Preclinical trial of a radiant heat device for whole-body hyperthermia using a porcine model.

After review of the published clinical experience with systemic hypothermia, we concluded that a simple system which controls radiant heat balance to supplement metabolic heat might provide several advantages, including: (a) decreased morbidity; (b) elimination of the requirement for general anesthesia; (c) improved patient comfort; (d) favorable cost-benefit considerations. We have tested a prototype radiant heat device for whole-body hyperthermia (WBH) in patients with disseminated cancer. From preclinical evaluation of this device, the lightly anesthetized pig was found to be an ideal model for WBH. This species has physiological characteristics closely resembling those of humans. The pig's core, pulmonary artery, liver, rectal, and esophageal temperatures were raised to 41.8 degrees in 80 to 90 min. The air temperatures near the chamber wall never exceeded 65 degrees while the air temperature adjacent to the animal was 46 degrees. Skin temperatures were approximately 42.5 degrees at a core temperature of 41.8 degrees. Once the core temperature is raised to 41.8 degrees, this temperature is maintainable for approximately 3.5 hr without additional external heating if evaporative losses are controlled. Prolonged WBH was accomplished with light sedation and without the requirement for endotracheal intubation. No significant acute toxicity was encountered in a series of 6 pigs undergoing 9 separate exposures to WBH. From these results, we conclude that our radiant heat apparatus is feasible for clinical trials. Additionally, the use of the pig as an appropriate animal model for further physiological and pharmacological WBH studies is strongly recommended.