Clinical accuracy of ultrasonography to predict the size of endotracheal tube in neonates: an observational study

Endotracheal tube (ETT) is the definitive method for the management of airway during

general anaesthesia in neonates undergoing surgery. Conventionally, ETT size in neonates is

selected according to the gestational age and weight. However, these criteria are not always

accurate to estimate the correct ETT size and multiple trials of intubation and tube changes

may be required to place an appropriate size ETT. This may cause hypoxia and may also lead

to airway mucosal edema. An inappropriately sized ETT can lead to morbidity as large ETT

can cause airway damage and injury, subglottic edema, post extubation stridor, local

ischemia, scar formation and subglottic stenosis after a prolonged duration of intubation.

A smaller sized ETT will lead to higher leaks and thus, insufficient ventilation, high airway

resistance, poor monitoring of end-tidal gases and higher risk of aspiration and thus, lung

infections. Therefore, it is essential to determine the appropriate size of ETT for each patient

at the first attempt.

Ultrasonography (USG) is a safe and reliable modality which allows for a real time

and non-invasive assessment of the airway and subglottic area for estimation of ETT size,

thereby reducing the associated complications associated with an incorrect size ETT. This

study therefore, aims to determine the accuracy of USG to predict the size of endotracheal

tubes in neonates.

Multiple studies have been done for estimating the appropriate size of ETT in paediatric

population using ultrasonography. However, there is limited published literature related to

determining the ETT size by ultrasonography in neonates.