TY - CHAP M1 - Book, Section TI - Chapter 88. Thermoregulation and Perioperative Hypothermia A1 - Grocott, Hilary P. A1 - Tran, Tony A2 - Longnecker, David E. A2 - Brown, David L. A2 - Newman, Mark F. A2 - Zapol, Warren M. PY - 2012 T2 - Anesthesiology, 2e AB - Adults thermoregulate with their environment by cutaneous vasomotor adjustments, sweating, shivering, and environmental behavioral adaptation (dressing appropriately, modifying environmental temperature).Neonates do not shiver but can generate heat via nonshivering thermogenesis.Heat loss occurs via sweating and cutaneous vasodilation. Heat conservation results from cutaneous vasoconstriction and behavioral adaptation.Although not precisely defined, core temperature reflects mean temperature of the well-perfused organs (eg, brain, heart, kidney, and lungs).Hypothermia that develops during general anesthesia typically follows a predictable pattern: (1) an initial rapid decrease in core temperature of between 0.5°C and 1.5°C during the first hour after induction, believed to be the result of internal redistribution of heat; (2) a more gradual linear decline in core temperature, usually lasting 2 to 3 hours, that results from cutaneous heat loss exceeding metabolic heat production (typically 0.5°C/h to 1°C/h); and (3) a plateau phase when core temperature stabilizes after 3 to 4 hours that results from the thermoregulatory balance of continual heat production and loss.Following redistribution-mediated decreases in temperature, body heat loss occurs via radiation (60% of heat loss) and convection (30%), with less than 10% occurring via evaporation, and a negligible amount via conduction.Postanesthesia shivering is most likely mediated via a normal thermoregulatory response to hypothermia.Hypothermia during regional anesthesia is caused by the depression of regional thermal afferent input and efferent responses, such as vasoconstriction and shivering, loss of heat to the operating room environment, and redistribution of heat within the body.Hypothermia during anesthesia may be prevented or treated by prewarming, the control of ambient temperature, skin insulation, warm intravenous solutions, heating and humidifying inspired gases, the application of a forced-air convective heating system, and the use of new-generation circulating-water convective heating systems.There is an abundance of experimental evidence for the neuroprotective effects of hypothermia; clinical applications include deep hypothermic circulatory arrest for cardiac surgery, patients having suffered from witnessed cardiac arrest from ventricular fibrillation, and possibly perinatal asphyxia. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/10/05 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=56656783 ER -