[The correct endotracheal tube size for infants and children].

The correct endotracheal tube size was assessed in 600 anesthetized infants and children. The correct tube size was determined by the airway pressure at which a gas leak around the endotracheal tube occurred, when the lungs were inflated with slowly increasing positive pressure. Endotracheal tube size correlated most with body length where the correlation coefficient was 0.973 (P less than 0.01), followed by body weight, tracheal size in X-ray photograph and age. But, there were four correct tube sizes for patients with the same body length.