The One lung ventilation (OLV) allows for increasingly complex intrathoracic surgery and is required with the increased use of minimally invasive techniques. The One lung ventilation facilitates surgical exposure of the unventilated lung, and can prevent lung rupture and contamination. However, OLV significantly alters intra-thoracic lung volumes, and the normal relationship between functional residual capacity and closing capacity. These alterations may be associated with life-threatening impairment of gas exchange. Blood flow through the unventilated lung cannot be oxygenated and contributes to arterial hypoxemia. In addition to hypoxemia, collapse of the non-ventilated lung, volutrauma of the ventilated lung and surgical manipulation may affect acid-base balance and hemodynamic homeostasis. Hypoxic pulmonary vasoconstriction (HPV), a homeostatic mechanism intrinsic to the pulmonary vasculature, plays an important role during OLV. Intrapulmonary arteries constrict in response to alveolar hypoxia, diverting blood to the better oxygenated lung segments, thereby improving ventilation-perfusion matching and systemic oxygen delivery. During OLV, anesthesia is maintained by delivering an inhalation anesthetic, such as Sevoflurane, to the ventilated lung or by infusion of an intravenous anesthetic, for example, Propofol. Due to the distinct pharmacological properties of each anesthetic, the method chosen to maintain anesthesia may affect the patients’ acid-base status and hemodynamic stability. As is well-known that Propofol may induce metabolic disturbances that occur primarily in intensive care patients with impaired oxygen delivery who receive prolonged infusions of high-dose Propofol.