Utilizing nasal-tragus length to estimate optimal endotracheal tube depth for neonates in Taiwan

To assess the application of the nasal-tragus length (NTL) to predict the proper endotracheal tube (ETT) depth; also, as relatively thinner size of Asian than Caucasian, the fitness of using the NTL to estimate the optimal ETT depth for neonates in Taiwan was examined.

The newborn infants who do need intubation orally were included. Those with midface dysmorphism, craniofacial anomalies, head trauma and/or facial injury in whom it was unable to measure NTL, were excluded. The data were collected after a satisfactory ETT tip position was confirmed on chest roentgenogram. Equations were established via the polynomial and the linear regression of the NTL and the actual ETT; simplified formulae as NTL+0.5 and NTL+1 were assumed accordingly. Paired t test was used to assess the coefficients.

The 63 neonates, weighing 410 through 4,196 g and with gestation 21 through 41 weeks, were enrolled. No statistical difference was found between the actual ETT depth and the estimated ETT depth via the NTL+1 cm in neonates weighing ≤ 2,500 g (n=41, p=0.06), and also between the actual ETT depth and the estimated ETT depth via the NTL+0.5 cm in group weighing >2,500 g (n=22, p=0.171).

Using the NTL to predict the optimal ETT depth with the formula, NTL plus 1 cm, was clinically practical for newborn infants in Taiwan weighing ≤ 2,500 g, and a modified formula, NTL plus 0.5 cm, was more suitable for neonates weighing >2,500 g.