# Optimal nasotracheal tube insertion depth in neonates

## TL;DR

This study confirms that body weight is the best predictor for correct nasotracheal tube placement in neonates and provides tools to help clinicians apply this in practice.

## Contribution

Quantitatively validated body weight as the most reliable predictor of optimal ETT insertion depth in neonates using a large prospective dataset.

## Key findings

- Body weight at the time of intubation showed the strongest association with optimal ETT depth (adjusted R2 = 0.88).
- A bedside chart and web-based tool were developed to standardize ETT insertion depth estimation.
- Findings support existing reference ranges across a broad range of gestational ages and body weights.

## Abstract

Existing recommendations for nasotracheal endotracheal tube (ETT) insertion depth in neonates have shown remarkable consistency over decades and have recently been prospectively evaluated in clinical practice. However, large prospective datasets systematically validating biometric predictors and quantifying expected variability remain limited. This study aimed to confirm established nasotracheal ETT depth recommendations using a large prospective cohort and to translate these findings into a standardized, evidence-based bedside reference.

We analyzed 497 nasotracheal intubations performed between 2017 and 2023 in a tertiary neonatal intensive care unit. Tube position was prospectively assessed after each intubation using standardized chest radiography. Optimal ETT placement was defined as the tube tip located between the clavicles and at least 1 cm above the tracheal carina. Clinical and biometric parameters were systematically recorded, and their associations with insertion depth were evaluated using LOESS curves and linear regression models.

Across a wide range of gestational ages and body weights, body weight at the time of intubation showed the strongest and most consistent association with optimal nasotracheal ETT insertion depth (adjusted R2 = 0.88; RMSE = 0.52). Based on these findings, an evidence-based chart with defined tolerance ranges and a complementary web-based decision-support tool were developed to facilitate standardized bedside estimation.

In this large prospective cohort, body weight at the time of intubation was confirmed as the most reliable single predictor of optimal nasotracheal endotracheal tube insertion depth in neonates. Our findings support established reference ranges and provide quantitative confirmation across a broad spectrum of gestational ages and body weights. By translating these data into a concise, evidence-based bedside chart and a complementary digital reference, this study strengthens confidence in existing recommendations and supports standardized clinical practice, while emphasizing the need for clinical judgement and post-intubation verification.