Flexible intubating video endoscope-guided determination of optimal oral endotracheal tube depth in infants: a prospective observational study

The weight-based APLS formula may be less applicable to Chinese infants undergoing elective surgery. A height-based formula demonstrated closer agreement with the FIVE-referenced depth. Because the model was developed and assessed in the same cohort, it should be considered preliminary and requires independent external validation (preferably multicenter) before widespread clinical use, particularly in non-elective or critically ill populations.