Randomised trial of estimating oral endotracheal tube insertion depth in newborns using weight or vocal cord guide

Background When intubating newborns, clinicians aim to position the endotracheal tube (ETT) tip in the midtrachea. The depth to which ETTs should be inserted is often estimated using the infant's weight. ETTs are frequently incorrectly positioned in newborns, most often inserted too far. Using the vocal cord guide (a mark at the distal end of the ETT) to guide insertion depth has been recommended. Objective To determine whether estimating ETT insertion depth using the vocal cord guide rather than weight results in more correctly positioned ETT tips. Design Single-centre randomised controlled trial. Setting Level III neonatal intensive care unit (NICU) at a university maternity hospital (National Maternity Hospital, Dublin, Ireland). Patients Newborn infants without congenital anomalies intubated in the NICU. Interventions Participants were randomised to have ETT insertion depth estimated using weight [insertion depth (cm) = weight (kg) +6] or vocal cord guide. Main outcome measure Correct ETT position, that is, tip between the upper border of the first thoracic vertebra (T1) and the lower border of the second thoracic vertebra (T2) on a chest X-ray as determined by one paediatric radiologist masked to group assignment. Results 136 participants were randomised. The proportion of correctly positioned ETTs was similar in both groups (weight 30/69 (44%) vs vocal cord guide 27/67 (40%), p=0.731). Most incorrectly positioned ETT (69/79, 87%) were too low. Conclusion Estimating ETT insertion depth using the vocal cord guide did not result in more correctly positioned ETT tips.