Accuracy of skin temperature over carotid artery in estimation of core temperature in infants and young children during general anaesthesia

BACKGROUND AND AIMS: Core temperature monitoring is essential in children under general anaesthesia as they are more susceptible to hypothermia. We aimed to use skin temperature over the carotid artery (T(sk)-carotid) with correction factors (Cf) to estimate core temperature. Primary outcome measure was to assess the sensitivity of T(sk)-carotid with Cf for detecting hypothermia. Secondary outcome measure was to assess the specificity of T(sk)-carotid with Cf for detecting hypothermia. METHODS: First consecutive 50 patients fulfilling the inclusion criteria were included in modelling group and next 60 in the validation group. In the modelling group, average estimation error between T(sk)-carotid and Tnaso was calculated and Cf was derived by multiple regression analysis (body surface area to mass ratio, body fat %, room temperature, relative humidity and warm Gamgee). In the validation group, Cf derived was used to predict Tnaso using T(sk)-carotid by the formula: Tnaso-predicted = T(sk)-carotid + Cf. Bland–Altman plots were used to assess the agreement between T(sk)-carotid with Cf and Tnaso in the validation group. RESULTS: The sensitivity for detecting hypothermia with the use of T(sk)-carotid and Cf was 100%. The final Cf derived was 0.064 × (room temperature) −2.65. Most of the measurements fell within 95% confidence limit of Bland–Altman plot; 95% confidence interval (0.504–[−0.451]). The specificity of this method was 11%. CONCLUSION: This method overestimated hypothermia in most cases and cannot be accurately used as a measure of core temperature monitoring perioperatively.