Background: Estimating the endotracheal tube size with the optimal internal diameter (ID) is of outstanding importance for airway management in pediatric patients. For many years different weight, height, and/or age-based formulas have been published. The aim of the present study was to identify and to compare published formulas to estimate optimal tube size in pediatric patients.
Materials and methods: A PubMed search was performed to identify published formulas for tube diameter in pediatric patients. The keywords "pediatric" or "paediatric", "anesthesia" or "anaesthesia", "anaesthesiology" or "anesthesiology", "size", "formula", "diameter", "tube" or "endotracheal tube" were used. Analysis was limited to articles published between 01.01.1951 and 30.06.2009. Additionally, similar publications retrieved from PubMed (related articles) and cited references were identified. Publications and formulas were assessed and classified by two independent colleagues.
Results: In the specified time-frame, 13 publications (11 original contributions and 2 letters to the editor) were identified with PubMed and 3 more formulas with the extended search. Altogether 22 formulas to estimate appropriate endotracheal tube size for pediatric patients (age 0-18 years) were identified: 12 age-based formulas for tubes without a cuff, 4 height-based formulas for tubes without a cuff, 2 weight-based formulas for tubes without a cuff and one multivariate formula for tubes without a cuff as well as 3 age-based formulas for cuffed endotracheal tubes.
Conclusions: The identified formulas were comparatively simple to apply but were validated only for pediatric patients older than 1 year. Using tubes with a cuff can minimize the problem of optimal tube size. If a tube without a cuff is intended to be used other sizes should also be available.