05/332703

01/14/1975

02/15/1973

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601/11

A61H9/00; A61H1/00

128/24R,DIG.20,60,64,297,299,38-40

3245405	Inflatable therapeutic device and method of making same	April 1966	Gardner
3303841	Process and apparatus for pressurizing lower extremities of a patient during ventricular diastole	February 1967	Dennis
3421504	VACUUM RECEPTOR	January 1969	Gibbons

Trapp, Lawrence W.

Cesari & McKenna

This application is a continuation-in-part of my abandoned U.S. Patent Application Ser. No. 321,313, filed Jan 5, 1973.

Having illustrated and described my invention, I claim

1. A therapeutic cuff for an animal body comprising

2. A therapeutic cuff in accordance with claim 1 in which said sheet increasingly frictionally adheres to said body portion when said chamber is pressurized.

3. A therapeutic cuff in accordance with claim 1 in which said sheet is sufficiently thin to snugly conform to a body contour it engages and sufficiently thick to withstand rupture by the chamber pressure.

4. A therapeutic cuff in accordance with claim 3 in which said sheet is formed of rubber.

5. A therapeutic cuff in accordance with claim 3 in which said sheet is formed of plastic.

6. A therapeutic cuff in accordance with claim 3 in which said sheet is formed of a plastic that is treated to increase its frictional engagement with a body surface it contacts.

7. A therapeutic cuff in accordance with claim 3 in which a viscous paste is applied between the body-conforming sheet and the body portion to which it is to be sealed to thereby increase adherence between said body portion and said sheet and further increase the security of the seal.

8. A therapeutic cuff in accordance with claim 1 in which said casing is cylindrical in shape and is adapted to completely encompass said body portion.

9. A therapeutic cuff for an animal body, said cuff comprising

10. A therapeutic cuff according to claim 9 in which said flexible wall comprises a resilient membrane diaphragm.

11. A therapeutic cuff according to claim 9 in which said flexible wall is in the form of a bellows.

12. A therapeutic cuff according to claim 9 which includes reciprocating means for moving said wall inwardly and outwardly of said chamber.

BACKGROUND OF THE INVENTION

A. Field of the Invention

The invention relates to a pressure cuff, and comprises a single walled pressure cuff with flexible, body conforming, adherent flaps of thin sheet material forming a fluid-type seal between the cuff wall and the body portion to which the cuff is connected.

B. Prior Art

Patients confined to bed for extended periods of time are highly susceptible to blood pooling in the lower extremities which frequently leads to the formation of blood clots in the veins. To alleviate this, techniques have been developed for cyclically applying pressure to the lower extremities to assist the venous return to the heart and thereby eliminate the pooling which leads to clotting. See, for example, U.S. Pat. No. 3,391,692 which issued to me on July 9, 1968.

The cuff used in that technique is double-walled, the inner and outer walls forming a fluid-impermeable chamber between them. This cuff is placed around the body portion to be treated, and the chamber is alternately expanded and contracted in a cyclical manner to pump the blood in the extremities back toward the heart. A travelling wave is set up by the pumping cycle to thereby establish a preferential direction for blood travel.

This cuff is highly beneficial in patient treatment, but it does have certain disadvantages. Thus, the inner wall of such a cuff is in essentially continuous contact with the body surface being treated, and can cause skin irritation if applied for extended periods of time. Further, moisture builds up at the skin surface under the cuff, thus causing further patient discomfort over extended treatment intervals. Of course, when medication is to be applied to the body portion being treated, or when it is to be inspected, the cuff must be removed. And whenever the body portion to be treated has surface lesions such as caused by a wound or a burn which would be aggravated by direct cuff contact or which would cause severe patient discomfort on such contact, the cuff cannot be used at all.

BRIEF DESCRIPTION OF THE INVENTION

A. Objects of the Invention

Accordingly, it is an object of the invention to provide an improved pressure cuff.

Further, it is an object of the invention to provide a pressure cuff characterized by minimal body contact surface.

