Thermoregulation and temperature monitoring

Body temperature is primarily controlled by two mechanisms: autonomic control and behavioral modifications. However, the anesthetized patient loses the behavioral control when rendered unconscious, and the autonomic nervous system is altered by medications affecting vessel tone. The anterior hypothalamus is the main temperature regulator of the body. Aδ and C fibers transmit temperature to the hypothalamus. Temperature is maintained tightly within 0.2°C from the hypothalamic set point, although the body varies by 1°C daily, with the lowest temperature occurring in early morning and the highest occurring approximately 12 hours later. The body produces heat through the conversion of glucose into ATP. Heat is then handled by the body with one metabolic equivalent (MET) being equal to the calorie consumption of 1 kCal/kg/h. As an estimate, two flights of stairs walked at a steady pace are equivalent to approximately four METs.