[Usefulness of a noncontact continuous tympanic thermometer in patients undergoing cardiac surgery using an artificial heart-lung machine].

BACKGROUND: Most of the thermometers used during operations are invasive and non-hygienic. The usefulness of a noncontact continuous tympanic thermometer under general anesthesia has been reported. We evaluated the usefulness of a noncontact continuous tympanic thermometer in patients undergoing cardiac surgery using an artificial heart-lung machine. METHODS: Twenty patients scheduled to undergo cardiac surgery using an artificial heart-lung machine were selected for this study. After induction of general anesthesia, thermistor probes were inserted into the rectum and esophagus for measurements of rectal and esophageal temperatures, respectively. A noncontact continuous tympanic thermometer was inserted into the ear canal on the right side. These temperatures were monitored and recorded at one-minute 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=0.983, P<0.05). Rectal temperature also showed a good correlation with esophageal temperature (r=0.923, P<0.05), but the coefficient of correlation was low compared to that of tympanic temperature. The mean difference between tympanic temperature and esophageal temperature was -0.022 degrees C, and standard deviation (SD) was 0.395 degrees C. The mean difference between rectal temperature and esophageal temperature was -0.299 degrees C, and standard deviation (SD) was 0.838 degrees C. CONCLUSIONS: A noncontact continuous tympanic thermometer is useful for measurement of core temperature during cardiac surgery using an artificial heart-lung machine.