Double lumen tube (DLT) needs to be intubated to isolate ventilations of left and right lungs for thoracic surgery. Post-operative sore throat and hoarseness are more frequent with DLT intubation than with single one. Which is may because DLT is relatively thicker, harder, sideway curved and therefore more likely to damage the vocal cord or trachea during intubation, and advanced deeper to the carina and main bronchus level. In the conventional method of intubation, DLT is rotated 90 degrees and advanced blindly to the main bronchus level after DLT is intubated through vocal cord using the direct laryngoscopy. After the blind advancement, the sufficient tube position needs to be gained and confirmed with the fiberoptic bronchoscope. In the bronchoscope guide method, after DLT is intubated through vocal cord using the direct laryngoscopy, the pathway into the targeted main bronchus is secured using the fiberoptic bronchoscope which is passed through a bronchial lumen of DLT. And then DLT can be advanced through the guide of the bronchoscope. In this study, we intend to compare post-operative sore throat, hoarseness and airway injury between the two methods. We hypothesize that the bronchoscope guide method can reduce the post-operative complications and airway injury because surrounding tissues of the airway can be less irritated by DLT intubation in the guide method than in a conventional.

For a constant guide effect, we use fiberoptic bronchoscopes with same outer diameter (4.1 mm) which can pass through a bronchial lumen of 37 and 39 Fr Lt. DLT and cannot pass through 35 Fr or smaller Lt. DLTs.

<Lt. DLT size selection>

• male: ≥160 cm, 39 French; < 160 cm, 37 French
• female: ≥160 cm, 37 French; < 160 cm, contraindication

Inclusion Criteria:

• ASA (American Society of Anesthesiologists) class I - III
• Elective thoracic surgery
• Left-sided DLT intubation for one-lung ventilation

Exclusion Criteria:

• Female, height < 160 cm
• Pre-existing sore throat, hoarseness or airway injury
• Duration of surgery > 6 h
• Upper respiratory tract infection
• Cervical spine diseases
• Presence of tracheostomy
• Pharyngeal neoplasm or abscess which can induce mechanical airway obstruction
• Mallampati score 4
• Obesity (BMI ≥ 35 kg/m2)
• Obstructive sleep apnea (OSA)
• Craniofacial anomaly
• Cormack grade 3b or 4
• History or high risk of difficult intubation / difficult mask ventilation
• Patients whom the direct laryngoscopy cannot be used for, because of weak teeth or small mouth opening
• Patients who refuse to participate in the study or from whom receive informed consent cannot be received.