WO1999037266A1

WO1999037266A1 - Venous boot

Info

Publication number: WO1999037266A1
Application number: PCT/US1999/001505
Authority: WO
Inventors: Ibrahim M. Ibrahim; Sharon Caruth Ibrahim; Robert Freidenrich
Original assignee: Englewood Research Associates
Priority date: 1998-01-24
Filing date: 1999-01-25
Publication date: 1999-07-29
Also published as: WO1999037266A9; WO1999037266B1; AU2561999A

Abstract

This invention is a portable apparatus (50) for applying cyclic pressure to veins within a person's leg by applying cyclic pressure to an outer surface of the leg. The apparatus comprises a first air chamber (40) having a flexible wall portion adapted to be situated adjacent an outer surface of the leg, and a second air chamber (51) adapted to be positioned beneath the person's heel. This second chamber (51) is compressed to force air out of it when the person's heel bears downward thereon, and returnable to its uncompressed state when the downward heel force is removed therefrom. Conduit means (57) for permitting airflow between the first, and second air chambers (51), whereby air flows from the second chamber (51) into the first chamber. Pressure is cyclically increased in the first chamber urging the wall portion against the leg when the person's heel presses downward on the second chamber (51) where air flows from the first to second chamber (51), and pressure on the leg is reduced when the person's heel stops pressing on the second chamber (51).

Description

VENOUS BOOT

FIELD OF THE INVENTION

The present invention relates to a compression apparatus for applying cyclic external pressure to the outer surface of a person's leg or other limb. In particular, the present invention relates to compression apparatus worn against the outer surface of the lower leg for reducing and controlling the discomfort and disease caused by various venous disorders occurring in the lower leg. BACKGROUND OF THE INVENTION AND DISCUSSION OF PRIOR ART

Venous disease is a common disorder that effects millions of people. The disease in many respects is more complex than arterial disease which is largely the result of obstructions in the vessels; however, the criticality of arterial disease and availability of various treatments has helped to focus the medical community's attention towards arterial disease instead of venous disease.

Venous disease effects many more people than those specifically identified and treated. Many of the unidentified ones suffer in silence as they voluntarily slow down, restrict their activities or learn to adjust by reducing the effects of gravity by elevating their legs or lying down. Disability from venous disease includes the regional problem usually occurring near the upper part of the ankle, but also there is a risk of escape of thrombi into the pulmonary circulation. The lost work time for patients is a substantial unregistered cost to society of the disease. Untreated patients are plagued with chronic edema, pigmentation, ulceration, pain, venous congestion and recurrent episodes of venous thromboses, a painful and disabling condition which is largely incurable, but controllable.

The obvious function of the venous system is to return blood to the heart from the capillary beds. The veins also play a role in regulating vascular capacity and are part of a peripheral pump mechanism which assists the heart in the transport of blood during exercise. Of the two types of veins, superficial and deep, the large superficial veins are relatively thick walled and easily visible structures which lie just beneath the skin. The deep veins are thin walled vessels lying deep within the musculature and are often accompanied by arteries. These deep veins are responsible for the majority of blood flow back to the heart and are often three times larger than the cross sectional area of the adjacent artery. Veins are passive conduits that contain one-way valves for unidirectional flow towards the heart. Venous disease is caused by either blockage of the deep veins in the leg or by incompetent valves in the veins of the legs. The resultant effect is an increase in pressure in the collateral venous circulation of the leg. The method of blood flow from the leg to the heart in an erect or active person is the muscle pump. In the calf the muscles contract, squeezing and emptying the veins. The blood flows in the vein towards the heart as a result of the one-way valve. Repetitive contraction of the muscles results in the continuous movement of venous blood antegrade towards the heart. If the valves are incompetent, blood can flow in either direction. If the vein is obstructed, blood flows only retrograde to make the valves appear incompetent. In either case for venous disease the normal muscle pump not only does not return blood to the heart, but actually increases the pressure in the leg.

Inadequate blood flow to the heart will result in swelling in the foot and lower leg which results in increased pressure in the leg. In a recumbent or supine position the pressure in the veins of the foot is about 12 MM Hg; when sitting it is about 56 MM Hg; when standing the pressure approaches 90 MM Hg. If a person with venous disease of the leg is standing versus recumbent there is an added approximately 80 MM Hg pressure on the capillary system, resulting in significant dilation of the veins and extravasation of fluid to the tissue. If this process continues, it can produce edema and subsequently other pathological changes such as skin ulcerations.

When a vein is obstructed, as shown in Fig. 1 of the drawings herein, blood that would normally flow upward in the vein, may exert enough back pressure to damage the adjacent valve. Thereafter, the damaged valve allows blood to be forced backward toward the foot. After such damage has occurred, the muscle pump not only does not effectively return blood to the heart but actually increases the pressure in the foot, as shown in Fig. 2, whether or not there is an obstruction. Valves may be incompetent for a number of reasons other than thrombosis. The incompetent valve will allow blood to flow away from the heart thus causing increased venous pressure in the foot. Some authorities believe that this additional, repeated increase in venous pressure at the ankle level that is caused by the contraction of the leg muscles is the principal cause of the swelling and resultant ulcerations that occur in these patients, in addition to the static pressure in the veins.

