Original article

Compression stockings for treating venous leg ulcers: measurement of interface pressure under a new ulcer kit B Partsch and H Partsch Private Practice for Dermatology, Angiology, Martinstrasse 1, A 1180 Vienna, Austria

Abstract Objectives: The aim of this study was to measure the interface pressure of a newly designed two-layer compression stocking (Mediven ulcer kitw Medi QMBH, Bayreuth, Germany) in different body positions and to compare the values with those obtained with another two-layer product. Methods: Interface pressure was measured on the distal medial leg in 16 legs of volunteers, with the basic layer alone and with the whole stocking kit in the supine, sitting and standing position for both stocking systems. The literature concerning ulcer-healing rates is reviewed. Results: Mediven ulcerkitw produced statistically significant higher pressure values than the ulcer stocking with a median resting value of 35.5 mmHg in the supine and 42.5 mmHg in the standing position. The pressure while standing comes close to values exerted by bandages. The basic layer alone applies a pressure of 20.5 mmHg. Conclusions: Especially designed compression stockings exerting sufficient interface pressure may be indicated in patients with small ulcers of short duration. Keywords: compression stockings; venous leg ulcers; interface pressure; stiffness

Introduction Duplex investigations in patients with venous leg ulcers have dramatically improved our pathophysiological understanding. Several studies have shown refluxes in the superficial venous system in about 80%, with or without involvement of the deep and perforating veins.1,2 This is the basis for the concept that the majority of patients with venous ulcers are potential candidates for abolishment of superficial refluxes.3 In fact, very promising results have been reported by stripping operation,4 by surgery of incompetent perforators,5 but also by sclerotherapy.6 However, these procedures will not be able to completely replace traditional compression therapy, which up to now consisted mainly in compression bandages. The effectivity of compression bandages has been demonstrated in many randomized Correspondence: B Partsch MD Email: [email protected] Accepted 9 May 2007

Phlebology 2008;23:40–46. DOI: 10.1258/phleb.2007.007018

controlled trials. Healing rates of more than 70% in 12 weeks have been reported.7 High compression was more effective than low compression, but there were no clear differences in the effectiveness of different types of high compression. Bandages with high compression are more difficult to apply, which explains the fact that the best results of ulcer healing come from experienced centres and cannot be extrapolated to the usual care of patients in the community. This inconsistency concerning the different quality of compression bandages and their application was one of the main reasons to investigate if medical compression stockings could be taken as alternatives. The Cochrane review7 quotes two randomized controlled trials in which compression stockings have been compared with compression bandages. One found a high compression stocking plus a thrombo stocking to be more effective than a short stretch bandage.8 The second small trial reported no difference between the compression stockings and Unna’s boot.9 In spite of the promising results of one of these trials that came from our group8, it

B Partsch and H Partsch. Compression stockings for treating venous leg ulcers

was only during the last few years that the idea to treat venous ulcers with compression stockings was taken up also by other groups who performed comparisons with compression bandages.10 – 12 Interestingly, data regarding the deciding ‘dosage’ of the exerted pressure of the material used have only rarely been presented. In the trial of our own group, it was shown that the pressure of the two superimposed stockings roughly correspond to the addition of the interface pressure exerted by the single layers.8 It was discussed that one of the reasons for the superiority of the stockings compared with the short stretch bandages in the control group might have been the much less pronounced pressure loss in the stocking group compared with the short stretch bandage group during the following hours and days. Ju¨nger et al. 13 measured the interface pressure of a readymade ulcer stocking for a period of 6 weeks and found no pressure loss. A high interface pressure of compression material on the leg is associated with better ulcer healing,7 probably because of the more pronounced haemodynamic effects on the veins.14,15 This was the background for the following investigation in which we compared the interface pressure of a newly developed ulcer stocking with that of another product also recommended for ulcertreatment.