A further object of the invention is to provide a pressure cuff which avoids moisture build-up at the skin surface.

Still another object of the invention is to provide a pressure cuff which allows the application of medication while maintaining pressure on the part being treated.

A further object is to provide a pressure cuff which facilitates direct inspection of the body portion being treated.

Yet another object of the invention is to provide a pressure cuff which allows the maintenance of a controlled environment of the body surface being treated.

Still another object of the invention is to provide a cuff for local hyperbaric treatment for cutaneous lesions such as burns.

Still a further object of the invention is to provide a cuff which can sustain both positive and negative pressures.

B. Summary of the Invention

As used herein, the term "pressure cuff" denotes a shell or casing for application over a body portion and having sealing means forming a pressurizable chamber between the casing and the body surface within the casing.

In accordance with the invention, I form a pressure cuff from a single-walled casing of limited resilience having one or more flaps of a thin, flexible, body-conforming, adherent sheet material connected to the ends thereof and forming a seal between the casing and a body portion to be treated. The casing, as well as the end flaps, are fluid-tight, and, when properly positioned around the body portion to be treated, form a chamber surrounding the body surface. A fluid such as air or other gas is admitted into, and vented from, this chamber by means of one or more valves extending through the casing wall. These valves are connected, respectively, to a fluid source and a fluid sink. For example, one of the valves, serving as an inlet valve, may be connected to a pump for pressurizing the chamber from a fluid source, with the other valve, serving as an outlet valve, being connected in the return line of the pump or alternatively being vented to the atmosphere.

With the pressure cuff of the present invention, the body portion being treated is substantially free of contact with the casing and thus there is no surface irritation engendered as the casing is periodically pumped. The only direct contact is with the sealing flaps and these are highly conformable to the body shape so as to cause minimal discomfort. This is especially advantageous for patients having wounds or skin lesions on the body portion which is to be pressure treated. Further, the moisture which forms at the body surface is continually purged during the pumping, and a further source of patient discomfort is thus eliminated. Moreover, the temperature of the pumping fluid can be regulated to the degree desired to best accomodate patient comfort and promote healing. Indeed, medication in desired amounts and at the desired intervals may be introduced at the chamber by means of the pumping system and this medication is brought into direct contact with the body surface being treated.

The wall of the casing, as noted above, is made from a material of limited resilience. For example, the casing may be formed from a cloth wall having an inner coating or lining of rubber or plastic to render the walls substantially fluid-impermeable; this construction is the type used in conventional blood pressure cuffs. Alternatively, the casing wall may be of a completely rigid material such as molded, hard plastic or even light metal such as aluminum. Preferably, however, whether rigid or of limited flexibility, the casing wall is advantageously formed from a translucent material which facilitates inspection of the body section without removing the pressure cuff, and one of the many plastics will thus frequently be found best.

The end flaps which form the seal between the casing and the body portion being treated are formed from a thin, highly flexible, deformable, body conforming adherent sheet. Thin sheets of numerous materials, including various rubbers and plastics among others, have the desired body-conforming and body-adherent characteristics. The adherence may be primarily mechanical in nature (due to surface roughness and similar factors), or primarily physio-chemical in nature (e.g., electrostatic properties caused by molecular polarization) or both.

The thickness of each flap is of the order of a few mils (thousandths of an inch) to ensure snug conformity with the body section. The flaps, which are securely fastened to one end of the casing cuff, are of sufficient length to extend a few inches from the point of attachment and along the body surface.

Because of their body-conforming characteristic, the flaps form a seal with the body over a large area and thus do not create excessive localized and flow-restricting pressure such as may be created by an elastic type restrictive seal.

When the cuff is applied to a body portion, the flaps are folded inwardly of the casing and the chamber formed by the casing and the flaps is pressurized. The air pressure in the chamber pushes the free ends of the flaps both outwardly and against the body portion over their length; the frictional and/or electrostatic forces between the flaps and the surface of the body portion resist the outward thrust on the flaps and hold them and the casing snugly in place. When the chamber is thus inflated, the casing is held away from the body surface and thus does not chafe or otherwise irritate it.

