US 3552390 A
Description (OCR text may contain errors)
United States Patent Filed John T. Muller Box 296, Hanover, NJ. 07936 721,301
Apr. 15, 1968 Jan. 5, 1971 Inventor Appl. No.
Patented CARDIOPULMONARY R ES USCITATING APPARATUS 25 Claims, 11 Drawing Figs.
U.S. Cl 128/145.6, 128/52 Int. Cl A62b 7/00 Field of Search 128/28,
 References Cited UNITED STATES PATENTS 3,209,748 10/1965 Thomas 3,254,645 6/1966 Rand et a1... 3,348,536 10/1967 Tambascia 3,385,294 5/1968 Sabathie et al.
Primary Examiner-Charles F. Rosenbaum Attorney-Miketta, Glenny, Poms & Smith ABSTRACT: Cardiopulmonary resuscitating apparatus for automatically providing constant, substantial rhythmic heart perfusion at a rate equal to a normal heart beat and timed ventilation of the patients lungs to provide artificial ventilation and circulation during cardiac arrest.
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It is well known that upon cardiac arrest, a patient's body organs and tissues remain alive for several minutes but that the blood is not receiving oxygen nor is the blood beingcirculated. Within a short time after the heart stops, this lack of circulation and oxygen will cause irreversible organic body damage. it has therefore been-known that artificial respiration, such as mouth-to-mouth ventilation or ventilation by some mechanical means, and concurrent artificial cardiac compression, may temporarily provide the lung and heart functions to prevent damage to the body. In some cases, where cardiac arrest involves only standstill and not fibrillation, it has been found that cardiopulmonary resuscitation'may induce spontaneous recovery of the heart.
' One medical technique for providing cardiac resuscitatio is open-chest heart massage. However, it is apparent that not only does application of this technique require a skilled medical practitioner to perform the thoractomy, butit can be performed only in the proper environment with suitable equipment. Moreover, open-heart massage will ordinarily be limited v resuscitation has been proven to be a valuable life saving technique=which can be applied in emergency situations by a mechanical apparatus. t
in the development of the external cardiac resuscitation technique, it has been found and reported by the American Heart Association, that effective heartpumping pressure can be maintained by applying an external pressure over the lower one-third of the sternum, depressing it approximately 1% inches. Specifically, it is recommended that the depression of the sternum to provide efficacious circulation, without physiological patient damage must be within a range of I it to 2 inches.
Prior art devices are known which provide-external compression of the heart, and in general, these devices operate by driving a compression or power rod through either a spring or fluid transmission means. In such'apparatus, the compression rod is provided with a pressure foot pad which engages the patient, but the stroke of the compression rod is variable, as determined by the spring or fluid pressure, and'must be monitored and controlled -by-a skilled person duringoperation. Furthermore, such deviceshave been'large in size and cumbersome in useso as to restrict their practical application to hospitals and other institutions which can accommodate such devices. The devices, requiring a constant monitoring and adjustment of the spring or fluid pressure so as to provide the correct compression stroke, also require constant maintenance and surveillance by skilled personnel. This limits such devices not only to a particular environment, but also restricts the use of such apparatus because of the limited number of skilled personnel who are capable of operating the machine.
One example of prior art resuscitators is shown as described in Rand et al. US. Pat. No. 3,254,645, issued June 7, 1966. In this device, the power means for driving a reciprocating cardiac compression rod or beam is connected to the rod through spring means, and the spring pressure may be adjusted manually. The adjusted spring pressure is shown by an indicating device which may be monitored-by the operator so that the spring pressure does not become sufficient to be injurious to the patient's body. It will be readily appreciated that, as indicated above. this device requires a skilled operator and constant monitoring of the operation of 'the device, and it produces variable stroke which is'controlled by the operator in accordance with the pressure. It is also noted that the stroke length will vary to an appreciable extent depending upon the fering from emphysema is likely to exhibit substantially increased resistance to sternum compression. Downward force of a certain amount on such a patient will then produce a smaller distance of movement than otherwise, resulting in inadequate perfusion in such cases.
Accordingly, it is the general object of the present invention to provide a novel cardiopulmonary resuscitating apparatus constituting a substantial improvement over prior art devices and which avoids the foregoing disadvantages of similar types of cardiopulmonary resuscitating apparatus used heretofore.
It is an object of the present invention to provide a closedchest cardiac resuscitation apparatus which in operation on a patient with heart arrest will automatically, rhythmically depress the sternum a fixed positive distance to effect optimum heart perfusion without injury to the patient and without the need of continual monitoring and control by a skilled operator. 7
Another object. of the present invention is to provide a carcardiac resuscitation apparatus which has a predetermined cardiac compression stroke range between critical distances with-no more than single initial adjustment of a compressor rod or beam dependent only upon the patients depth of chest physical'condition of the patient. For example, a patient sufv and needing no further adjustment during operation, so as to minimize the skill required andthe attendance necessary during operation of the apparatus.
lt is a further object of the present invention to provide a cardiac resuscitation apparatus which has a positive mechanical connection between a pressure foot pad bearing upon the patients sternum andv an electric drive motor during a predetermined portion of the compression stroke, assuring effective heart perfusion without body injury, the total stroke length depending in only a minor degree upon the patient's body condition. v
A still further object of the present invention is to provide a cardiac resuscitation apparatus comprising a reciprocating member having compression and release strokes, driven by a undirectional motor and interconnecting means adapted to disconnect the motor from the reciprocating member at a predetermined point in the downstroke of the reciprocating member, and in which the upward movement of the member on the release stroke is retarded by applying a minor proportion of motor power through the interconnecting means to the reciprocating member. 1 Yet another object of the present invention is to provide a cardiac resuscitation apparatus .having a motor and reciprocating compression member interconnected by clutch means which clutch is actuated at a predetermined point in the downstroke of the compression member to partially disengage the clutch so as to control a portion of the stroke length by providing partial driving connection resisted by the patient's body.
