Comparative accuracy of oro-helix length, naso-tragus length, and gestational age-based methods for endotracheal tube depth prediction in neonates ≤1,500 g

Objective To evaluate the accuracy and reliability of the Oro-helix length (OHL), Naso-tragus length (NTL), and gestational age-based table (GA table) in predicting the ideal endotracheal tube (ETT) depth in neonates. Study design This prospective study enrolled orally intubated neonates weighing ≤1,500 g admitted to a level IIIC neonatal intensive care unit (NICU) from April 2022 to February 2024. For each patient, the ETT insertion depths were predicted using OHL and NTL measurements, along with the GA table. To compare the accuracy of these methods, all predicted depths were assessed against the ideal depth determined by chest radiograph (CXR). Statistical analyses were conducted using a linear regression Bland–Altman model. Results Fifty were enrolled with a mean gestational age of 26.6 ± 1.5 weeks and a mean intubation weight of 953 ± 246.8 g. Among the three methods compared, NTL measurements demonstrated the greatest bias (−0.61 cm) and less agreement (−1.78 to 0.56 cm) than either OHL (−0.96 to 1.27 cm) or the GA table (−1.37 to 0.91 cm). OHL had the least bias (0.15 cm) and showed the strongest correlation with gestational age (slope = 0.09, R2 = 0.12, p = 0.02). In contrast, the correlations with gestational age for NTL and the GA table were weaker and not statistically significant (NTL: slope = 0.05, 95% CI: −0.02 to 0.13, R2 = 0.04, p = 0.16; GA table: slope = 0.02, 95% CI: −0.04 to 0.07, R2 = 0.01, p = 0.58). Conclusion In neonates ≤1,500 g, OHL is the most accurate and reliable method for predicting ETT depth. OHL outperforms the NTL and GA tables based on CXR and thus may potentially be preferred approach for accurate ETT depth determination.