Age-related thermoregulatory differences in a warm operating room environment (approximately 26 degrees C)

Inadvertent hypothermia occurs frequently at typical ambient operating room (OR) temperatures, especially in elderly patients receiving general anesth esia. The aims of the current study were to 1) determine the incidence and magnitude of core hypothermia in an unusually warm OR environment, and 2) t o assess age-related differences in perioperative thermoregulatory response s under these circumstances. Forty patients receiving general anesthesia fo r orthopedic surgical procedures (20 younger patients, 20-40 yr old) and (2 0 older patients, 60-75 yr old) were enrolled. Mean ambient temperature in the ORs was 25.8 degrees +/- 0.2 degrees C. Core temperature, vasoconstrict ion, and shivering were compared in the younger and older age groups. Mean core temperature on admission to the postanesthesia care unit was not signi ficantly different in the younger (36.7 degrees +/- 0.1 degrees C) and olde r (36.4 degrees +/- 0.1 degrees C) age groups. Only 10% of patients (n = 4, younger, 3 older) were admitted with a core temperature <36.0 degrees. Onl y 2% of patients (n = 1, older group) had a core temperature (35.5 degrees C. This very mild degree of hypothermia was associated with postoperative v asoconstriction in 80% of the younger and 55% of the older patients (P = 0. 18). Postoperative shivering occurred in 40% of the younger patients and in 10% of the older patients (P = 0.06). in summary, an ambient OR temperatur e near 26 degrees C (79 degrees F) is effective in preventing core hypother mia during general anesthesia regardless of patient age. Even very mild pos toperative hypothermia may initiate thermoregulatory responses. Implication s: By increasing ambient temperature in the operating room to 26 degrees C (79 degrees F), the incidence of cure hypothermia can be dramatically reduc ed in both younger and older patients.