A Wearable Compression Device to Normalise Calf Muscle Pump Function in Chronic Venous Insufficiency for Each Postural Position.

Abstract

For the currently used compression therapy, the applied compression pressure is usually inadequate to exert an effective impact on the veins in different body positions. The aim was to assess the venous ejection fraction achieved by a new compression device which automatically adjusts the interface pressure to body position in an acute experimental setting. A new portable, battery driven compression device providing pressure adjusted to allow for body position, and connected to a less or very stiff calf cuff wrap was tested. In patients with superficial venous incompetence, the ejection fraction (EF) of the calf pump was measured by strain gauge plethysmography. Applied in a random sequence, values achieved without compression, with the two cuffs, and with compression stockings exerting 23-32 mmHg, were compared. The applied compression pressures were simultaneously recorded in the supine and standing positions, and during walking. Comfort was assessed by a visual analogue scale (VAS) with 0 corresponding to very low comfort and 10 to very comfortable. In 16 patients with CEAP clinical stage C3-C6, EF without compression was 37%, increasing to 46.9% with stockings, to 64.8% (p < .001) by less stiff and to 75.5% (p < .001) by stiffer wraps. The median interface pressure (supine/standing) was 31/56 mmHg for the less stiff device, 32/68 mmHg for the stiffer device, and 23/26 mmHg for the stockings. The static stiffness index and the walking pressure amplitudes were significantly higher than those generated by the stocking, and the highest values were found with the stiffer wrap material. The device comfort was high both in the supine and standing positions (VAS 8 ± 2). The tested devices were comfortable at rest and haemodynamically effective during walking by automatically adjusting compression pressures to body position. They are significantly more effective than elastic stockings in improving EF. The system is able to overcome the problems of fast pressure loss by continuously re-adjusting the compression pressure.