Microcirculation in the legs and the effects of postural change in homozygous sickle cell (SS) disease - abstract

ABSTRACT

Chronic leg ulceration is a considerable cause of morbidity in homozygous sickle-cell disease. The role of cutaneous blood flow in the pathogenesis of the ulcers is unknown. Compromised perfusion is assumed but there is no direct evidence to support this. We evaluated the response of cutaneous red cell flux (RCF), an index of cutaneous blood flow, to postural change in patients with SS disease, with and without a history of ulcers and in AA controls. Using laser Doppler flowmetry, measurements were made at two sites in the leg in the following groups-SS patients with a history of ulceration (Group A = ulcers, Group B = scars); without a history of ulceration (Group C) and AA controls (Group D). In Groups A & B, the sites were the ulcer/scar site and a normal site; in Group C & D, medial and lateral sites above the malleoli. A triad of measurements was performed - the leg horizontal, lowered, then returned to the horizontal. Regardless of history of ulceration, SS patients showed a smaller fall in flow on dependency (p < 0.001), indicating failure of normal postural vasoconstriction. In Groups A & B, the greater fall in flow observed at the ulcer/scar site compared with the normal site may be significant in the development/recurrence of ulcers at these sites. Clarification of the underlying mechanisms of these observations through further study may be important for improving skin nutritive perfusion (AU)