GB2218638A

GB2218638A - Therapeutic stockings

Info

Publication number: GB2218638A
Application number: GB8911487A
Authority: GB
Inventors: James Hicks Hasty; Betsy Carolyn Westlake
Original assignee: Kendall Co
Current assignee: Kendall Co
Priority date: 1988-05-20
Filing date: 1989-05-18
Publication date: 1989-11-22
Also published as: JPH0219501A; FR2631546A1; SE510157C2; GB8911487D0; IT8947974A0; ES2016449A6; DE3916447A1; BE1003601A3; NL8901212A; SE8901425D0; BR8902360A; SE8901425L; IT1231787B

Description

1 2 r-l. 8 6 3 8 "THERAPEUTIC STOCKINGS" The present invention relates to

therapeutic 5. stockings.

Therapeutic stockings which exert a compressive pressure against a patient's leg are known, and the problem of the definition of an appropriate compression stocking for the managment of the venous system in the 10. lower extremities has been a topic of discussion for many years. Various types of stockings and compression profiles have been used, but it has been unclear what the appropriate compression profile should be to deal with the enormous spectrum of venous disorders found in 15. the ambulatory patient.

In the early experimental work of Sigel, Edelsteinj Savitch, Hasty, and Felix (Arch. Surg., Vol.

110, Feb. 1975, pp.171-175), the appropriate pressure gradient was defined to optimally compress the lower 20. extremity to produce the greatest increase in femoral vein flow velocity consistent with safety and practi cality of hospital use of elastic stockings. However, this definition was directed to the prophylaxis of deep vein thrombosis during inactive recumbency. The defi 25. nition of appropriate compression profiles for the management of venous difficulties in the lower extremi ties of ambulatory individuals is a totally different problem. A stocking which exerts compressive pressure against the leg is disclosed in our copending GB 30. Application No. 8621879 Serial No. 2180161 and GB Application No. 8906079;-Serial No. divided therefrom. However, it is found that by changing the.

compressive pressures slightly in the calf and thigh a 2 region of the stocking for mild venous disease, improved durability of the stocking is obtained, and an improvement in manufacture to produce the stocking consistently is obtained. A stocking with a pressure 5. gradient is disclosed in the U.S. Patent 3,889,494 incorporated herein by reference.

According to the present invention a therapeutic stocking for mild venous disease of the leg comprises, a boot portion for covering a substantial portion of 10. the leg,, the said boot portion having an ankle portion for exerting a substantial compressive pressure against the region of the ankle, a calf portion for exerting a compressive pressure in the range of 49% to 69% of the ankle pressure in the region of the calf, and a thigh portion f or exerting a compressive pressure in the range of 35% to 55% of the ankle pressure in the region of the mid-thigh.

More specifically a therapeutic stocking for mild venous disease of the leg comprises a boot portion for 20. covering a substantial portion of the leg, the said boot portion having an ankle portion f or exerting a substantial compressive pressure against the region of the ankle,, a calf portion f or exerting approximately 59% of the compressive pressure exerted by the ankle 25. portion in the region of the calf, and a thigh portion for exerting approximately 45% of the compressive pressure exerted by the ankle portion in the region of the mid-thigh.

Preferably the stocking has a foot portion which 30. exerts a compressive pressure in the range of 53% to 83% of the ankle pressure in the region of the foot, more preferably approximately 6.8% of the compressive pressure exerted by the ankle portion in the region of 1 1 1 a 1 4 -11 3 the foot.

The ankle portion of the stocking preferably exerts a compressive pressure in the range of 20 to 24 mm of mercury in the region of the ankle, e.g. approximately 22 mm of mercury against the region of the ankle.

In a specific form of the invention a stocking for mild venous disease of the leg comprises a boot portion for covering a substantial portion of the leg, the said 10. boot portion having an ankle portion which exerts a compressive pressure in the range of 20 to 24, preferably 22, mm of mercury, in the region of the ankle, a calf portion which exerts a compressive pressure in the range of 11.8 to 14. 0, pref erably 13, mm of mercury in 15. the region of the calf, and a thigh portion which exerts a compressive pressure in the range of 8.5 to 11.0, preferably 10, mm of mercury in the region of the mid-thigh.

The stocking preferably has a foot portion which 20. exerts a compressive pressure in the range of 12.7 to 16.6, preferably 15, mm of mercury in the region of the foot.

