Rise of Tissue Temperature Induced by Reduced Blood Perfusion Caused by External Pressure

When homeostatic control is suppressed by anesthetizing patients, their body temperatures tend to lower to room temperature. To keep the patients’ body temperatures in an appropriate range, they are laid on warming mattresses in which warm water is circulated through flexible tubes embedded in plastic mattresses. Even though the water temperature is accurately controlled within a safe limit to avoid burn injuries, there have been cases where the body portions contacting the mattresses suffered from severe damage, showing symptoms of thermal injuries after a prolonged surgery of more than five hours (Crino & Nagel 1963, Scott 1967). Although the damage seemed light at the surface, it was often severe at deeper tissues. While it is likely that reduced perfusion is the origin of the injury, the process involved in the injury is still unknown. By close look at the various conditions related to the damage by warming mattresses, it has been suggested that the damage may be caused by some thermal conditions leading to burn injuries. Simple analysis of heat transport (Tanaka et al. 1991) has been reported showing that such burn injury may be possible if metabolic heat generation exists even under the conditions of reduced blood perfusion and thermal insulation to outside.