 During mechanical ventilation, the alveolar recruitment maneuver ARM is to apply a positive end-expiratory pressure PEEP generally 30 cm H2O for a period of at least 30 seconds. The realization of MRA is one of three main elements of mechanical ventilation called protective. This ventilatory strategy, originally described for the ventilation of acute respiratory distress syndrome ARDS, and pulmonary and during abdominal surgery is based on a decrease tidal volumes, optimization of PEEP and the realization of MRA. Protective ventilation limit the occurrence of atelectasis, the surdistentions and, ultimately, significantly decreases postoperative complications. 