Abstract

Background and Aims: Over the years conventional formulas based on age, height or weight is being used for endotracheal tube (ETT) selection in paediatrics. Ultrasound is gaining popularity as an easy, simple and non-invasive aid with good reliability in the assessment of ETT tube size. The aim of the study was to compare the appropriateness of micro-cuffed ETT size selected based on ultrasound assessment of subglottic diameter and ETT size as predicted by Motoyama formula in children undergoing surgical procedures under general anesthesia. Methods: A total of 80 patients belonging to ASA1 and ASA 2 aged between 2 to 12 years of either gender posted for elective surgery under general anaesthesia were included in the study. In all the participants, the subglottic diameter which was measured by the ultrasound was considered as the outer diameter of maximal allowable ETT. Leak test was performed to assess the appropriateness of ETT size selected. The other parameters studied were ETT size based on Motoyama formula and post-operative complications. The Statistical software namely SPSS 18.0, and R environment ver.3.2.2 were used for the analysis of the data. Student t test (two tailed, dependent) has been used to find the significance of study parameters on continuous scale within each group. Bland and Altman was performed to measure the agreement of parameters studied. Pearson correlation between study variables was performed to find the degree of relationship. Results: The incidence of appropriate tube selected based on ultrasound assessment of subglottic diameter was 96.3% compared to only 36.3% when Motoyama formula was applied. There was a strong correlation between outer diameter of the optimal ETT used and the ultrasound assessed subglottic diameter. Conclusion: Ultrasonographic assessment of the subglottic diameter is a better tool in predicting the appropriate size micro-cuff ETT when compared to Motoyama’s formula.

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