Prediction of the Appropriate Uncuffed Endotracheal Tube Size for Pediatric Anesthesia

We evaluated the validity of Cole's formula (tube size=age/4+4) for the prediction of endotracheal uncuffed tube size, and devised a new formula, the multiple regression formula for predicting the most appropriate size with a statistical method using age, height and weight of 604 pediatric patients. In 96 cases the tube size actually used deviated by 0.5mm or more from the tube size predicted by Cole's formula. The multiple regression formula between tube size and two combined factors, age and height, was "tube size=0.101×age+0.023×height+2.487". These two combined factors showed the highest correlation coeffi-cient (r=0.879) with the actual tube size. The actual tube size deviated by 0.5mm or more from the tube size predicted by this multiple regression formula in 71 cases. The difference in number between the 71 cases and the 96 cases is significant. We conclude that this multiple regression formula is more useful than Cole's formula for the prediction of uncuffed endotracheal tube size.