US3403673A - Means and method for stimulating arterial and venous blood flow - Google Patents

Description

N. A. M LEOD Oct. 1,1968

MEANS AND METHOD FOR STIMULATING ARTERIAL AND VENOUS BLOOD FLOW Filed July 14,- 1965 m t 6 w w HZ WA W N 9 ||||1 .NMA L v m m 5 3 0' m n 0 w, I." mn MM 2 A. 3 5 N W m United States Patent Oifice 3,403,673 Patented Oct. 1, 1968 six percent to R. Welton Whann and ten percent to Frank F. Reed, both of Los Angeles, Calif.

Filed July 14, 1965, Ser. No. 471,926 17 Claims. (Cl. 128-40) ABSTRACT OF THE DISCLOSURE Apparatus for and method of improving blood circulation including in one embodiment a rigid longitudinally split casing shaped generally to conform to a part of a human body or other animal, and having a seal between the casing sections and between an end of the casing and a body part extending through the end into a sealed chamber formed by the casing, the casing having a valved fluid connection by which the chamber around the body part can be filled with a fluid, such chamber also having a connection with a pump of the piston-cylinder type in which the piston has a one-way adjustable spring loaded valve to enable applying positive-negative pressure impulses to the fluid in the chamber.

In another embodiment there is provided an inner longitudinally split casing of elastic material arranged to snugly fit the body part and coact with the sections of the casing so that the casing may be opened to enable placement of the body part therein, the inner casing coacting with the outer casing to form a sealed space or chamber surrounding the body part for receiving a liquid or gas to which pressure impulses are applied by the pump.

In certain treatments, the apparatus and method utilize in combination therewith a one-way check valve in an artery for permitting normal flow therein, but preventing reverse flow.

This application is related to my copending applications, Ser. No, 289,653 (U.S. Patent No. 3,292,613) filed June 21, 1963, Ser. No. 289,655 (U.S. Patent No. 3,329,- 142) filed June 21, 1963, and Ser. No. 378,665 (U.S. Patent No. 3,286,711) filed June 29, 1964.

This invention relates to means and a method of improving blood circulation, and more particularly, to improve blood circulation where the patient may have a weak heart or is otherwise in a serious condition.

When a man is engaged in muscular exercises, such as walking, running, climbing and the like, the circulation of the blood and lymph through the body depends not only on the pumping action of the heart, but also upon the pumping action of the muscles used in the exercises. In the same manner that the heart operates by a system of controlled muscular contractions and relaxations, in conjunction with a system of check valves allowing blood flow in only one direction, the muscles of the legs, arms and torso act in compression on the venous blood to force such blood back to the heart.

Although in any exercise the cardiac output is augmented, this augmentation involves a concomitant augmentation in venous return due to the pumping action of the muscles. During the relaxation and contraction of the exercised muscles, the intramuscular capillaries take in blood from the arteries and then empty into the veins. The veins have check valves in considerable numbers and these valves are found particularly in the mouths of the tributaries and also in the main vein below the entrance of the tributaries.

In my United States Letters Patent No. 3,094,983 and the above copendin-g applications, I have recognized the influence of a rapid rhythmical cycling of pressures, be-

tween the negative and positive as compared to the atmospheric pressure, in the augmentation of venous blood action to the heart using a confined liquid bath to transmit these rapid pressure changes. However, there are certain situations where a patient may be too ill to sustain such a hydraulic system, where it is inconvenient to use, or where the maximum elfects resulting from the use of a liquid bath are not needed.

In a situation where a patient is in a critical condition due to a heart attack, any lightening of the cardiac burden is highly desirable and the arrival of venous blood to the heart at an increased pressure assists materially in the circulation of the blood. The result of such a sustained enhancement of circulation not only releases the heart of part of its work, but also improves the metabolism of the whole body and in turn assists the body in the process of repairing the damaged heart.

In addition to this specific application of rhythmic positive pressure pulses in -a heart condition there is also a wide application of this treatment for bed rest patients. Prolonged periods of inactivity due to bed rest can actually delay recovery and contribute to fatal results. In such bed rests there is a marked reduction of blood circulation, which is ordinarily about 3,000 to 4,000 cc./min.-increasing to 10,000 to 15,000 cc./min. in exercise, and this reduction results in bed sores, loss of appetite, urinary and intestinal malfunctioning, all of which are associated with the deprivation of the body of its need of exercise and concomitant augmented circulation and metabolic rate.