Material and methods A total of 16 legs from eight volunteers (three males, five females, age 28– 67, median 50.5), clinical CEAP-classes C0 – C2 were investigated. The probands were informed about the measuring procedure and gave their consent to participate in the investigation. For each leg, the circumference at the ankle and below the knee was measured as well as the distance between the heel and the capitulum fibulae. Custom-made ulcer stockings (Mediven ulcer kitw and a competing product, called ulcer stocking) were provided by the medi-company (Bayreuth, Germany). Both stockings are knee-high and consist of two layers: one ‘liner’ to keep the local ulcer dressing in place and one stocking applied over it. Interface pressure was measured by an air-filled pressure transducer (Kikuhimew small, Medi Trade, Soro, Denmark) that showed a satisfying precision when tested with a blood pressure cuff connected to a manometre.16 The probe with the dimension 30  38  3 mm was attached to

Original article

the area where the medial gastrocnemius-muscle changes into its tendinous part (point B1). Measurements were performed in the supine, sitting and standing position with a relaxed anklejoint and after one maximal dorsiflexion with the liner and then with the second stocking donned over. Mediven ulcer kitw was applied on one leg, the ulcer stocking on the contralateral leg. The sequence of the left and right side was allocated in a randomized order. After measuring the interface pressure in the different body positions and a resting period of 15 min, new samples of Mediven ulcer kitw and of the ulcer stocking were donned to the respective opposite leg and the measuring procedure was repeated so that each product was tested in a total of 16 legs. The ‘static stiffness index (SSI)16,17 was calculated by subtracting the supine pressure from the standing pressure.

Statistics Median values with interquartile ranges are given. To compare the measuring values from the two products (right leg vs. left leg), the non-parametric Mann-Whitney test was used. Comparisons between the pressure changes induced by changes of the body position under the same compression stocking were made by a paired t-test. P values lower than 0.05 were considered as statistically significant.

Results (1) Mediven ulcer kit w vs. ulcer stocking The Mediven ulcer kit reveals significantly higher interface pressure values in the supine and standing position compared with the ulcer stocking (P , 0.0001). Both stockings show a significant pressure increase by standing up from the supine position (P , 0.0001) (Figure 1). (2) Mediven ulcer (basic-layer) vs. liner of the ulcer stocking The basic layer of the Mediven ulcer kitw exerts more than double as high interface pressures compared with the basic layer of the ulcer stocking (P , 0.0001). There is a significant pressure increase by standing up for the Mediven layer (P , 0.01), but not for the liner of the ulcer stocking (Figure 2). (3) Static stiffness index There is no significant difference of the SSI between Mediven ulcer kitw and the ulcer stocking (Figure 3). Phlebology 2008;23:40–46

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B Partsch and H Partsch. Compression stockings for treating venous leg ulcers

Figure 1 Interface pressure measured at B1 using a small Kikuhime transducer in the lying (L) and standing (St) position under the double layer Mediven ulcer kitw in comparison with another double layer ulcer stocking. (Median values, minimum, maximum, interquartile range, n ¼ 16)

(4) Pressure increase due to dorsiflexion Both stockings show a statistically significant increase of pressure by dorsiflexion in the supine, sitting and standing position (P , 0.0001) (Figures 4 and 5). (5) Correlation between SSI and pressure increase by dorsiflexion in the supine position There is a significant correlation between the

Figure 2 Comparison of the basic layer stockings of the two products. Same measuring parameters as in Figure 1 were used

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Figure 3 Comparison of the static stiffness index (SSI) of the two products (SSI ¼ standing pressure –supine pressure). (Median values, minimum, maximum, interquartile range, n ¼ 16)

pressure increase induced by standing SSI and by dorsiflexion (Figure 6) demonstrating that both the parameters can be used as indicators for stiffness.17

Discussion Several studies have shown that the haemodynamic efficacy of compression therapy depends mainly on two factors: interface pressure and stiffness.17 In order to effectively narrow leg veins in the

Figure 4 Pressure of the Mediven ulcer kitw in the supine, sitting and standing position before and after one dorsiflexion. (Median values, minimum, maximum, interquartile range, n ¼ 16)

