Inclusion Criteria:  Admitted to one of the participating ICUs; Receiving invasive ventilation through a standard endotracheal (i.e., oral) tube; Expected to be ventilated > 24 hours; and Ventilation is applied by a ventilator that can provide INTELLiVENT-ASV and conventional ventilation.  Exclusion Criteria:  Age under 18 years; No written informed consent; Morbidly obese; and Any contra-indication for use of INTELLiVENT-ASV