Utility of the tympanic membrane temperature probe for continuous core temperature monitoring during general anesthesia: in vitro laboratory validation and prospective observational study

Background: Continuous tympanic membrane temperature (T-TM) monitoring is minimally invasive and may be suitable for core temperature measurement during anesthesia. This study aimed to evaluate the accuracy and safety of T-TM compared to infrared tympanic thermometer temperature (T-IRT) and esophageal temperature (T-ESO).Methods: This study included both in vitro validation and a prospective observational study conducted at a tertiary hospital. In vitro agreement between T-TM and T-ESO over a temperature range of 32 to 42°C was assessed using Bland−Altman analysis. Clinically, 40 adults undergoing general anesthesia were under continuous T-TM and T-ESO monitoring, with T-IRT measured at three perioperative time points. Agreement was evaluated using Bland−Altman analysis, and temporal changes were assessed using repeated-measures analysis of variance. Hypothermia was defined as core temperature < 36.0°C. Safety was assessed using otoscopy before and after anesthesia.Results: In vitro, T-TM and T-ESO showed minimal mean bias (−0.01°C; 95% confidence interval [CI], −0.03 to 0.00°C), with limits of agreement (LoA) ranging from −0.22 to 0.20°C. Clinically, T-TM was comparable to T-IRT (mean bias: 0.04°C; 95% CI, 0.00 to 0.07°C; LoA: −0.33 to 0.41°C) but consistently higher than T-ESO as anesthesia progressed (mean differences: 0.31 to 0.80°C; P < 0.001). Hypothermia detection was lower with T-TM (37.5%) than with T-ESO (85.0%) (P < 0.001). No otological complications were observed.Conclusions: T-TM demonstrated excellent agreement with T-ESO in vitro and was comparable to T-IRT in clinical settings. However, it tended to yield slightly higher readings than T-ESO, which should be considered during perioperative temperature monitoring.