RECOVERY FROM MILD HYPOTHERMIA CAN BE ACCELERATED BY MECHANICALLY DISTENDING BLOOD-VESSELS IN THE HAND

Peripheral vasoconstriction decreases thermal conductance of hypotherm ic individuals, making it difficult to transfer externally applied hea t to the body core. We hypothesized that increasing blood flow to the skin of a hypothermic individual would enhance the transfer of exogeno us heat to the body core, thereby increasing the rate of rewarming. Ex ternal auditory meatus temperature (TEAM) was monitored in hypothermic subjects during recovery from general anesthesia. In 10 subjects, hea t (45-46 degrees C, water-perfused blanket) was applied to a single fo rearm and hand that had been placed in a subatmospheric pressure envir onment (-30 to -40 mmHg) to distend the blood vessels. Heat alone was applied to control subjects (n = 6). The application of subatmospheric pressure resulted in a 10-fold increase in rewarming rates as determi ned by changes in T-EAM [13.6 +/- 2.1 (SE) degrees C/h in the experime ntal group vs. 1.4 +/- 0.1 degrees C/h in the control group; P < 0.001 ]. In the experimental subjects, the rate of change of T-EAM decreased sharply as T-EAM neared the normothermic range.