Based on standard and historical practice, the predictive size of the endotracheal tube (ETT) to be used in children has been based on various formulas. However, no study has clearly compared these formulas to determine the optimal size of cuffed ETTs. Furthermore, they were developed when using a polyvinylchloride cuff and not the thinner polyurethane cuff which is in common clinical use today. Hence, the purpose of this current study is to evaluate which of the currently available formulas most closely predicts the appropriate size of cuffed ETT to be used based not only on the fit within the trachea, but more importantly the intracuff pressure after the cuff is inflated to seal the airway.

Inclusion Criteria:

• Children who are less than 8 years of age and are scheduled for surgical procedures requiring endotracheal intubation with a cuffed ETT.

Exclusion Criteria:

• Children with airway anomalies or other factors that may impact tracheal size will be excluded from the study.

Children requiring an endotracheal tube for surgery.