Supplementary Material for: Prospective Validation of a Length-Based Nasotracheal Intubation Depth Table ('Hamburg NNTT Table') in Neonates

Background: Accurate endotracheal tube (ETT) placement is crucial for safe ventilation in neonates. Traditional formulae based on weight or gestational age often yield suboptimal accuracy. The length-based “Hamburg Neonatal Naso-Tracheal Tube Table” (Hamburg NNTT Table) was proposed to improve precision. This study aimed to evaluate the clinical applicability and accuracy of the Hamburg NNTT Table in a tertiary neonatal intensive care unit (NICU).Methods: In this prospective single-centre study, 72 neonates (58 preterm, 14 term) requiring nasotracheal intubation were enrolled. Crown-heel length was measured, and ETT depth determined according to the Hamburg NNTT Table. Correct placement was defined radiographically as the ETT tip in the middle third of the trachea.Results: Correct positioning occurred in 90.3% of cases. Accuracy was lower in extremely preterm infants (<28 weeks; 80.6%) compared to older infants (97.6%; p=0.016).Conclusions: The Hamburg NNTT Table provides a simple and accurate method for neonatal nasotracheal tube placement, though refinement is warranted in extremely preterm infants.