Observation and recording of the dislocation of the periportal end of the DLT in group II
dislocation
Adopting the flat maxillary incisor at the periportal end of the DLT as the zero point, the dislocation of the DLT relative to the incisor before and after the patient was moved to a lateral position was observed and recorded. The tube moving outward toward the incisor was recorded as a positive value, while the tube moving inward from the incisor was recorded as a negative value.