable to be pushed away from said platform 'by a patients rib cage expansion; a pnuematically operated timing control valve; gas supply means to said valve; controlled gas conduit means through said valve to said cylinder; said valve including a valve element shiftable between a first position allowing gaseous flow from said supply connection means to said cylinder, to a second position allowing exhaust from said cylinder to the atmosphere; piston means contained in a piston chamber and connected to said element, being responsive to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either end of said piston chamber, the reciprocation of said valve causing alternate How to either side of said chamber in its alternate positions with shifting thereof; and pressure build up regulating means in said gas passage means allowing time control of pressure build up suflicient to shift said piston means and valve element; and manually shiftable, pneumatic valve switch means in said gas passage means and in said gas supply means, shiftable between a first position allowing the as pressure to operate said valve element in both directions, and a second position allowing manual operation of said valve element.

14. The apparatus in claim 13 wherein said valve switch in said second position allows reduced pressure actuation of said valve element in one direction and prevents pressure actuation of said valve element in the opposite direction to require manual shifting thereof.

15. A cardiac compressor apparatus, comprising: a base, and support means for supporting a reciprocable compressor over said base, and a reciprocable compressor on said support means; timing control means causing timed pulses of said compressor toward said base to apply pressure intermittently to the sternum and heart of a patient on said base; and pressure increase rate control means to said compressor maintaining the time constant for pressure increase on said compressor and thus by said compressor to a patient on said base to be at least about 015 second to develop pressure to within (1/e)th of the normal maximum operating pressure wherein e is the Napierian logarithm base.

16. A cardiac compressor apparatus, comprising: a base, and support means for supporting a reciprocable compressor over said base, and a reciprocable compressor thereon; timing control means causing timed pulses of said compressor toward said base to apply pressure to a patient on said base; and pressure increase rate control means for said compressor maintaining the time constant for pressure increase of said compressor to a patient on said base to at least 0.15 second to develop pressure to within (l/e)th of the normal maximum operating pressure wherein e is the Napierian logarithm base, and pressure decrease means allowing practically instantaneous release of pressure of said compressor.

17. The apparatus in claim 16 wherein said compressor includes a fluid pressure cylinder and a piston plunger therein, said increase rate control means is a gaseous flow restrictor, and said decrease means is an unrestricted gaseous exhaust port means.

13. A cardiac compressor, comprising: a base, forming a back supporting platform; one end of said base being hollow; a support column extending vertically up from said one end; a compressor arm extending radially from said column and terminating in a fluid cylinder; a piston plunger in said cylinder, reciprocable toward and away from said platform and having a sternum contact pad on its lower end; said supporting column being cylindrical; said arm having a collar around said column; releasable binding means in said collar against said column to allow vertical and radial adjustment of said arm when loosened; said binding means including a threaded stud with a pair of surrounding binding elements thereon, having facing tapered ends contacting an arcuate portion of said cylinder adjacent to and opposite each other; and a knob on said stud allowing said elements to be forced together against said cylinder and lock said collar and arm thereon.

19. A cardiac compressor, comprising: a base having a support platform; a support column; a compressor arm; and a reciprocable compressor on said arm including a fluid cylinder and a reciprocable piston plunger in said cylinder, with a sternum contact pad on its lower end; said supporting column being cylindrical; said arm having a collar around said column; releasable binding means in said collar against said column to allow vertical and radial adjustment of said arm when loosened with respect to a patient on said paltform; said binding means including a threaded stud with a pair of surrounding binding elements thereon, having facing tapered ends contacting an arcuate portion of said cylinder adjacent to and opposite each other; and a knob on said stud allowing said elements to be forced together against said cylinder and lock sail collar and arm thereon; indicator markings at vertical intervals on said plunger, enabling its degree of extension from said cylinder to be readily seen as it reciprocates, thereby enabling the compressor operator to accurately visually determine depth of chest compression; said column, arm and compressor constituting one assembly removable as a unit from said base; said column having an attachment plate on its lower end; said base having one hollow end and having thereabove a surface to engage said plate; a plate retention flange projecting up from the end of said surface closest said platform, and extending out over said surface, under which one end of said plate nearest said platform can be slid; releasable latch means between said base and the opposite end of said plate, to retain said column upright and retain said one plate end under said flange during cardiac compression; said latch means includes an opening in said base, a slotted projection extending down from said plate to be received by said opening, and a latch blade pivotally attached near one end to said base, and movable and biased traversely of said projection into its slot to retain said assembly until released; said column being hollow and comprising a gas storage and buffer chamber; a pneumatically operated timing control valve in said hollow base end; gas supply connection means to said valve; gas conduit passageway means between said gas supply line connection, said chamber, and said control valve, including coincident ports in said base and said plate; said ports including compression seals between said base and plate, automatically sealing around said ports with connection of said plate to said base; said valve including a valving element shiftable between a first position allowing gaseous flow from said supply line connection to said cylinder, and a second position allowing exhaust from said cylinder to the atmosphere; a pair of pistons contained in pressure chambers and connected to said valving element in opposition to each other, being responsive to gaseous pressure from said supply line connection to shift said element between said positions; said piston means being magnetically responsive; magnetic attraction means adjacent the pistons, alternately biasing them and said valving element in each of the shifted positions, to obtain a snap action of said element upon the occurence of a pressure increase on one of the pistons greater than the biasing force caused by the magnetic attraction; means for adjusting the magnetic attraction of said magnetic attraction means for said pistons to vary the time of pause of said valve element at each position;

