Is Ultrasonography a Better Method of Endotracheal Tube Size Estimation in Pediatric Age Group than the Conventional Physical Indices-Based Formulae?

BACKGROUND: Providing safe anaesthesia to paediatric patients is a challenging task. This requires a thorough knowledge of the soft and pliable paediatric airway. Owing to the vulnerability of the anatomical structures involved, choosing an appropiate sized endotracheal tube (ETT) is important in these cases. A larger sized ETT may lead to trauma and a smaller one would result in leakage and risk of aspiration. Both situations demand an immediate tube change, thereby complicating the condition. The physical indices- based formulae have often failed to justify the purpose leading to repeated laryngoscopy and tube change during intubation. The increase in availability of the modern ultrasound devices have shown promise in these cases. AIMS AND OBJECTIVES: In this study we examine the accuracy of ultrasonography (USG)to assess the appropriate ETT size, comparing it with physical indices based formulae suggested ETT size so that repeated attempts on intubation can be minimized. MATERIALS AND METHODS: The study group included 100 patients of 1-5 years, ASA I- II, requiring orotracheal intubation under general anaesthesia. The tracheal sub-glottic diameter was estimated by pre-anaesthetic USG to determine the ETT size, both cuffed and uncuffed. ETT data obtained by these methods were compared by Pearson's correlation coefficient and t-test. RESULTS: USG predicted ETT size were significantly more consistent than the physical indices based formulae. Also the age based formulae were found to be more precise than the height based ones. Seven patients required change of tube once. CONCLUSION: Ultrasonography is an effective tool in predicting paediatric ETT size.