One more object of the present invention is to provide a cardiopulmonary resuscitation apparatus including the cardiac resuscitation apparatus of the above-described type in combination with respiration means and including means for synchronously timing the respiration cycle with the cardiac commensufficient to produce effective heart perfusion and protection against body damage by allowingthe lower extremity of the vention further contemplates coordinated artificial respiration BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an exemplary embodiment of a cardiopulmonary apparatus, shown in position for use, constructed in accordance with the present invention;
FIG. 2 is a front elevation view of a portion of the apparatus shown in FIG. 1;
FIG. 3 is a top plan view of the portion of the apparatus shown in FIG; 2;
FIG. 4 is a side elevation sectional view of a portion of the apparatus which the torso of a patient shown in clotted outline;
FIG. 5 is a fragmentary rear elevation view of a portion of the apparatus;
FIG. 6 is a fragmentary side elevation view of a portion of the apparatus looking in the direction opposite to that of FIG.
FIG. 7 is a fragmentary sectional view of a portion of the apparatus taken along the line VII-VII of FIG. 5;
FIG. 8 is a fragmentary sectional view taken along the lines VIII-VIII of FIG. 4;
FIG. 9 is a fragmentary sectional view of resilient means, taken along the line IX-IX of FIG. 5; I
FIG. 10 is a fragmentary rear elevation view of a portion of the artificial respiration means forming a part of the apparatus, and FIG. ll is a circuit diagram embodied in the apparatus shown in conjunction with schematic illustrations of several mechanical portions of the apparatus.
DETAILED DESCRIPTION Referring now to FIG. 1, there is shown an exemplary apparatus which is completely portable. Apparatus 20 com prises a case having a bottom wall 21 and hinged front and rear wall sections 22 and 23, respectively. The case also includes'a frame indicated generally at 24 having end walls 25 :and 26 and an upper case housing 27 containing the working elements of the cardiopulmonary apparatus. The upper wall of the case housing has attached thereto a carrying handle 28. Since the entire apparatus weighs less than 20 pounds, the case in its folded condition may be easily carried using carrying handle 28.
The frame 24 is attached to base 21 by means of latching clips, one of which is shown at 29, so that the frame may be detached from the assembly including the base and front and rear wall sections, thus permitting the assembly to be easily slid beneath a supine patient. The frame may then be subsequently reattached to the base by means of clips 29 so that 'the apparatus is properly positioned with respect to the patient.
The cardiopulmonary apparatus generally comprises an artificial respiration assembly including a respirator drive motor 30, an actuating arm assembly indicated generally at 31, and air bellows 32. Air bellows 32 has a conventional air intake and an air outlet 33 connected to a flexible hose or tube 34 having a face mask 35 attached to the free end thereof. Bellows outlet 33 may have a pressure relief valve (not shown) disposed therein so as to prevent the forced air from causing stomach distension of the patient.
I patients breathing airway. Moreover, there are provided on front section 22 of the case, straps 38 for securing mask 35 4 over the mouth of the patient to prevent leakage of the foi'ced air supplied during respiration.
. For a complete description of the portable case comprising a part of the cardiopulmonary apparatus, attentio nisdrawn to the copending application, Ser. No. 549 ,84=7"'-assigned to the same assignee as is the present application. i
CARDIAC RESUSCI'IATION APP ARATDS For a more detailed description ofjtlie cardiac resuscitation apparatus reference is now made t'o'FIGSQZ' through 7. As seen best in FIGS.'2 and'3, and with particular attention to the mechanical elements of the cardiac resuscitation apparatus; it is seen that the drive motor is mounted on base hr the case frame 24. Cardiac drive motor 40has an output shaft 46 connected to a gear reducer shown at 47 for rediic ingthe speed of the motor 40 in a manner well known in the arpGear reducer 47 is mounted on 'a housing 48 which'in'turnis'supported by base 45 of the case frame 24$ The output of gear reducer 47 is connected to a magnetic clutdhat 49 for connecting the drive motor with t'he reciprocable compression beam. The magnetic clutch may, for mple, be of a-type manufactured by Warner Electric Brakedz Clutch Co. of Beloit, Wisconsin.
The output shaft 50 of magnetic clutch 49 is connected to further gear reducing means comprising a first gear 51 mounted on shaft 50 which is rotatably supported in housing 48 and a second gear 52 mounted on a second shaft 53 as seen best in FIGS. 4 and 5. On the free end of shaft 53is mounted a spiral spring 54 having a tension adjustment arm 55 and, a retaining screw 56 as seen best in FIG..9. Internally of housihg 48, as seen best in FIG. 7, there is mounted a pinion gear 57 on shaft 53. Housing 48 is also provided with a vertical cylindrical opening having a cylindrical bearing 58 disposed therein for receiving the compression member 41 which is prevented from rotation by key 41a. The compression member or beam 41 supports a gear rack such as at 59, machined in the rod itself, it being understood that the gear rack must be fixedly mounted on but not necessarily integral with the compression member 41. Pinion gear 57 engages rack gear 59 for reciprocably driving the compression beam 41.
