Cardiopulmonary exercise testing is recommended for preoperative evaluation and risk stratification of lung resection candidates. Ventilatory efficiency (VE/VCO2 slope) has been shown to predict morbidity and mortality in lung resection candidates and has been shown superior to peak oxygen consumption (VO2). Patients with increased VE/VCO2 during exercise also exhibit increased VE/VCO2 ratio and decreased end-tidal CO2 at rest. Our first hypothesis is that rest ventilatory parameters predict morbidity and mortality in patients undergoing thoracic surgery. VE/VCO2 is well correlated with ventilation-perfusion mismatch, therefore it may be useful in hypoxemia prediction during one-lung ventilation during thoracic surgery. Our second hypothesis is that patients with high VE/VCO2 will be prone to hypoxemia development during one-lung ventilation.

Inclusion Criteria:

• thoracotomy because of lung infiltration (confirmed or highly suspicious lung tumor)

Exclusion Criteria:

• none

Consecutive patients planned for thoracotomy because of lung infiltration (confirmed or highly suspicious lung tumor). Patients will be recruited from 2 centers in the Czech Republic (St. Anne's University Hospital, Brno, Czech Republic and University Hospital in Brno).