Effects of local heat on blood flow in infected and normal hands

Changes in response to heat in the dermal, subcutaneous, and muscle blood flow in the hands of 10 patients with hand infections were studied using 133Xe and recording of clearance data. A further 15 normal hands were studied in a similar manner. The application of topical heat to normal hands resulted in a decrease in the dermal blood flow (p less than 0.001), an increase in the subcutaneous blood flow (p less than 0.05), and perhaps an increase in the intramuscular flow (p less than 0.1). This suggests that surface heat promotes a shunting of the blood from the skin to deeper tissue layers. In infected hands, the blood flow was found to be significantly increased threefold in the intradermal circulation (p less than 0.01) and eightfold in the subcutaneous circulation (p less than 0.03) when compared to controls. In contrast to normal hands, in the infected hands, the blood flow decreased in all three compartments by 50 percent following application of heat. The blood flow of the normal hand in patients with infection did not respond to heat in the normal pattern. We conclude that the application of local heat to normal tissues results in shunting of blood flow from superficial tissues such as dermis to deeper ones such as subcutaneous fat and muscle. In infected tissues, the blood flow was found to be much higher than normal; however, the traditional belief in the improvement in blood flow by the application of heat was not confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)