Rational: Partial automation of mechanical ventilation in resuscitation has been available for several years. It can deliver a continuous ventilation adapted in real time to the patient's clinical condition,and decrease care workload and ventilation weaning duration. New modalities are being developed to completely automate ventilation and oxygenation parameters (IntelliVent®) and preliminary studies show that over short periods (2 to 4 h) such a system can ventilate patients more optimally and more safely, with a better ventilation efficiency (comparable effect on gas exchanges for a less "aggressive" ventilation). This pilot study compares over a longer period (48 hours), the safety and efficacy of IntelliVent®, versus a usual ventilation modality.