A formula based on body length for determining the size of an uncuffed endotracheal tube for pediatric cardiac anesthesia

Three hundred and thirty-four pediatric patients less than 4 years old who underwent surgery for congenital heart disease were retrospectively studied to devise a practical formula for predicting the appropriate size for an uncuffed endotracheal tube for pediatric cardiac anesthesia. Furthermore, this formula was compared with that for non-cardiac anesthesia obtained from 409 patients without congenital heart disease. A simple regression equation between tube size and body length resulted in the simple predictive formula: "tube size = 0.04 x body length + 1.6" for pediatric cardiac anesthesia. This formula had the same slope and an approximately 0.3 mm larger intercept on the Y-axis compared with that for pediatric non-cardiac anesthesia. Therefore, a one-size larger endotracheal tube is more suitable for use in pediatric cardiac anesthesia than in pediatric non-cardiac anesthesia for the same body length.