Selection of cuffed endotracheal tube for children with congenital heart disease based on an ultrasound-based linear regression formula.

It remains to be discovered whether a formula predicting the subglottic transverse diameter measured by ultrasound (SGD) for the selection of an appropriate endotracheal tube (ETT) for children without congenital heart disease (CHD) is useful for children with CHD. A formula for predicting SGD was established after assessing 60 children ≤ 8 years without CHD and validated on 60 children with CHD. We selected the cuffed ETT size based on the SGD by ultrasound (SGD). Subsequently, the fit of the ETT cuff in 60 children with CHD was examined via air-leak test. The maximum allowed difference between the SGD and the ETT size that fit was 0.2 mm. The agreement among and accuracy of SGD, SGD, and the ETT used in children was analyzed. For children without CHD, we adopted a linear formula, given by SGD (mm) = 0.4 × age + 5.3. For children with CHD, allometric formula was adopted, given by SGD (mm) = 5.4 × age. A stronger agreement exists between SGD and ETT size compared to that between SGD and ETT size. And the mean bias (SGD-ETT size and SGD-ETT size) was 0.21 mm (95% confidence interval, - 0.59 to 1.01 mm) and 0.00 mm (- 0.79 to 0.84 mm). For the CHD group, the ultrasound-based method yielded a 78% success rate of ETT size choice, while the formula-based method permitted an appropriate ETT size in only 32% of subjects (P < 0.001). Our analysis showed that measuring the SGD was more accurate in predicting the correct OD of the ETT in children with CHD undergoing cardiovascular surgery, based on the correlation and agreement with ETT OD.