THERMAL INCREMENT PROVIDED BY INHALATION REWARMING FROM HYPOTHERMIA

To quantify the core temperature gain from inhalation rewarming, 10 subjects were immersed in seawater (mean temperature 12.degree. C) until a 2.degree. C drop in rectal temperature occurred, and were then rewarmed by breathing hot saturated air at 45.degree. C for 30 min. Each subject was rewarmed once breathing air and once rebreathing a controlled fraction of expired air adjusted to produce a hyperventilation of 50 l/min. After 30 min of rewarming mean rectal temperature increased 0.39.degree. C in subjects breathing air and 0.77.degree. C in those hyperventilating (P < 0.01). Corresponding gains in tympanic temperatures were 1.1 and 1.5.degree. C, respectively. Calculations indicated that the additional heat input with hyperventilation yielded a core (rectal) temperature gain of 5.1 .times. 10-4.degree. C/l. Each additional 10 l/min of ventilation of hot saturated air increases the rate of core rewarming from hypothermia by approximately 0.3.degree. C/h.