In the exemplary embodiment of this invention, compression beam 41 has a cylindrical opening therein for telescopically receiving a bar 60 having a bifurcated lower end for pivotally supporting a pressure foot pad 61 through a piyotpin 62. The upper end of compression beam 41 includes a collar 63 and a nut 64 threadedly engaging an upper end of the beam 41 so as to secure a trip arm 65 thereon. A second collar 66 is disposed above nut 64 fixedly mounted on the upper end of from passing completely through the compression beam 41 when adjustment pin 68 is removed. Patients 'having a chest depth of various sizes may thus be accommodated by the apparatus through the above-described adjustability means.
Means are provided in accordance with the present inven tion for controlling the clutch connection between the reciprocable compression member 41 and the cardiac drive motor 40. Referring to'FlGS. 4, 6 and 8, the trip arm 65 is secured against rotational movement with respect to the compression beam 41 by means of a pin secured at its upper end to trip arm 65 and slidably received in a cylinder 81 fixed to housing 48. Disposed laterally adjacent to slidable pin 80 is a plunger rod 82 slidably received in housing 48 and having a cap 83 attached to the upper end thereof and abuttable by trip 110, a spring 111 and fixed collar 112.
Contact wheel support arm 87 is normally biased outwardly by means of spring 89. A switch actuating member 90 in the form of a cylinder is fixedly attached to plunger rod 82 so that upon reciprocation of plunger rod 82 electrical contact switch 85 I will be alternately opened and closed. Contact switch 85 constitutes a first meansfor controlling the voltage impressed upon magnetic clutch 49 in a manner,and for reasons, to be explained more fully hereinafter.
A second contact switch 95 is also mounted on a second portion 86b of supportplate 86, as seen best in- FIG. 8. Contact switch 95 is mounted in a plane normal to that of switch 85. Switch 95 includes a contact roller 96 rotatably supported on the free end of a resiliently biased arm 97. Contact roller 96 normally extends through an opening'98 in portion 86a of support plate 86.'An actuating member for contact switch 95,
in the form of a rectangularcam 99 is mounted on plunger rod 82 below first cam actuating member 90 and will be seen to actuate switch 95'only upona substantial downstroke of plunger rod 82. Switch 95 constitutes'second means for controlling the clutch connection between cardiac drive motor 40 and reciprocable compressionbeam 41 in a manner, and for I reasons, to be explained more fully hereinafter.
' ARTIFICIAL RESPIRATIGN MEANS As indicated above, the cardiopulmonary apparatus indudes in combination with the cardiac resuscitation apparatus an artificial respiration means. Attention is directed particularly to FIGS. 2, 3, Sand for an illustration ofm'echanical elements of the artificial respiration'means. The respiration means includes the drive motor 30 and a gear reducer 105 mounted on a bracket 106 supported on the base of the case frame 24. I'he output shaft 1070f the gear reducer has connected thereto a crank arm 108. On the free end of arm 108 is a slider pin 109 rotatably supporting a slider collar The artificial'respiration means also includes an actuating ann assembly including a standard 113 mounted on base 45 and having a head 114 at the upper end thereof. An actuating arm 115 is pivotally attached near one end to head 114 and adapted to pivot thereabout. The other end, of actuating arm 115' is pivotally connected through a pin.116 to a bifurcated bracket 117 which is mounted on a plate, 118 secured to air bellows 32. Disposed'centrally in actuating arm 115 is a longitudinally extending slot 119 for receiving slider engagement collar 110. It will be readily seen that rotation of respirator drive motor 30 causing rotation of crank arm 108 will cause actuating arm 115 to reciprocate arcuately so as to extend and compress air bellows 32 creating a'source of forced air supply for lung ventilation of the patient.
'I'he respirator also includesv means for coordinated,
supports two diametrically oppositely spaced contacttabs for engagement with resiliently biased contact am 126. Ratchet wheel 127 is prevented from free rotation by frictional biasing means indicated at 131.
projections 130 will engage switch am 126 so as to close the normally open electrical switch 125.
Since switch 125 is only momentarily closed during continuous reciprocation of the compression beam, means are provided for causing the respirator to continue through a complete cycle of inspiration and expiration after switch 125 resumes its normally open condition. This is accomplished by providing a second normally open'switch 135, paralleled with switch 125, together with means 'camming switch into closed condition as long as the respirator is not at its rest position. More specifically, respirator actuating arm normally open contact switch 135 is mounted on a plate 136 secured to and therefore actuating arm 115, switch 135 will be closed so as to provide continuing current to motor 30 through one arcuate cycle of actuating arm 115.
. CONTROL CIRCUIT The schematic diagram. shown in FIG. 11 illustrates preferred circuitry for the practice of the present invention. Terminals and 151 are adapted to be connected to an external source of alterriating current power at, say 115 volts. This power is fed through a conventional switch 152 and a fuse 154 to the. supply terminals 'I55'and 156, for distribution therefrom to the several electrical components of the invention, namely respirator drive motor 30, cardiac drive motor 40, a timing motor and magnetic clutch49.
