The study compares automated settings (Intellivent) with protocolized settings of the ventilator after cardiac surgery. The settings concern the respiratory rate, the inspiratory and expiratory pressure and FiO2. The aim of the study is to demonstrate that automated settings are feasible and safe.

The study design is a randomized controled study. 30 patients will be ventilated with automated mode and 30 patients with protocolized settings after cardiac surgery.

The hypothesis is that the automated mode allows a safer ventilation with better maintain of the patient in predefined optimal zone of ventilation.

Aim: feasibility and safety study = evaluation of the possibility for a fully automated ventilator to safely manage the ventilation and oxygenation after cardiac surgery

Hypothesis:

Intellivent will maintain the patient with " optimal ventilation " better than during usual management with a minimal number of interventions

Monocentric: IUCPQ, Hôpital Laval, Québec Randomized controlled safety study, unblinded Patients after elective cardiac surgery Two arms Intellivent (fully automatic ventilation) Protocolized ventilation 4 hours study 60 patients planned to be included Primary outcome: number of episodes in the " not acceptable " zone of ventilation and duration

Secondary outcome:

Number of episodes in the " acceptable " zone of ventilation and duration Number of manual settings and duration of interventions Comparison of arterial blood gases Time to wean the FiO2 the PEEP Time to begin the assisted ventilation Duration of mechanical ventilation

Criteria for consent (before surgical procedure):

• Elective cardiac surgery
• Age 18 to 90 years
• Absence of pregnancy
• Body Mass Index < 40 kg/m²
• Creatinine < 200micromol/L)
• Baseline PaCO2 > 50 mmHg)

Exclusion Criteria:

• Unexpected surgical procedure
• Major complication during surgery
• Early extubation expected (< 1 hour)
• Broncho-pleural fistula
• Study ventilator not available