40 patients to undergo video-assisted thoracoscopic radical resection of esophageal carcinoma through right thoracotomy were randomly divided intogroup of horizontal position( group S) and group left lateral position(group L),and with 20 patients in each group respectively. The bronchial occluder was placed into the right bronchia guided by fiber bronchoscope after tracheal intubation following the anesthesia induction in each group,while the occluder of group S was placed under the left lateral position,wh...