US2142689A - Apparatus for stimulating blood circulation - Google Patents

Description

Jan. 3, 1939. J, H, EMERSON 2,142,689

APPARATUS FOR STIMULATING BLOOD CIRCULATION Filed June 13, 1935 4 Sheets-Sheet l Jan. 3, 1939. J. H. EMERSON 2,142,639

APPARATUS FOR STIMULATING BLOOD CIRCULATION Filed June 15, 1955 v 4 sheets-sheet 2 'Jan. 3, 1939. J. H. EMERSON APPARATUS FOR STIMULATING BLOOD CIRCULATION Filed June 13, .1935

4 Sheets-Sheet 3 Jan. 3, 1939.

.17 H. EMERSON 2,142,689 APPARATUS FOR STI'MULATING BLOOD CIRCULATION Filed June 15, 1955 4 Sheets-Sheet 4 Y Y i a; FF- 5 A I 1 39 .54 H 1 i9 Ill 66 62 7/ 5; I! 6;

in? 6'0 f '64 I I if 17w erzkr (fem/ECW719070 7 47 I) [W yf j W I/$95M? Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR STIMULATING BLOOD CIRCULATION Claims.

This invention utilizes the broad principle of placing the portion of the body to be treated in an air-tight enclosure and then causing alternate negative and positive or atmospheric pressures to be created within the enclosure and upon the surface of the enclosed portion of the body.

Since such an apparatus may be used for treating different diseases and varying degrees of blood circulation afilictions, and since different doctors frequently desire different pressure conditions, different durations of each cycle of positive and negative or atmospheric pressures and different ratios of negative pressure time to positive pressure time or atmospheric pressure time in each cycle for the treatment of the same affliction it is of great importance and utility to provide adjustable means for controlling these conditions.

In use the effect which the apparatus is having upon the member being treated can best be determined by observing the variations of surface color of the member and it is therefore important to provide an enclosure for the member which is both transparent and non-shatterable, the former quality allowing inspection of the member during treatment and the latter quality providing an enclosure which will not only withstand the pressures necessarily exerted upon the interior of the enclosure by the apparatus, but will also withstand accidental exterior shocks or forces the breaking effect of which upon the enclosure is greatly increased when in use because of the negative pressures upon the interior thereof. For example, glass has been found unsatisfactory for the manufacture of such an enclosure due to. its shatterab-le qualities and the resultant danger of cutting the patients body in the event of breakage.

The principal object of this invention is to provide a novel apparatus for stimulating blood circulation in portionsof the humanbody.

Further objects are to provide an apparatus of this character with adjustable means for controlling the intensitiesof both negative and positive pressure; with adjustable means for controlling the duration of each cycle of negative and positive pressures and with adjustable means for increasing or decreasing. the ratio of each period of negative pressure to each period of positive pressure in each cycle.

Another object is to provide an apparatus of this character which will produce alternate negative and atmospheric pressures upon the portion 5 of the body being treated, and which is provided with adjustable means for controlling the intensities of negative pressure; with adjustable means for controlling the duration of each cycle of negative and atmospheric pressures and with 10 adjustable means for increasing or decreasing the ratio of each period of negative pressure to each period of atmospheric pressure in each cycle.

A further object is to provide a novel means for enclosing the portion of the body to be treated.

Further objects are to provide enclosing means which is both transparent and non-shatterable and to provide enclosing means for the leg and. foot capable of receiving any size leg and foot.

A further object is to provide novel means for sealing between the enclosing means and the patients body. Another object is to provide means for adjusting the size of the sealing means.

Other objects relate to the construction and. mode of operation andwill be apparent from consideration of the following description and accompanying drawings which exemplify one embodiment of my invention chosen for the purposes of illustration.

