Axillary versus rectal temperature monitoring in patients undergoing ear, nose, and throat surgery under general anesthesia

Abstract

© JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND 2020. Background: Inadvertent perioperative hypothermia is a common occurrence during procedures performed under general anesthesia. Core temperature monitoring via esophageal, nasopharyngeal, or rectal temperature measurement has been considered reliable methods. However, placing a temperature probe at these sites might be unsuitable for patients undergoing ear, nose, and throat (ENT) surgery. Objective: Therefore, the present study aimed to determine the correlation of axillary temperature with that of rectal temperature for temperature monitoring. Materials and Methods: Forty adults with the American Society of Anesthesiologists physical status I-III that underwent ENT surgery were enrolled. All patients got standard perioperative warming procedures. Intraoperative axillary and rectal temperature measurements were concurrently obtained at 15-minute intervals. The data were analyzed using Pearson or Spearman correlation and repeated measures Bland-Altman analysis. Results: Axillary and rectal temperatures were well correlated with each other (r=0.549, R2=0.301, p<0.001). The Bland-Altman plot showed that the mean axillary temperature was 0.9℃ less than the mean rectal temperature. Overall, the 95% limit of agreement was 3.4℃ (–2.6 to 0.9), yielding a relatively poor agreement between axillary and rectal temperatures. Nevertheless, the mean bias was reduced to 0.6℃ when the measurements obtained 90 minutes after anesthesia induction were separately analyzed. Conclusion: Under standard warming procedures, axillary temperature monitoring may correlate well with rectal temperature starting of 90 minutes after induction of general anesthesia in patients that underwent elective ENT surgery with the difference of 0.6℃.