In the upper portion of FIG. 11 there is provided the circuitry for. driving the respirator drive motor previously referred-to and indicated generally at 30, the motor'including to be now described. The normally open switch 125 previously referred to is connectedbetween point 163 of lead 162 and one end 164 of winding 160, and is paralleled by the second normally open switch 135 previously mentioned. Means are proyided in conjunction with switch 135 for maintaining that switch closed during slightly less than one complete cycle ofthe respirator motor. In the present schematic showing, such means include the actuating arm 1l5 having an end portion 165 adapted to close switch 135 immediately upon the commencement of arcuate movement of actuating arm 115 and serving to maintain such switch closed until a full cycle is completed. At that time end portion 165 permits the normally open switch 135 to return to its open position. Lead 161 is connected to the other end 167 of motor winding 160.
'. Power is also supplied from-supply terminals 155, 156
through leads 169, 170 to'the other mentioned electrical components of the present invention, including the cardiac drive motor, a timing motor and, through a full wave rectifier and control circuitry, to the magnetic clutch.
More specifically, the cardiac drive motor 40 is connected to the supply leads 169, 170 through'conductors 173, 174, respectively, connected across the winding 176 of the cardiac drive motor.
. -A timing motor 180, preferably a synchronous motor, is
mounted within control circuit'box 43 previously indicated,
The cam' 99 mounted on plunger rod 82 supports an up- I standing pawl 132 for indexing ratchet wheel 127 upon reciprocation of plunger rod 82. In the particularembodiment illustrated, ratchet wheel 127 is provided with 10 teeth, so that upon five reciprocal cycles-of plunger rod 82 of the contact and is supplied with power from leads 169,170 through conductors 181, 182 across winding 183 of the timing motor. It will be noted that, so long-as main switch 152 is closed, the windings 176 and 183 of the cardiac drive motor and of the timing motor, respectively are continuously energized and these two motors are accordingly constantly rotating.
Means are provided in accordance with the present invention for controllably energizing-the magnetic clutch 49,
in the lower portion of FIG. 11 there is shown apreferred form of circuitry for cyclically applying selected voltages to the magnetic clutch 49, and thereby to determine the amount of downwardly directed force applied to the beam 41. A DC power supply is indicated generally at 190 and includes a full wave rectifier indicated generally at 191 of conventional construction fed by lines 193 and 194 from lines 169, 170 respectively, and providing aDC output at terminals 197 and 198, with a capacitor 199 between the terminals in order to ininimizeripple in the output, in accordance with conventional practice. The DC output from terminals 197, 198 if fed through a normallyclosed switch 85 previously referred to in connection with FIG. 4, and through gating means such as a silicon controlled rectifier indicated generally at 200. The DC outputthus controlled is impressed across a'voltage dividing network indicated generally at 202, and also, through diode 204 and resistor 205, across the winding 206 of the magnetic clutch 49.
With particular reference to the gated rectifier 200 and its energizing circuit, it will be seen that the timing motor 180 drives a rotatable cam 210 having lobes 211, there being three lobes in the present illustrative embodiment of the invention.
- The normally open switch indicated generally at 212 includes a follower 213 contacting the cam 210 and its lobes 211, so that switch 212 is momentarily closed cyclically during rotation of cam2l0. Closure of switch 212 permits a positive gating voltage pulse, through resistor 214, which may have a resistance of approximately 5,600 ohms, to be applied through gate element 216 to the gating rectifier 200, thereby triggering the latter into conductive condition. The DC voltage at supply terminals 197, 198 is accordingly now made available at'terminals 217 and 218. Disregarding the negligible forward resistance of diode 204, this voltage, minus the voltage drop across resistor 205, is therefore impressed acrossthe winding "206 of the magnetic clutch 49. The electrical values in the circuit are so chosen that the voltage across winding 206 of the magnetic clutch under these conditions is substantially equal to the rated voltage for the clutch. Thus, exem'plarily, the DC voltage available at the output tenninals 197, 198 of DC power supply 190 may be assumed to be in the neighborhood of 150 volts. A typical magnetic clutch 49 suitable for use in the present invention may have a rated voltage of 90 volts, and include a winding 206 having a resistance of approximately 1,150 ohms. Under these conditions, and allowing for a few volts drop in the gated rectifier 200 and the diode 204, the resistance of resistor 205 may be approximately 600 ohms.
Means are desirably provided in accordance with the invention for supplying a retarding, snubbing or damping voltage to the winding 206 of the clutch 49. The maximum value of such damping voltage is selectively adjustable in the present embodiment of the invention, and may be assumed to be approximately 15 volts, that is, approximately one-sixth of the clutchrated operating voltage, previously assumed to be 90 volts. The means for supplying the retarding voltage to the clutch winding 206 in the present illustrative circuitry includes the voltage divider 202 heretofore mentioned,.comprising resistor 221, adjustable resistor 222 and resistor 223, the three re sistors being connected in series as shown between points 217, 218. It will be seen that the slider 226 of the adjustable resistor 222 serves to pick off and apply through diode 228 a desired charging voltage at points 229, 230 across capacitor 231.
