Reliability of Tracheal Temperature as a Measurement of Core Body Temperature During Cardiac Surgery Using Cardiopulmonary Bypass.

: To compare tracheal temperature (T) with nasopharyngeal temperature (T) in patients undergoing cardiac surgery using cardiopulmonary bypass (CPB). : T was measured using a thermistor in the cuff of an endotracheal tube and T was monitored using an esophageal stethoscope. Depending on the management of the CPB strategy, the operation was divided into four periods (pre-CPB, cooling, rewarming, and post-CPB). A Bland-Altman analysis was carried out to compare T with T in each period. The concordance correlation coefficient for repeated measures analysis and various time lags was used to validate the time lag maximizing the concordance correlation coefficient between the two methods. : A total of 7191 pairs of temperature recordings acquired from 24 patients were included in the analysis. During steady normothermia, 81.7% (95% confidence interval [CI], 79.8-83.5%) of the pairs had a difference within ±0.5 °C, with a mean bias of -0.28 °C and limits of agreement (LOA) of -0.74 °C to 0.18 °C. The LOA during the cooling and rewarming phase of CPB were -1.13 °C to 0.51 °C and -0.91 °C to 1.29 °C, respectively. The mean bias and LOA throughout the entire operation were -0.10 °C and -0.98 °C to 0.77 °C, respectively. Throughout the entire operation, -2 min of time lag on T maximized the concordance correlation coefficient (0.94 [95% CI, 0.92-0.96] to 0.95 [95% CI, 0.93-0.96]), indicating an earlier response of T than T. : T could be an alternative to T during cardiac surgery using CPB.