[Mechanical ventilation during surgery -can we prevent postoperative lung injury?-]

We have patients who develop lung injury after surgery even they are without lung diseases preoperatively. What is the cause of this perioperative complication? Can we prevent postoperative lung injury by any measures during surgery? In the present paper, the etiology of acute respiratory distress syndrome (ARDS) is reviewed and possible methods to prevent ARDS is discussed. Inflammation occurs during surgery, the degree of which depends on multiple factors including surgical insults, the use of cardiopulmonary bypass (CPB), ischemia and reperfusion of any organ during surgery, transfusion, and organ damages. Preexisting conditions such as malignancy, sepsis; shock and lung diseases are other factors that may lead to lung injury. Mechanical ventilation does not initiate lung injury by itself; however, conventional mechanical ventilation (tidal volume of 10-12 ml x kg-1 ideal body weight) may induce ARDS if lungs are primed. Accordingly, lung protective strategies should be carried out if patients have such condition or does receive such surgery. The brief outline of the lung protective strategies is to reduce tidal volume, to apply open lung approach with positive end-expiratory pressure and lung recruitment maneuver, and to avoid any lung lesion causing hypoxia during CPB or one-lung ventilation.