Non-dependent HFPPV Versus CPAP for Video-assisted Thoracoscopy

Video-assisted thoracoscopic surgery (VATS) is usually performed using well-collapsed lung is essential for optimum surgical visualization and resection. However, one lung ventilation (OLV) is associated with deleterious impaired oxygenation secondary to the increases in shunt fraction.1 There are different approaches for the recruitment of the non-dependent lung (NL) during OLV such as the selective application of continuous positive pressure ventilation (CPAP) or high frequency positive pressure ventilation (HFPPV) to the non-dependent lung.2-4 These strategies may improve arterial oxygenation and reduce shunt fraction,2-4 However, the use of high CPAP levels impaired the surgical conditions during thoracotomy.2-3 On contrary, the application of HFPPV either to both lungs5or to the non-dependent lung permits adequate surgical conditions during thoracotomy.4 The investigators hypothesize that the application of volume-controlled HFPPV to the non-dependent lung during OLV for video-assisted thoracoscopic surgery may provide better surgical field and adequate oxygenation than the use of CPAP 2 cm H2O. The investigators will evaluate the effects of the selective application of conventional one lung ventilation, HFPPV, or CPAP 2 cm H2O to the non-dependent lung on surgical field conditions, and arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2, respectively) during OLV in the patients scheduled for video-assisted thoracoscopic surgery.