The impact of moderate ambient temperature variance on the relationship between oral, rectal, and tympanic membrane temperatures.

We examined the effect of moderate ambient temperature variance on the relationship between oral (OT), rectal (RT), and tympanic membrane (TMT) temperature in 21 healthy adults. Calibrated digital electronic thermometers were used to assess OT and RT, while TMT was measured using an infrared detection device and microprocessor. Recordings were made at baseline and after 15 and 20 minutes of exposure to either warm (35 degrees C) or cool (18.3 degrees C) environmental temperatures. Differences were examined for the three temperature sites and times using repeat measures analysis of variance. No significant differences in RT (37.7 degrees +/- 0.3 degrees C; mean +/- SD) were observed at any time. Both OT (+0.5 degrees C) and TMT (+0.7 degrees C) were significantly changed during warm, but not cool exposure, compared to baseline conditions. We conclude that OT and TMT have a predictable relationship to RT at normal ambient temperature. However, in warm examination areas, spuriously elevated OT and TMTs may occur.