Evidence for an abnormal peripherally mediated vascular response to temperature in Raynaud's phenomenon.

It is unclear whether an abnormal vascular response to temperature change, independent of central sympathetic control, exists in Raynaud's phenomenon. We investigated this using the hyperaemic response to localized heating of dorsal foot skin, recorded by laser Doppler flowmetry. Fifteen normal adults, nine patients with primary, and seven with secondary Raynaud's phenomenon were studied. On warming, blood flow normally increases gradually at first, followed by rapid vasodilatation at temperatures above 33 degrees C. Normal geometric mean (95% confidence interval) blood flows at 33 degrees C and 36 degrees C were 0.19 (0.16-0.22) and 0.39 (0.29-0.53) arbitrary units respectively. In primary Raynaud's phenomenon, blood flows were 0.53 (0.44-0.62) and 1.07 (0.86-1.35) arbitrary units respectively (P less than 0.01 compared to normal subjects), showing early vasodilatation. Normal women have an intermediate response between men and primary Raynaud's patients. Responses in secondary Raynaud's phenomenon widely overlap the other groups. We conclude that an abnormal peripheral vascular response to temperature change exists in primary Raynaud's phenomenon.