B Partsch and H Partsch. Compression stockings for treating venous leg ulcers

Figure 5 Pressure of the ulcer stocking in the supine, sitting and standing position before and after one dorsiflexion. (Median values, minimum, maximum, interquartile range, n ¼ 16)

upright position, an external pressure is needed that comes close to the intravenous pressure.14 Plethysmographic experiments have taught us that higher external pressures lead to a more pronounced reduction of venous reflux18 and to an increase of expelled volume in patients with venous insufficiency.19,20 These haemodynamic effects correspond with a higher ulcer-healing rate demonstrated in clinical trials.7 The other frequently underestimated factor is stiffness that characterizes the elastic property of a compression device. According to the definition in

Original article

a European prestandard on compression hosiery (CEN),21 stiffness is defined by the increase of interface pressure due to an increase of the leg circumference occurring with muscle contractions during dorsiflexion and during every step, but also by simple standing. The site on the lower leg where the changes of the circumference are greatest22 is the so-called B1 area where the muscular part of the gastrocnemius muscle inserts into its tendon. Changes of the local curvature by muscle protrusion that differ from one individual to the other also have a considerable influence on the pressure registered. Measuring the pressure changes by standing up or by dorsiflexion, an inelastic, nonyielding compression material will produce a higher increase than an elastic textile. Compression stockings are made up of elastic material in order to allow them to be donned over the heel, which could not be done with stiff material. However, the elastic property of stockings varies from one brand to the other and influences their performance. Stockings with higher stiffness have a higher anti-oedematous efficacy23 and show a more pronounced improvement of the venous refilling time in patients with venous incompetence.24 The SSI which has been defined by the difference of the interface pressure between standing and supine gives us a simple instrument to differentiate the elastic property of a specific textile or also of the combination of several materials on an individual leg.17 As shown in Figure 5, there is a significant correlation between the SSI and the pressure increase induced by one dorsiflexion pointing to the fact that the pressure in the standing position can be taken as a surrogate parameter for the pressure peaks that occur during the dynamic situation of walking.25 The pressure measured during standing can be considered as a snapshot of a short moment during a step presenting the advantage of a good and easy reproducibility, in contrast to an exercise programme.17

What are the practical consequences of our measurements?

Figure 6 Correlation between the pressure increase by standing up (static stiffness index SSI) (x-axis) and by dorsiflexion in the supine position (y-axis)

The Mediven ulcer kitw exerts a resting pressure between 28 and 56 mmHg (median value 35.5 mm Hg) (Figure 1). We know from previous experience that such a pressure range with resting values over 30 mmHg may be unpleasant for the patient and could even cause damage to the skin. Therefore, it is advisable to follow the recommendation of the producers to remove the outer stocking overnight and to sleep only with the basic stocking on the Phlebology 2008;23:40–46

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B Partsch and H Partsch. Compression stockings for treating venous leg ulcers

leg exerting a pressure of 20.5 mmHg (Figure 2). This basic stocking does not only keep the local ulcer dressing in place, but certainly has a positive effect by accelerating the venous blood flow in a similar way as was shown for thromboprophylactic stockings.26 When the patient stands up, the interface pressure of Mediven ulcer kitw rises to values over 40 mm Hg (Figure 1), which is a range comparable with that exerted by a four-layer bandage. The tested ulcer stocking produces a significantly lower pressure with values in the supine position that are in the same magnitude as those of the basic Mediven layer alone (Figures 1 and 2). These stockings could be tolerated by the patients also during night time. There is a considerable increase of pressure by standing up. However, the standing pressure of this product is still lower than the supine pressure of the Mediven ulcer kitw. Comparing the SSI of the two products (Figure 3), it can be seen that the Mediven ulcer kitw has a slightly lower index than the ulcer stocking. This is remarkable since there is a significant increase of the pressure under the basic layer of the Mediven product, but not under the liner of the ulcer stocking (Figure 2). The relatively high stiffness of the complete ulcer stocking must therefore be explained by a rather inelastic structure of the outer stocking layer. In a previous study,27 we were able to demonstrate that the superposition of two stockings does not only increase the interface pressure, but leads also to an overproportional increase of the stiffness of the final stocking combination. The principle concept to use two stockings, one over the other, instead of one stocking with a higher compression class has therefore theoretical and practical advantages.

