Rewarming hypothermic piglets with 2.45 GHz microwave radiation

Microwave radiation (2.45 GHz) was examined as a heat source for rewarming chilled neonatal piglets. A multi-mode cavity (60 x 60 x 60 cm) was constructed of 22 gauge perforated galvanized steel. The radiation applicator was a slotted waveguide, 70 cm in length, which was located centrally 46.5 cm above the floor of the cavity. Hypothermic piglets (mean rectal temperature 26.0 +or- 0.2 degrees C) (n=32) were exposed to either infrared (120 W) or microwave (76 W) radiation until the rectal temperature reached 37.5 degrees C. The local specific absorption of microwave radiation as determined in piglet cadavers was 0.15 W kg-1 per mW cm-2 of exposure power. Microwave exposed piglets recovered from hypothermia significantly (p0.05) difference in body mass at 21 d between male piglets of either treatment group; however, female piglets rewarmed with microwave radiation weighed significantly (p<0.05) less than female piglets rewarmed with infrared radiation (5020 +or- 481 g versus 5713 +or- 379 g) at 21 d of age. The difference in body mass in the rewarmed female piglets was probably a result of differential mortality since the 3 smallest piglets exposed to infrared radiation subsequently died as a result of crushing..