In the drawings:-

Fig. 1 is a view in side elevation of a casing for enclosing the leg of a patient, with a sealing member in place on one end thereof;

Fig. 2 is an end view of the casing shown in Fig. l, with sealing member removed;

Fig. 3 is an end View of a sealing member having two telescoping inserts for reducing the inside circumference thereof;

Fig. 4 is a view in perspective of the sealing member and inserts shown in Fig. 3;

Fig. 5 is a view in side elevation, with parts broken away, of an apparatus for producing alternate variations of pressure;

Fig. '6 is a plan view of the apparatus shown, in Fig. 5;

Fig. 7 is a view in side elevation of the lower part of the apparatus shown in Fig. 5, taken from the reverse side thereof;

Fig. 8 is an enlarged view in side elevation, with parts broken away and shown in section, of the valves for placing sources of different pressures alternately in communication with the casing and of valves for regulating the intensities of positive and negative pressures thus placed in communication with the casing;

Fig. 9 is an enlarged section on the line 99 of Fig. 8;

Fig. 10 is an enlarged section on the line IIl--I 9 of Fig. 8;

Fig. 11 is an enlarged plan view of the mechanism for varying the duration of each cycle of negative and positive or atmospheric pressures and for alternately opening and closing communications between sources of such pressures and the casing; and

Fig. 12 is a view in cross section, with parts broken away, of a sealing member and two telescoping inserts of modified form.

Referring to Figs. 1 and 2, the means for enclosing the portion of the patients arm or leg and foot comprises a hollow casing I0 made of a strong, non-shatterable, transparent material, such as cellulose acetate. This casing has one end which is open and one end which is closed by an end piece II. The casing is of substantially elliptical cross section and its side wall tapers inwardly from the closed end to the open end. The arcuate side wall of the casing is made of two flat sheets of cellulose acetate (see Fig. 2), each of which is bent or bowed outwardly so that their longitudinal edges overlap. The portion of overlap is sealed and partially secured by a coating of any suitable cement and the side wall sheets are retained in outwardly bowed shape by means of metallic reinforcing bands I2 which extend transversely around the outside of said sheets in contact with the outer surfaces thereof.

A standard I3 is secured to the casing adjacent its closed end to support and steady it when used in horizontal or inclined position. A pipe or conduit I4 provides a communication between the interior of the casing l0 and a pressure controlling mechanism hereinafter more fully described. A gauge I5 communicates with the interior of the casing and indicates the variations of pressure therein above and below atmospheric pressure.

The open end of the casing is of sufiicient size to admit a very large sized human foot with the ankle properly flexed, and the closed end of the casing is of sufficient size to accommodate such a foot when extended at right angles to the patients leg.

A casing so constructed can also be used with smaller feet and shorter legs, and although with a shorter leg, the foot will be located at some distance from the closed end of the casing, the walls are tapered so as to accommodate different decreasing sizes of feet, as shown by the dot dash leg and foot in Fig. 1. This casing may also be used for the treatment of arms and hands.

A tubular rubber collar l6, preferably made of sponge rubber and having a flexible impervious rubber coating or skin 93 on the outside, is provided to seal the space between the open end of the casing and the adjacent portion of the patients leg or arm. In use one end of the collar snugly encircles the leg or the arm of the patient and the other end of the collar snugly encircles the outer wall at the open end of the casing, as shown in Fig. 1.

A tubular reinforcing member 91 made of nonexpansible material such as a woven fabric impregnated with rubber is provided to surround the portion of the rubber collar which encircles the patients leg or arm. This reinforcing member ensures an air-tight seal between the patients leg or arm and the rubber collar since it prevents expansion of the periphery of the collar even when high positive pressures are exerted Within the casing. The reinforcing member may be physically attached to the outside of the rubber collar or it may be a separate piece, and slipped over the collar.

A tubular rubber insert II, also preferably of sponge rubber, is of such a size that its outer circumference snugly fits within the inner circumference of the tubular collar I6, as shown in Figs. 3 and 4. This insert may be considerably shorter than the collar and in use it encircles the patients leg or arm and does not encircle the open end of the casing. The insert is thus used to supplement the rubber collar I6 in the treatment of legs or arms too small to be sealed by the larger diameter of the rubber collar.

If desired, additional inserts I 8 may be provided to accommodate still smaller legs or arms.

The modified type of insert 90 illustrated in Fig. 12 is provided with a bead or flange 9| on its outer end. This flange contacts the outer end of the collar I6 and prevents the insert from sliding through the collar when the leg or arm of the patient is inserted therein. Additional inserts 92 are also provided with flanges which.

contact the respective adjacent outer ends of the adjacent inserts.

When the casing I0 and the rubber collar I6 are in place upon the portion of the body to be treated they provide an air-tight chamber surrounding said portion.

