Concordance of esophageal and tracheal temperatures in patients using breathing circuit with heated wire humidifierA prospective observational study

No study has compared tracheal and esophageal temperatures when a breathing circuit with a heated wire humidifier was used. This study aimed to investigate the correlation between tracheal and esophageal temperatures in patients using a breathing circuit with heated wire humidifiers. Tracheal temperatures measured by the cuff sensor correlated well with esophageal temperatures while using a heated wire humidifier breathing circuit in patients with anesthesia duration of > 2 hours. Thirty-eight patients who underwent general anesthesia for > 2 hours were enrolled. Tracheal and esophageal temperatures were recorded at 5-minute intervals, starting from the insertion of the esophageal temperature probe to the end of anesthesia. The temperatures were compared by Bland-Altman analysis, calculating the proportion of tracheal temperature measurements within +/- 0.25 degrees C of esophageal temperatures, and linear mixed-effects model. Univariate analysis was performed to assess whether any variables influenced the proportion of differences within +/- 0.25 degrees C. Results: After excluding 4 patients with an anesthesia duration of < 2 hours, data from 34 patients (1163 sets of tracheal and esophageal temperatures) were analyzed. Concordance correlation coefficient was 0.78. The overall mean bias (95% limits of agreement) between the tracheal and esophageal temperatures was -0.16 degrees C (-0.65 degrees C to 0.34 degrees C). The percentage of temperature differences within +/- 0.25 degrees C was 73.5% +/- 32.3, with a median of 89.4% [0,100]. The linear mixed-effects model revealed that the estimated intercept was 0.17 degrees C with a 95% confidence interval (CI) of 0.13 degrees C to 0.22 degrees C. The duration of anesthesia and the number of temperature measurements were associated with higher concordance between the tracheal and esophageal temperatures in univariate analysis.