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Updated: Jun 27, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Concordance Between Anthropometric Formula Predictions and Chest Radiograph-Confirmed Endotracheal Tube Depth in
Volodymyr Mavrych1, Kashif Majeed2, Saleh Alshehri2
1College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia.
Insights
Published formulas for endotracheal tube depth in infants and young children are unreliable. A new weight-based formula developed from patient data offers a more accurate bedside tool for determining correct endotracheal tube depth.
Area of Science:
- Pediatric Critical Care Medicine
- Anesthesiology
- Pediatric Emergency Medicine
Background:
- Accurate endotracheal tube (ETT) depth is crucial in pediatric patients to prevent tracheal malposition complications.
- Existing formula-based ETT depth estimations lack robust characterization in children under two years old within general pediatric intensive care units (PICUs).
Purpose of the Study:
- To evaluate the performance of commonly used ETT depth formulas in children aged 1-24 months admitted to a PICU.
- To identify a more accurate method for determining ETT insertion depth in this vulnerable pediatric population.
Main Methods:
- Retrospective analysis of 115 pediatric patients (1-24 months) undergoing orotracheal intubation.
- Comparison of five established formulas (height-based, weight-based, ETT size-based, two Lee formulas) against radiographically confirmed ETT depth.
- Assessment of agreement using Lin's concordance correlation coefficient (CCC) and Bland-Altman analysis.
Main Results:
- None of the five published formulas demonstrated acceptable concordance (CCC < 0.75) for ETT depth prediction.
- Over 50% of initial intubations resulted in non-ideal ETT positioning.
- A novel, cohort-derived weight-based formula (Depth = 0.385 × Weight + 9.145) significantly outperformed all existing formulas.
Conclusions:
- Established formulas for ETT depth are unreliable in children aged 1-24 months.
- The developed weight-based formula offers improved accuracy for bedside use in this age group.
- Prospective validation of the new formula and continued radiographic confirmation of ETT placement are essential.
Abstract:
Background: Accurate endotracheal tube (ETT) insertion depth is critical in infants and young children, where tracheal malposition carries significant risk. Formula-based depth estimation is widely used at the bedside, but the performance of published formulas in children under two years of age admitted to a general PICU remains poorly characterized. Methods: A retrospective, single-center study was conducted at the PICU of King Saud Medical City, Riyadh. A total of 115 patients aged 1-24 months requiring orotracheal intubation were included. ETT depth was predicted using five established formulas: height-based [(H/10)+5], weight-based [W+6], ETT size-based [ETT×3], Lee weight-based [5.5+0.5W], and Lee height-based [3+0.1H]. Agreement between predicted and radiographically confirmed insertion depth was assessed using Lin's concordance correlation coefficient (CCC), Bland-Altman analysis, and clinical classification of predictions. Results: None of the five formulas achieved acceptable concordance (CCC < 0.75 for all). The height-based formula performed best among published formulas, with negligible bias and the highest proportion of clinically acceptable predictions. Both Lee formulas showed near-universal systematic underestimation and are not suitable for this age group. Over half of all intubations resulted in non-ideal ETT position on the first post-intubation chest X-ray. Novel cohort-derived regression equations outperformed all published formulas, with the weight-based equation (Depth = 0.385 × Weight + 9.145) emerging as the strongest predictor of insertion depth. Conclusions: No published formula achieved reliable concordance with radiographic ETT depth in children aged 1-24 months. The cohort-derived weight-based formula represents a more accurate bedside tool for this population and warrants prospective external validation. Post-intubation radiographic verification remains essential.
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