Endotracheal tube size estimation for children with pathological short stature.

Objective: To compare length-based estimates of endotracheal tube (ETT) size and age-based estimates with anesthesiologist-selected ideal ETT size in children with medical conditions affecting normal growth, known as pathological short stature (PSS).

Methods: We conducted a retrospective review of the anesthesia database of all children undergoing tracheal intubation for any surgical procedure during a 3-year period. The anesthesiologist-selected ideal ETT size was defined as that selected and successfully used throughout the case under the supervision of a board-certified pediatric anesthesiologist. Objective criteria, such as leak test and adequate oxygenation/ventilation, were used to validate the appropriateness of the ETT chosen. For analysis, the children were classified as normal length for age versus PSS, defined as less than 5% length for age on the Centers for Disease Control and Prevention growth chart. The proportions of clinically relevant predicted ETTs, within +/-0.5 mm of the anesthesiologist-selected ideal ETT size, based on both age- and length-based formulas for each group were then compared.

Results: Five thousand one hundred seventy-five patient records were analyzed. In children with normal stature, age-predicted ETT size was within the clinically relevant range in 89.8% (95% confidence interval [CI], 88.9%-90.7%), and length-predicted ETT size was within the clinically relevant range in 92.8% (95% CI, 92.0%-93.6%). In children with PSS, age-predicted ETT size was within the clinically relevant range in 86.6% (95% CI, 84.3%-89.0%), and length-predicted ETT size was within the clinically relevant range in 92.2% (95% CI, 90.3%-94.0%). The correlation coefficient for age to anesthesiologist-selected ideal ETT size was strong for both normal and PSS patients (r = 0.91 and r = 0.93, respectively). Length was also highly correlated to actual ETT size used for both groups (r = .91).

Conclusions: Length-based prediction of ETT size is at least as accurate as age-based estimation in both normal and pathologically short children.