In seriously ill patients, the slowing of circulation has many serious effects, such as the clotting of blood and pulmonary embolisms, as well as congestion of the lungs and arthritic effects in shoulders and the neck. In such cases where the hazard of exercise is very great, the present invention is of benefit. Insofar as the lack of exercise involves a general reduction in blood and lymph flow, and this can contribute to the deterioration of a patients condition in bed rest, the augmentation of arterial and venous blood flow by simulating the effects of exercise, according to the invention, to any desired degree of intensity can, in periodic use, help to maintain the health of a bed-rest patient, There is a specific application of this invention in cases of strokes and paralysis where the muscles can no longer rely on the nervous system for their operation and the patient is thus temporarily or permanently deprived of the blood circulation benefits of muscular exercise.

In the prior art, when a positive pressure pulse was applied to a limb, for example, the effect was to force all the venous and arterial blood in the enclosed limb toward the heart. That is, the venous blood would flow in its normal direction, but the arterial blood would tend to flow backwards toward the heart. This would be particularly true if the arteries or capillaries were somewhat obstructed downstream of or in the area of the positive pressure pulse. For example, if a rapid series of positive pressure pulses were applied, say one per second, then with pressures of one to five p.s.i., which is a reasonable operating range, the arterial blood flow, usually at a pressure indicated as to mm. Hg, would be seriously impaired and actually prevented during the period of peak pressure in the higher portion of the pressure range. Thus, the net result of a series of positive pressure pulses applied to a limb would be to reduce the blood content of the limb since while venous blood would be assisted in its normal flow towards the heart, the flow of arterial blood would be reduced since each positive pressure impulse would act against the normal blood pressure delivering blood to the limb. Therefore, where pressure pulses are applied to a limb, to maintain an adequate arterial blood flow to the J limb, where no occlusion of the arteries is attempted to prevent reverse flow, the average pressure applied to the limb during a pressure fluctuation cycle, from positive to negative, should not be positive. If it were preponderantly positive, it could interfere with arterial flow from the heart to limb. It should, instead, be atmospheric or slightly negative. In other words, according to the invention, to achieve maximum blood flow and therapeutic effect, there should be a series of negative and positive pressure impulses in which a value of an average positive impulse should not exceed a value of an average alternate negative impulse. In such a negative-positive pressure cycle, rapid cycling, i.e. cycle periods of less than five seconds and as little as one-half second cycle, can be used.

To achieve a negative or zero average pressure impulse, a rigid outer shell and sealing means for the limb is used to prevent loss of suction by leakage of air or liquid between the surface of the limb and the surrounding shell. When this device and method are used for bed-fast or post-operative patients, the device may preferably be pneumatic rather than hydrodynamic so as to avoid the possibility of liquid leakage. A pneumatic system should use as little an air volume around the limb as possible, in order to reduce the power requirements for the device. A volume of of a cubic foot would require a much smaller reciprocating piston volume for the same pressure fluctuation than would be required by one cubic foot of air surrounding a limb.

To reduce the included air volume between the limb and the rigid outer shell, the shell should conform to the contour of the limb, only allowing enough clearance for air passage. To easily accomplish this result, the shell is made in a longitudinal split-form. The problem of sealing the limb and the shell at the shell opening is simplified if a thin elastic lining is used and which conforms to and snugly fits on the limb. The air space then would exist between the inner elastic lining and the inner wall of the rigid shell. Such a device is also made by having an inner lining in two halves whereby each half is sealed with the outer rigid shell to provide a sealed space between the two. In such a device liquid can be conveniently used as tthere is no problem of leakage. Where liquid is used the extent of the volume is not a problem.

While such devices by themselves produce an excellent exercising of the blood and lymphatic circulatory systems and therefore would have significant use in the avoidance of pulmonary embolisms, for example, a condition often resulting from blood clots in the leg veins after surgery and when a patient is immobilized in bed, there are extreme conditions, such as those involving incipient gangrene due to circulatory failure where more radical treatment is required in order to save a leg.