In order to provide the desired voltage across capacitor 231,
I resistor 221 mayhave a resistance of 600 ohms; resistor 222 may have a resistance of 100 ohms; and resistor 223 may have .a resistance of 50 ohms. It will thusbe seen that the voltage between point 218 and slider 226 may be adjusted to be from about one-tenth to about one-fifth of the total available-voltage between points 217 and 218. It will be noted that, so long as the voltage across clutch winding 206 is greater than the voltage across capacitor 231, the capacitor is effectively isolated from such higher voltage by reason of diode 235 v.between the positive terminals 229. and 236 of capacitor 231' and winding 206 respectively.
mately 560 ohms, or. approximately half the typieal r It will be recalled thaithegiiorrnally closed switch is actuated into open position at apredetermined pointin the lower portion of the downward stroke of the reciprocable compression beam 41. Opening of switch 85 quenches gated rectifier 200 and removes the rated volts frorn the winding206 of the magnetic clutch, and the volt a'ge j'across f that winding "thereupon falls very'rapidlyfo the voltage of capaci'tof'231.
Moreover, as will be readily "urrd'e'rStodd', the voltage of capa'citor 231 will immediately commence the typical logarithmicp es At and immediately following 'the instant when normally closed switch 85 is opened, the movement of beam4l of the present device, both as to direction and speed, will be determined by the interrelationship of upwardly and downwardly directed forces applied to the beam. The downward directed forces include-the momentum of the moving parts, principally the reciprocable beam 41;,and the decaying force supplied to those parts through the magnetic clutch 49.'The upwardly directed forces includethat of the restoring springz54, plus the resilience of, the patients body, more particularly the force from within his body tending to restore the downwardly deflected sternum and rib cage to their unstressed condition.
Within a short period after switch 85 is opened, ,the
resultant of the forces just mentioned causedthe beam 41,30 r
reverse its downward direction of movement and commence moving upwardly. If too rapid,'the upward movement of the beam'may be undesirable physiologically, as well as possibly damaging to the machine itself particularly as the beam approaches and reaches theupp 'tpf its travel. It been found that the force tending rldiupward movement of the beam resulting from the decaying torque transmitted .by
magnetic clutch 49 can be jma'de 'to properly balancethe up- 'wardly directed forces involved, so that no physiological harm to the patient or possible damage to the machine results.
Means may be provided in accordance with the present invention for effectively, very "substantially increasingthe rate of decay of the voltage acrossclu'tch winding 206 supplied -by capacitor 231 and thus to morerapidly remove'the efi'ectof torque transmitted by the clutch to' the moving parts. This may be desirable, for example, when the machine of the" present invention is operated for testing or' demonstration purposes without a patients chest positiohedunderthe beam 413lltmay also be applicable when the machine is Used 't'orevlve a patient whose sternum exhibits a comparatively lowrestorativefdrce The-foregoing objectionable operating characteristics can be avoidedbyprovision of means-for much more rapidlydischarging capacitor 231, thereby to remove theeffect of torque transmitted by the magnetic clutch to thereciprocable member 41.-More specifically, the normallygopen; switch previously mentioned and indicated generallyat, 5,.is.con nected in series with the resistor 240 across capaciton 231. It will be recalled that switch isactuated to closed position in the event that the beam moves downwardly substantially beyond the point at which the downward movement of .the beam 41 opens the normally closed switch 85,, .v
Closing of switch 95'serves to provideanother th,; in,agld i tion to the winding 206 of clutch'49,,for capacitor 231, and therebylto more rapidly de ergiiethe magnetic clutch 49. In a typical installation irt accordance with the present invention where the capacitzgirice of, c acitor 231 is mfd., the resistance of resistor 2 40maybc rdxiof 1,150 ohms assumed for clutch viinding2'06'.
OPERATION or THITC'KRDIOPULMQNARY APPARATUS Operation of the cardiopulmonary device may now be described. The apparatus 20, being completely portable, may be carried to the location of a patient who has experienced heart arrest. The case of the apparatus is then opened so that the rear and forward sections 22 and 23 are lying flat and generally coplanar with base 21, and the frame 24 is removed from the base by unlatching clips 29. The lower portion of the case is then slid beneath the patient so that the patients neck lies above neck rest 37. The respirator mask 35 is then placed over the patients mouth and secured thereto by means of straps 38.- The upper portion or frame24 of the case may then be positioned with respect to the patient by attaching clips 29. The frame must be carefully positioned longitudinally relative to the patient so that the pressure foot pad 61 is positioned directly above the lower one-third of the patients sternum. The foot pad is then adjusted vertically by moving adjustment bar 60 within compression beam 41 byremoving adjustment pin 68 and allowing the bar 60 and foot pad 61 to rest upon or be held above the patients chest. Adjustment pin 68 is then repositioned through one of the lateral openings 71 in the bar 60 so as to connect the bar 60 and foot pad 61 to the reciprocable compression beam 41. k
The device may be used by connection to a source of alternating current power, such as in a building, or may also be connected to a source of direct current power such as if used in an ambulance or other vehicle, .with appropriate electrical changes as will be obvious. When properly connected and positioned with respect to thepatient, the device may be operated to provide the cardiopulmonary resuscitation.
