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Conversely, when normothermia was maintained, a cost savings of up to $7,000 per patient was realized.Evidence-based practices to prevent perioperative hypothermia include identifying risk factors, measure-www.aana.com/aanajournalonline AANA Journal n February 2015 n Vol. 83, No. 1 65ing temperature, and initiating preventive and active warming measures.28 Risk factors are independent pre-dictors used to determine the potential for developing hypothermia. They include extremes of age, female gender, length and type of procedure, administration of general and spinal anesthesia, ambient temperature of the operating room (OR), and preexisting conditions (ex-tensive burns, endocrine disorders, pregnancy, and large open wounds).27 No single method of measuring temper-ature is deemed the gold standard. Core temperature may be measured in the distal esophagus, pulmonary artery, nasopharynx, or adjacent to the tympanic membrane.25 Use of an esophageal temperature probe in the intubated patient is the most reliable method. Skin temperature is approximately 2°C less than core temperature; thus, forehead skin temperature measurement only estimates core temperature. Clinical research suggests that rectal temperature lags behind temperature measured in the esophagus and the pulmonary artery. Moreover, rectal temperature measurement fails to appropriately rise during malignant hyperthermia and therefore must be used with caution.25The American Association of Nurse Anesthetists Standards for Nurse Anesthesia Practice29 requires tem-perature monitoring of all patients receiving anesthesia for whom large temperature changes are intended, an-ticipated, or suspected. Therefore, patient temperature should be monitored at no less than 15-minute intervals during all general and regional anesthetic procedures of more than 60-minute duration and during all pediatric procedures that are 30 minutes or longer.25The greatest decline in patient temperature occurs during the first hour of surgery.27 The CRNA should intervene immediately on entering the surgical suite by applying warm blankets to limit the patient’s skin exposure to low ambient temperature.