Immersion of distal arms and legs in warm water (AVA rewarming) effectively rewarms mildly hypothermic humans.

INTRODUCTION: Active rewarming of hypothermic victims for field use, and where transport to medical facilities is impossible, might be the only way to restore deep body temperature. In active rewarming in warm water, there has been a controversy concerning whether arms and legs should be immersed in the water or left out. Further, it has been suggested in the Royal Danish Navy treatment regime, that immersion of hands, forearms, feet, and lower legs alone might accomplish rapid rates of rewarming (AVA rewarming).

METHODS: On three occasions, six subjects (one female) were cooled in 8 degrees C water, to an esophageal temperature of 34.3+/-0.8 (+/-SD) degrees C. After cooling the subjects were warmed by shivering heat production alone, or by immersing the distal extremities (hands, forearms, feet and lower legs) in either 42 degrees C or 45 degrees C water.

RESULTS: The post cooling afterdrop in esophageal temperature was decreased by both 42 degrees C and 45 degrees C water immersion (0.4+/-0.2 degrees C) compared with the shivering alone procedure (0.6+/-0.4 degrees C; p < 0.05). The subsequent rate of rewarming was significantly greater with 45 degrees C water immersion (9.9+/-3.2 degrees C x h(-1)) than both 42 degrees C water immersion (6.1+/-1.2 degrees C x h(-1)) and shivering alone (3.4+/-1.5 degrees C x h(-1); p < 0.05).

CONCLUSION: The extremity rewarming procedure was experienced by the subjects as the most comfortable as the rapid rise in deep body temperature shortened the period of shivering. During the extremity rewarming procedures the rectal temperature lagged considerably behind the esophageal and aural canal (via indwelling thermocouple) temperatures. Thus large gradients may still exist between body compartments even though the heart is warmed.