Comparison of Three Methods in Estimating the Oral Endotracheal Tube Insertion Depth in Neonates: Nasal Septum-Tragus...

This study compared the performances of nasal septum-tragus length (NTL)-based formula, body weight-based formula, and gestational age (GA)-based table in estimating the depth of oral endotracheal tube (ETT) insertion in neonates.

Neonates undergoing oral endotracheal intubation were recruited in this study. The depths of orotracheal tubes were estimated using NTL-based formula (NTL + 1 cm for neonates weighing < 2500 g and NTL + 0.5 cm for neonates weighing ≥ 2500 g), body weight-based formula (Duke formula for neonates weighing < 1000 g and "weight in kilograms + 6 cm" for neonates weighing ≥ 1000 g), and GA-based table. The neonates were also divided into subgroups according to their corrected GA (< 37 and ≥ 37 weeks) and body weight (< 2500 and ≥ 2500 g). The proper position of ETT tip placement was considered to be between the upper border of T1 and the lower border of T2 on a chest radiograph.

In this study, 102 neonates (GA of 22-41 weeks) were included. The rates of proper ETT placement were not significantly different between the NTL (48.6%), weight (44.1%), and GA (45.4%) methods. The rate of proper ETT tip placement was the highest in the NTL group. The correlation between the estimated ETT depth and the optimal ETT depth was the strongest in the NTL group for all patients and subgroups. This positive correlation was significant only in the NTL group for neonates weighing ≥ 2500 g (r = 0.646 and p = 0.009) and those with a corrected GA of ≥ 37 weeks (r = 0.757 and p = 0.011).

The NTL formula (NTL + 1 cm for neonates weighing < 2500 g and NTL + 0.5 cm for neonates weighing ≥ 2500 g) may be more reliable for estimating ETT depth in neonates.