TY - CHAP M1 - Book, Section TI - Thermoregulation and Perioperative Hypothermia A1 - Grocott, Hilary P. A2 - Longnecker, David E. A2 - Mackey, Sean C. A2 - Newman, Mark F. A2 - Sandberg, Warren S. A2 - Zapol, Warren M. PY - 2017 T2 - Anesthesiology, 3e AB - KEY POINTSAdults thermoregulate with their environment by cutaneous vasomotor adjustments, sweating, shivering, and, when not under anesthesia, 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, lungs).Hypothermia that develops during general anesthesia typically follows a predictable pattern: (1) an initial rapid decrease in core temperature ranging between 0.5°C and 1.5°C during the first hour after induction principally the result of internal redistribution of heat; (2) a more gradual linear decline in core temperature, usually lasting 2-3 hours that results from cutaneous heat loss exceeding metabolic heat production (typically 0.5-1°C/hour); and (3) a plateau phase when core temperature stabilizes after 3-4 hours, representing 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 <10% occurring via evaporation, and a negligible amount via conduction.Postanesthesia shivering is most likely mediated via normal thermoregulatory response to hypothermia.Hypothermia during regional anesthesia is caused by depression of both 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 ameliorated by patient prewarming.The control of ambient temperature, skin insulation, warm IV 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.Although there is an abundance of experimental evidence for the neuroprotective effects of hypothermia, aside from the clinical application for cardiac surgery under deep hypothermic circulatory arrest, there are few, if any, other settings where its efficacy is well founded. Any protection afforded to it may be the result of its ability to prevent postcerebral injury hypothermia. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1144136663 ER -