Selection of the DLT
LEAKAGE
Based on the endotracheal diameter (taken at the level of the sternoclavicular joint), which was measured preoperatively by chest computed tomography, the DLT model was determined by selecting the one with the largest diameter possible for the patient. When the tracheal inner diameter measurement value was ≥ 17 mm, a 39 Fr was selected; when the tracheal inner diameter was ≥ 15 mm, a 37 Fr was selected; when the tracheal inner diameter was ≥ 13 mm, a 35 Fr was selected; and when the tracheal inner diameter was ≥ 11 mm, a 33 Fr was selected. The bronchial cuff was inflated by 2–4 ml and the tracheal cuff by 6–8 ml to prevent air leakage. If the inflation volume was greater or lower than the above range, the tube selection was considered inappropriate and excluded from the study.