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Updated: Dec 25, 2025
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Published on: February 26, 2021
Ideal endotracheal tube insertion depth in neonates with a birthweight less than 750 g
Syusuke Takeuchi1,2, Junichi Arai1, Motomichi Nagafuji2
1Department of Neonatology, Ibaraki Children's Hospital, Mito, Japan.
Insights
Endotracheal tube (ETT) depth in neonates under 750g is best estimated by birthweight, not gestational age. This finding is crucial for accurate ETT placement in extremely low birthweight infants.
Area of Science:
- Neonatal Medicine
- Pediatric Critical Care
- Respiratory Care
Background:
- Accurate endotracheal tube (ETT) insertion depth is critical for neonates.
- Current formulas may overestimate ETT depth in extremely low birthweight infants (<750g).
- Gestational age is useful but its advantage over birthweight for ETT depth is debated.
Purpose of the Study:
- To estimate the appropriate ETT insertion depth in neonates weighing less than 750g.
- To investigate correlations between neonatal physique and ETT depth.
- To compare ETT depth estimation methods in SGA and non-SGA infants.
Main Methods:
- Retrospective observational study of neonates <750g requiring intubation.
- ETT depth assessed radiographically relative to thoracic vertebrae.
- Pearson's correlation coefficient used to analyze relationships between gestational age, birthweight, and ETT depth.
Main Results:
- Forty neonates (mean GA 26.3 weeks, mean BW 620g) were studied; 20 were SGA.
- The endotracheal tube was placed too deep in 35 out of 40 cases.
- Birthweight showed the strongest correlation with ETT insertion depth; gestational age did not show a significant correlation.
Conclusions:
- Ideal ETT insertion depth in neonates <750g correlates with birthweight.
- Relying on gestational age for ETT depth may be unreliable in populations with many SGA infants.
Background:
Appropriate management of the endotracheal tube (ETT) insertion depth is important. The depth calculated using Tochen's formula is overestimated in extremely-low- birthweight infants, particularly those with a birthweight <750 g. Gestational age has been shown to be particularly useful in the Neonatal Resuscitation Program, 7th edition.5 However, a randomized trial for estimating the ETT insertion depth failed to show the advantage of using gestational age over birthweight.6 Therefore, we aimed to estimate the appropriate ETT insertion depth in neonates weighing <750 g.
Methods:
This was a single-center, retrospective observational study including neonates weighing <750 g who required intubation. The appropriate depth was determined by adjusting the distance between the actual ETT position and the area from the first to the second thoracic vertebra on the radiograph. Correlations between gestational age and physique were investigated using Pearson's correlation coefficient. We examined small-for- gestational-age (SGA) infants and non-SGA infants separately.
Results:
Forty neonates were enrolled in this study. The mean gestational age and birthweight were 26.3 weeks and 620 g respectively. Twenty infants were SGA. The ETT position was deep in 35 of 40 cases, with the strongest correlation between weight and ETT insertion depth. The correlation with gestational age was not observed in this study.
Conclusions:
Our study showed that the ideal ETT insertion depth at birth correlates with birthweight in neonates weighing <750 g. Therefore, determination by gestational age may not be feasible in populations with a high proportion of SGA infants.
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