It has already been recognized in my copending application, Ser. No. 289,653, filed June 21, 1963, that it is diflicult to produce occlusion in the femoral artery as in the region of the groin this artery is deep-seated. It is also indicated in that application that there are significant benefits to circulation which derive from causing a partial or complete occlusion of an artery during a positive pressure application to that portion of the body beyond the artery and distal from the heart.

According to the invention, to overcome the problem of occluding a deep-seated artery, I have conceived of the use of a check valve, permitting normal fiow from the heart through the artery but preventing the possibility of reverse flow toward the heart. This valve is constructed of soft flaccid material so that its closing and opening would do no damage to blood cells. Such a valve could be biological or inert in nature. If the former, it could be made by taking a section of a suitably sized vein, containing a valve, and inserting it into the artery so that it is open in the direction of normal blood fiow away from the heart. In such a situation, the patient would be his own donor. It is also possible to construct a valve of suitable living tissue, such as a cartilage and inserting this into the artery.

lternatively, a suitable inert material for the valve is Dacron, formed as a sleeve and having a ball or disc to prevent back-flow of arterial blood beyond the designated point. Such a valve can be permanently installed and can actually help blood flow during the exercise of the limbs. In this connection, it should be noted that a man six feet tall, walking at five miles per hour, can generate a force of 1 /2 to 3 times that of gravity in his feet as a result of centrifugal action, his leg being considered as a pendulum, thus, assisting the flow of arterial blood to the foot while it is in motion. This valve would conserve the pressure increase, resulting from the pendulum action of the foo during the period the foo-t is on the ground and at rest, and, hence, act to assist blood flow.

Where such a check valve is used in an artery, posit ve pressures from to 250 mm. Hg can safely be applied to a limb within the rigid shell device of the invention and this pressure is also substantially transmitted to the arteries to force the blood in a normal direction toward the veins. Since these high pressures are generated within the artery by compressive forces external to the arterial wall, there is no danger to the artery, such as that of an aneurism which can occur when pressures are generated inside the artery as a result of heart pressure. That is, even if the artery were weak or damaged, the external forces compressing it could not cause an aneurism. Therefore, with the use of an intermittent arterial valve, according to the invention, very considerable driving pressures can be employed safely to force blood from a valved artery through the capillary beds to the veins, and this can be most valuable in opening up clogged or impaired circulation channels.

By using intermittent femoral artery blocks on both legs or even on arteries in the lower abdomen and applying a cycling pressure sequence of positive and negative pressure pulses to the legs and lower abdomen, power significantly greater than that of a heart beat can be utilized during each pressure cycle in driving the blood from the femoral arteries through the capillary beds to the veins and back to the heart. Actually, venous blood can be forced into the heart at a sufiiciently high pressure to substantially assist in the work of the heart. Stated differently, the use of the invention provides a secondary heart action in the limb, since blood is sucked into the limb during the period of negative pressure and forced onward through the arterioles and capillaries during the period of positive pressure. Any such cycling pressure return therefore relieves the heart of a considerable part of its work load in that the circulation of blood in the limb does not require any heart assist, while on the other hand venous blood can be forced from the limb to the heart under pressure. Where the patent may have a weak heart the pressure used can be less, but the secondary heart action is similarly effective.

Accordingly, it is an object of the present invention to provide an improved method and an improved apparatus for augmenting blood circulation.

It is another object of the present invention to provide an improved method and an improved apparatus to augment blood and lymph circulation with alternate positive and negative pressure impulses where no occlusion of an artery is attempted immediately upstream of the area of pressure impulses.

It is still another object of the present invention to provide a method and means for augmenting the blood and lymph circulation in a limb by means of positive and negative pressure impulses in situations where it may be required that an artery upstream of the area of pressure impulses be occluded to prevent *backflow of the blood toward the heart during the positive pressure impulses. It is a further object of the invention to provide a new means for occluding arteries in the situations described.

Further objects and advantages of the invention may be brought out in the following part of the specification wherein small details have been described for the competence of disclosure, without intending to limit the scope of the invention which is set forth in the appended claims.