Valves extending through the casing allow pressurization of the chamber. This pressurization may be cyclic, to assist venous return to the heart, or may be static, to provide hyperbaric treatment, as desired. A pumping source connected to the valves not only establishes the desired pressure and pressure cycle but also conditions the fluid (e.g., by removing moisture from it) and medicates it as desired.

As long as the cuff is to be used with pressures above atmospheric pressure a single sealing flap around the enclosed body portion is adequate. For a cuff which must accomodate both positive and negative pressures, however, a modified form of seal is provided. The modified seal has two parts, a first of which is identical to the single (positive-pressure) seal described above and a second of which is a negative pressure seal formed by a resilient sheet attached on all sides to the interior wall of the casing adjacent the body portion with which a seal is to be formed and forming a closed cell containing air or other expansible fluid. The cell normally contributes little, if anything, to sealing the cuff when the cuff is pressurized to a positive (above atmospheric) pressure, but expands and seals the cuff to the body portion it encloses when the cuff is evacuated to a negative (below atmospheric) pressure. For this purpose, the cell may be closed off at atmospheric pressure and will thus follow changes in applied pressure by expanding or contracting as the cuff pressure drops below, or rises above, atmospheric pressure.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing and other and further objects and features of the invention will be more readily understood from the following detailed description, when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view in perspective of one form of cuff in accordance with the present invention and prior to its application to a body section;

FIG. 2 is a view in perspective of the cuff of FIG. 1 applied to a leg and having a pumping and fluid treatment system connected to it;

FIG. 3 is a vertical side sectional view of the cuff of FIG. 2 taken along the lines 3--3 of FIG. 2;

FIG. 4 is a side view of another sectional embodiment of my invention showing a single walled pressure cuff having only one open end;

FIG. 5 is an end sectional view taken along the lines 5--5 of FIG. 4;

FIG. 6 is a vertical side sectional view of another embodiment of the invention utilizing a rigid shell with internal support and showing an alternative construction for attaching the sealing flaps;

FIG. 7 is an end sectional view along the lines 7--7 of FIG. 6;

FIG. 8 is a vertical side sectional view of still another embodiment of the invention showing a further alternative construction for the end flaps;

FIG. 9 is an end sectional view along the lines 9--9 of FIG. 8;

FIG. 10 is a vertical side sectional view of still another embodiment of the invention showing yet another construction for attaching the end flaps;

FIG. 11 is an end sectional view along the lines 11--11 of FIG. 10;

FIG. 12 is a sketch of another form of cuff of the present invention with portions broken away for clarity, illustrating its use in providing hyperbaric treatment of the upper body, including the head;

FIG. 13 is a view in perspective of a mouth mask constructed in accordance with the present invention; and

FIG. 14 is a view in perspective of the mask in FIG. 12 as applied to the mouth of the patient.

FIG. 15A- C are side sectional views of an alternative cuff in accordance with the present invention which accomodates both positive and negative cuff pressure;

FIG. 15D is a side sectional view of an alternative embodiment of the cuff of FIGS. 15A- C.

FIG. 16 is a side sectional view of another embodiment of the cuff shown in FIG. 15; and

FIG. 17 is a side sectional view of still another embodiment of the cuff shown in FIG. 15.

In FIG. 1, one embodiment of a pressure cuff in accordance with the present invention that is especially useful for application to the lower extremities has a single-walled, outer cylindrical casing 10 to which are secured end flaps 12 and 14 respectively. The casing is preferably formed from a translucent plastic material such as vinyl, while the flaps 12 and 14 are formed from a thin, flexible, body conforming, adherent sheet of material such as rubber or a silica-filled vinyl sheet (the silica providing frictional properties). The length of the flaps in the longitudinal direction (i.e., in a direction parallel to the axis of the cylindrical cuff 10) should be of the order of 3 to 4 inches to provide sufficient sealing surface for contact with the body portion. Notches 16 may be formed around the periphery of the outer ends of the flaps 14 to assist in conforming the flaps to the smaller diameter of the body portion which they are to encompass. Valves 18 and 20 extend through the wall 12 to the interior of the cuff.

