Comparison of esophageal, tympanic, and forehead skin temperatures in adult patients

Study Objective: To compare esophageal, tympanic membrane, and forehead skin t Design: Prospective clinical study. Setting: Operating room and postanesthesia care unit of a tertiary care teaching hospital. Patients: 40 adult ASA status I, II and III patients requiring anesthesia and surgery. Intervention: Application of crystalline thermometry strips to the forehead of patients. Measurements and Main Results: Concurrent forehead skin, tympanic membrane, and lower esophageal and skin temperatures was 0.3 degrees C, between tympanic membrane and skin was 0.5 degrees C, and between esophageal and tympanic membrane was -0.1 degrees C. The limits of agreement (precision) between esophageal and skin temperatures were: -1.64 degrees C to +2.32 degrees C, between esophageal and tympanic membrane were: -1.02 degrees C to +0.74 degrees C, and between tympanic membrane and skin were: -1.48 degrees C to +2.52 degrees C. There was no significant relation between the change in skin temperature and change in esophageal temperature, whereas there was a weak linear relation between change in skin temperature and change in tympanic membrane temperature (y = -0.03 + 0.09, r = 0.12). Conclusion: There was a lack of precision between the clinically accepted measurements (lower esophageal and tympanic membrane) and the skin temperature measurement. The data suggest that forehead skin temperature is not interchangeable with standard core temperture measurements, and that sole reliance on the forehead skin measurement in the perioperative setting could adversely affect patient care.