As schematically shown in Figs. 3 A and 3B, veins in the leg such as the femoral vein 10 contain cusp-shaped valve flaps 12 that allow blood flow upward per arrow 13, and under normal conditions meet to prevent blood from flowing in the downward direction indicated by the arrow 14 toward the patient's foot. When an obstruction 16 develops in the vein impeding blood flow per arrow 15, damage to these flaps may result when blood pressure in the vein below the obstruction is locally increased. Such pressure rise occurs when there is contraction of the adjacent leg muscle causing the inward-directed pressure indicated by arrows 17 in Fig. 3 A and the resulting constriction 18. Valve flaps 12 below the constriction 18 are subjected to excessive back pressure that may stretch or tear the inner edge 19 of a valve cusp. This damage renders the valve incompetent for the task of preventing the downward flow of blood in the veins of the leg.

It is estimated that there are 4,880,000 new cases of venous disease treated each year. This included 2,800,000 deep vein thrombosis, 1,400,000 post-phlebitic syndrome, 600,000 pulmonary embolisms, and 80,000 procedures for venous insufficiency/varicose veins. It is estimated that the prevalence of varicose veins is closer to 24,000,000 cases.

These numbers reflect the patients treated and do not include the expectant management patients which could make themselves available for a viable treatment. This disease is largely incurable and the new invention presented herein is largely palliative in nature. Therefore, the number of available patients increases with time. The new apparatus of the present invention will be especially useful as the society at large ages. It is estimated that the new device will be used on both legs for each patient even if the patient presents a problem in only one leg. It is expected there will be a higher patient compliance with this device since patients can actually feel the product working.

The treatment for this disorder involves three modalities, all of which rely on the same basic principle, namely the application of external pressure on the lower extremity to counteract the increased pressure on the collateral circulation. Apparatus for these three treatments are described as follows.

The first modality is the application of so called compression or surgical stockings. Elastic stockings are commonly worn by persons having venous disease such as venous ulcers, incompetent venous valves, deep venous thrombosis and varicose veins to prevent the swelling of the feet and the lower legs. One type of this compression stocking is an Ace^* bandage. Also, there are stockings sold under the names Camp*, Jobst*, and Sagvaris* that incorporate enough elastic bands in them to exert selected variable amounts of pressure on the lower extremity. The stockings are tailored to each individual leg by actually measuring the circumference of the leg at different levels and then manufacturing the stocking to have the particular degree of compression required by the severity and nature of the patient's disorder at a given time.

Surgical stockings are difficult to put on because of the considerable strength required to stretch the stocking until it is properly positioned. Furthermore, dressings that may be applied to an ulcer in the leg may become displaced while the stocking is being put on. Also, many of these patients are elderly with one or more arthritic problems, and applying the stockings is so difficult

Trademark of Manufacturer that assistance of another person is required. Finally, when the swelling begins to subside, obviously the stocking becomes very loose and loses its effectiveness, so that a new stocking has to be purchased as the disease process ameliorates.

Compression devices such as surgical stockings that diminish the extravasation of fluid, thereby retarding the formation of edema, have been the mainstay of therapy for the above described problem. However, the constant compression provided by these stockings does not correct the repetitive, harmful increase in back pressure that is produced by contraction of the patient's leg muscles during walking. Nor do such devices recreate the dynamic, repetitive increase in the blood flow that occurs in healthy veins as the patient's leg muscles contract during walking.

The second modality is the so-called Unna* boot or Dome* paste. This is a medicated bandage that is applied circumferentially over the leg starting at the toes and extending all the way up to the knee. This is a semi-rigid dressing in that it is not as flexible as the surgical stockings, but also not as rigid as a plaster cast. This is the type usually used in cases of open ulcerations. After use this dressing cannot be removed for a few days, but once it is removed, a new one has to be applied. Also, it cannot be allowed to get wet. If it is too tightly applied, it may impede the circulation, thus jeopardizing the extremity. The Unna* boot is considered by some as more effective than the surgical or compression stocking since it has a semi-rigid quality.

The third modality is the intermittent pneumatic compression device, namely, a plastic boot than can be pressurized by a pump. This device is applied on the leg and then attached to a compressor which pumps air into the device to a pre-set pressure, lets it remain there for a few second, and then releases it. This is best used to relieve very significant edema in the extremities. Unfortunately, this system of boot and compressor is heavy and cannot be used continuously. Thus, its use is mainly confined to the hospital or the patient's home, and obviously, with this device the patient has little or no mobility.

Each of the three modalities of treatments above have numerous and serious drawbacks has been described. SUMMARY OF THE INVENTION

A principal object of the present invention is to treat venous disease of the leg by providing dynamically variable compression to the outer surface of the lower leg.

