[Usefulness of an earphone-type infrared tympanic thermometer for intraoperative core temperature monitoring].

Background: Thermometers widely used intraoperatively are invasive and non-hygienic. We developed an earphone-type infrared tympanic thermometer and evaluated its usefulness as a core temperature monitor.

Methods: Sixteen adult patients who required nonabdominal surgery under general anesthesia were enrolled in this study. After induction of general anesthesia, thermistor probes were inserted into the rectum and esophagus for measurements of rectal and esophageal temperatures, respectively. An earphone-type infrared tympanic thermometer was inserted into the ear canal on one side. These measured temperatures were monitored and recorded at 1-min intervals. Regression analysis and Bland-Altman analysis were used to compare the data (tympanic/rectal temperatures) with esophageal temperature as a core temperature.

Results: Tympanic temperature showed a good correlation with esophageal temperature (r = 0.976, n= 2490, P < 0.001). The mean difference between these temperature monitors was+0.06 degrees C, and 2x standard deviation (SD) was 0.32 degrees C. Rectal temperature also showed a good correlation with esophageal temperature (r = 0.946, P < 0.001). The mean difference between these monitors was+0.22 degrees C, and 2 SD was 0.28.

Conclusions: The earphone-type tympanic thermometer can be used in a clinical setting as a reliable core temperature monitor.