15 gas passage means from said supply connection means through said valve to said chambers; said valve causing alternate flow to said chambers with shifting thereof; pressure build up regulating means in said gas passage means allowing time control of pressure build up suflicient to shift said piston means and valve element, thereby allowing control of pressure pulse applications and releases; said gas conduit passageway means including restriction control means to increase the time constant of pressure increase in said cylinder to at least about 0.15 second pressure to develop to within (1/e)th of stable pressure wherein e is the Napierian logarithm base; and said valve including exhaust means to the atmosphere allowing cylinder pressure exhaust with a time constant of at least about 0.05 second to decrease pressure to within (1/e)th of atmospheric pressure; and manually shiftable, to pneumatic valve switch means in said gas conduit passageway means and said gas passage means, shiftable between a first position allowing the gas pressure to operate said valve element in both directions, and a second position allowing manual operation of said valve element; said valve switch in said second position allowing reduced pressure actuation of said valve element in one direction and preventing pressure actuation of said valve element in the opposite direction to require manual shifting thereof.

20. A pneumatically operated, pneumatically controlled system, comprising: fluid responsive means; a pneumatically operated timing control valve; gas supply means to said valve; controlled gas conduit means through said valve to said fluid responsive means; said valve including a valve element shiftable between a first position allowing gaseous flow from said supply connection means to said responsive means, to a second position allowing exhaust from said fluid responsive means to the atmosphere; piston means contained in a piston chamber and connected to said element, being responsive to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either end of said chamber, the reciprocation of said valve causing alternate flow to either end of said chamber in its alternate positions with shifting thereof; and pressure build up regulating means in said gas passage means allowing time control of pressure build up sufiicient to shift said piston means and valve element.

21. A pneumatically operated, pneumatically controlled system, comprising: fluid responsive means; a pneumatically operated timing control valve; gas supply connection means to said valve; controlled ga conduit means from said valve to said fluid responsive means; and said valve including a valving element shiftable between a first position allowing gaseous flow from said supply connection means to said fluid responsive means, to a second position allowing exhaust from said fluid responsive means to the atmosphere; piston means contained in a piston chamber and connected to said element, bing responsible to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either end of said piston chamber, the reciprocation of said valve causing alternate flow to either end of said chamber with shifting thereof; pressure build up regulating means in said gas passage means allowing time control of pressure build up sufiicient to shift said piston means and valve element; said controlled gas conduit means including restriction control means to maintain the time constant of pressure increase in said fluid responsive means to at least about 0.15 second for build up to within (1/ a) th of stable pressure.

22. A pneumatically operated, pneumatically controlledsystem, comprising: a pneumatically operated timing control valve; gas supply means to said valve; controlled gas conduit mean through said valve to said fluid responsive means; said valve including a valve element shiftable between a first position allowing gaseous flow from said supply connection means to said fluid responsive, to a second position allowing exhaust from said fluid responsive means to the atmosphere; piston means contained in a piston chamber and connected to said element, being responsive to gaseous pressure from said supply to shift said element between said positions; gas passage means from said supply connection means through said valve to either end of said piston chamber, the reciprocation of said valve causing alternate flow to either end of said piston chamber, the reciprocation of in its alternate positions with shifting thereof; and pressure build up regulating means in said gas passage meant allowing time control of pressure build up sufiicient to shift said piston means and valve element; and manually shiftable, pneumatic valve switch means in said gas passage means and said gas supply means, shiftable between a first position allowing the gas pressure to operate said valve element in both directions, and a second position allowing manual operation of said valve element.

23. The apparatus in claim 22 wherein said valve switch in said second position allows reduced pressure actuation of said valve element in one direction and prevents pressure actuation of said valve element in the opposite direction to require manual shifting thereof.

References Cited UNITED STATES PATENTS 2,071,215 2/1937 Petersen 12828 3,013,531 12/1961 Mueller et al. 3,160,486 12/1964 Busch 137-624. 14 X 3,209,748 10/1965 Thomas 128-53 3,219,031 11/1965 Rentsch 12828 3,277,887 10/1966 Thomas 12853 3,291,124 12/1966 Jennings et al. 12853 FOREIGN PATENTS 673,551 3/1939 Germany. 673,551 3/1939 Germany 12853 L. W. TRAPP, Primary Examiner.

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Classifications
U.S. Classification601/106, 137/624.14, 601/107, 251/65
International ClassificationA61H31/00
Cooperative ClassificationA61H2201/1246, A61H31/008, A61H31/006
European ClassificationA61H31/00H4, A61H31/00S