Regulation

General and regional anesthesia are often associated with disregulation of body temperature and thus decreases in core body temperature. Most of the body heat lost during anesthesia is via convection and radiation, with some losses caused by conduction and evaporation. Principally, anesthetics cause the core body heat to redistribute to the periphery, resulting in a drop in core body temperature (58). Under anesthesia, patients become poikilotherms (have minimal ability to thermoregu-late). Therefore, multiple modalities to maintain normothermia during surgery have been developed, including forced-air warming devices, fluid warmers, ventilator humidifiers, water mattresses and vests, radiant lamps, and warm blankets. Other modalities for warming patients include altering ambient room temperatures or the temperatures of irrigation solutions.

Importantly, postoperative hypothermia may be associated with (1) delayed awakening from general anesthesia, (2) slowed drug metabolism, (3) coagulopathy, (4) vasoconstriction and poor tissue perfusion, (5) increases in blood viscosity, and/or (6) induced shivering. Importantly, postoperative shiver may be detrimental in patients with coronary artery disease because shivering causes increases in oxygen consumption and tachycardia. Currently, meperidine is clinically approved for treatment of excessive shivering in postoperative situations.

7. MYOCARDIAL PRECONDITIONING WITH INHALATIONAL

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