Skin temperature over the carotid artery provides an accurate noninvasive estimation of core temperature in infants and young children during general anesthesia

Abstract

Background The accurate measurement of core temperature is an essential aspect of intraoperative management in children. Invasive measurement sites are accurate but carry some health risks and cannot be used in certain patients. An accurate form of noninvasive thermometry is therefore needed. Our aim was to develop, and subsequently validate, separate models for estimating core temperature using different skin temperatures with an individualized correction factor. Methods Forty-eight pediatric patients (0-36 months) undergoing elective surgery were separated into a modeling group (MG, n = 28) and validation group (VG, n = 20). Skin temperature was measured over the carotid artery (T sk-carotid), upper abdomen (Tsk-abd), and axilla (T sk-axilla), while nasopharyngeal temperature (Tnaso) was measured as a reference. Results In the MG, derived models for estimating T naso were: Tsk-carotid + 0.52; Tsk-abd + (0.076[body mass] + 0.02); and Tsk-axilla + (0.081[body mass]-0.66). After adjusting raw Tsk-carotid, Tsk-abd, and T sk-axilla values in the independent VG using these models, the mean bias (Predicted Tnaso - Actual Tnaso [with 95% confidence intervals]) was +0.03[+0.53, -0.50]°C, -0.05[+1.02, -1.07]°C, and -0.06[+1.21, -1.28°C], respectively. The percentage of values within ±0.5°C of Tnaso was 93.2%, 75.4%, and 66.1% for T sk-carotid, Tsk-abd, and Tsk-axilla, respectively. Sensitivity and specificity for detecting hypothermia (T naso < 36.0°C) was 0.88 and 0.91 for Tsk-carotid, 0.61 and 0.76 for Tsk-abd, and 0.91 and 0.73 for T sk-axilla. Goodness-of-fit (R2) relative to the line-of-identity was 0.74 (Tsk-carotid), 0.34 (Tsk-abd), and 0.15 (Tsk-axilla). Conclusions Skin temperature over the carotid artery, with a simple correction factor of +0.52°C, provides a viable noninvasive estimate of Tnaso in young children during elective surgery with a general anesthetic. © 2013 John Wiley & Sons Ltd.