Simple calculation of the optimal insertion depth of esophageal temperature probes in children

Placing an esophageal temperature probe (ETP) in the optimal esophageal site is important in various anesthetic and critical care settings to accurately monitor the core temperature of a pediatric patient. However, no reported study has provided a formula to calculate the optimal insertion depth of ETP placement in children based on direct measurement of the optimal depth. The aim of this study was to develop a simple and reliable method to determine the optimal depth of ETP placement in children via their mouth. Using preoperative chest computed tomography scans, intraoperative chest X-rays, and the actual depth of ETP insertion, we measured the optimal depth of ETP placement retrospectively in 181 children aged 3–13 years who underwent minimally invasive repairs of the pectus excavatum and removal of a pectus bar. A linear regression analysis was performed to assess the correlation of the optimal depth of ETP placement with the children’s age, weight, and height. The optimal depth of ETP placement had a greater correlation with height than with age or weight, and the best-fit equation was ‘0.180 × height + 6.749 (cm) (R² = 0.920).’ We obtained three simplified formulae, which showed no statistically significant difference in predicting the optimal depth of ETP placement: height/6 + 8 (cm), height/5 + 4 (cm), and height/5 + 5 (cm). The optimal depth of ETP via children’s mouths has a close correlation with height and can be calculated with a simple formula ‘height/5 + 5 (cm)’.