In FIG. 2, the cuff 10 of FIG. 1 is shown applied to the lower leg of a patent. The cuff completely encompasses a portion of the leg, and the flaps 14 are folded inwardly of the casing 12 and snugly fold around the leg within the cuff. The cuff forms a chamber 22 which is sealed fluid-tight by the flaps 14, 16 when the chamber is pressurized. Fluid is admitted to this chamber through valves 18 and 20 which are connected to a pumping source 24 through lines 26 and 28. Valves 30 and 32 respectively, are positioned in these lines. When the valves 30 and 32 are closed, the pumping source 24 provides fluid under pressure to the interior of the cuff 10 in a closed loop from the source 24 through the valve 30 and line 26, to the cuff 10, thence back through the line 28 and valve 32 to the pumping source 22. Valve 32 is a three position valve which may alternatively be positioned to vent the fluid from the casing 22.

In addition to providing pressurized fluid to the cuff 10, the pumping source 24 may condition the fluid it supplies. Thus, for example, the source 24 may contain moisture extraction apparatus (not shown) to remove excessive moisture from the fluid supply to the cuff. Alternatively, it may supply moisture to the body segment within the cuff when the moisture level is too low. Additionally, it may be connected to receive medication from a source 34 and apply it in controlled and timed amounts to the body segment in cuff 10. Thus, the environment of the body segment within the cuff 10 may be precisely controlled.

FIG. 3 is a cross-section of the cuff 10 of FIG. 2. As shown in FIG. 3, those portions of the flap 14 nearest the casing 12 are bowed outwardly by the pressure within the cuff, while the ends of the flaps farthest from the casing are pushed against the body portions by the pressure within the cuff 10 and snugly conform to the body portion at the areas of contact. The snug adherence between the flaps 14 and the body portion prevent the flaps from being pushed completely out of the cuff. Thus, they form effective seals with the leg and allow pressurization of the chamber 22.

In FIG. 4, an alternative embodiment of the invention is shown in which the pressure cuff is formed from a rigid or semi-flexible casing 40 having only a single open end 42 sealed by a thin, flexible, circumferentially extending, body-conforming adherent flap 44 and forming a chamber 46 encompassing the leg. This form of pressure cuff is especially useful in counterpulsation treatment. Again, the flap 44 is several inches in length to allow sufficient surface contact area with the body portion to thereby form an effective seal. Valves 48 and 50 extending through the casing 40 provide a means of admitting fluid to the chamber 46 and discharging it from that chamber, respectively. A foot rest 52 is desirably provided to elevate the patient's leg but may be pushed out of the way if desired. The cuff is sufficiently large to enable the patient to move his legs to comfortable positions as desired. Note that both legs may be enclosed within the casing simultaneously so that both can be subjected to even pressure without squeezing them together.

Turning now to FIGS. 6 and 7, the pressure cuff 60 shown there has a rigid casing 62 terminating at one end in an inwardly turned generally circular flange 64. A thin, flexible, body-conforming, adherent flap of sheet material 66 is firmly secured to this flange, (for example, by adhesive or by thermoforming techniques) and extends inwardly several inches within the casing and in contact with the surface of the leg positioned within the casings 62. The casing forms a chamber 68 which is sealed by the flaps 66 against fluid leakage. Pressurizing fluid is admitted to the chamber by means of a valve 70 and is discharged from the chamber by means of a valve 72. A sling 74 may be attached to the casing for providing a rest for a limb within it.