A further object of this invention is to reduce or prevent additional damage to already damaged veins in the leg. More particularly, we seek to recreate a dynamic and repetitive inςrease of the pressure on the extremity from the foot upwards as the leg muscles contract. Thus, we seek to counteract the repetitive increase in the retrograde pressure on the lower extremity by muscular contraction.

A still further object of this invention is to provide a convenient, comfortable and totally mobile apparatus for applying dynamic pressure to wearer's lower leg, the apparatus preferably being a boot worn on the leg.

Another objective is to provide a mobile dynamic compression apparatus for the lower leg where the user can inflate a pressure chamber merely by walking with no requirement for a pump or other external source of compressed air.

The present invention achieves these and other objectives by an apparatus generally in the form of a boot which includes (a) a pressure application means such as an air cell or resilient air chamber situated adjacent the wearer's lower leg, (b) a pump means such as compressible and resilient bulb or air chamber situated below the wearer's heel, (c) a fluid conduit means, such as a tube providing an air passage between the pump means and the pressure application means, and (d) appropriate valve means.

This invention is an apparatus and method for applying cyclic pressure to the outer surface of a person's lower leg while the person is walking and remains fully mobile. A bladder or other elastic air chamber is situated against the leg and cyclic air pressure is applied via the bladder to the surface of the leg. This cyclic air pressure is supplied by a pump preferably situated below the person's heel so that as he walks each step downward on the heel actuates the pump to drive air into the bladder. Further stepping off the heel releases the pump to draw air back.

This cyclic pressure applied to the blood vessels within the leg substitutes for or supplements the pumping action that would occur in a normal healthy leg by contractions of the calf muscle. Because the venous disease greatly diminishes this pumping effect, the expanded air cell or bladder will apply a substitute pressure to drive the blood upward and not let excessive pressure develop below the obstacle or damaged valve.

In this operation the bladder and pump comprise a closed air system. A valve device is provided to allow this system to operate selectively in any of three modes: information of the system, cyclic pressure mode during walking, and deflation of the system. Inflation may be from an external source of compressed air, or preferably is achieved by appropriate operation of valves as the user takes a number of steps, hence the title herein "Self-Inflating Venous Boot."

To achieve this inflation a charge of air is drawn into the system by expansion of the pump when the foot is lifted; as the person steps down air is then driven by the pump into the bladder. This procedure is repeated number of time until the system is adequately inflated to approximately 50 MM Hg. The system is then closed and isolated from further inlet air, such that air merely reciprocates between the pump and the bladder as the person walks. The pressure can be increased or decreased as required by inlet or release of air from the system, and when desired the system can be fully deflated by opening the system via appropriate valve means to the atmosphere. The preferred embodiment disclosed herein includes a single compact valve unit that allows all of the above-described modes of operation.

The bladder or pressure chamber is situated in the area slightly below the knee (4 to 5 CM below the patella), covering the calf to the ankle and metatarsal area. This bladder may fully surround the leg or pressure may be applied to selected areas of the leg. The pumping action is achieved merely by walking and using the person's own weight, with no additional muscle effort required and no additional or external power source or apparatus required. This inflatable bladder is sufficiently flexible to generally conform to the shape of the calf and leg and distribute the pressure substantially evenly and cause minimum discomfort. The apparatus is designed to avoid hard contact or excessive pressure with the protruding malleolus of the tibia and fibula.

In a preferred embodiment the pump is configured to fit within a relatively normal appearing shoe, and the primary pressure-applying chamber is a sleeve or boot-like member that surrounds or is situated against the lower leg. In such preferred embodiment additional compression means is provided by an elastic sock or partial sock surrounding the instep or portion of the foot forward of the ankle including or not including the toes. The pump in one convenient form is a resilient elastic chamber that is compressed by heel pressure and upon absence of heel pressure expands naturally and draws air back into it from the bladder.

The valve means for this air system comprises various valve functions which may be separate valves or as in the preferred embodiment are combined into a single device. In inflation mode air is allowed by an inlet check valve to enter the system but not escape; then air must flow from the pump into the bladder but not return to the pump. During the normal operation of walking mode air must freely reciprocate between the pump and the bladder. Finally, in release mode air must be free to exit the system and deflate the bladder. With the combination valve apparatus, the user manually adjusts the valve for the selected mode of operation. Alternatively, the valve means can operate automatically to close at a pre-set pressure during inflation mode.

In one embodiment the boot or bladder has an inner surface or layer of fleece or other natural or synthetic material that is soft and washable, allows movement of air or perspiration on the surface of the leg, and permits application of medication to the skin if necessary. The bladder itself may be formed of a sheet or cuff that is wrapper around and secured to the leg, and subsequently inflated so as to apply pressure inward against the leg. Alternative pressure means may be used against specified parts of the leg. In a still further version one or more semi-rigid sheets, such as a set of front and rear sheets encase the leg with the bladder or other elastic air chamber between the leg and an inner surface of a shell. Inflation of the chamber within the confined space between the shell results in pressure application against the leg.