Referring to the accompanying drawings, which are set forth for illustrative purposes:

FIG. 1 is a side elevational view, partially in crosssection, of an apparatus according to the present invention;

FIG. 2 is a cross-sectional view taken as indicated by the line 22 in FIG. 1;

FIG. 3 is an enlarged fragmentary view of the piston shown in FIG. 1;

FIG. 4 is a side elevational view, partially in crosssection, of another embodiment of the invention;

FIG. 5 is a cross-sectional view taken as indicated by the line 55 in FIG. 4; and

FIG. 6 is a cross-sectional view of a check valve in an artery, such as the femoral artery as may be found in the leg in FIG. 4.

Referring again to the drawings, in FIGS. 1 and 2, there is shown an elongated chamber 10 shaped to conform to a human leg 11 therein. The chamber is formed of allochirally-shaped half-members 12 and 13, each having an external configuration, generally of half a leg. The internal configurations of each of the shell forming members 12 and 13 are such that they, when they surround a particular leg, will particularly conform to it or be adaptable to conform closely to it.

The members 12 and 13, each have a surrounding flange 17 and 18, respectively, longitudinally directed, and terminating in radially directed flanges 19 and 20, respectively. The members 12 and 13 and their flanges are rigid and may be made of any hard leakproof material, such as plastic or metal. The members are joined along their longitudinal flanges, having an elastomeric sealing gasket or strip 23 extending therebetween. A plurality of spring-type clamps 24 are fitted over the external surfaces of the flanges 17 and 18 to sealingly secure the latter together.

When the chamber 10 is designed to closely conform to the shape of a leg, or even a particular leg, it is desirable that the two members 12 and 13 be placed in sealing relationship with the leg therein. So formed the chamber has a generally circular opening 25 from which an upper portion of the leg 11 extends outwardly. Snugly fitted on the leg at the opening 25 is an elastomeric sealing member 26. The member 26 forms a seal on the surface of the leg and has extending therefrom a radial annular flange 29 which abuts the outer faces of the flanges 19 and 20. Surrounding the outer surface of the flange 29 is a rigid ring 30 and it and the flange 29 are secured together and to the flanges 19 and by means of spring clips 31 so as to completely seal the opening 25.

The member 12 has a filling tube 32 sealingly secured thereto and which may be opened and closed by means of a valve 35. A tube 36 provides communication between the chamber 10, through the wall of the member 13 in which it is sealingly secured, and a cylinder 37. Slidably and sealingly engaged in the cylinder is a piston 38, adapted to be reciprocated to vary the pressure within the chamber 10. As may be best seen in FIG. 3, extending through the piston is an aperture 41 which, when open, provides a passage from one side of the piston to the other. The aperture is normally closed by means of disc valve 42, held in its closed position by means of a spring 43. The spring can be adjusted by means of a screw 44 so as to vary the value of the pressure on the opposite side of the piston which will cause the valve 42 to open.

Connected to the outer face of the piston 38 is a connecting rod 47 which has its outer end pivotally connected to one end of a link 48. The other end of the link 48 is pivotally connected to a rotatable disc 49 at a pivot 50.

The disc 49 is rotatably driven by a motor 53. The pivot point 50 is eccentric with respect to the drive shaft of the motor and the axis of the disc 49 so that the rotation of the latter causes the piston 38 to reciprocate in a predetermined stroke. The stroke may be varied by the position of the pivot 50 on the disc.

The chamber 10, as shown, with a low volumetric space between its Wall and the surfaces of the leg 11, can be used with either gas or liquid as a pressure transmitting medium to the arteries, capillaries, veins and lymph system. When liquid is used, the extent of the volume of the space around the leg is not important but it must be filled completely. Because of the compressibility of gas, the volume of the space around the leg should be as small as possible when air, the typical gas, is used. When air is the desired pressure transmitting medium as it is likely to be in the device as shown when used on a patient in a bed, if the volume around the leg is not as small as may be desired, nonporous padding can be inserted so as to reduce the volume.

In operation, after the leg has been scaled within the chamber 10, surrounded by air, and the valve 35 has been closed, the pressure in the chamber then being atmospheric, any movement of the piston will vary the pressure on the leg, and also vary the pressure on the circulatory system members within the leg.