Turning first tothe operation of the cardiac resuscitation apparatus, energizing of the cardiac motor 40 supplies mechanical power through output shaft 46 into gear reducer 47. Power is simultaneously supplied to timing motor 180 to drive cam 210 and thus to close switch 212, thereby triggering silicon controlled rectifier 200 so that the rated voltage of the clutch 49 is impressed thereupon. With clutch 49 fully engaged, power is transmitted through gear reducer 47 to gear 51 and through gear 52 to shaft 53 and pinion 57 engaging gear rack 59 thereby driving compression beam 41 downwardly.
As beam 41 progresses in its downstroke, the trip arm 65 moves downwardly a distance preferably of 1 %inches, or less than l %inches, and then contacts cap 83 of plunger rod 82. Plunger rod 82 is moved downwardly so that cylindrical cam 89 engages contact roller 37 forcing contact arm 86 of switch 85 inwardly so as to instantly open normally closed switch 85. Opening of switch 85 removes the rated voltage from the winding of the magnetic clutch 49 and the voltage across the mitted through partially engaged clutch 49. The amount of force transmitted through the clutch. will be dependent upon the voltage supplied by capacitor 231. However, it will be understood that the capacitor voltage decays rapidly and thus the clutch 49 continually transmits a lesser amount of torque. When the compression beam 41 has moved upwardly to a distance whereby trip arm releases cap 83 of plunger rod 82, switch 85 will be reclosed. At a point subsequent to the reclosing of switch 85 the timing motor 180 through rotation of cam 210 and closure of switch 212 will again trigger the As pointed out above, if the sternum of the patient (such as an adolescent patient) does not provide sufficient restorative force, the compression beam in its downward stroke will continue to a point which may be physiologically damaging to the patient. However, there is provided the second switch 95, which upon travel of the compression beam further downwardly, will cause the rectangular cam 99 on plunger rod 82 to contact wheel 96 thereby depressing resilient contact arm 97 of switch so as to close that normally open switch. Closing of switch 95 very quickly relieves the voltage across capacitor 231 and therefore across winding'206 of magnetic clutch 49 so that virtually no further power is transmitted through the clutch to the compression beam 41. The relatively small restorative force of the patients sternum will then overcome the momentum of the compression beam 41 reversing its direction.
The last described operation of the apparatus is also applicable to use of the apparatus in the absenceof a patient such as when the device is being tested in the field to assure its continued proper operation. In this situation, it has been found, that the compression beam collar 63 may strike the housing 48 with sufficient force so as to damage the gear train of the device, particularly pinion gear 57. The upward movement of the compression beam in the absence of a patient, of course, will be provided by the resilient force produced by the spiral spring 54 which overcomes the momentum of beam 41 when no torque is transmitted through clutch 49.
'Tuming nowto the operation of the respirating means, it will be noted that upon each downstroke of the compression beam 41, the pawl 132 on the subsequent upstroke will cause the ratchet wheel 127 to index a distance, in the illustrated winding falls rapidly to the voltage of capacitor 231. It will be recalled that subsequent to the triggering of silicon controlled rectifier 200, voltage will be impressed upon capacitor 231 charging it to exemplarily 15 volts.
The momentum ofthe compression rod and other moving parts of the mechanical system will cause the compression beam to proceed further in its downward stroke. The distance greater than the predetermined-limit distance, as established by the position of switch 85, will be determined by the forces acting upon the compression beam 41. These forces, as previously noted. include principally the momentum of the beam acting downwardly and the reduced driving force of the power means through-the partially engaged magnetic clutch and the restorative force of the patients sternum acting upwardly. Obviously, the downward travel of the compression beam will be reversed when the upward force of the patients sternum overcomes the momentum of the beam.
The compression beam then commences its upward stroke. The speed of the upward stroke of the compression beam 41 will be determined by the restorative force of the patients sternum, but will also be controlled by the continuing downward driving engagement between the pinion 57 and the compression beam gear rack 59 since some torque is transembodiment, corresponding to one-tenth of one revolution. After five strokes of the compression beam 41, and'therefore after five pumping actions of the patients heart, the contact projection on hub 129 attached to ratchet wheel 127 will depress the contact arm 126 so as to close switch 125. The momentary closure of switch 125 (since on the subsequent stroke of the compression rod the switch 125 will be opened) will momentarily energize the respiration motor 30 so as to rotate crank 108 and thereby begin arcuate movement of actuating am 115.
Slight movement of arm 114 causes the rearward end portion 165 thereof (see FIG. 11) to close the switch so as to provide continuing current to the respirator motor 30 after switch 125 is opened. Switch 135 will remain closed until actuating arm 115 has caused bellows 32 to be completely depressed and then expanded at which time arm 115 and the cam portion thereof permits switch 135 to reopen. The actuation of the bellows '32 will supply air for lung ventilation of the patient.
