Abstract
Forearm blood flow (FBF) was measured in 23 patients with homozygous sickle cell (SS) disease and 20 controls with normal hemoglobin genotype (AA) using venous occlusion air plethysmography to examine the pattern of peripheral blood flow in both groups at rest, and in response to thermal stimuli. The mean resting FBF in SS patients was more than twice that in AA controls (P <0.001). Indirect cooling (15°C) of the left forearm for 2 minutes evoked a significant increase (P <0.005) in FBF in the opposite arm in both SS patients and AA controls, with the response being greater in the controls. Indirect heating (40°C) for 2 minutes evoked a decrease in FBF of a similar magnitude in both groups. The increased FBF in response to moderate cooling in SS patients may be part of an important reflex mechanism which could support the concept of the ‘steal' syndrome, as recently postulated, as a possible explanation for the cold-related initiation of the painful crisis of SS disease.