Where the circulation within the leg is to be augmented without the occlusion of an artery, which in the case of the leg would be the femoral artery, to maintain adequate arterial blood flow into the leg, by varying the pressure in the chamber with alternate positive and negative pressure impulses, the total pressure impulse of each alternate positive and negative impulse should either be zero or slightly negative. That is, the negative pressure impulses should be greater than the positive pressure impulses or equal thereto. -In this sense, an impulse is measured by multiplying value of the force by the time during which the former acts, thus, the impulses can be varied in value either by varying the amount of pressure or the period it is applied.

In the embodiment shown, by means of the spring loaded valve 42, it is intended that the pressure be varied so as to either maintain the negative impulses greater than the positive or equal thereto. As the piston is reciprocated at one to two pulses per second whereby the pressure changes within the chamber would be between three to five p.s.i., the positive stroke in which the piston is moved to the left would be regulated in the amount of pressure by the setting of the spring 43 on the valve 42 so that the positive pressure within the cylinder and the chamber would not exceed the value of the negative impulse which would occur when the piston is moved to the right in the drawing.

It should be realized that having the positive impulse greater than the negative is not important where the patient has a good heart, and that an important part of the concept here is that there may be a negative-positive pressure cycle in which there is rapid cycling, the cycle periods being of less than five seconds and as short as one half second per cycle. This type of cycling for the benefit of a seriously ill patient, without an excessive positive pressure, is extremely beneficial.

As indicated, with the use of the valve 42 the positive pressure is limited as desired so that the total positive pressure impulse is not greater than the alternate total negative impulse. Since the pressure impulse is a function of both time and the force, the negative impulse can be made equal to or greater than the positive impulse by slowing the negative stroke so as to maintain the negative pressure for a greater length of time. This can be done with a variable speed motor and a timing device which would slow down the motor on the negative stroke.

In the device, as shown in FIGS. 4 and 5, there is a rigid outer shell 54, formed of two halves or shell members 55 and 56 of leakproof material. Each shell member, 55 and 56, has a longitudinally directed flange, 59 and 60, respectively, and which terminate in semicircular flanges 61 and 62, respectively.

Sealingly secured to each of the members 55 and 56 is an inner half or shell forming member, 65 and 66, respectively. These inner members are made of leakproof elastomeric material and are relatively thin compared with the outer rigid members. They may be similar to a rubber stocking. In the embodiment shown, the members 65 and 66 are allochirally arranged and shaped as that of a human leg and foot and are designed so that, when placed over a leg as 67, they will each fit snugly on it. Each of them has a longitudinally directed flange, 68 and 69, respectively, as shown in FIG. 5, and terminate in a semicircular sealing member having an inner circumferential portion, as 71 in FIG. 4, adapted to form a seal on the leg. Extending radially outwardly from the inner portion is a semicircular flange, as 72, shown only for the inner member 65.

The flanges 68 and 69 with their respective end sealing portions, as 71 and 72, are each secured to a respective outer shell member, 55 and 56, prior to the time that the members are joined to be fitted upon a leg. By this arrangement, a permanent seal may be maintained between the flanges 59 and 68 and 60 and 69 so that in the respective spaces 73 and 74 between the inner and outer members there are formed permanently sealed chambers. Thus, for a bed patient, this arrangement is particularly convenient in that the spaces or chambers 73 and 74 may be prefilled or permanently filled with liquid by means of the tubes 75 and 76 which support filling valves 77 and 78, respectively.

In the embodiment shown, in view of the fact that the volumes of the spaces 73 and 74 are relatively small, air may be used as the pressure transmitting medium. However, in an embodiment of this kind when liquid is used, the volume of the spaces 73 and 74 is not important and this provides the advantage of permitting the outer members 55 and 56 to be of larger size so that they will fit on any limb. However, the elastomeric members 65 and 66 must be limited in size so that they fit snugly on any particular limb.

When the respective inner and out rejoined casing members are fitted over a leg, for example, they are spaced by a longitudinally directed sealing gasket 80, as shown in FIG. 5, and which may be varied somewhat in thickness to provide adjustability for the size of the elastomeric members 65 and 66 relative to the particular limb on which they are to be fitted. As shown in FIGS. 4 and 5, the members 55, 65, and 56, 66 are joined with the gasket 80 therebetween by means of the screws 81.

