Metabolomic Study in Exhaled Breath Condensate of Thoracic Surgical Patients

Acute lung injury (ALI) following thoracic surgery remains a major source of morbidity and mortality after lung resection. Despite the advancement in both the surgical techniques and the perioperative management, the incidence of postoperative ALI remains remarkable. Risk factors for postoperative lung injury are evident, including preoperative pulmonary function, type of surgical procedure, intraoperative fluid management, one-lung ventilation, and ventilator settings. One-lung ventilation (OLV) is usually required in thoracic surgery. OLV is also an important predictor of postoperative ALI. Recent laboratory findings suggested that tissue hypoxemia and ischemia / reperfusion injury of the collapsed lungs during OLV is the major cause of lung injury. Exhaled Breath Condensate (EBC), which is the exhalate from breath typically collected by cooling device, contains most molecules found in the airway. EBC analysis has potential applications in lung disease, such as severity of airway inflammation in asthmatic patients. Collecting EBC is simple and non-invasive, in contrast to bronchoscopy for lung biopsy or bronchoalveolar lavage. Metabolomics refers to systematic and scientific study of chemical processes involving metabolites. This study will collect EBC from thoracic surgical patients before, during, and after OLV. The investigators will perform metabolomic analysis and aim to elucidate the biochemical reactions during one-lung ventilation and pathological mechanisms of acute lung injury following thoracic surgery.