The accuracy and precision of body temperature monitoring methods during regional and general anesthesia

We tested the hypotheses that accuracy and precision of available temperatu re monitoring methods are different between spinal anesthesia (SA) and gene ral anesthesia (GA), and that patients receiving SA are at equal risk for h ypothermia as those receiving GA. Patients scheduled for radical retropubic prostatectomy were enrolled. Either GA (n = 16) or SA (n = 16) was given a ccording to patient and clinician preference. Temperatures were monitored w ith thermocouple probes at the tympanic membrane, axilla, rectum, and foreh ead skin surface. Tympanic temperatures were also measured with an infrared device, and forehead skin temperatures were monitored with two brands of l iquid crystal thermometer strips. Accuracy and precision of these monitorin g methods were determined by using tympanic membrane temperature, measured by thermocouple, as the reference core temperature (T-c). At the end of sur gery, T-c was similar between SA (35.0 +/- 0.1 degrees C) and GA (35.2 +/- 0.1 degrees C) (P = 0.44). Accuracy and precision of each temperature monit oring method were similar between SA and GA. Rectal temperature monitoring offered the greatest combination of accuracy and precision. All other metho ds underestimated T-c. These findings suggest that patients receiving SA or GA are at equal and significant risk for hypothermia, and should have thei r temperatures carefully monitored, recognizing that most monitoring method s underestimate T-c. Implications: Body temperature should be monitored dur ing spinal anesthesia because patients are at significant risk for hypother mia. Rectal temperature is a valid method of measuring core temperature, wh ereas other methods tend to underestimate true core temperature.