When the device is secured on the leg 67, as shown, there is a space 82, which extends longitudinally on the leg and foot, immediately inwardly of the gasket 80 and between the flanges 68 and 69 on the inner elastomeric members. Although not shown, this space also extends between the spaced ends of the sealing members 71 and 72 and which form a seal between the inner and outer members at their ends and between the leg and the inner members. The sealing members, having radially directed flanges, as 72, abut the flanges 61 and 62 on their inner faces and abut a ring 83 with their outer face-s, these end members being secured sealingly together by the screws 84.

For patients in a serious condition, the embodiment shown in FIGS. 4 and can be operated in the same way as that shown in FIG. 1, the pressures on the inner casing being transmitted to the leg. However, where the femoral artery in the leg 67 is occluded during the positive pressures may be applied and there need be no concern that the positive pressure totals are greater than the negative pressure totals. Such a means of occlusion is the valve 87, shown in FIG. 6. This valve has been inserted into the femoral artery 88 by means of surgery. Here, the artery has been severed and each of the cut ends, as 89 and 90, have been fitted over sleeve portions 93 and 94 on the ends of the genrally cylindrical and elongated valve body 95. The valve has a cylindrical chamber 96 which when the valve is open, provides a passage between those in the sleeves 93 and 94. The chamber 96 has four ribs 99 which space a ball valve 100, when in the open position at the left in FIG. 6, from the walls of the chamber so as to permit flow around the ball and between the ribs 99, the normal arterial flow being from right to left in the drawing. The ball valve is shown, during the period of positive pressure, in the closed position on its seat 101 provided by the end of the sleeve 94 and the omission of the ribs 99.

This valve provides for a normal one-way flow through the artery and when the pressure in the leg and artery downstream of the valve is increased the ball is moved from left to right to the position on its seat 101 and thereby occludes the artery and prevents backflow toward the heart during the positive pressure pulses. Such valves may be made of Dacron and the 'ball should be soft enough so as to not damage the blood cells.

Another method of inserting such a valve into an artery includes the cutting of longitudinally directed and circumferentially spaced slits in the artery. The valve then can be inserted into the artery through one of the slits and the slits can be sutured as necessary to aid the artery in healing and growing around the valve.

As indicated, where an arterial block, such as the valve 87, is used relatively high positive pressures can be developed within the artery with safety and so as to obtain the important result of washing out the capillary bed and the veins.

In the use of the invention so as to pressure cycle the lower torso and/or a limb, it is advantageous to synchronize the cycling with the heart heat so that the positive pressure is applied just as the left ventricle of the heart forces blood through the aortic valve to the aorta and the valve closes. The positive pressure pulse can be applied with each heart beat, with every alternate heart beat, or with every third heart beat and so on. However, the duration of the positive pressure application should not extend beyond the limits set by the closing of the aortic valve and its next opening. When the aortic valve is open, applied pressure should be negative or zero. As the ventricular systole usually takes about one third of a second and the heart beats about times a minute, the positive pressure can only be applied for a period of about /2 a second. As such a short duration pressure pulse involves a fast rise and fall of pressure, then a closed and completely filled liquid environment for the portion of the body being treated is necessary, or if air is used, the space between the outer rigid shell and the portion of the body being treated should be as small as possible.

The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangement hereinbefore described being merely by way of example. I do not wish to be restricted to the specific forms shown or uses mentioned, except as defined in the accompanying claims, wherein various portions have been separated for clarity of reading and not for emphasis.

I claim:

1. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or of an animal, comprising:

(a) a rigid, sealable outer casing formed of two sepable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing being spaced from the corresponding half of said outer casing,

.(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(e) said inner casing being sealable to said body part at its opening,

(f) said inner casing being adapted to conform to body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with fluid; and

(h) means to vary the pressure of all of said fluid on said inner casing so as to vary the pressure on said body part.

2. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or of an animal, comprising:

(a) a rigid, sealable outer casing formed of two separable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing conforming to and being closely spaced from the corresponding half of said outer casing,

(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(e) said inner casing being sealable to said body part at its opening,

(f) said inner casing being adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with gas; and

(h) means to vary the pressure of all of said gas in said space and on said inner casing so as to vary the pressure on said body part.

3. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or of an animal, comprising:

.(a) a rigid, sealable outer casing formed of two sepable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing being spaced from the corresponding half of said outer casing,

(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(e) said inner casing being sealable to said body part at its opening,

(f) said inner casing being adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with liquid; and

(h) means to apply varied positive and negative pressure impulses to all of said liquid so as to vary the pressure on said inner casing and on said body part.

4. A variable fluid pressure device for affecting blood circulation in part of a body of a human being or of an animal, comprising:

(a) a rigid, sealable outer casing;

(b) an elastic sealable inner casing within said outer casing and being spaced therefrom;

(c) each of said casings having corresponding openings in register so that a part of said body can extend into said inner casing when it is within said outer casing,

(d) said inner casing being scalable to said body part at said openings,

(e) said outer and inner casings being sealable from each other at said openings to provide a sealed space therebetween,

(D said inner casing being adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said space with liquid; and

(h) means to vary the pressure of all of said liquid so as to vary the pressure on said inner casing and 'on said body part.

5. A variable fluid pressure device for aifecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable casing for containing fluid under pressure,

(b) said chamber having an opening adapted to receive a part of a body;

(c) a seal being formable at said opening in contact with said body part to close said chamber;

((1) means to fil-l said chamber with fluid after said opening is closed;

(e) means to vary the pressure of the fluid in the chamber; and

(f) a check valve means permitting one-way, normal direction flow in an artery to said body part.

6. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable casing for containing fluid under pressure,

(b) said chamber having an opening adapted to receive a part of a body;

(c) a seal being formable at said opening in contact with said body part to close said chamber;

(d) means to fill said chamber with liquid after said opening is closed;

(e) means to apply positive pressure pulses to all of said liquid; and

(f) a check valve permitting one-way, normal direction flow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

7. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a chamber for containing a gas under pressure and having an opening to receive a part of the body;

(b) said chamber being adapted to conform to the shape of said part and the interior surfaces of said chamber being adapted to be in juxtaposition with corresponding surfaces of said part;

(c) a seal being formable at said opening in contact with said body part to close said chamber;

(d) means to fill said chamber with gas after said opening is closed;

(e) means to alternately apply positive and negative pressure pulses to said gas in said chamber; and

(f) a check valve permitting one-Way, normal direction flow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

8. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normaldirection flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable casing for containing fluid under pressure,

(b) said chamber having an opening adapted to receive a part of a body;

(c) a seal being formable at said opening in contact with said body part to close said chamber;

(d) means to fill said chamber with liquid after said opening is closed;

(e) means to alternately apply positive and negative pressure pulses to said liquid in said chamber; and

(f) a check valve permitting one-way, normal direction flow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

9. A variable fluid pressure device for aflecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable outer casing;

(b) an elastic sealable inner casing with said outer casing and being spaced therefrom;

(c) each of said casing having corresponding openings in register so that a part of said body can extend into said inner casing when it is within said outer casing,

(d) said inner casing being sealable to said body part at said openings,

(e) said outer and inner casings being sealable from each other at said openings to provide a sealed space therebetween,

(if) said inner casing being adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said space with liquid;

(h) means to apply positive pressure pulses to all of said liquid; and

(i) a check valve permitting one-way, normal direction flow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

10. A variable fluid pressure device for aflecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable outer casing formed of two separable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing conforming to and being closely spaced from the corresponding half of said outer casing,

(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(c) said inner casing being sealable to said body part at its opening,

(f) said inner casing being adapted to conform to the :body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with gas;

(h) means to apply positive pressure pulses to all of said gas; and

(i) a check valve permitting one-way, normal direction flow in an artery to said body part to prevent blood fiow in said artery from said part toward the heart during the periods of said positive pressure pulses.