The apparatus for producing alternate pressure variations is mounted in a cabinet I 9 (Fig. 5) which is provided with rollers or casters so that it may be easily moved from place to place. Upon a suitable support in the lower compartment of the cabinet is mounted a motor 20 which is connected to an electric cable 2| which may be plugged into a source of electric current, such as a wall socket. A rotary compressor 22 is likewise mounted in the lower part of the cabinet and is capable of producing a constant source of both positive and negative pressures of substantially' constant intensities, the compressor being driven by the motor 20 by means of a belt 26.

The positive pressure is conducted from the compressor by a conduit or pipe 23 provided with a suitable filter 24 and the negative pressure is conducted from the compressor by means of a conduit or pipe 25.

A valve casing 21 (Figs. 5 and 8) is supported by a fixture 28 in the upper portion of the cabinet. The valve casing 21 has four axial chambers 29 each of which has three ports, the first port, a positive pressure port 30 at the upper end communicating with the positive pressure conduit 23 by means of the passage 3I in the fixture 28; the second port 32, a negative pressure port, at the lower end communicating by means of the conduit 33' with the negative pressure conduit 25; and the third port 34, intermediate the first two ports and communicating with the conduit I4 leading to the casing II].

A positive pressure valve 35, located adjacent the outside of the positive pressure ports 30, is adapted to open and close said ports 30. A spring 36 bears against the outside of said positive pressure valve 35 and exerts pressure against it normally tending to hold it in closed position with respect to said positive pressure ports.

A negative pressure valve 31 located adjacent to the outside of the negative pressure ports 32 is adapted to open and close said ports. The

'valves s35. and 31:.are secured to valve stems .38

which are slidably :"mounted in .suitableguides, the inner-endstof the valvesstems being ."main itainedin'abuttingrelation. These stems 38 are 'made' of' such lengths that'when their ends abut 'the valvesare held further apart thanthe distance' between the valve :seats and consequently both valves can not be closed at the same time.

The springs3fivnormallyuholds the positive pressure valve ':35 closed and the negative pressure valves! open. When the valves ares insuch positions the casing Ill is inicommunication with the :constant negative: pressure created by the compressor. Such communicationis provided by-the conduit I t, the dust filtery39,.theports 34, the

valve chambers-29, the'ports '32,'the conduit133,

the safety valve 83 and the conduit 25.

The negative pressure valve3'l is closed and the positivev pressure valve 35 is'zopened byzexerting force upwardly against the 'negative'valve31 through the stem 38 'to the positive "pressure valve 35 and thence against the lower end-"of the spring 36, thereby moving said valves upwardly with'respect to the chambers 29, andthereby :alsocompressing the spring "36. As soon as this compressor by means of theiconduit M, the valve chambers 29, the positivepressure'ports 30, the passage 3| and the conduit23.

The upward force .for closing the :negative valves and compressing the spring '36 is created by rotating a crank 40 (Figs. 5'and-7). The free end of this crank is pivotally connected by a pivot pin 5! to the lower end of a connecting rod-4|,

and the upper end of said rod is connected to the lower end of a spring 42. Theiupper end of the spring is connected to the lower end of another connecting: rod and the upperiend of this'con- 'necting rod is threaded and'pa'sses'freely through an aperture in-one end of the lever. Ana'djusting'nut'45 is:screwed uponthe protruding threaded end of therod43.

The other =end=of 'the :lever 44 engages the lower end of a rod 46(Fig..8) and the upper end of the rod 46 engages the outer end of the lower valve-stem "33. Alsylphon '41 providesa flexible air-tight seal :between the rod '46 andthe negative pressure chamber 48.

A bracket 'l attached to thefixture 28 is provided at its lower end with aslot'to receive the lever and'the lever .is pivotally supported in the slot by meansoi .aifulcrumpinifl 1 extending transversely through the lever and the si'des of said slot in the bracket 4-9 thereby forming a fulcrum about which the lever may rotate for a short distance in .a verticalzplane.

