Unveiling myths of the paediatric larynx: a comprehensive review of anatomical publications and modern insights on cuffed endotracheal tubes

Abstract

This review critically analyses literature on the anatomy of the paediatric larynx published from 1897 to 2024, with an emphasis on key studies by Fayoux et al. and Isa et al. These pivotal investigations highlighted significant misconceptions and gaps in knowledge concerning the use of cuffed endotracheal tubes (ETTs) in infants and young children. Despite a comprehensive body of research spanning over a century, essential findings related to laryngeal dimensions and injury mechanisms during intubation were often overlooked or misrepresented in both historical and modern publications. Isa et al. conducted a detailed anatomical study using fresh paediatric larynges from autopsies, comparing their results to prior landmark research. Their methods included placing cuffless ETTs and Microcuff tubes (MCTs) in the laryngeal lumen and measuring the placement at the vocal cord level. The study demonstrated that the cricoid outlet (CO) is a rigid, circular structure—the narrowest part of the paediatric airway—and that it remains less distensible than the glottis or trachea. Fayoux et al.’s earlier work with 150 neonatal specimens confirmed this rigidity and emphasised the potential for significant airway damage when oversized ETTs are forced through the CO. This review highlights that radiological and endoscopic approaches often fail to accurately represent paediatric laryngeal anatomy, leading to clinical practices where inappropriate tube sizes are used. MCTs, despite their popularity, were shown to exceed CO dimensions in infants, risking mucosal damage and scarring. The failure to adopt these anatomical insights into clinical guidelines has led to practices that may compromise patient safety, such as using MCTs in premature infants where the deflated cuff’s outer diameter (OD) exceeds CO diameters. Key measurements from Isa et al. reaffirm that cuffless ETTs based on ODs, rather than internal diameters, are more appropriate for the paediatric airway. This review urges the inclusion of accurate anatomical data, such as the findings of Fayoux et al. and Isa et al., into clinical protocols to prevent airway trauma and improve paediatric intubation outcomes.