Evaluating endotracheal tube length in very and extremely preterm infants

Our study objective was to evaluate changes in ETT tube depth throughout the initial intubation course in very and extremely preterm infants in order to evaluate the risk of outgrowing an endotracheal tube (ETT).

This was a retrospective cohort study of preterm infants born at <32 weeks of gestation who were admitted to the NICU between 2012 and 2021 and required intubation for mechanical ventilation. Infants who were intubated only for surfactant administration and those with airway malformations were excluded. Descriptive statistics were used to define the range of ETT depths at the time of extubation, stratified by gestational age (<28 weeks vs 28-32 weeks of gestation). Relative ETT depth was defined as the final depth minus the initial depth.

Out of 496 infants, 140 patients met all criteria for inclusion. Descriptive analysis of extubation depths across the populations demonstrated median relative ETT depth of 0 cm for the 28-32-week gestational age group, and -0.25 cm for the <28-week gestational age group. The 95th percentile for both gestational age groups was a relative depth of 0.5 cm and the 99th percentile was 1.0-1.5 cm.

The results of our study suggest that the vast majority of patients in the NICU are unlikely to "outgrow" ETT tube length which should be taken into account when deciding where to trim the ETT in order to minimize airway resistance.