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 (Tsk-carotid) with correction factors (Cf) to estimate core temperature. Primary outcome measure was to assess the sensitivity of Tsk-carotid with Cf for detecting hypothermia. Secondary outcome measure was to assess the specificity of Tsk-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 Tsk-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 Tsk-carotid by the formula: Tnaso-predicted = Tsk-carotid + Cf. Bland-Altman plots were used to assess the agreement between Tsk-carotid with Cf and Tnaso in the validation group.

RESULTS

The sensitivity for detecting hypothermia with the use of Tsk-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.