There will be an optional air pump such as an electric motor pump the patient can use at home or office when he is relatively inactive and not walking. Such pump would produce cyclic pressure applied to the bladder's air system whenever desired.

Further variations and developments of the present invention with pump means beneath the heel and cyclic pressure applied to the person's calf include the following. In addition to applying cyclic pressure to the calf region, we can apply cyclic pressure to the surfaces of the ankle and/or to the surfaces of the foot.

Applying cyclic pressure to the ankle surface may be achieved by extending the walls of the earlier-described boot from the heel area forward to overlie the rear and sides of the ankle. The side extensions may engage and overlie the front of the ankle, or a strap may join these side parts. Such strap may be inflatable or non-inflatable, and the latter may be elastic or non-elastic. Also, the strap width may be extended forward toward the toes to overlie part or all of the instep.

In these embodiment the cyclic pressure on the ankle and foot surfaces is in phase with cyclic pressure applied to the calf, and this is achieved typically by forming the air chambers in the ankle and foot areas to be contiguous with the air chamber in the calf region. Thus, when a person walks and applies downward pressure on the air chamber beneath the heel, the air in the remaining chambers is subject to a rise in pressure.

Whether or not the structure is used to apply cyclic pressure to the ankle and foot areas, the basic pressure apparatus may have boot elements as described above and a separate pump means below the heel, or it may be formed as a generally one-piece boot where the pump means is merely a small portion of a single contiguous air chamber which extends below the heel and about the calf and in these further embodiments extends about the ankle and/or about the foot.

In all these embodiments a still further variation would allow the boot to be used on a non- ambulatory patient's leg by connection of the air chamber in the boot to an external pump producing cyclic pressure. Such cyclic pressure application may be used advantageously for treating venous thrombosis prophylaxis, chronic venous disease, lymphoedema, and for reduction of edema, prevention of blood clots, and as an orthotic device for stabilizing the ankle. The one-piece version is especially desirable for its simplicity and economy of manufacture, its ease of use and its beneficial results. The basic construction elements are two overlying air impervious sheets with specified areas heat sealed together to define and form the respective air chambers and joining air passages or conduits between the air chambers.

A venous boot of the type described above may have a multi-position or equivalent valve means to allow air flow between the heel pump area and other areas when a patient walks, or to allow an external pump to provide cyclic air flow when a patient is non-ambulatory. Such valve should also allow an input of initial air to establish a base pressure typically of about 75 MM Hg, with the added pressure of about 25 MM Hg from walking or from the external pump.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is prior art showing a sequence of venous volume changes in the calf with walking.

Fig. 2 is a sectional view of a femoral valve in its pre-repair damaged state and post-repair after the leading edge of casp was shortened.

Fig. 3 A is a schematic representation of the affect of an obstruction in a vein on a valve action in the vein.

Fig. 3B is a schematic representation of the affect of an incompetent valve on antigrade venous circulation.

Fig. 4 is a schematic drawing showing the pressure system of this invention comprising a pump, valves, and an air cell pressure chamber.

Fig. 5 is a side elevation view of the new self inflating venous boot.

Fig. 6 is similar to 6 A and is cut away to show components of the new venous boot.

Fig. 7 is a side elevation view similar to Fig. 6B showing further detail of the construction of the boot in another embodiment.

Fig. 8 is a rear perspective view of the boot of Fig. 7 showing additional construction thereof.

Fig. 9 is a fragmentary view of the boot showing the valve inserted in a holding cover.

Fig. 10 is a plan view of the fabric pattern form for constructing the air cell or air pressure chamber.

Fig. 10A is a sectional view taken along lines A and A of Fig. 10.

Fig. 11 A-l IE are views of the pump, respectively of top plan, left side elevation, first sectional, rear end, second sectional, and third sectional views.

Fig. 12 is a front elevation view of a preferred embodiment of the valve assembly.

Fig. 13 is an enlarged sectional view of the valve assembly of Fig. 12 with the valve assembly switched for "Inflation" and operating in "Bladder Fill" mode.

Fig. 14 is a view similar to Fig. 13 with the valve assembly switched for "Inflation" and operating in "Foot Pump Fill" mode.

Fig. 15 is a view similar to Fig. 13 with the valve assembly switched for "Walking" and operating in "Reciprocating" mode.

Fig. 16A is a front elevation view of a sheet form or blank for the inside layer of a first embodiment of my new one-piece boot.

Fig. 16B is a rear elevation view of a sheet form or blank for the outside layer of the boot of Fig. 16 A. Fig. 16C is a top and right side perspective view of the boot made from the sheets of Figs. 16A and l6B.

Fig. 16D is sectional view taken long line 16D-16D in Fig. 16C.

Fig. 17A is a front elevation view of a sheet form or blank for the inside layer of a second embodiment of my one-piece boot.

Fig. 17B is a rear elevation view of a sheet form or blank for the outside layer of the boot of Fig. 17 A.