The invention may be put into practice in various ways and one specific embodiment will be described to 25. illustrate the invention with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a compression stocking which is illustrative of a knit construction utilized for the stockings of the present invention; 30. - Figure 2 is a diagrammatic representation of the front of a fabric comprising the knit construction for the stockings, showing the stitches; Figure 3 is a schematic representation of the knit a 4 construction; Figure 4 is a legend showing coding and symbols used i n Figures 2 and 3; Figure 5 is a diagrammatic view of a model of a 5. venous pump in a patient's leg; Figure 6 are diagrammatic views of the ven ous pump during three phases of the pump; Figure 7 is a diagrammatic view of the venous pump in a patient's leg; and 10. Figure 8 is an elevational view showing a stocking of the present invention for use with a patient having a mild venous disease in the leg.

A preferred knit construction for use with the stockings of the present invention is disclosed in 15. connection with Figures 1-4. This knit construction is disclosed and claimed in U.S. Patent 4.494,388, corresponding to GB Application No. 8315475 Serial No. 2127444 incorporated herein by reference.

Turning now to the drawings, Figure 1 illustrates 20. a therapeutic anti-embolism stocking, generally designated 10, comprising a boot or leg portion 12 having a welt portion 14 at the upper end thereof, a heel portion 16, a foot portion 18, and a toe portion 19. The entire stocking, except for the welt portion 14 and 25. the toe portion 19, may be of fabric knit according to the present description. The welt, heel, and toe may be of conventional jersey knit.

The fabric is a knit construction comprising a repeating six-course, twowale pattern. As shown in 30. Figures 2 and 3, the six courses (designated 1 through 6 respectively) repeat through the height of the stocking; the two wales (designated 20 and 22 respectively) repeat around the stocking circumference.

1 ' 1 ' I 91 Courses 1 y 3 F 4 and 6 are a textured nylon yarn such as that sold by E. I. duPont; courses 2 and 5 are bare or covered elastomeric yarn. such as duPont Lycra. Each course 1 comprises, f rom right to left as shown, alternating knit and tuck stitches. Courses 2 comprise alternating knit and f loat stitches; and courses 3 comprise alternating knit and tuck stitches. The knit stitches of courses 1 j 2 and 3 lie in wales 20, i.e. are vertically aligned with each other in every other wale.

Each course 4 comprises, again from right to left as shown, alternating tuck and knit stitches, as does each course 6. Each course 5 comprises alternating float and knit stitches. The knit stitches of courses 4, 5 and 6 lie in wales 22y intermediate the wales 20 containing the knit stitches of courses 1, 2 and 3.

As previously stated, the first and third stitches of courses 1, 2 and 3 are all knit stitches and lie in wales 20. The f irst and third stitches of courses 1 loop the f irst and third stitches of courses 2; the first and third stitches of courses 2 loop the f irst and third stitches of courses 3; and the f irst and third stitches of courses 3 pass over the first and third stitches of course 5 (which are f loat stitches) and, with the first and third stitches of courses 4 and 6 (both of which are tuck stitches), loop the first and third stitches of the next repeat of course 1.

In wales 22, the second and fourth stitches of courses 1 pass over the second and fourth stitches (the float stitches) of courses 2; and the second and fourth stitches of both of courses 1 and 3 are tucked behind. the loops formed by the second and fourth stitches (the knit stitches) of courses 4.

6 It will be seen that the_ pattern of courses 4-6 essentially repeats that of courses 1-3, except that it is offset one wale so that the wales 22 containing the knit stitches of courses 4-6 lie between wales 20 of 5. the knit stitches of courses 1-3.

Thus, in wales 22, the second and fourth stitches of courses 4 (which are knit stitches) loop the second and fourth stitches of courses 5; and the second and fourth stitches of courses 5 loop the second and fourth 10. stitches of courses 6. Further, the second and fourth stitches of courses 6 pass over the float stitches (the second and fourth stitches) of course 2 and, with the second and fourth stitches (both tuck stitches) of courses 1 and 3 of the next repeat, loop the second and 15. fourth stitches of the next repeat of course 4.

In wales 20, the first and third stitches of courses 4 (botl tuck stitches) pass over the first and third stitches (the float stitches) of courses 5, and the first and third stitches of both of courses 4 and 6 20. are tucked behind the loop formed by the f irst and third stitches (the knit stitches) of courses 1.

