Mechanical ventilatory support allows patients who have CAO to gain time for pharmacologic treatment to work and to avoid and/or recover from respiratory muscle fatigue. The cornerstone to avoiding associated morbidity with mechanical ventilation in these patients is to prevent dynamic hyperinflation of the lung by limiting minute ventilation and maximizing time for expiration and by inducing synchronization between the patient and mechanical ventilator. When mechanical ventilation is necessary, NPPV should be considered first, whenever possible, in these patients. Patients who have CAO requiring mechanical ventilatory support have an increased risk of death following such an event. Therefore, careful followup is needed after hospital discharge.