Fig. 17C is a top and right perspective view of the boot made from the sheets of Figs. 17A and 17B.

Fig. 18 is a perspective view similar to that of Fig. 17C, with an added strap across part of the instep.

Fig. 19A is a front elevation view of a sheet form or blank for the inside layer of a third embodiment of my one-piece boot.

Fig. 19B is a rear elevation view of a sheet form or blank for the outside layer of the boot of Fig. 19A.

Fig. 19C is a top and right perspective view of the boot made from the sheets of Figs. 19A and 19B.

Fig. 19D is a sectional view taken along line 19D-19D through Fig. 19 A.

Fig. 19E is a section taken along line 19E-19E through Fig. 19C.

Fig. 19F is a perspective view similar to that of Fig. 18, but with a strap overlying the top and sides of the instep.

Fig. 17D is a top front perspective view of the boot seen in Fig. 17C, now shown with the side flaps in open position and the ventilation holes omitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the new invention is shown in Fig. 6B as applied to a person's leg and in Fig. 4 in schematic form. The components as seen in Fig. 4 are a pump 20, a switchable valve 22, a bladder or flexible air chamber 24, an inlet check valve 25, a one-way valve 26 and a pressure gage 27. Between valve 22 and bladder 24 is an inflating line 28 and a separate exchange line 29.

In use the bladder 24 is applied to or wrapped around and secured to the patient's leg. Valve 22 is switched to open the line 28 to pump 20, and to close the line 29 to pump 20. A compression stroke of pump 20 as applied by the person's heel when walking drives air via open line 28 through one-way valve 26 into the bladder. This air cannot escape via line 29 which is closed by valve 22; the air cannot escape via line 28 because of one-way valve 26.

By beginning to take a step the person's heel lifts off the pump which then expands and draws in air via inlet valve 25. On the next step downward the heel compresses the pump and drives this additional charge of air through line 28 into the bladder further inflating it. This charge of air from the pump cannot flow elsewhere than to the bladder, because valve 22 is closed to line 29 and valve 27 is one-way "in" only.

After a number of steps, 5 to 10, the bladder is adequately inflated, which can be verified by pressure gage 27. Then inlet valve 25 is closed by control 25 A, and valve 22 is switched to open line 29 between pump and bladder 24 and to close line 28 from the pump to the bladder. Now there may be free reciprocal flow in line 29 between the pump and the bladder with each step onto and off the pump.

Finally, when the patient seeks to terminate this session he merely opens release valve 23 and air over atmospheric pressure will flow out of the system via line 29.

The new venous boot, also called AirSoc* or Self-Inflating Boot of the present invention is shown generally schematically in Figs. 5-8. In Fig. 5 the venous boot 30 comprises the wrap around outer shell 32, the Velcro* tabs 34 for adjustably securing the boot around the foot and calf, the valve assembly 36 which is located in a convenient place for the user to reach and operate with one hand, and a valve assembly/tube cover 38 which houses the valve conveniently in the vicinity of the person's ankle.

Fig. 10 shows the outer shell 32 in its flat form as a two-layer sheet 50 having a generally trapezoidal shape with top edge 51 A and bottom edge 5 IB. The peripheral edges of the two layers are sealed to form an inflatable bladder which is described in greater detail later. Fig. 6 is partially cut away view of the venous boot of Fig. 5 and illustrates the bladder or air chamber 40 divided into separate pockets 40A, 40B, 40C etc. A lower sock 42 is situated at the bottom of the boot for surrounding or encasing the middle of the user's foot. Adjacent the lower sock is the upper sock portion 43, and at the top of the upper sock is the valve assembly housing 37. Situated below the user's foot and situated within a pocket at the bottom of the lower sock or below and adjacent lower sock bottom is an innersole pump 44. From the innersole pump is a connector tube 46 which extends to the valve assembly 36 in housing 37. An outlet tube directs air from the valve 36 into the bladder 40.

Figs. 7 and 8 illustrate further details of the construction of the lower and upper sock or slight variation thereof for this boot. The same reference numbers are used for similar components as in Fig. 6. The boot's outer shell 32 has a lower part 32A which is joined to the upper sock 43 along a seam 45. An additional seam 47 is shown joining the lower sock 42 to the upper sock 43 as shown in Figs. 7 and 8. There is stitching 48 forming a path for the tubing 46 on the inside of the sock. This tubing 46 leads to the valve 22 situated in valve assembly housing 37. Obviously it is important that tubing 46 be situated and protected such that it will not get pinched and block any air flow from pump 44 (Fig. 6) to the valve 36. Also the valve is situated in this embodiment at the rear of and slightly above the ankle so that it is easily accessible but not likely to interfere with walking or be struck by the opposite foot or by anything against which the leg is likely to brush.

The lower sock 42 is elastic that it is stretched circumferentially when put on the foot and applies inward compression to the foot. Upper sock 43 is made of the same elastic to snugly encompass the heel and the remainder of the foot rearward of the lower sock. The elastic may be generally similar to the elastic strip used in an ACE* bandage.

