Very Low Tidal Volume vs Conventional Ventilatory Strategy for One-lung Ventilation in Thoracic Anesthesia

Pulmonary postoperative complications (PPCs) are the most frequent adverse events after thoracic surgery. Acute respiratory distress syndrome (ARDS) is the most severe among PPCs. Injurious mechanical ventilation is a recognized risk factor associated with ARDS and PPCs after major thoracic surgery. International literature reports a wide use of tidal volume around 5-6 ml/kg predicted body weight (PBW) during one lung ventilation (OLV) but variable use of PEEP and alveolar recruitment maneuver (ARM). The aim of this multicenter, randomized, single blind study is to determine if a protective ventilatory strategy during OLV based on low tidal volume, PEEP and alveolar recruitment maneuver compared to conventional strategy can reduce ARDS and PPCs after major pulmonary resection. Primary outcome is the incidence of in-hospital ARDS. Secondary outcomes are in-hospital incidence of postoperative pulmonary complications (PPCs), major cardiovascular events, unplanned Intensive Care Unit admission, in-hospital length of stay and mortality RANDOMIZATION Patients are randomly assigned to receive protective or conventional OLV according to a computer-generated randomization list (1:1 ratio) before anesthesia induction. Patients are blinded to the treatment. Anesthesiologists and surgeons are unblinded to the treatment during the surgical procedure and the postoperative outcome assessment. MEASUREMENTS Intraoperative collection of ventilatory settings, airway pressures, arterial blood gases analysis at the following time points: T1: two lung ventilation in supine position before placing the patient in lateral decubitus; T2: 30 minutes after OLV start; T3: 60 minutes after OLV start; T4: 20 minutes after lobectomy/pneumonectomy (during OLV); T5: 15 minutes after ARM in supine position and during two lung ventilation. Postoperative data collection 1, 12, 24, 36, 48 hours after surgery and at discharge. Arterial blood gas analysis will be performed 1 hour after extubation and 24 and 72 hours after surgery (or in case of respiratory insufficiency).