11. A variable fluid pressure device for affecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable outer casing formed of two separable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing conforming to and being closely spaced from the corresponding half of said outer casing,

(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(e) said inner casing being sealable to said body part at its opening,

(f) said inner casing being adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with gas;

(h) means to alternately apply positive and negative pressure pulses to all of said gas in said spaces; and

(i) a check valve permitting one-way, normal direction fiow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

12. A variable fluid pressure device for atlecting blood circulation in a part of a body of a human being or an animal for use in combination with a check valve permitting one-way, normal direction flow in an artery supplying blood to said part, comprising:

(a) a rigid, sealable outer casing formed of two separable halves;

(b) an elastic, sealable inner casing within said outer casing and formed of two separable halves;

(c) each of said halves of said inner casing being sealingly secured to a corresponding half of said outer casing, each half of said inner casing conforming to and being closely spaced from the corresponding half of said outer casing,

(d) said casing halves when joined having corresponding openings in register so that a part of said body within said inner casing can extend outwardly of said casings,

(e) said inner casing being sealable to said body part at its opening,

(i) said inner casing bein adapted to conform to the body part and to fit snugly thereon;

(g) means to fill said spaces between said inner and outer casings with liquid;

(h) means to alternately apply positive and negative pressure pulses to all of said liquid in said spaces; and

(i) a check valve permitting one-way, normal direction flow in an artery to said body part to prevent blood flow in said artery from said part toward the heart during the periods of said positive pressure pulses.

13. A method for affecting blood circulation in a part of a body of a human being or an animal, comprising:

(a) enclosing a part of a body to be treated in a chamber;

(b) sealing said part in said chamber;

(c) filling said sealed chamber with liquid; and

(d) varying the pressure of all of said liquid with alternate positive and negative pressure impulses at predetermined rates, the value of the negative impulses being greater than the value of the positive impulses.

14. A method for aflecting blood circulation in a part of a body of a human being or an animal, comprising:

(a) enclosing a part of a body to be treated in a chamber;

(b) sealing said part in said chamber;

(c) filling said sealed chamber with liquid; and

(d) varying the pressure of all of said liquid with alternate positive and negative pressure impulses at predetermined rates, the total of each alternate positive and negative impulse being zero.

15. A method for affecting blood circulation in a part of a body of a human being or an animal, comprising:

(a) enclosing a part of a body to be treated in a chamber;

(b) sealing said part in said chamber;

(c) filling said sealed chamber with liquid;

((1) inserting a normal direction flow check valve in an artery to said part to prevent flow in said artery toward the heart; and

(e) applying alternate positive and negative pressure pulses to all of said liquid in predetermined amounts at predetermined rates. I

16. A method for affecting blood circulation in a part of a body of a human being or an animal, comprising:

(a) enclosing a part of a body to be treated in a chamber;

(b) sealing said part in said chamber;

() filling said sealed chamber with liquid;

((1) applying alternate positive and negative pressure pulses to all of said liquid in predetermined amounts at predetermined rates; and

(e) preventing reverse flow of blood to the heart in 14 an artery to said part by a check valve in said artery.

17. A method for afiecting blood circulation in a part of a body of a human being or an animal, comprising:

(a) enclosing a part of a body to be treated in a chamber, said chamber having an elastic inner wall and a rigid outer wall with a sealed space therebetween;

(b) snugly fitting said inner wall on said body part;

(c) sealin said part within said inner wall;

(d) filling said sealed space with a fluid;

(e) varying the pressure of all of said fluid with alternate positive and negative pressure pulses at predetermined rates to exert pressure pulses on said body part through said inner wall; and

(f) preventing reverse flow of blood to the heart in an artery to said part by a check valve in said artery.

References Cited UNITED STATES PATENTS 2,055,128 9/1936 Hermann 128-299 2,113,253 4/1938 Gray 128--299 2,134,646 10/1938 Sauzedde 128-299 2,893,382 7/1959 Demeny 12864 3,053,249 9/1962 Smith 128-64 3,303,841 2/1967 Dennis 12824 L. W. TRAPP, Primary Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.0. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,403,673 October 1, 1968 Norman A. Mac Leod It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 54, "patent" should read patient Column 7, line 43, "out" should read outer line 69, after "positive" insert pressure impulse, substantially greater positive Signed and sealed this 24th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. JR. Attesting Officer Commissioner of Patents

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