Fig. 9 shows greater detail of the valve assembly housing or pocket 37 wherein valve 36 is situated. The valve assembly 36 is positioned to engage and seal with the upper end of tube 46. At the top of the valve is a lever or knob for the user to easily actuate the valve between its various modes of operation.

Fig. 10 shows a cutout pattern or form for the bladder or air pressure chamber. This form is somewhat butterfly-shaped in appearance, with a central part 52 with opposite left and right or side wings 53A and 53B. These wings have mating tab parts with Velcro* tape 54A and 54B respectively so that the central part 52 can be wrapped around a person's leg, and then tab 54B can be flapped over to engage the mating Velcro* tab 54A. The Velcro* tape is situated such that it can engage in a variety of different positions, and thus the tightness of the boot wrapped around the leg can be easily adjusted. There are smaller wings 55A and 55B which engage similarly as the other wings at the lower part of the leg below the calf.

This sheath or web is wrapped around the leg as readily seen in Figs. 5 and 6 where the Velcro* tabs are visible in front. Fig. 10A shows a cross-sectional view of the boot webbing of Fig. 10. As is apparent this web is formed of two layers 52 A on the inside and 52B on the outside. These layers are joined together by heat sealed welds at numerous places represented by the example 56. As can be seen in Figs. 10 and 10A the air chamber extends through the majority of the web except that internal air flow must pass around any of these welded areas 56 which join and secure layers 52A and 52B together. This is to prevent 52A and 52B from billowing out into the shape of a balloon. Accordingly this bladder can be inflated so that inside surface 52A presses in the direction of 52C (See Fig. 10A) while retaining its general shape in the form of a mattress. These various welded areas 56 optionally and as shown have apertures 59 punched therethrough to allow air to flow in through the boot and onto the patient's skin or sock or other covering that he might be wearing. Fig. 10 further shows the pocket area 59P for receiving and holding the valve 36 if appropriate cutouts are made for tube 46 from the pump to reach and connect with the valve and for another tube to extend from the valve to an inlet nipple (not shown) into the bladder.

The air chamber of the bladder of the preferred embodiment is two layers of 5^J/2 mil polyurethane. In the structure shown herein the outer layer is 420 Dernier Nylon with a 5V-2 mil coating of polyurethane as its inner surface. The peripheral edges of the two polyurethane layers and various spaced intermediate areas 56 of these layers are heat sealed together. The nylon fabric is generally non-stretchable to provide appropriate strength to the bladder. This fabric is available from Mann Industries Inc. of Birmingham, Massachusetts 01701.

Figs. 11 A-l IE show the construction of the foot pump (innersole pump) 44 as indicated schematically in Fig. 6. This is a one-piece molded resilient rubber or plastic device. Fig. 11 A shows embodiment 60 as somewhat rectangular with the rear end 60R rounded to generally conform to the inner heel area of a person's shoe. Fig. 1 IB shows that the pump 60 is tapered generally conforming to the arch of a person's foot so that top portion 60 A is positioned directly under the person's heel and arch, and lower portion 60B resides adjacent the bottom of the person's shoe.

Fig. 11C is a cross-sectional view of Fig. 1 IB with 62 being an aperture of inlet/outlet nipple 62 which is later connected to tube 46 as seen in Fig. 6. Fig. 1 ID is a rear end elevation view, and Fig. 1 IE is a sectional view similar to 1 ID. Finally, Fig. 1 IF is a sectional view showing the inner structure of the device of Figs. 11 A and 1 IE. Fig. 1 IF shows more clearly the outlet nipple 62 which is directed to and coupled to tubing 46. As stated earlier, this pump is a one-piece molded resilient plastic or rubber apparatus. Obviously, there are many variation constructions, including a flexible but not resilient pump chamber with an internal spring urging the pump to its expanded state.

As shown the pump has an air volume of about 4-5 cubic inches, a 65% pumping efficiency, and is constructed of an 80 Durometer elastomeric material that can sustain multiple impacts at pressures of up to approximately 385 psi without rupture.

Fig. 12 shows a plan view of the valve assembly 70; Figs. 13, 14 and 15 show sectional views of this valve in three different modes of operation. Valve 70 has two fittings or nozzles 71 and 72 for connection to the exchange line 29 and the inflation line 28 respectively of Fig. 4. The inner structure and operation are described as follows. The valve assembly 70 (designated 22, 23, 25 in Figs. 4 A and 36 in Figs. 5-8) comprises a bottom or housing 73 which defines a cylindrical bore 74, a rotary piston 75, an actuator or rotary knob 76, a disc check valve 77, and a relief check valve 78. This valve assembly has three modes of operation; however, first we will describe certain structural and functional features.

