The usefulness of an earphone-type infrared tympanic thermometer for Intraoperative core temperature monitoring

BACKGROUND: In this study we sought to determine the usefulness of a novel earphone-type infrared tympanic thermometer (IRT) for core temperature monitoring during surgery. METHODS: Two groups of patients were studied under different surgical conditions. The first group consisted of 18 adult patients (ASA I or II) who had been scheduled for elective surgery under general anesthesia. Before induction of general anesthesia, an earphone-type IRT was inserted into either the left or right ear canal. Tympanic temperature was monitored and recorded along with both rectal and esophageal temperatures during anesthesia. The second group consisted of eight adult patients (ASA II or III) who had been scheduled for cardiac surgery with cardiopulmonary bypass. Similar to the first group, tympanic temperature was measured by the earphone-type IRT and recorded along with the rectal and esophageal temperatures during cooling and rewarming phases of cardiopulmonary bypass. RESULTS: Study 1-The average temperature (+/- 2 SD) measured with the IRT was +0.08 degrees C (0.34 degrees C) above the esophageal temperature, and that with the rectal temperature was +0.11 degrees C (+/- 0.55 degrees C) above the esophageal temperature. Study 2-The average temperature (+/- 2 SD) measured with the IRT was +0.72 degrees C (+/- 2.2 degrees C) above the esophageal temperature during cooling and warming phases during cardiac surgery with cardiopulmonary bypass. CONCLUSIONS: The earphone-type IRT might be used in a clinical setting for reliable and continuous core temperature monitoring during an operation.