MICROVASCULAR REACTIONS TO POSTURAL CHANGES IN PATIENTS WITH SICKLE-CELL-ANEMIA

Normal microcirculation of the lower extremity is characterized by the venoarteriolar vasoconstriction reflex and the disapperance of vasomo tion in the dependent position. Patients with sickle cell disease are prone to develop ischemic leg ulcers at an early age. Dysfunction of t he microcirculation might promote the development of leg ulcers in pat ients with sickle cell disease. Using laser Doppler equipment we have studied the changes of blood flux in the skin overlying the medial mal leolus after leg lowering. Contrary to the normal physiological situat ion seen in our control persons, the venoarteriolar reflex was abolish ed and vasomotion preserved in the dependent position of the leg in bo th patients. We conclude that this may represent an adaptation to the dependent position in sickle cell disease.