Front teeth-to-carina distance in children undergoing cardiac catheterization

Background Knowledge of normal front teeth-to-carina distance (FT-C) might prevent accidental bronchial intubation. The aim of the current study was to measure FT-C and to examine whether the Morgan formula for oral intubation depth, i.e., endotracheal tube (ETT) position at front teeth (cm) = 0.10 x height (cm) + 5, gives appropriate guidance when intubating children of different ages. Methods: FT-C was measured in 170 infants and children, aged I day to 19 yr, undergoing cardiac catheterization. FT-C was obtained as the sum of the ETT length at the upper front teeth/dental ridge and the distance from the ETT tip to the carina. The latter measure was taken from an anterior-posterior chest x-ray. Results: There was close linear correlation between FF-C and height: FT-C (cm) = 0.12 x height (cm) + 5.2, R-2 = 0.98. The linear correlation coefficients (R-2) for FT-C versus weight and age were 0.78 and 0.91, respectively. If the Morgan formula had been used for intubation, the ETT tip would have been at 90 4% of FT-C. No patient would have been bronchially intubated, but the ETT tip would have been less than 0.5 cm from e carina in 13 infants. Conclusions: FT-C can be well predicted from the height/ length of the child. The Morgan formula provides good guidance for intubation in children but can result in a distal ETT tip position in small infants. Careful auscultation is necessary to ensure correct tube position.