Reduced temperature afterdrop in rhesus monkeys with radio frequency rewarming

Rhesus monkeys were anesthetized and rendered hypothermic by icewater immersion. Rewarming by radio frequency (RF) energy at 13.56 MHz or by a surgical heating pad was initiated either immediately after removal from the icewater or after a delay of 20-26 min. Rectal temperature (Tre) was monitored during each experiment, and RF energy, initially applied at a specific absorption rate (SAR) of 10 W.kg-1, was able to raise Tre an average of 3 degrees C in 20 min. For an equivalent period of rewarming with the heating pad, Tre had not yet recovered from the immersion-induced afterdrop. It is concluded that RF rewarming offers a special advantage when applied to the treatment of immersion hypothermia.