Lung isolation technique is useful for lung or heart surgeries for better visualization. Double lumen endobronchial tube and bronchial blocker are available for lung isolation. Adding disconnection technique before lung isolation is helpful to accelerate the lung deflation. However, the utility of disconnection technique has never been evaluated in comparison of double lumen tube and bronchial blocker. Therefore, the utility of disconnection technique in two different lung isolation technique, double lumen tube and bronchial blocker will be evaluated

Inclusion Criteria:

• patients scheduled for wedge resection for pneumothorax, unilateral
• ASA class I, II

Exclusion Criteria:

• know lung disease
• any kind of lung abnormality on preoperative chest x-ray
• coronary artery occlusive disease
• cerebrovascular disease
• pregnancy
• unable to understand the informed consent form