Noninvasive temperature monitoring in postanesthesia care units

Initial postoperative core temperature is a physician and hospital performance measure. However, the extent to which core temperature changes during emergence from anesthesia and transport from the operating room to the postanesthesia care unit (PACU) remains unknown. Similarly, the accuracy of many noninvasive temperature-monitoring methods used in the PACU has yet to be quantified. This study, therefore, quantified the change in core temperature occurring during emergence and transport and evaluated the accuracy and precision of eight noninvasive thermometers in the PACU.

In 50 patients having laparoscopic surgery, the authors measured temperatures upon PACU arrival and 30 and 60 min thereafter. Monitoring methods included oral, axillary, temporal artery, forehead skin-surface, forehead liquid-crystal display, infrared aural canal, deep forehead, and deep chest. Bladder temperature was used as the reference and was also measured at the end of surgery. The primary outcome was agreement between individual temperatures from each method and bladder temperature in the PACU. A priori, the authors chose 0.5 degrees C as a clinically important temperature deviation.

Bladder temperature increased 0.2 +/- 0.3 degrees C (95% confidence interval 0.1 to 0.3 degrees C), P < 0.001, during transport. None of the tested noninvasive thermometers was consistently within 0.5 degrees C of bladder temperature. However, oral, deep forehead, and temporal artery temperatures were significantly better than other methods and agreed reasonably well with bladder temperature.

Invasive temperature monitoring available intraoperatively is more accurate than any generally available postoperative methods. Physician performance measures should therefore not be based exclusively on postoperative temperatures. Among the generally available postoperative monitoring methods, electronic oral thermometry appears to be the best.