In FIGS. 8 and 9, a pressure cuff 80 has a casing 82 with a flanged, inwardly turned end wall portion 84 at one end thereof. A cylindrical ring 86 of dimensions somewhat larger than the maximum cross section of the body section being treated is attached to the end wall 84 and a thin, flexible, body conforming, adherent flap 88 connected to the ring 86. Ring 86 lightly engages the limb positioned within it. Its purpose is to minimize any outward bowing of the flap 88 and thus this ring need not itself provide the sealing action, the latter being provided completely, or nearly completely, by the flap 88. The casing 82 forms a chamber 90 which is sealed by flap 88. The chamber is pressurized and depressurized by means of valves 92 and 94, respectively. A foot rest 96 may be provided within the casing 82 for the patient's comfort.

In FIGS. 10 and 11, a thin, flexible, circumferentially extending, body-conforming, adherent flap 100 extends between an end segment of a casing 102 and a cylindrical ring 104. The ring 104 is of sufficient diameter to allow the body segment to be treated to be extended through it without discomfort, and it serves to anchor the flap 100 against outward bowing when the chamber 106 within the casing is pressurized. The ring 104 need not itself provide any sealing action and thus need not be pressed tightly against the body section. The casing 102 forms a pressure chamber 106 which is sealed by the flap 100. Valves 108 and 110 are provided for pressurizing and depressurizing the chamber 106, respectively. A rest 112 may be provided for comfort of the patient.

FIG. 12 shows a form of pressure cuff suitable for hyperbaric treatment of patients with respiratory problems. In this instance the cuff takes the form of a preferably rigid semi-cylindrical casing 110 with rounded top suspended on the shoulders of the patient by means of straps 112 and forming a pressure chamber 114. The casing is, of course, preferably of a translucent meterial. A sealing flap 116 of thin, flexible, body-conforming, adherent material such as saran extends between in-turned edges 118 of casing 110 and a ring 120 of sufficient diameter of fit over the patient's head. The flap 116 is snugly engaged against the patient's chest when the chamber 114 is pressurized. Valves 122 and 124 allow chamber 114 to be pressurized and depressurized, respectively.

In FIG. 12 a mask 128 adapted to fit over a patient's mouth is shown. The mask has a generally oval cross-section and is formed from an outer semi-flexible or rigid casing 130 having a thin, flexible, body-conforming, adherent flap 132 attached to its rim. A pair of valves 134, 136 extend through the casing 130 for pressurizing and depressurizing the interior thereof when the casing is applied against the mouth of the patient. A pair of straps 136, 138 are also attached to the casing 130 for holding the casing against the mouth of the patient as shown in FIG. 14. When the cuff is applied to the patient, the flap 132 is extended inwardly toward the housing 130. When the interior of the housing is pressurized, the flap is pushed snugly against the patient's skin and forms a fluid tight seal with it.

The pressure cuff may in the same manner be advantageously used in hyperbaric treatment of the eye, since it allows free eye movement beneath it. It also may beneficially be applied as an ostomy or stoma cover (as in a colostomy, urostomy or iliostomy, and contains gas release since it forms a tighter seal as the pressure increases.

In certain types of treatment it is desirable to provide for positive as well as negative pressures within the cuff. For example, in a type of therapy known as "counterpulsation" therapy, one cyclically and alternately applies positive and negative pressures to a body portion to assist the pumping action of the heart and thereby relieve strains on the heart caused by its normal pumping action. The cuff of the present invention is especially suited to this type of therapy since it offers greater comfort to the patient, and the patient may therefore be placed in it for treatment for extended periods of time without undue discomfort. However, in order to accommodate negative as well as positive pressures, the sealing flap illustrated and described in connection with FIGS. 1 through 14 must be modified.

