Sizing guidelines for selecting an ETT

When selecting an endotracheal tube (ETT), what sizing guidelines are suggested? 

There are a number of ways to ensure selection of properly sized ETTs for children. The most often cited is the following age-based formula:ETTinternaldiameter(mm)=(16+yearsofage)/4ETTinternaldiametermm=16+yearsofage/4

Another “rule of thumb” is really a “rule of finger.” Research has demonstrated that the width of the child’s fifth fingernail is approximately equal to the outer width of the appropriately sized ETT. Most emergency physicians use uncuffed tubes for children younger than 10 years, because in these patients, the anatomic narrowing at the level of the cricoid cartilage provides a natural “cuff.” However, in the in-hospital setting, a cuffed tube has been shown to be as safe as an uncuffed tube for infants beyond the newborn period. In some circumstances (e.g., poor lung compliance, high airway resistance, or a large glottic leak), a cuffed tube may be preferable. 


American Heart Association: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Part 10: Pediatric Basic and Advanced Life Support. Circulation 2010;122:S466-S515.


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