In wales 20,, it will be seen that the knit stitches of courses 3 and the tuck stitches of courses 4, i.e. the stitches that pass over the float stitches 25. of courses 5 of elastomeric yarn, have relatively long, free "legs" extending generally along the wales, as do the knit stitches of courses 6 and the tuck stitches of courses 1 (i.e. the stitches that pass over the floa-t stitches of courses 2) in wales 22. This construction 30. permits the fabric to stretch in a horizontal or circumferential direction (parallel to the courses 2, 5 of elastomeric yarn). Stretch in the vertical.

direction is provided largely by the tuck stitches, h 7 which as shown in Figure 2 extend diagonally of the fabric when the fabric is relaxed.

When the fabric is in its relaxed condition, the number of cqurses and wales per inch at various regions of the stocking, and the circumference of one size stocking, typically are generally as shown in the following table.

TABLE

Circum- Courses/ courses/ Wales/ Wales/ Rec jion ference Inch CM Inch cm Ankle 4.75" (12 cms) 40-50 16-20 80-100 32-40 Calf W' (20 cms) 30-40 12-16 50-60 20-24 Thigh ll,' (28 ans) 25-30 10-12 35-45 14-18 When worn, the stocking typically will stretch lengthwise (i.e. along the wales) some 20%-30% in the ankle region, about 50% in the calf region, and 100% or more in the thigh region. The difference in relative stretch is a primary factor contributing to the large variance of gradient in the pressure profile of the stocking, there being less pressure in areas of greater lengthwise stretch. The disclosed fabric is capable of producing very rapid changes in the exerted compressive pressure along the length of the leg.

The fabric may be knit using any of a number of knitting machines having a wide range capability. Such machines include the Zodiac 4G manufactured by Billi S.p.A. Firenze Cinstruzione Macchine Tessili of Italy, the Lonati 303 manufactured by Lonati Macchine 30. Circolaci Per Calcifici of Italy,, and the Nagata KTSuper 24 manufactured by Nagata Seiki Co. Ltd. of Japan. Such wide-range machines may be ordered new to produce a specified fabric, or existing machines may 25.

k 8 readily be modified or adapted as required. In general, the modifications required involve needle selection and placement, and cutting the jacks in the correct order.

5. In other embodiments, the two courses of elasto- meric yarn may be knit-tuck rather than knit-float, in which case the fabric will be double rather than single face; courses 1, 3, 4 and 6 may be any of a wide range of desired yarns, including textured filament, flat 10. filament or spun yarn; and courses 2 and 5 may be any desired elastomeric yarn, either bare or covered.

As a background f or the stockings of the pre^sent invention, the proper definition of compression profiles requires an understanding of the physiology of

15. the lower extremities for the various venous conditions under consideration as follows: (1) symptomic/yet mild venous disease (tired, aching legs), (2) superficial venous insufficiency, and (3) deep venous insufficiency. The starting point.for the definition of the 20. compression profiles will be an analysis of the venous pump as it reflects one model of the mechanism by which 30.

blood is drained from the leg in normal physiology in the various pathological conditions. The view of Figure 5 shows the musculo-venous pump section which 25. provides the anatomical configuration through which the venous pump ejects blood from the lower limb tissue via a dynamic action of the muscle working withlon the venous vessels and in conjunction with the uni- directional venous valves ejects the blood from the tissue.

The action of the venous pump has been divided into three components or phases:

1. Diastole II (see Figu.re 6a) - the state of slow steady f low prior to muscle contraction in which 1 W 11 9 10.

the blood is flowing through valves at a slow rate.

2. Systole (see Figure 6b) - the state during muscle contraction when pressure in the deep crural veins or trunk rises above that in the popliteal vein, 5. and blood is forced out of the musculofascial compartment. The normal valve function prevents the flow of blood from deep to superficial system at this time, and also prevents the flow of blood in the distal direction of"the superficial system.

3. Diastole I (see Figure 6c) - upon cessation of. muscle contraction the pressure in the deep system falls suddenly, and the popliteal valve closes to prevent retrograde flow in the deep system.

The valves in the superficial segment or vein close to prevent retrograde flow of blood. Due to the low pressure in the fascia cruris, flow will occur from the superficial to the deep system via the perforator veins. Flow from the muscle tributaries or intramuscular veins will cause the pressure to increase in the 20. central deep vein until the pressure at the popliteal inverts causing the valve to open. At this point the cycle is complete and diastole II begins again.