It will now be understood that the lung ventilation occurs in a ratio of one to five with the compression and consequent perfusion of the patients heart. Thus, lung ventilation is provided without any interruption of the cardiac resuscitation,
. thereby avoiding the critical drop of blood flowand blood damage to the patient. Moreover, in the event that the pal0 tients body condition allows the downward stroke of the compression beam to approach the maximum recommended distance of 2 inches, there is provided further means to limit the momentum por'tion'of the downward stroke. Finally, it will be appreciated that the above-described device will not require any monitoring and control by an operator of the deflection of the patients sternum and is responsive to the patients body condition only after a predetermined minimum depression of the body is accomplished through positive drive interconnection In summary as to the electrical control circuitry of the invention, it will be understood that it is assumed that the amount of torque transmitted by the interconnecting means or clutch 49 will be generally proportional to the value of the input signal impressed thereon, relative to the maximum .or rated value of the input signal corresponding to zero slip. It will further be seen that the value of the input signal to the clutch is maintained at said rated value during the major portion of the downward stroke of the beam or rod. At the instant when the beam arrives at the first predetermined point, opening of normally closed switch 85 causes the value of the input signal to the clutch to decrease very rapidly to a value heretofore referred to as snubbing, retarding or damping value. Moreover, by reason of the RC circuit including capacitor 231 and magnetic clutch winding 206, the input signal will decay approximately in accordance with the well-known logarithmic relationship in a time constant circuit, modified slightly by the effect of the inductance of clutch winding 206. Furthermore, if the beam continues downwardly as far as the second predetermined point, spaced below the first point, arrival of the beam there closes normally open switch 95, thusshunting the clutch winding by resistor 240 and thereby more rapidly decreasing the value of the input signal to the magnetic clutch winding. Effectively, following such actuation of normally open switch 95 to its closed position, the input signal is decreased virtually instantaneously to such a small value as to cause no sensible amount of torque to be transmitted by the magnetic clutch to the beam.
signal, nevertheless it is to be understood that the damping signal may vary substantially from such exemplary value, depending upon mechanical and electrical parameters and other design factors. in fact under some operating conditions, the damping signal may be virtually zero, or even eliminated if not required by reason of the spring rate and other constants of a particular machine.
Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. ltis therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.
l. A cardiac resuscitation apparatus comprising:
a pressure foot pad;
means for supporting said pad in a position exteriorly of the body ofa supine patient substantially directly over a portion of the sternum of the patient;
power means for reciprocating said pressure foot pad at a rate approximately equal to the normal rate of heart beat to alternately inwardly deflect and release the sternum thereby causing an artificial heart pumping action;
clutch means for connecting said power means and said foot pad support means; i
means for disengaging said clutch means at a predetermined point in the downward stroke of said foot pad support means and reengaging said clutchmeans-on the upward stroke; and 3 whereby a predetermined minimum depression of thepatient's sternum is positively provided and the totaldepression depends upon the upward forceexerted bythe patients body. t I 2. The apparatus of claim 1 wherein said means for disengaging said clutch is operative to provide only partial disengagement between said power means and said foot pad support means during the downward stroke,so that said power means supplies a diminished downwardly directed force to said foot pad support means. I a
3. The apparatus of claim 2 wherein said means for partially disengaging said clutch between said power means and ,said
foot pad support means during the downward-stroke provides a decreasing clutch partial engagement. I
4. The apparatus of claim 3 wherein said clutch means comprises an electrically operated magnetic clutch device'which transmits maximum torque when a first voltage is impressed upon said clutch device.
5. The apparatus of claim 4 wherein said means for partially disengaging said clutch device comprises a normally closed electrical switch and means for opening said switch actuated by the arrival of said foot pad support'means at said predetermined point during reciprocation of said foot pad support means. 1 t
6. The apparatus of claim 5 wherein said means for partially disengaging said clutch device additionally includes circuit means including capacitance means charged, when said electrical switch is closed, to a secon'dvoltage less than said first voltage and initially impressing said second voltage upon said magnetic clutch when said electrical switch is'opened so that said clutch transmits less than maximum torque between said power means and said foot pad support means.
7. The apparatus of claim 1 additionally including means for b v retarding the upward stroke speed of said foot pad support means.
8. The apparatus of claim 7 wherein said means for retarding the upward stroke speed of said foot pad support means includes said means for disengaging said clutch means, and circuit means for rendering said clutch means particularly operative during at least part of the upward stroke of said foot pad support means. I
9. A closed-chest heart resuscitating apparatus comprising: a pressure applicator pad; means for positioning said pressure pad in'a position exteriorly of the body of a patient and substantially over the resilient breastbone of the patient,'said means'including a reciprocable substantially vertical beamsupporting said pressure pad on its lower end and including vertical adjusting means -for initially locating and maintaining said beam and said pressure applicator pad with said pad in contact'with the patients breastbone; power means imparting rhythmic reciprocating motion to said beam at a rate approximately equal to' the normal rate of heart beat and with compressiondo'wnstro ke'force sufficient 'to depress the breastbone to effect substantial perfusion of the heart and releasing said beam to be returned upwardly by the breastbone restoring force; clutch meansfor connecting said power means and said vertical reciprocable beam; means for controlling said clutch connection, said means providing engagement of said clutch during the compression stroke-of said-beam until the resilient breastbone has been depressed a predetermined distance, said distance being less'than the 'distance required to effectmaximuin heart perfusion, where after said control means sudws no more than partial engagement of said clutchf beam momentum during the compression stroke moving said beam so as to depress the breastbone a' distance beyond said predetermined distance, said additional 13 a distance being determined by the momentum of said beam and the resiliency of the breastbone; and
said controlling means providing reengagement of said clutch when said beam moves upwardly on the successive upstroke.