† The resulting pressure of two stockings applied †

over each other corresponds to the sum of the pressure exerted by the single stockings;8 The stiffness of two stockings applied over each other is even higher than that of a single stocking exerting the same resting pressure;27

† Especially for old patients with restricted mobility, it is much easier to apply two stockings over each other than one single high compression class stocking. In our experiments, the ulcer stocking system was easier to apply to the leg than the Mediven ulcer kitw, mainly because of the low pressure of the basic stocking. The shear gliding surface of this liner facilitates the donning of the second stocking. For applying the Mediven ulcer kitw, it is highly recommendable to use one of the donning aids provided by the manufacturer, as for instance the Mediven Butlerw or the Medivenw 2 in 1 system.

Can compression bandages be replaced by stockings in the future? There are a few randomized controlled trials in which compression stockings and bandages have been compared concerning their efficacy of healing venous ulcers (Table 1). One small trial found no difference between compression stockings and Unna’s boot.9 Our own group8 reported a healing rate in three months with 21/25 (84%) of those patients who received a combination of a thromboprophylactic stocking plus Sigvaris 503w compared with 13/25 (52%) of those receiving one short stretch bandage (Rosidal Kw) applied over a thin polyurethane padding layer (Haftanw). In both groups an indifferent absorbing local dressing was used over the ulcers, on top with an individually modelled rubber foam pad. Two explanations for the superior results obtained with the stockings were discussed: (1) Their basic characteristics in the two treatment groups were unequal with higher age, longer ulcer duration, larger ulcer area and higher incidence of a positive Stemmer’s sign on the foot in the bandage group; (2) The loss of interface pressure in the first 24 h was between 44% in the supine and 36% in the standing position in the bandage group,

Table 1 Randomized-controlled trials comparing compression stockings with bandages for the healing of venous ulcers First author (Ref ) 9

Hendricks Horakova8 Koksal10 Ju¨nger12 Ju¨nger11

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N 21 50 53 121 178

Weeks

Healing rate with stocking

Type of stocking

Healing rate with bandage

Type of bandage

.18 12 16 12 12

71% in 18,4 weeks 84% 81% 48% 58%

Futuro style 50 Trombo þ Sigvaris 503w Class II Venotrain ulcertecw Tubulcusw

70% in 7.3 weeks 52% 74% 32% 57%

Unna’s boot 1 Rosidalw Unna’s boot 2 Roselasticw 1 Rosidalw

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B Partsch and H Partsch. Compression stockings for treating venous leg ulcers

in contrast to only 9% and 16% after one week in the stocking group. It was concluded from this study that the patients with small ulcers (diameter ,5 cm) and a short duration (,3 months) might be candidates for a therapy with good compression-stockings exerting a pressure in the standing position of about 40 mmHg. One randomized controlled trial compared a combination of hydrocolloid dressing and medical compression stockings vs. Unna’s boots.10 The healing rate after 16 weeks was 74% with Unna’s boots and 80% with stockings þ hydrocolloid (no significant difference). The result may be flawed by the fact that no specific local dressing was applied in the bandage group. Two randomized controlled trials using stockings have been published by Ju¨nger et al. 11,12 One trial compared a ready-made tubular compression device (Tubulcusw, Rosidal mobilw) with one short stretch bandage (Rosidalw) in a total of 178 ulcer patients.11 Only small ulcers with a short duration of the ulcer were included. Complete healing after 12 weeks was obtained in 58% of patients in the tubular compression device and in 56.7% in the bandage group. In another randomized controlled multicentre trial on 134 patients, a comparison was made between a newly designed compression stocking and two short stretch bandages (Roselasticw).12 The patients were allowed to change both devices at their discretion. Venous ulcers with a median area of 2.7 and 3.7 cm2 and with a mean duration of 4 – 6 months were included. The healing rates after 12 weeks were 29/61 (47.5%) in the stocking group and 19/60 (31.7%) in the bandage group (P , 0.01). From this overview on randomized controlled trials, it may be concluded that good compression stockings may successfully heal small ulcers within short duration. However, more data considering stratification by site, ulcer duration and size, mobility and venous pathology are needed to recommend compression stockings for the treatment of venous ulcers on a larger scale.

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Acknowledgement This study was supported by a grant from Medi Bayreuth, Germany.

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