Because hypercapnia or low tidal volume alone may cause dyspnea and cause the patient to breathe in a fashion that is not coordinated with the ventilator, analgesics (fentanyl or morphine) and sedatives (eg, propofol initiated at 5 mcg / kg / minute and increasing to effect up to 50 mcg / kg / minute; because of the risk of hypertriglyceridemia, triglyceride levels should be checked every 48 hours) may be needed.