The'nut-45 is adjusted so that thesumof the operative lengthof the connecting rod 43, the

length of the contracted spring 42 and the-operative length of the connecting rod"4| will equal thedistance between the'lower surface'of the'nut -55 and the connecting pin 51 when the crank is inhorizontal position, the positive valve 35 closed, the inner ends of the valve stems 38 abutting-and the lower end of the rod46 abutting the upper adjacent surface ofthe lever 44 as shownin Figs. 5 andB. Thus' when the crank is in horizontal position such as atthethree or nine-oclock po- .sitions looking atiFig. '7 no tensionwillbe created liinxthe connecting rods 4|:and43 or in the spring s42 butzasxthe crank rotates. in a clockwise direction: from threeto nine oclock, tension willbe created in said rods and spring during said intervaliof rotation, and the lever will be :moved' 5 -sli'ghtiy:in.-a verticalxplane about its fulcrum'i50 -an d will cause an upward force to be exerted on :the. rod 45, therebyrclosing the negative pressure valve 31; opening thefpositive pressure valve 35 sand scompressing the spring 36l During thisim portion of'the:cranks rotation, the coil spring 42 'will beigradually extended as the crank moves 'iromthree to six .oclock and gradually collapsed as itsmoves fromsix to nine oclock. As soon as the crank "reaches the nine oclock position the=15 spring M iscompletely collapsed and the tension in the rods 4 land43 is released and remains released while the crank travels from nine tothree oclock position. Thus at nine o'clock upward forcein'the rd 46 is released and the spring 3mm) closes the positive pressure valve 35 and opens the negative-pressure valve 31 and these valves "will remainin such positions until the crank again reaches three oclock position and again creates tension inthe connecting rods 4|. and 4323 @One. complete revolution of the crank will'thus causea completecycle of positive and negative pressureswithinxthe casing and if, for example, the crankmakesonerevolution in twenty seconds there will-"be tenseconds of negative pressure'andtao ten seconds of positive pressure created in the easing I0. If, for example, fifteen secondsof negative and ffive seconds of positive pressure is desired during each twenty-second cycle the nut 45 isunscrewed far enough to increase the operasativezlength of' the rod 43 so that tension will be createdinthe connecting rods 43 and 4! "and in the spring 42 during only one-fourth of each revolution ofthe crank thereby causing the positive pressure valve to be held open only one-fourth of s the revolution, namelyfive seconds, and the neg- --:ative pressure valve to be held open duringthe other three-fourths of the-revolution, namely fifteen seconds. By adjusting the nut any ratiooftduration-of positive pressure to durations of negative pressure 'duringeach cycle may be obtained.

The crank. is :journaled in transverse holes in the parallel spaced standards 53and-secured to a gear152 located between said standards so'that both'crank and-"gear rotate together at the-same speed. "A friction wheel 54 is mounted for rotationbetweentheistandards 53-and above the gear :52. A gear 55'is mounted for rotation between the standards 53 intermediate thefriction wheel. and the gear 52and is adapted to mesh with suitable gears thereon and thereby to transmit the "rotary motion 'of the wheel to thepigear 52 and to the crank: attached thereto, as illustrated. The -standards *53 are-pivotally mounted on a horizon-1:0 tal rod which passes through iholes near "the lower extremities-of said standards. The horizontal rod"56 is supported "by the vertical 5 rod 51 to which one of its ends isifirmlyattached. 'The 'vertical'rod fil is provided near its lower end with? a horizontal shoulder 58 which bears upona'plate 55 "and I this plate is attached to 5 a frame member 'of'the cabinet by the screw 60. Theupper end of the-vertical rod 5! extendsloosely through 'ahole in the fioor of the upper portion of the rcabinet i'm and a horizontal handle 6 l is firmly. attached to the upper end of thevertical' rod. 3

The plate 59 is provided with 'two upstanding stops ii'3 which are 'highienoughto contact the frreeend" ofithe horizontallrodfifizto confine rotat1;

" tion of the'vertical rod 5'! to the angle formed by lines'drawn from the stops to the vertical rod as shown in the dot and dash positions of the horizontal rod 56 in Fig. 11.

A horizontal projecting member 62 has one end firmly attached to the vertical rod 51 near its lower extremity. A spring 64 has one end bearing against the horizontal projecting member 62 and the other end bearing against a cross piece 65 which is firmly attached between the standards 53 by means of screws 66a. This spring tends to exert force against the left-hand edge of said cross piece 65 (looking at Figs. 7 and 11) and thus tends to rotate the standard 53 clockwise in a vertical plane about the horizontal rod 56. Said cross piece 65 also acts as a spacing member to hold the standards 53 in parallel spaced relationship.