10. The apparatus of claim 9 wherein said predetermined distance is less than Wainches.
11. The apparatus of claim 10 wherein the downward momentum of said reciprocating beam when depressing the resilient breastbone of a patient which produces a restoring force of at least 60 pounds when depressed linches will be. equal to said restoring force before the breastbone is depressed a total distance, including saidpredetermined distance, of no more than 2 inches. g
12. The apparatus of claim 9 additionally including second clutch engagement control means providing virtually total disengagement of said clutch after said beam has moved downwardly beyond said predetermined distance.
13. The apparatus of claim 12 additionally including spring means resisting downward movement of said vertical beam and having a spring force capable of moving said vertical beam upwardly only when said clutch is virtually totally disengaged.
I pressure foot pad in a position exteriorly of the body of a power means including an electric motor and gear means for interconnecting said motor and said substantially vertical reciprocable beam; and v means for alternately connecting and releasing said electric motor and said gear means during each reciprocation of said beam so that said power means. when connected drives said pressure foot pad downwardly with a force sufficient to depress the sternum to effect perfusion of the heart and when released allows the pressure foot pad to be moved upwardly by the restoring force of the depressed sternum, said reciprocation stroke being at a rate approximately equal to the normal rate of heartbeat.
15. The apparatus of claim 14 additionally comprising means for controlling said connecting means, said means normally connecting said vertical beam with said power means, and substantially disconnecting said beam from the power means at a predetennined point in the :downward stroke of said foot pad.
16. The apparatus of claim 15 wherein said means for connecting said electric motor and said gear means comprises an electrically operated magnetic clutch.
17. The apparatus of claim 16 wherein-said means for controlling said connecting means, comprises an electric circuit including a normally closed electrical switch for impressing a first voltage upon said magnetic clutch, said switch being mechanically opened by downward motion of said vertical beam past said predetermined point and means for impressing a second voltage upon said clutch, said magnetic clutch transmitting a maximum torque when said first voltage is impressed thereon and tramitting less than maximum torque when said second voltage is impressed thereon.
18. A cardiac resuscitation device comprising:
a portable frame adapted to be positioned over a patient 14 an electrically operated magnetic clutch opera'tively connected to said electric motor; i gear means, including speed reducer gears and a pinion gear operatively connected to said magnetic clutch, said pinion gear engaging said reciprocating compression beam rack gear means; i
' said magnetic clutch transmitting maximum torque from said power means to said reciprocating compression beam when a first voltage is impressed upon said clutch and transmitting partial torque when a second voltage is impressed upon the clutch; I f
an electrical contact switch normally closed so that said first voltage is. impressedv upon said clutch and mechanically actuated by reciprocating motion of said compression beam at a predetermined point in the downstroke of said beam so that no more than said second voltage is impressed upon said clutch until mechanical actuation of said switch at said predetermined point in the successive the resilient upward force exerted by the patients sternum being less than the downward force of said compression beam when maximum torque is transmitted through said clutch and being greater than the downward force of said compression beam when partial torque is transmitted .through said clutch so as to overcome the downward momentum of said compression beam. 5
19. The device of claim 18 wherein said circuit means additionally includes capacitance means, charged when said mechanically actuated contact switch is closed, and initially impressing said second voltage upon said clutch.
20. The device of claim 19 additionally including:
a second electrical contactswitch mechanically actuated by reciprocating motion of said compression rod so as to prevent any voltage from being impressed upon said clutch after a second predetermined point in the downstroke of said beam is reached, said second predetermined point being below said first 'point and being reached only in the absence of substantial upward force of resilient sternum of a-patient, said'clutch transmitting substantially no torque when no voltage is impressed thereon; and 1 resilient means operatively engaging said compression beam" to exert an upwardforce thereon less than the downward force of said compression beam when partial or maximum torque is transmitted through ,said clutch but greater than the downward force of said compression beam when'no torque is transmitted through said clutch. Zl The device of claim 18 wherein said compression beam is hollow and said means for pivotally mounting said pressure foot pad to said compression beam includes a bar telescopically'received in said hollow beam and additionally'cor'nprising means for adjustably vertically positioning said bar" and pressure foot pad relative to said compression beam and the sternum of the patient. I
22. The device of claim 18 additionally comprising means for artificial respiration of the patient and means operatively connecting said compression beamwith said artificial respiration means for periodic actuation of said respiration means.
23. The device of claim 22 wherein said artificial respiration means and connecting means comprises:
forced air supply'means in fluid communication with the lungs of the patient; power means operatively connected circuit means including at least one electrical contact switch mechanically periodically actuated by said reciprocating compression beam to energize said power means so as to supply a predetermined volume of air to the lungs of the patient. 24. The device of claim 22 wherein said artificial respiration means and connecting means includes:
a bellows mounted on said frame having an air inlet and an air outlet;
a flexible air tube having a face mask on one end and connected at the other end to said air outlet;
an electric motor mounted on said'frame including crank means;
an actuating arm pivotally supported at one end in vertical spaced relation to said frame and pivotally connected at the other end to said bellows, said crank means operatively connecting said motor and said actuating arm for reciprocating arcuate operation of said actuating arm and vertical movement of said bellows; and
means for periodically and synchronously energizing said a respiration actuating arm electrical contact switch I mounted adjacent said actuating arm and mechanically actuated by movement of said'arm so as to maintain electrical current to said motor through one arcuate cycle of said arm.