Measurement of hand microvascular blood flow with isolated cold stress testing and laser Doppler fluxmetry.

Isolated cold stress testing applies cold thermal stress to an extremity for noninvasive study of skin surface temperature as an index of digital microcirculation. In this study, laser Doppler fluxmetry was combined with isolated cold stress testing to examine the relationship between digital thermoregulation (measured by isolated cold stress testing) and digital microcirculatory blood flow (measured by laser Doppler fluxmetry) in 50 healthy men and women. After a 5-minute baseline period, both hands were subjected to cold stress (average, 8 degrees C) for 20 minutes and then returned to room temperature for 20 minutes. Digital temperatures and laser Doppler measurements were graphed to document individual responses. The 25 women had lower digital temperatures, lower laser Doppler fluxmetry values, and less average rewarming than the 25 men. Statistical cluster analysis revealed a cold pattern, found predominantly in women, and a warm pattern, found predominantly in men. These patterns of response may help to elucidate the pathogenesis of the vascular occlusive syndromes occurring predominantly in women.