The circumference of the friction wheel 54 is provided with a friction surface, for example, a rough rubber tire 66 and this friction surface contacts a conical shaft 61. The spring 64 tends to hold this friction surface in constant contact with the shaft 6! by the force which it exerts against the edge of the cross piece 65.

The motor 20 rotates the conical shaft 61 at a constant speed, and the shaft in turn rotates the Wheel 54, which by means of the gears 55 and 52, rotates the crank 40 at a constant speed.

The speed of rotation of the crank 40 can be varied by rotating the handle 6| in a horizontal plane since such movement of the handle rotates the vertical rod 51 and the friction wheel 54 n horizontal planes. As the friction wheel 54 is rotated horizontally in a clockwise direction,

looking at Fig. 11, its surface contacts a smaller circumference of the conical shaft 61 and consequently the speeds of the wheel 54 and the crank 40 are correspondingly reduced. Thus by moving the handle 6| the time taken for each cycle of the crank 4|] may be varied and controlled and consequently the time of each cycle of positlve and negative pressures is correspondingly varied or controlled.

A slotted member 10 is provided to retain the handle 6| in any desired position (Fig. 6). l

A positive pressure safety valve H is provided above the ports 12, which ports communicate with the upper ends of four axial chambers 13 in the valve casing 14. A chamber 15 above the valve 1| communicates with atmospheric pressure through the port 16. The valve is mounted on the fixture 28 above passage 3| in said fixture and the lower ends of the axial chambers 13 communicate with the passage 3| which in turn communicates with the positive pressure line 23 by means of the protruding pipe conduit I1. One end of the spring 18 bears against the top of the valve 1| and the other end bears against the lower surface of a shoulder 19. The shoulder 19 1s attached to the lower end of the stem of the thumb screw 80 which is mounted for turning movement in the upper end of the valve casing 14. Suitable air-tight packing 8| is provided between the valve casing and the stem of the thumb screw.

The spring 18 normally tends to hold the valve H in closed position with respect to the port 12. When the positive pressure in the chamber 3| reaches a great enough intensity to force the valve upwardly and to thus compress the spring 18, the chamber 3| will be connected with atmospheric pressure through the axial chambers 13, the chamber 15 and the port 16 and the intensity of positive pressure in the chamber 3| will be diminished by this source of atmospheric pressure until the force in the spring 18 forces the valve closed again. By tightening or loosening the thumb screw 80 the force exerted by the spring 18 against the valve II is increased or decreased and the force resisting opening of the valves by positive pressure in the chamber 3| is corrspondingly increased or decreased. Since the valve casing 14 is located on the positive pressure line between the source of positive pressure and the casing I0, it aifords adjustable means for controlling the intensities of positive pressures which may pass through the positive pressure line to the casing I0.

A negative pressure safety valve 82 is provided in a valve casing 83 which is mounted upon the fixture 28. This casing, like the positive pressure safety valve, is provided with four axial chambers, but the lower ends of these axial chambers communicate with atmospheric pressure through a port 84. A threaded thumb screw is mounted in the top of the valve casing 83, and the lower end of the thumb screw stem is provided with a shoulder which abuts the upper end of a spring. The lower end of the spring bears against the upper surface of the valve 82 and tends to hold it in closed relation with respect to the ports in the upper ends of the axial chambers 13. The conduit 25 from the negative pressure side of the compressor is connected by means of the port 85 with a chamber in the valve casing located above the valve 82, and this chamber is connected with the negative pressure side of the alternating valve 31 through the port- 86 and the conduit 33.

When the negative pressure in the conduit 25 reaches a great enough intensity the valve 82 is sucked upwardly and opens communication with atmospheric pressure through the chambers 13 and the port 84. When the atmospheric pressure has sufliciently reduced the intensity of the negative pressure the spring will close the valve 82. By tightening or loosening the thumb screw, the force exerted by the spring against the top of the valve 82 is increased or decreased and the maximum intensity of negative pressure in the conduit 33 is correspondingly increased or decreased. This device thus affords adjustable means for controlling the intensities of negative pressure which may pass from the compressor to the casing l0.