When the piston is rotated air flow passages are established as shown by the dashed line 79 in Fig. 13 or by dashed line 8 in Fig. 14. These lines include passages transversely through the piston in Fig. 13. When the piston is rotated 90° as shown in Fig. 15 the above-mentioned through-passages are blocked and sealed, but instead there is a different internal passages shown by dashed line 81 whereby the piston blocks the prior passages. Disc check valve 77 allows flow from left to right in Fig. 13 but not from right to left in Fig. 14. Relief check valve 78 allows flow in from the atmosphere per arrows 81 in Fig. 14 when the pump creates a partial vacuum as applied to fitting 71. Under a positive pressure situation in Fig. 13 the relief check valve 78 remains closed.

In the Bladder Fill Mode of Fig. 13, the foot pump outlet tube is connected to fitting 71. Air flow under positive pressure occurs along dotted line 79 through one-way check valve 77 and into the bladder. Successive pressure strokes of the pump add incremental charges of air into the bladder until it is adequately filled. With each pressure stroke air can enter the bladder but not leave. All other passages within the valve assembly 70 are blocked.

After each pressure stroke of the pump there is a suction stroke, Foot Pump Fill Mode of Fig. 14, where the pump expands and draws in a new charge of air. The new air comes from outside the system via relief check valve 78 and passage 80. During this mode the pump creates negative pressure in the system, which both draws in air via valve 78 and holds closed check valve 77, the latter thus preventing escape of air from the bladder while the pump draws in a fresh charge of air.

Next is the Reciprocating Mode illustrated in Fig. 15 where piston 75 has been rotated 90 °, passage 79 (Fig. 13) is blocked, and air pressure within the "system" comprising the pump, the bladder and interconnecting passage 81 is al positive. Accordingly any air in part 79a of line 79 would cause check valve 77 to remain closed, and air would merely reciprocate in line 81 between the pump and the bladder as the person walks.

Lastly, when the user wishes to cease the pump action and deflate the system, he merely rotates the knob and pison back 90° to the condition of Fig. 13, and then presses actuator 90 of relief valve 78. This allows air under pressure to exit from the pump via line 80 (Fig. 14) and from the bladder via line 79A (Fig. 13) by bleeding out past check valve 77, the latter being closed in reaction to pressure spikes, but not under this deflation bleeding condition.

In the operation of this valve the bladder is inflated to about 2 V∑- to 3 psi or other comfort level. In Reciprocating mode the pressure periodically spikes to about 5 psi. The relief check valve includes a spring that holds this valve closed with a force of abut 0.3 pounds. During Fill mode (Fig. 13). The pump's suction is easily enough to open this valve.

In summary, valve assembly 70 is a very compact and efficient apparatus to handle all modes of operation with a single small mechanism, and with knob or actual movable between only two states, and finally a simple relief valve to deflate. Obviously, all these functions could be separated: the intake valve could be on or associated with the bladder directly and the relief valve could be on or associated with the bladder directly. Then the principal reciprocating mode would be much simpler; however, such would require three separate valves instead of one as disclosed herein.

The one-piece boot embodiment 10 of Fig. 16A is formed of outer sheet 12 of Fig. 16B and inner sheet 14 of Fig. 16 A. Outer sheet 12 has exposed air valve means 16 seen in Figs. 16 and 16C. In manufacture, sheet 12 is placed to overlie sheet 14, and the two sheets are heat sealed by a known RF technique or other suitable method. The seals are along lines a, b, c and d to create a single contiguous air chamber 18 which has port 20 to overlie the calf region, part 21 to overlie the ankle region, and part 22 to overlie the heel region. Additional heat seal lines at e and f on sheet 14 in Fig. 16A join the edges at e, f, of sheet 12 in figure 16B to produce left and right side flaps 23 and 24 which are shown to overlap in Fig. 16C. These flaps are releasably and adjustably secured together by VELCRO^® or equivalent fastening means 23 V and 24V as seen in Fig. 16D. The areas 27 and 28 of sheets 14 and 12, respectively, when heat sealed along the sides of their periphery from the heel pump and the area near reference point 28 forms a passageway for air to flow to and from this heel pump.

Valve and inlet means 16 allows air flow into and out of the main air chamber which overlies the person's calf.

In use the boot would be wrapped about a person's foot, the VELCRO* fastener flaps engaged and air introduced via valve means 16 from a hand pump 30 as seen in Fig. 16C. The air chamber is pumped up to about 7 MM Hg. This can be determined from a pressure gauge, or preferably the hand pump has an integral release valve to release at 75 MM Hg. Thus, the operator of the pump cannot create a pressure greater than the 75 MM Hg release pressure. Then the valve is closed to ingress and egress of air, and the hand pump disengaged. Stepping on the pump portion increases the pressure about 25 MM Hg to about 100 MM Hg with each heel-down cycle of walking. As suggested earlier, the valve/inlet can be connected to an external pump that applies an appropriate cyclic air pressure to the air chambers of the boot.

A boot as seen in Fig. 16C may allow the person's foot to be placed in a shoe or it can be used without a shoe.

