The use of ultrasound compared to an age- based formula to estimate endotracheal tube size in an academic hospital

Abstract

Background An accurate estimation of tracheal diameter for endotracheal tube size selection is imperative in the pediatric population, with ultrasound shown to be an acceptable and superior method of endotracheal tube size estimation when compared to conventional age-based methods. Aim To compare the accuracy of endotracheal tube size estimation using airway ultrasound to age-based formula in the South African pediatric population. Methods This was a prospective observational study, with 54 patients, American Society of Anesthesiologists physical status I–III, aged two to 12 years old, scheduled for elective surgery at Chis Hani Baragwanath Academic Hospital, South Africa. Patients were allocated to two groups, the age-based method group or ultrasound method group. The accuracy of each method used for endotracheal tube estimation was assessed using a standardized leak test. Post intubation endotracheal tube cuff pressures were measured and post operative follow up was done to assess for features of airway injury. Results The ultrasound method was a more accurate estimate of endotracheal tube size (74.47%) compared to the age-based method (29.63%) (p = 0.0011). In all cases a cuffed endotracheal tube was used. No difference was seen between the mean endotracheal tube cuff pressure between the groups with a large proportion of patients having underinflated endotracheal tube cuffs. Conclusion Ultrasound is a more accurate predictor of appropriate ETT size in the pediatric population compared to a conventional age-based formula. The use of ultrasound for the estimation of ETT size is an accurate, non-invasive, and reproducible technique with potential for long-term cost saving and reduced complications. Ultrasound is iii becoming readily accessible in the theatre setting in South Africa and with appropriate training and expertize, this bedside tool has the potential for more widespread uptake and may be a more accurate means of determining endotracheal tube size in children.