The components of the cycle discussed above are disclosed in Figure 6a to 6c in connection with 25. diastole II, systole. and diastole I.

The above-described function reflects a normal venous pump. Due to venous distension and/or venous valve destruction, the various venous pump pathologies arise as a result of loss of the valvular function needed to ensure one-way blood flow. In the case of deep venous insufficiency where total deep valvular destruction, such as the popliteal vein or the musculofascio compartment, as well as incompetent perforator 30.

veins are present, the blood f low pattern changes drammatically over the three phases of venous pump function compared to normal, and results in an inability of the venous pump to reduce the venous pressure during ambulation. Since the present case is concerned with mild venous disease, deep venous insufficiency and superficial venous insufficiency will not be discussed.

Mild varicose veins, or mild venous disease,, by definition is not that different from normal physiology with respect to gross parameters such as venous pressure and yet under certain experimental regimens, abnormalities can be measured in localized regions of small vessel circulation. These changes in venous is function could be the result of a number of microscopic hemodynamic conditions such as localized edema in areas surrounding venules.

The problem can be described in connection with Figure 7 as follows. In mild venous disease the valves are largely competent. In the proximal portion of the leg, localized microscopic hemodynamics may or may not be present. In the distal portion of the leg, no gross hemodynamic abnormalities are found since the valves are functional. However, under specific workload 2. regimen, localized miproscopic abnormalities in tissue are present.

The objectives of the invention for mild venous diseases may be defined as follows:

Mild Venous Disease Distal 11 Support small vessel hemodynamics; and Requirements 21 Mild valve support.

I d; X 9 t 11 Proximal 11 Support small vessel hemodynamics; and Requirements 21 Mild valve support.

1 All of the above support functions must be accomplished 5. without impeding the outflow parameters of venous blood from the leg or the arterial blood into the leg.

In addition to meeting the above functional objectives for the support of the venous system, it is important for patient compliance to avoid excess forces 10. on the foot,, and at the same time avoid venous congestion in the foot which could potentially be produced by a tourniquet effect.

A low compression stocking generally designated 60 for treatment of mild venous disease in a patient's leg is illustrated in Figure 8. The stocking 60 has a boot portion 32 for covering a substantial portion of the patient's leg, with the boot portion 32 having an ankle portion 34 for exerting a substantial compressive pressure against the region of the patient's ankle, a 20. calf portion 36 for exerting a compressive pressure in the region of the patient's calf,, a thigh portion 38 for exerting a compressive pressure in the region of the patient's thigh, and a foot portion 40 for exerting a compressive pressure in the region of the patient's 25.- foot. An important feature of this stocking 60 is the mild support of valvular structure and support of localized microscopic hemodynamics. The highest pressure in the pressure profile is exerted by the ankle portion 34 in the region of the ankle, and is 30. designated as 100% of the pressure. The pressure exerted by the ankle poiftion 34 may be in the range of 20 to 24 mm of mercury, and is preferably approximately, 22 mm of mercury.

a 12 As shown, the compressive pressure exerted by the calf portion 36 in the region of the calf is preferably approximately 59% of the compress ive pressure exerted by the ankle portion 34 in order to provide support and yet avoid venous congestion. The compressive pressure exerted by the calf portion 36 may be in the range of 49% to 69% of the compressive pressure exerted by the ankle portion 34. The compressive pressure exerted by the calf portion 36 may be in the range of 11.8 to 14.0 mm of mercury, and is preferably approximately 13.0 mm of mercury.

The compressive pressure exerted by the thigh portion 38 in the region of the mid-thigh is preferably approximately 45% of the compressive pressure exerted by the ankle portion 34 to provide microvascular support and complement valvular function without interf ering with venous outf low. The compressive pressure exerted by the thigh portion 38 in the region of the mid-thigh may be in the range of 35% to 55% of the compressive pressure exerted by the ankle portion 34. The compressive pressure exerted by the thigh portion 38 may be in the range of 8.5 to 11. 0 mm of mercury, and is preferably approximately 10.0 mm of mercury. With the improved pressures in the calf and thigh portions of the present invention, improved durability is obtained, and improved manufacturing consistency to produce the product is obtained.