Alternate negative and atmospheric pressures may be obtained in the casing by removing the conduit 23 from the protruding pipe 11. The valve 35 then communicates with atmospheric rather than positive pressure.

In practice the following conditions are frequently prescribed: cycles varying from ten to sixty seconds; from one-half to four-fifths of each cycle negative pressure and from one-fifth to one-half the cycle either positive or atmospheric pressure; negative pressures up to twelve centimeters of mercury and positive pressures up to ten centimeters of mercury. I do not propose to prescribe any of the above conditions for the treatment of any disease or afliiction. I give them merely as rough estimates for air in designing a compressor, motor, safety valves and alternating mechanism for an apparatus of this character.

In operation the handle 6| is adjusted to give the desired duration of each cycle of alternate pressures, the nut 45 is adjusted to provide the desired duration of negative pressure and the desired duration of positive pressure during each cycle, and the thumb screws on the positive and negative safety valves are adjusted to provide therespective desired intensities of positive and negative pressures. The leg or arm of the patient is then inserted through the opening in the rubber collar, one end of which is in place around the open end of the casing. The power is then switched on, actuating the motor, the compressor and the alternator. The operator may then observe the gauge IE to check the conditions within the casing, and during treatment he may observe both the gauge l5 and the member being treated, and if variations of the aforesaid conditions are desired during treatment they can be made without stopping the motor by adjusting the handle 61, the nut 45-or the safety valve thumb screws.

If operation to provide alternate negative and atmospheric pressures is desired, the conduit 23 is disconnected from the projecting pipe i l and the procedure is then the same as with alternate positive and negative pressures, excepting that no adjustment of the positive pressure safety valve is required.

I claim:

1. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with a source of positive pressure and another port communicating with a source or negative pressure, a valve-associated with said positive pressure port, a valve associated with said negative pressure port, resilient means associated with oneof-said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports and means for periodically compressing said resilient means, comprising a lever pivotally mounted ona fulcrum intermediate'its ends, one end of said lever associated with said resilient means and adapted to compress the same, the other end of said lever connected to one end of a connecting member, the other'end of said connecting member connected to the free-end of 'a crank, and means to rotate the crank in a complete cycle, said connecting member being of such an operative length that tension is created therein during only part of each cycle of the crank, thereby causing the lever to move about the fulcrum and to compress said resilient means during only part of each cycle of the crank.

2. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing'and the patients body, a chamber communicating with said casing, said chamber having a port communicating with atmospheric pressure and another port communicating with a source of negative pressure, a valve associated with said atmospheric pressure port, a valve associated with said negative pressure port, resilient means associated with one of said valves normally holding one valve in closed position and the other valve in open position with respect to their re? spective ports and means for periodically compressing said resilient means; comprising a lever pivotally mounted on a fulcrum intermediate its ends, one end-of 'said-dever associated with said resilient means and adapted to compress the same, the other'end'of said lever connected to one end of a connecting member, the other end of said connecting member connected to. the free end of a crank and means to rotatethe crank in a complete cycle, said connecting mem-l her being of such an operative length that tension is 'created therein during. only part of each cycle of the crank, thereby causing the lever to move about said fulcrum and to compress said resilient means during part of eachcycle of the crank.

3. An apparatus for stimulating blood-circulation "comprising. a hollow casing for receiving a portion of the patientsbody, means for forming an air-tight seal between the casing and'the patients body, a chamber communicating with said casing, said chamber having a "port communicating with a source'of positive pressure and another port communicating with a source of negative pressure, a valve associated with said positive pressure port, a valve associated with said negative pressure port, resilient means associated with one of said valves normally holding one valve in closed position and the other valve in open position: with respect to their respective ports and means for periodically compressing said resilient means comprising a lever pivotally mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to compress the same, the other end of said'lever connected to one end of a connecting member, the other end of said connectingi'member connected to the free end of a crank, means to rotate the crank in a complete cycle, and means on said connecting member to vary the operative length thereof thereby varying the portion of the cycle'of the crank during" which tensionis created in theconnecting member.