Such a modified form of seal is shown in FIGS. 15A-15C, together with a modified form of cuff which is especially suited to applying alternate positive and negative pressures to a patient. The particular type of cuff shown has a single open end and is specifically adapted to counterpulsation treatment, but it will be understoood that a cuff of the type shown in FIGS. 1-3 and open at both ends is equally well adapted to the modified seal now to be described. As shown in FIGS. 15A-15C, a cuff 110 is formed from a relatively inflexible or even rigid casing 112 of sufficient size to confortably accommodate the body portion to be treated. One end of the casing 112 is closed by a resilient membrane 114 to form a chamber 115 interior to the casing. The membrane is connected to a shaft 116 through an adapter 118. The adapter 118 is firmly attached to the membrane 114 and pivotally connects the shaft to the membrane. A crank arm 120 is pivotally connected to shaft 116 at one end thereof and is connected at the other end to a pin 122 on the outer perimeter of a wheel 124. The wheel 124 is rotated by a motor 126. A guide block 128 has a groove 130 in which a follower block 132 rides. The block 132 is connected to the pivot between arms 116 and 120.

A body portion 134 such as the lower torso of a patient, is placed within the casing 112. As was previously the case, a footrest 136 may be provided in the casing for the patient's comfort. A thin, flexible, body-conforming adherent flap 140 of sheet material having one edge firmly attached to an end 112a of the casing 112 is positioned to form a fluid-tight seal with the patient's body. The flap extends circumferentially around the patient's body as was the case in FIGS. 1 thorugh 14 to thereby form an airtight seal with it. A flexible, resilient flap 142 also extends circumferentially around the patient's body at the open end of the cuff 110. It is sealed to the casing 112 at both its edges to form a closed cell 144 containing an expansible gas such as air. A wall 112a of the casing extends into the casing adjacent the flap 142.

As illustrated in FIG. 15A, the chamber 115 is initially at atmospheric pressure. For purposes of illustration, it will be assumed that the cell 144 was closed off under atmospheric pressure so that the pressure within the cell as illustrated in FIG. 15A is also atmospheric. The flap 140 lies against the body and conforms lightly to its contour. The flap 142 rests lightly against the body at the upper portion thereof, but is drawh away from the body by its own weight at the lower portion thereof. In this position, the pressure in the chamber 115 is in equalibrium with the pressure outside this chamber and neither the flap 140 nor the flap 142 need provide any sealing action.

Turning now to FIG. 15B, as the motor 126 turns the wheel 124, the arm 116 moves to the right and drives the adapter 118 to the right. This moves the membrane 114 inwardly into the chamber 115 and diminishes the free volume of this chamber, thereby causing a pressure rise within it. The seal 140 conforms more snugly to the body portion which it encircles, and prevents escape of air from the chamber 115. At the same time, the flap 142 has a net pressure exerted on it from the chamber 115 and thus the volume of the cell 144 diminishes, while the pressure inside the cell increases. No sealing action is provided by the flap 142 in this condition; instead the entire sealing is provided by the flap 140.

As the motor 126 continues to rotate the wheel 124, the shaft 116 reverses its motion and moves to the left, thus drawing the membrane 114 outwardly of the chamber 115. This increases the effective volume of the chamber and thereby diminishes its pressure. When this occurs, air would normally move into the chamber 115 under the flap 140 and thereby break the seal otherwise provided by this flap. However, this is prevented by the seal 142 which, in response to the drop in pressure in chamber 115, expands outwardly, thereby increasing the volume of chamber 144, and diminishing its pressure. In expanding outwardly, it presses against the flap 140 and pushes this flap firmly against the body portion 134, thus maintaining the effective seal between flap 140 and the body portion 134. The wall 112a ensures that the flap 142 expands against the body surface. Thus, the chamber 115 can be dropped to a pressure below atmospheric (negative pressure), without leakage of air into it from the outside of the cuff.

As the pressure in the chamber is cycled between sub-atmospheric pressure and super-atmospheric pressure, therefore, the seals 142 and 140 alternately become effective to provide the desired sealing action. In no event, however, is the maximum sealing pressure greater than either atmospheric pressure or the maximum pressure in the chamber 115. Further, this pressure is maintained over a substantial area and is not confined to a thin, ring-like section which may cause patient discomfort.

