Cyanosis and Raynaud's phenomenon: the relation to underlying disease and venous abnormalities

Matched groups of 7 to 8 patients with primary Raynaud's phenomenon, systemic sclerosis, and undifferentiated connective tissue disease and cold tolerant normal control subjects were studied by simultaneous digital strain gauge plethysmography and laser Doppler capillary velocimetry during two controlled cycles of hand warming and cooling. Nailfold capillaroscopic assessments and measures of in vivo platelet activation were performed. Triphasic color changes were present in all patients with systemic sclerosis, in 6 of 8 with undifferentiated connective tissue disease, but in only 1 of 7 with primary Raynaud's phenomenon. The occurrence of cyanosis correlated with evidence of impaired venous volume by strain gauge plethysmography and with higher degrees of capillary loop architectural abnormalities. The authors conclude that the presence of digital cyanosis is indicative of connective tissue disease and related to evidence of impaired digital venous capacitance. This may underlie the frequent presence of edema in these patients and may be implicated in the pathogenesis of capillary loop abnormalities.