4. An apparatus forstimulating blood circulation comprising a hollow casing for receiving a portion of the patientsbody, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port *communi'cating with atmospheric pressure and arrother port communicating with a source of negative pressure, a'valve associated with saidatmospheric pressureport, a valve associated with said negative pressure port, resilient means associated with one of said valves normally holding one valve in-closed position and the other valve in open position with respect to their respective ports and means for periodically compressing said resili'entmeans, comprising alever mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to compress the same, the otherend of said lever connectedto one end of a connecting member, the other end of said'connecting member connected to the free endof a crank, means to rotate the crank in acomplete cycle and means on said connecting member to vary the operative length thereof thereby varying the portion'of 'the cycleof the crank during which tension is'createdin the connecting member.

5. An apparatus for stimulating blood circulationcomprising a hollow casing for receiving a portion of the patients body, means for formingan air-tightseal between the casing and the patients body, a chamber communicatingwith said" casing, said chamberhavinga portcommunicating with a sourceof positive. pressure and another port communicating with a source ofnegative-pressure, a valve associated with said positive pressure port, "a valve associated with said negative pressure port, resilient meansassociated with one of said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports and means for periodically extending said resilient means, said means for extending comprising a lever pivotally mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to extend the same, the other end of said lever connected to one end of a connecting member, the other end of said connecting member connected to the free end of a crank, and means to rotate the crank in a complete cycle, said connecting member being of such an operative length that tension is created therein during only part of each cycle of the crank, thereby causing the lever to move about the fulcrum and to extend said resilient means during only part of each cycle of the crank.

6. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with atmospheric pressure and another port communicating with a source of negative pressure, a valve associated with said atmospheric pressure port, a valve associated with said negative pressure. port, resilient means associated with one of said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports and means for periodically extending said resilient means, said means for extending comprising a lever pivotally mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to extend the same, the other end of said lever connected to one end of a connecting member, the

other end of said connecting member connected to the free end of a crank and means to rotate the crank in a complete cycle, said connecting member being of such an operative length that tension is created therein during only part of each cycle of the crank, thereby causing the lever to move about said fulcrum and to extend said resilient means during part of each cycle of the crank.

7. An apparatus for stimulating blood circulation comprising a .hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with a source of positive pressure and another port communicating with a source of negative pressure, a valve associated with said positive pressure port, a valve associated with said negative pressure port, resilient means associated with one of said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports and means for periodically extending said resilient means, said means for extending comprising a lever pivotally mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to extend the same, the other end of said lever connected to one end of a connecting member, the other end of said connecting member connected to the free end of a crank, means to rotate the crank in a complete cycle, and means on said connecting member to vary the operative length thereof thereby varying the portion of the cycle of the crank during which tension is created in the connecting member.

8. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with atmospheric pressure and another port communicating with a source of negative pressure, a valve associated with said atmospheric pressure port, a valve associated with said negative pressure port, resilient means associated with one of said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports and means for periodically extending said resilient means, said means for extending comprising a lever mounted on a fulcrum intermediate its ends, one end of said lever associated with said resilient means and adapted to extend the same, the other end of said lever connected to one end of a connecting member, the other end of said connecting member connected to the free end of a crank, means to rotate the crank in a complete cycle and means on said connecting member to vary the operative length thereof thereby varying the portion of the cycle of the crank during which tension is created in the connecting member.

9. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with a source of positive pressure and another port communicating with a. source of negative pressure, a valve associated with said positive pressure port, a valve associated with said negative pressure port, resilient means associated with said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports, and means for periodically extending said resilient means, said means for extending comprising a lever mounted for movement about a fulcrum, a connection between said lever and said resilient means, and means for periodically actuating said lever about said fulr crum to extend said resilient means from its normal position.

10. An apparatus for stimulating blood circulation comprising a hollow casing for receiving a portion of the patients body, means for forming an air-tight seal between the casing and the patients body, a chamber communicating with said casing, said chamber having a port communicating with a source of positive pressure and another port communicating with a source of negative pressure, a valve associated with said positive pressure port, a valve associated with said negative pressure port, resilient means associated with said valves normally holding one valve in closed position and the other valve in open position with respect to their respective ports, and means for periodically compressing said resilient means, said means for compressing comprising a lever mounted for movement about a fulcrum, a connection between said lever and said resilient means, and means for periodically actuating said lever about said fulcrum to compress said resilient means from its normal position.

JOHN H. EMERSON.

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