Height best predicts the optimal insertion length of orotracheal tubes in children

Abstract

Introduction Accurate formulae to predict the optimal insertion length of endotracheal tubes (ETT) are necessary for safe care and have been based on height, weight, age, and ETT size. We believe height best reflects the somatic growth of the trachea. Our goal is to compare a formula generated using height for optimal initial insertion length of ETT to previously published formulae based on height, weight, age, and ETT size. Methods We retrospectively reviewed chest radiographs over a two-year period where the head was assured in midline and midposition. We excluded children with conditions altering tracheal dimensions or stature, and scoliosis. We chose 2 cm above the carina to be the optimal insertion length of the ETT which was then correlated to height. We created linear regression equations and Bland-Altman plots. Results Two hundred three orotracheally intubated children were included. The optimal ETT insertion length using the formula Height (cm)/8 + 3.4 had a high association with linear regression and Bland-Altman plots had the narrowest 95% limits of agreement as compared to previously published formulae. Conclusions We found optimal insertion length = Height (cm)/8 + 3.4 is more accurate as compared to commonly used formulae that are based on weight, age, or ETT size. This formula places the ETT 2 cm above the carina which should be safe until a chest radiograph is obtained. We find that the use of formulae that divide the height by 10 overestimates the depth of insertion in younger, smaller children and underestimates the depth of insertion in older children.