Prediction of endotracheal tube size using airway ultrasonography and correlation with traditional formulas in pediatric patients undergoing cardiac surgery

Accurate endotracheal tube (ETT) size selection is essential in pediatric patients undergoing cardiac surgery to minimize airway trauma and post-extubation complications. Traditional weight- and height-based formulas often fail to provide reliable predictions, necessitating the use of alternative methods, such as airway ultrasonography (USG). This study aims to assess the predictive effectiveness of USG in determining ETT size compared to conventional formulas. This prospective, single-center study included 20 pediatric patients younger than one year of age undergoing cardiac surgery. Preoperative ETT size predictions were obtained using USG, weight-based, and height-based formulas. The clinically applied ETT size was recorded, and statistical analyses, including correlation analysis, multivariate logistic regression, and Bland-Altman analysis, were performed to compare predictive accuracy. USG-predicted ETT sizes showed complete agreement with the clinically used ETT in all cases (100%), demonstrating a perfect correlation (r=1.00, p<0.001). The weight-based formula correctly predicted the clinical ETT size in 50% of cases (r=0.48, p=0.03), while the height-based formula had the lowest accuracy, with a match rate of 40% (r=0.38, p=0.08). Bland-Altman analysis confirmed that USG measurements exhibited the minimal bias and the tightest limits of agreement in comparison to conventional formulas.  Airway ultrasonography is a superior and highly accurate method for predicting optimal ETT size in pediatric cardiac surgery patients, outperforming traditional weight- and height-based formulas. USG should be considered a standard tool in pediatric anesthesia to enhance airway management and reduce complications associated with incorrect ETT sizing.