Ventilator induced lung injury and infection in the critically ill.

Background: Traditional approaches to mechanical ventilation use tidal volumes of 10–15 ml/kg body weight and may cause stretch-induced lung injury in patients with acute lung injury and the acute respiratory distress syndrome. We therefore conducted a trial to determine whether ventilation with lower tidal volumes would improve the clinical outcomes in these patients. Methods: Patients with acute lung injury and the acute respiratory distress syndrome were enrolled in a multicenter randomized trial. The trial compared traditional ventilation treatment, which involved an initial tidal volume of 12 ml/kg predicted body weight and an airway pressure measured after a 0.5 s pause at the end of inspiration (plateau pressure) of 50 cm H2O or less, with ventilation with a lower tidal volume, which involved an initial tidal volume of 6 ml/kg predicted body weight and a plateau pressure of 30 cm H2O or less. The primary outcomes were death before a patient was discharged home and was breathing without assistance and the number of days without ventilator use from day 1 to day 28. Results: The trial was stopped after the enrollment of 861 patients because mortality was lower in the group treated with lower tidal volumes than in the group treated with traditional tidal volumes (31.0% vs 39.8%, P=0.007), and the number of days without ventilator use during the first 28 days after randomization was greater in this group (mean (SD) 12 (11) vs 10 (11); P=0.007). The mean tidal volumes on days 1–3 were 6.2 (0.8) and 11.8 (0.8) ml/kg predicted body weight (P<0.001), respectively, and the mean plateau pressures were 25 (6) and 33 (8) cm H2O (P<0.001), respectively. Conclusions: In patients with acute lung injury and the acute respiratory distress syndrome, mechanical ventilation with a lower tidal volume than is traditionally used results in decreased mortality and increases the number of days without ventilator use. (N Engl J Med 2000;342:1301–8)