As shown, the pressure exerted by the foot portion 40 in the region of the f oot is relieved to approxi- mately 68% of the compressive pressure exerted by the ankle portion 34 in order to enhance application of the. stocking 60 and comfort to the patient while avoiding tourniquet effects.The compr essive pressure exerted $1 Z 13 by the foot portion 40 may be in the range of 53% to 83% of the compressive pressure exerted by the ankle portion 34. The compressive pressure exerted by the foot portion 40 may be in the range of 12.7 to 16. 6 mm of mercury, and is preferably approximately 15.0 mm. of mercury.

The pressure in the foot portion 40 is reduced relative to the pressure exerted by the ankle portion '3 4. Since the foot is a bony structure excess pressures exerted on the foot would tend to break down the soft tissue in the foot resulting in damage to the soft tissue, such as the instep, or squeezing of the toes. The relieved foot pressures in the stockings of the invention minimize the possibility of this result.

Also, with an appropriate sizing system consistent with the general population, a meaningful pressure gradient is always maintained with an acceptable number of sizes. This aspect of the invention is a key to physiological function, and is not achieved with a majority of ambulatory stockings in today's marketplace.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

1 a 14

Claims

5.

1. A therapeutic stocking for mild venous disease of the leg comprising a boot portion for covering a substantial portion of the leg, the said boot portion having an ankle portion f or exerting a substantial compressive pressure against the region of the ankle,, a calf portion f or exerting a compressive 10. pressure in the range of 49% to 69% of the ankle pressure in the region of the calf, and a thigh portion for exerting a compressive pressure in the range of 35% to 55% of the ankle pressure in the region of the midthigh.

15.

2. A therapeutic stocking for mild venous disease of the leg comprising a boot portion for covering a substantial portion of the leg, the said boot portion having an ankle portion for exerting a 20. substantial compressive pressure against the region of the ankle, a calf portion for exerting approximately 59% of the compressive pressure exerted by the ankle portion in the region of the calf, and a thigh portion for exerting approximately 45% of the compressive 25. pressure exerted by the ankle portion in the region of the mid-thigh.

3. A stocking as claimed in Claim 1 or Claim 2 including a foot portion which exerts a compressive 30. pressure in the range of 53% to 83% of the ankle pressure in the region of the foot.

A stocking as claimed in Claim 1, 2 or 3 1 ' 1 i 1 Z 1 including a foot portion which exerts approximately 68% of the compressive pressure exerted by the ankle portion in the region of the foot.

5. 5. A stocking as claimed in any one of Claims 1 to 4 in which the ankle portion exerts a compressive pressure in the range of 20 to 24 mm of mercury in the region of the ankle.

10. 6. A stocking as claimed in Claim 5, in which the ankle portion exerts a compressive pressure of approximately 22 mm of mercury against the region of the ankle.

15. 7. A stocking for mild venous disease of the leg comprising, a boot portion for covering a substantial portion of the leg, the said boot portion having an ankle portion which exerts a compressive pressure in the range of 20 to 24 mm of mercury in the region of 20. the ankle, a calf portion which exerts a compressive pressure -in the range of 11.8 to 14.0 mm of mercury in the region of the calf, and a thigh portion which exerts a compressive pressure in the range of 8.5 to 11.0 mm of mercury in the region of the mid-thigh.

25.

30.

1 8. A stocking as claimed in Claim 5, 6 or 7 including a foot portion which exerts a compressive pressure in the range of 12.7 to 16.6 mm of mercury in the region of the foot.

9. A therapeutic stocking for mild venous disease of the leg comprising, a boot portion for covering a substantial portion of the leg,. the said' 16 boot portion having an ankle portion which exerts a compressive pressure of approximately 22 mm of mercury in the region of the ankle, a calf portion which exerts a compressive pressure of approximately 13 mm of mercury in the region of the calf, and a thigh portion which exerts a compressive pressure of approximately 10 mm of mercury in the region of the mid-thigh.

10. A stocking as claimed in Claim 9 including a 10. foot portion which exerts a compressive pressure of approximately 15 mm of mercury in the region of the f oot.

11. A stocking as claimed in Claim 1 substan- 15. tially as specifically described herein with reference to the accompanying drawings.

20.

25.

30.

Publis aed 1989 at The Patent Office. State House, 66"71 High Holborn. London WClR. 4TP Rzmlier copies mkybe obtained from The Patent OfEice. Sales Branch, St Mary Cray. Orpington, Kent BR-5 3RD. Printed by Multiplex techniques It4d. St Mary Cray. Kent, Con, 1187 A S