EFFECT OF A PROTECTIVE-VENTILATION STRATEGY ON MORTALITY IN THE ACUTERESPIRATORY-DISTRESS SYNDROME

Background In patients with the acute respiratory distress syndrome, m assive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury. We deter mined whether a ventilatory strategy designed to minimize such lung in juries could reduce not only pulmonary complications but also mortalit y at 28 days in patients with the acute respiratory distress syndrome. Methods We randomly assigned 53 patients with early acute respiratory distress syndrome (including 28 described previously), all of whom we re receiving identical hemodynamic and general support, to conventiona l or protective mechanical ventilation. Conventional ventilation was b ased on the strategy of maintaining the lowest positive end-expiratory pressure (PEEP) for acceptable oxygenation, with a tidal volume of 12 ml per kilogram of bodyweight and normal arterial carbon dioxide leve ls (35 to 38 mm Hg). Protective ventilation involved end-expiratory pr essures above the lower inflection point on the static pressure-volume curve, a tidal volume of less than 6 ml per kilogram, driving pressur es of less than 20 cm of water above the PEEP value, permissive hyperc apnia, and preferential use of pressure-limited ventilatory modes. Res ults After 28 days, 11 of 29 patients (38 percent) in the protective-v entilation group had died, as compared with 17 of 24 (71 percent) in t he conventional-ventilation group (P<0.001). The rates of weaning from mechanical ventilation were 66 percent in the protective-ventilation group and 29 per cent in the conventional-ventilation group (P=0.005); the rates of clinical barotrauma were 7 percent and 42 percent, respe ctively (P=0.02), despite the use of higher PEEP and mean airway press ures in the protective-ventilation group. The difference in survival t o hospital discharge was not significant; 13 of 29 patients (45 percen t) in the protective-ventilation group died in the hospital, as compar ed with 17 of 24 in the conventional-ventilation group (71 percent, P= 0.37). Conclusions As compared with conventional ventilation, the prot ective strategy was associated with improved survival at 28 days, a hi gher rate of weaning from mechanical ventilation, and a lower rate of barotrauma in patients with the acute respiratory distress syndrome. P rotective ventilation was not associated with a higher rate of surviva l to hospital discharge. (C) 1998, Massachusetts Medical Society.