Figs. 17A-17C show components of a boot and an assembled boot generally similar to Figs. 16A-16C, except that in the areas 32, 33 in Fig. 17B, the blank extends outward as compared to the deep recess as in Fig. 16 A. The result seen in Fig. 17C is a boot where the side parts extend forwardly about the sides of the ankle. This is seen more clearly in Figs. 16C and 16C which correspond to Figs. 1C and 2C, respectively.

The typical small circles 40 in Fig. 18 with smaller holes 41 in all the figures are heat seal areas to join the two layers at those spots while allowing air to pass holes 41 through the two layers. Thus, the internal air chamber remains contiguous but air can pass to ventilate the leg of the user of this boot.

Fig. 18 is a variation of Fig. 17C with a strap 42 extending between and releasably linking the opposite sides of the boot on the instep region.

Fig. 19F shows a further variation of Fig. 18, where the strap 44 overlies substantially the entire instep region. In Figs. 18 and 19F, the strap may be non-inflatable with the general air chamber for applying cyclic pressure or it may be inflatable, and be elastic or inelastic for applying a more constant pressure. Figs. 19A-19E illustrate schematically a further embodiment 50 corresponding generally to the boot of Fig. 19F. Here, the boot has the same general shape in the calf and ankle areas, but has a forward extending sole 51 and an over-the-instep strap 52. The sole may extend to an area beneath the toes as in Fig. 19F or it may be shorter, but either type can function as a shoe sole to protect the foot while walking especially where this boot is worn without a shoe.

The boot of Figs. 19A-19C has its heel ump formed at 55, and its inflatable strap at 56 with an air conduit 57 connecting these areas.

The boots of Figs. 17C and 18 have the pressure regions substantially covering the ankle to apply pressure and to stabilize the area, thus serving as an orthotic device for an injured ankle or nearby areas.

These boots may extend upward to overlie the calf as discussed earlier, or may have reduced height to cover essentially only the ankle. In the latter case, the boot, on walking, applies pressure and massage to the ankle area, and stabilizes if the boot overlies a substantial part of the ankle.

Boots as described above are preferably made from two sheets, namely non-stretchable nylon on the outside and stretchable nylon on the inside. A variety of alternate materials may be used, including urethane and vinyl. The heat seals are achieved by standard RF welding or other common techniques. The valve 16 of Fig. 16C shown is a flow control valve, Model No. V15910BPGC made by Halkey Roberts Co. The hand pump 30 of Fib. 16C is a standard product made by the Martin-Weston Co.

These new venous boots have the advantage of being usable by ambulatory patients without any connection to an external pump, or by non-ambulatory patients with an external pump, or the same boot can be used initially by a non-ambulatory patient who later uses it when he or she becomes ambulatory.

Some versions of these boots may extend from the heel only up to and covering the ankle to produce a massaging and/or stabilizing effect without the application of pressure to the calf. The pressure or massage may be cycled at a variety of rates and levels as dictated by the doctor or specialist. The boots which substantially surround the ankle can provide both stabilization and pressure to reduce edema and massaging effect to east pain.

The boot schematically illustrated in Figs. 16A-16C is made by overlying sheets 12 and 14 and heat sealing or RF welding along the solid lines a-g. This creates a single air chamber extending from the heel area to the upper leg area. The flaps 23, 24 are laminated but do not have means for air inlet and thus remain essentially flat and re not inflated. The Velcro* strips are similarly sealed onto the flaps.

The boots of Figs. 17A-17C and 19A-19C are made generally similarly with the inner and outer sheets shown, which are joined along the seal lines seen in Figs. 17A and 19A. The heel for a typical boot is formed, as seen in Figs. 17B and 17C; by folding the tab 34 at a right angle about fold line 34F, and folding sides parts of the blank about fold lines 35F and 37F until edge 38 aligns with 37 as seen in Fig. 17C and edge 36 aligns with 35, and these aligned pairs of edges are joined together. For this junction aspect a small strip or tab of extra material is provided along the joining edges to be overlapped before the welding takes place.

The invention has been described with particular reference to a presently preferred embodiment. However, it will be apparent to one skilled in the art that variations and modifications of the disclosed embodiment are possible without departing from the spirit and scope of the invention claimed below.

Claims

IN THE CLAIMS

1. A portable apparatus for applying cyclic pressure to veins within a person's leg by applying cyclic pressure to an outer surface of the leg, the apparatus comprising: a - a first air chamber having a flexible wall portion adapted to be situated adjacent an outer surface of the leg, b - a second air chamber adapted to be positioned beneath the person's heel, this second chamber being compressible to force air out of it when the person's heel bears downward thereon and returnable to its uncompressed state when the downward heel force is removed therefrom, c- conduit means for permitting air flow between said first and second air chambers, whereby air flows from the said second chamber into said first chamber and pressure is cyclicalUy increased in said first chamber urging said wall portion against the leg when the person's heel presses downward on said second chamber, and air flows from the first to second chamber and pressure on the leg is reduced when the person's heel stops pressing on said second chamber.