Temperature dependence of the circulation pattern in the upper extremities.

1. The rate of blood flow D through the hand and the rate of heat H transferred by that blood flow into the hand were measured on eleven subjects between 18 and 22 years old. The hand was immersed in water, at temperatures ranging from 10 to 40 degrees C. 2. The rate of blood flow was measured with a water-air displacement plethysmograph, which was adapted also to give heat loss measurements. 3. Comparison of the relative values of D and H at different temperatures gives information about the change in distribution of blood flow with temperature. On decreasing water temperature, the change in distribution starts at about 25 degrees C and continues gradually to about 15 degrees C, suggesting that more and more blood is shunted to deep veins. For one of the subjects, no change in distrubiton pattern was found.