Neonatal Endotracheal Intubation: Comparison of Existing Formulae for Accuracy

Abstract

Background There are several formulae proposed to calculate the ideal depth of insertion of the endotracheal tube (ETT) in neonates, none of which are universally accurate. Our objective is to identify the most accurate of these formulae and to determine the most suitable formula for babies weighing less than 1 kg. Methods This is a retro-prospective observational study conducted in a tertiary neonatal intensive care unit. All intubated babies, irrespective of their gestational age, were included in this study. Those with congenital airway anomalies or syndromes with involvement of the upper airway and those who required short-term ventilation restricted to the theatre complex were excluded. The ideal insertion depth was determined via a chest X-ray (CXR) with the ETT projecting between thoracic vertebrae 2 and 3. Predictions from eight formulae investigated in the Indian population were analysed using paired Wilcoxon tests and Bland–Altman plots. Results The sample size was 83, of which 16 weighed less than 1 kg. Neither weight-based nor naso-tragal length (NTL)-based formulae were universally accurate in the prediction of the ideal depth of insertion, and using either of the formulae resulted in a high rate of malpositioning. Amongst the NTL-based formulae, Tatwavedi and Singh’s adjustments worked better than the original. Conclusion The currently available formulae remain inaccurate in the prediction of the ideal length of insertion of ETT, more so in babies less than 1 kg in our study population.