Effect of Lung Protective One-lung Ventilation With Fix and Variable PEEP on Oxygenation and Outcome

During One-lung ventilation, the use of lower tidal volumes (VT) is helpful to avoid over-distension, provide sufficient oxygenation, but can result in increased atelectasis. Nevertheless, it is not known if, during one-lung ventilation with constant low VT, moderate levels of PEEP combined with lung recruitment maneuvers are superior to variable PEEP for intraoperative oxygenation and protection against PPCs. Aim of the study is to compare a strategy using constant tidal volume with recruitment maneuvers versus variable PEEP with recruitment maneuvers during thoracic surgery in adults. The investigators hypothesize that in adult, non-obese patients undergoing thoracic surgery under standardized OLV with variable PEEP and recruitment maneuvers as compared to constant PEEP without recruitment maneuvers prevent PPCs. Patients will be randomly assigned to one of two groups: FIX PEEP VOLUME GROUP (Groupfix): mechanical ventilation with constant (6 ml/kgIBW) tidal volume and PEEP of 5 cmH2O with recruitment maneuvers VARIABLE PEEP GROUP (Groupvar): mechanical ventilation with constant (6 ml/kgIBW) tidal volume with variable PEEP with recruitment maneuvers.