Measurement of Left Mainstem Bronchus Using Multiplane CT Reconstructions and Relationship Between Patient Characteristics or Tracheal Diameters and Left Bronchial Diameters

Study objectives To measure the tracheal diameters (TDs) [transverse (Tr) TD, and anteroposterior (AP) TD] and left main bronchus diameters (LBDs) [Tr and AP] using multiplane CT scan reconstructions with a tridimensional correction of the declination. To evaluate the relationship between clinical variables and CT scan diameters of the tracheobronchial tree. To aid in the selection of a double-lumen tube of appropriate size. Design Prospective observational study. Setting Private and university hospitals. Patients A total of 206 patients (105 women and 101 men) undergoing a CT scan for medical investigations or preoperative evaluation. Intervention No intervention. Measurements and results TDs and LBDs are greater in men (p ie , the lesser of the Tr-LBD or the AP-LBD [called the smallest LBD ]) is the Tr-LBD in 25.2% of the cases. The mean (± SD) ratio of the smallest LBD/Tr-TD is 0.70 ± 0.14 for men and 0.65 ± 0.12 for women. The estimated (Est) LBD is calcuted using this ratio. The mean value for Est-LBD minus the smallest LBD is 1.6 ± 1.3 mm, and this difference is Conclusions In conclusion, the left main bronchus is most often elliptic, and the smallest LBD cannot be accurately evaluated using patient characteristics or a ratio from TD.