Postoperative airway clearance and recovery of pulmonary function after lung resection is critical in patients undergoing pulmonary resection surgery. The investigators hypothesized that vibratory positive expiratory pressure using the Acapella device may improve pulmonary function recovery in patients undergoing video-assisted thoracoscopic lung resection surgery.

Inclusion Criteria:

• patients between 20 and 65 years old
• undergoing video-assisted thoracoscopic lung resection surgery for suspicious lung cancer
• admission to intensive care unit in extubate state
• with intravenous patient-controlled analgesia

Exclusion Criteria:

• body mass index of less than 15 kg/m2 or more than 30 kg/m2
• history of respiratory tract infection within 3 months
• emergency surgery
• preoperative supplemental oxygen or ventilator care
• preoperative PaO2 of less than 70 mmHg or PaCO2 of more than 50 mmHg
• preoperative FEV1 of less than 30% of predicted value
• unconsciousness or neuromuscular disease