One-lung ventilation (OLV) is required for the most thoracic surgery to facilitate surgical visualization by collapsing the lung. The double-lumen tube (DLT) and Uniblocker are the commonly used device for OLV.The objective of our study was to comparison the safety and effectiveness of the intubation of the Left-sided Double-lumen Tube and the Uniblocker under the guidence of chest computed tomography (CT) image.

One-lung ventilation (OLV) is required for the most thoracic surgery to facilitate surgical visualization by collapsing the lung. The double-lumen tube (DLT) and Bronchial blockers (BBs) are the commonly used device for OLV.The objective of this study is to comparison the safety and effectiveness of the intubation of the Left-sided Double-lumen Tube and the Uniblocker under the guidence of chest computed tomography (CT) image(the operator count the number of CT slices (slice thickness is 5mm) from vocal cord slice to carina slice to calculate the distance between vocal cord and carina) then measure a distance on the DLT or Uniblocker from the upper edge of the cuff to the mouth side and made a marker on the DLT or Uniblocker.During the intubation the operator insert the DLT or Uniblocker into the trachea via video laryngoscope, after passing the glottis the DLT or Uniblocker are advanced toward the left main-stem bronchus, once the anesthesiologist see the marker on the DLT or the Uniblocker just above the vocal cord stop the insertion.

Inclusion Criteria:

• Adult patients undergoing left side thoracic surgery

Exclusion Criteria:

• 1.Age>70 or <18 years 2.ASA classifications >III 3.BMI >35kg/m2 4.Modified Mallampati classification ≥III 5.Thoracic surgery within the last one month 6.Severe cardiopulmonary disease