An alternative method of attaching flap 142 is shown in FIG. 15D. there shown, one edge of this flap is attached directly to an inner edge of wall 112a; the opposite edge of this flap is attached to the rear wall 112b of the casing. The flap 142 forms closed chamber 144a with the walls 112a and 112b. This chamber expands and contracts in the manner described in connection with FIGS. 15A-C to allow sealing of the open casing end under both positive and negative pressure conditions.

It is, of course, possible to omit the sealing flap 140 entirely and instead use only the flap 142 which forms and expansible chamber. In such a case, the flap 142 must effectuate a seal under both positive and negative pressure conditions. This is accomplished by first placing the body portion to be treated in the casing with the chamber 144 formed by the flap 142 collapsed to permit this. This chamber is then pressurized to a pressure in excess of atmospheric pressure and of sufficient magnitude that it can maintain a seal with the body portion even when the chamber 115 is pressurized; it will thus also maintain a seal at or below atmospheric pressure. This type of seal may also replace the seal 14 shown in FIGS. 1-3. However, this type of seal exerts pressure above atmospheric pressure at all times, and thus will in general not be as comfortable as the seals shown in FIGS. 1 and 15 which comprise an open flap with a free end (FIGS. 1-14) and both an open flap with a free end and a closed flap forming an expansible chamber.

Various arrangements may also be used to provide the cyclic pressire for counterpulsation and other types of treatment. Two such alternatives are shown in FIGS. 16 and 17, respectively. In FIG. 16, the flexible membrane 114 is replaced with a bellows 150 which is fluid-tight sealed at an end 150a and which communicates with a chamber 115 at the other end 150b. As was the case with the membrane 114, the bellows 150 is reciprocated by a rod 116 to alternately raise and lower the pressure in the chamber 115 by changing the effective volume as the rod 116 reciprocates.

In FIG. 17, the casing 112 terminates in an enlarged segment 112c which is sealed fluid-tight by a correspondingly enlarged diaphragm 114a. This provides an enlarged chamber 115A whose effective volume is changed as rod 116 is reciprocated. By providing a chamber 115A of broad diameter but narrow width, the combined effective volume of chambers 115 and 115A (and thus the fluid pressure in these chambers) can be changed quite rapidly and over a wide range.

From the foregoing, it will be seen that I have provided an improved pressure cuff. The cuff is single walled and is readily supported away from the surface of the body portion being treated so as to prevent the discomfort normally caused by frictional contact of the cuff with the patient. A simple yet effective seal is formed on the cuff by means of one or more flaps of a flexible, thin, body-conforming, adherent sheet of material which snugly conforms to the body portion when the interior of the casing is pressurized. The sealing force is distributed over a large area in this type of seal, and this eliminates any excessive localized sealing pressure which would otherwise impede blood circulation in a patient's body. The single walled casing allows direct access of the pressurizing fluid to the body surface and thus provides a convenient means for medicating this surface or otherwise controlling the atmosphere surrounding it. By utilizing a translucent material for the casing itself, continuous visual access to the surface being treated is provided.

The thickness of the sealing material is, of course, dependent on the material being used and the pressures to be applied, as well as the duration and repetition rate of the pressure application. In general, the seal must be thick enough to withstand the applied pressure and not distort excessively under it, and yet must be thin enough to snugly conform to the body section to which it is applied to thereby form a fluidtight seal. For plastic materials such as a vinyl, sheets of less than 0.005 inches thick will be found useful, while with other materials this thickness may be greater or less.

It may sometimes be found desirable to further improve both the adherent characteristics of the sealing material and its sealing ability by applying a small amount of viscous paste to the interface between the sealing flaps and the body portion. This is especially the case when the sealing material has poor (low) frictional characteristics.

It will be understood that the foregoing material is illustrative only and that various modifications may be made to the invention as described herein without departing from the spirit or the scope of the invention, the scope of the invention being defined in the claims.