Lung Collapse With Bronchial Blocker

Lung isolation is frequently used during thoracic surgery. Two techniques are principally used: the double lumen tube (DLT) and the bronchial blocker (BB). BB is easy to use but its reputation is darken by the need of multiple repositioning during surgery and especially by a slower lung collapse than the DLT. Reading recent literature on the subject and according to the vast experience of numerous hospital centers, it seems that the slowness of lung collapse remains without any solution. This slowness in lung deflation is detrimental to the initiation of video-assisted thoracoscopy surgery (VATS) and could be exacerbated in chronic obstructive disease (COPD) patients. For this reason, BB use is discredited in numerous centers. However, at IUCPQ, the investigators rarely observe slow lung collapse when BB are used. For many years, the investigators have used a systematic denitrogenation of the lung before the initiation of one lung ventilation (OLV). Furthermore, when the patient is positioned in lateral decubitus, the investigators impose an apnea period of about 30 seconds to favor collapse of the isolated lung before inflating the cuff. This apnea is always limited by the occurrence of oxygen desaturation (≤97%). The investigators also proceed to a second period of apnea of 30 seconds associated to a deflated BB's cuff at the pleural opening. Subsequently, the investigators inflate the BB's cuff to obtain definitive lung isolation. The investigators hypothesis is that the use of two apnea periods, when isolating the lung with a BB, will allow the same quality of surgical exposure at 0, 5, 10 and 20 minutes post opening of the pleura, compared to the one obtained with a DLT. The main objective of this study is first to compare the delay between the initiation of OLV and complete lung collapse obtained with BB and DLT, in two groups of patients undergoing VATS. Secondary objectives are: 1) to evaluate the quality of surgical exposure associated to the level of lung