Predicted vs. Actual Endotracheal Tube Size in Pediatric Cardiac Surgery for Children with Down Syndrome

BACKGROUND: Children with Down syndrome have a higher risk of upper airway obstruction and smaller tracheal lumens due to conditions like subglottic stenosis and laryngomalacia. While the Cole formula is widely used to predict endotracheal tube (ETT) size in non-syndromic children, this formula may be inappropriate for children with Down syndrome undergoing cardiac surgery. OBJECTIVES: The primary objective was to determine whether the actual endotracheal tube size used in children with Down syndrome undergoing cardiac surgery matches the size predicted by the Cole formula. The secondary objectives included age-stratified comparisons (<1 year vs. ≥1 year) of predicted versus actual endotracheal tube size used, along with the impact of airway characteristics, drug usage, and postoperative outcomes on the actual endotracheal tube used. SETTINGS AND DESIGN: A retrospective cohort study at a single tertiary pediatric cardiac center. MEASUREMENTS AND MAIN RESULTS: A total of 182 pediatric patients with Down syndrome who had cardiac surgery were enrolled. Data were collected from patients with Down syndrome who had cardiac surgery with tracheal intubation using uncuffed ETTs. Patients were divided into two groups: those under one year of age and those one year or older. RESULTS: The actual ETT size used was statistically different from the size predicted by the Cole formula across all patients (P < 0.001). The difference between the actual and predicted ETT sizes remained significant in both age groups and did not decrease with age [both groups: P <0.001]. For the entire cohort, the actual ETT size was smaller than predicted by the standard Cole formula, with a correlation coefficient of 0.797. Infants with Down syndrome under one year of age were more likely to be on anti-failure medications (64.2% vs. 43.9%, P = 0.011) and have more complex cardiac anomalies (RACHS-1 score) compared to older children. These conditions had not impact on the endotracheal tube size used. The incidence of reintubation was 11.9% in the younger group and 7.0% in the older group, with respiratory causes being the most common reason. CONCLUSIONS: The Cole formula consistently overestimated the required ETT size for children with Down syndrome undergoing cardiac surgery. While Cole's formula can serve as a general guide, in children with Down syndrome, individual anatomical variations necessitate clinical judgment and adjustments. This highlights the need for improved methods to predict ETT size in this population.