Tympanic membrane temperature as a measure of core temperature

Background-Ear thermometers are becoming popular as a method for measuring deep body (core) temperature. Aim-To determine the variability of a single user's tympanic membrane tear) temperature measurements. Subjects-Forty two, afebrile, healthy children, and 20 febrile children wit h acute burns. Results-In afebrile children measurements made in both ears (and within jus t a few minutes of each other) differed by as much as 0.6 degrees C. Operat or measurement error, s(w) of three consecutive measurements, in the same e ar, was 0.13 degrees C. In the group of febrile, burned children, core temp erature was measured hourly at a number of sites (ear, rectum, axilla, blad der). A peak in core temperature occurred approximately 10-12 hours after t he burn. Measurement error was calculated in 14 febrile, burned children wi th a peak temperature in excess of 38 degrees C. For the left ear, measurem ent error was 0.19 degrees C and for the right ear, 0.11 degrees C. In the febrile children agreement between the ears was poor. The Limits of agreeme nt were 0.4 degrees C to -0.8 degrees C. It was not possible to predict the occasions when the temperature differences between the ears would be large or small. Conclusions-The measurement error of one recording from the next is probabl y acceptable at about 0.1 to 0.2 degrees C. To limit the variations in temp erature of one ear to the other, measurements should be restricted to one o f the ears whenever possible and the same ear used throughout the temperatu re monitoring period. Nurses and parents should take more than one temperat ure reading from the same ear whenever possible.