The accuracy of a disposable noninvasive core thermometer.

Purpose: Perioperative hypothermia is still a common occurrence, and it can be difficult to measure a patient's core temperature accurately, especially during regional anesthesia, with placement of a laryngeal mask airway device, or postoperatively. We evaluated a new disposable double-sensor thermometer and compared the resulting temperatures with those of a distal esophageal thermometer and a bladder thermometer in patients undergoing general and regional anesthesia, respectively. Furthermore, we compared the accuracy of the thermometer between regional and general anesthesia, since forehead microcirculation might differ between the two types of anesthesia.

Methods: We assessed core temperature in 36 general anesthesia patients and 20 patients having regional anesthesia for orthopedic surgery. The temperatures obtained using the double-sensor thermometer were compared with those obtained with the distal esophageal thermometer in the general anesthesia population and those obtained with the bladder thermometer in regional anesthesia patients.

Results: In our general anesthesia patients, 90% (95% confidence interval [CI] 85 to 95) of all double-sensor values were within 0.5°C of esophageal temperatures. The average difference (bias) between the esophageal and double-sensor temperatures was -0.01°C. In patients undergoing regional anesthesia 89% (95% CI 80 to 97) of all double-sensor values were within 0.5°C of bladder temperatures. The average difference (bias) between the bladder and double-sensor temperatures was -0.13°C, limits of agreement were -0.65 to 0.40°C.

Conclusions: In a perioperative patient population undergoing general or regional anesthesia, the accuracy of the noninvasive disposable double-sensor thermometer is comparable with that of the distal esophageal and bladder thermometers in routine clinical practice. Furthermore, the sensor performed comparably in patients undergoing regional and general anesthesia.