Limitations of temperature measurement in the aural canal with an ear mould integrated sensor

摘要

Aural canal temperature measurement using an ear mould integrated sensor (T_(ac)) might be a method suited for continuous non-invasive core temperature estimation in operational settings. We studied the effect of ambient temperature, wind and high intensity exercise on T_(ac) and its ability to predict esophageal (T_(es)) and rectal temperatures (T _(re)). Seven subjects performed a protocol of rest at 21, 10 and 30 °C, followed by exercise and recovery at 30 °C. The subjects performed the protocol twice: with and without face-wind from halfway through the 30 °C rest period. Extra auricle insulation was applied at one side. Ambient temperature changes affected T_(ac) significantly, while T_(es) and Tre remained stable. Insulating the auricle reduced but did not abolish this effect. Wind had an immediate cooling effect on T_(ac) independent of auricle insulation. During exercise and recovery in 30 °C, T_(ac) provided acceptable group predictions of T_(re) in trials without wind (bias: -0.66 0.21 °C covered, -1.20 0.15 °C uncovered). Bias was considerably higher with wind, but variability was similar (-1.73 0.11 °C covered, -2.49 0.04 °C uncovered). Individual predictions of T _(es) and T_(re) showed more variation, especially with wind. We conclude that T_(ac) may be used for core temperature assessment of groups in warm and stable conditions.