Tidal volume reduction for prevention of ventilator-induced lung injury inacute respiratory distress syndrome

Because animal studies have demonstrated that mechanical ventilation at hig h volume and pressure can be deleterious to the lungs, limitation of airway pressure, allowing hypercapnia if necessary, is already used for ventilati on of acute respiratory distress syndrome (ARDS). Whether a systematic and more drastic reduction is necessary is debatable. A multicenter randomized study was undertaken to compare a strategy aimed at limiting the end-inspir atory plateau pressure to 25 cm H2O, using tidal volume (V-T) below 10 ml/k g of body weight, versus a more conventional ventilatory approach (with reg ard to current practice) using V-T at 10 ml/kg or above and close to normal Pa-CO2. Both arms used a similar level of positive end-expiratory pressure . A total of 116 patients with ARDS and no organ failure other than the lun g were enrolled over 32 mo in 25 centers. The two groups were similar at in clusion. Patients in the two arms were ventilated with different V-T (7.1 /- 1.3 versus 10.3 +/- 1.7 ml/kg at Day 1, p < 0.001) and plateau pressures (25.7 +/- 5.0 versus 31.7 +/- 6.6 cm H2O at Day 1, p < 0.001), resulting i n different Pao, (59.5 +/- 15.0 versus 41.3 +/- 7.6 mm Hg, p < 0.001) and p H (7.28 +/- 0.09 versus 7.4 +/- 0.09, p < 0.001), but a similar level of ox ygenation. The new approach did not reduce mortality at Day 60 (46.6% versu s 37.9% in control subjects, p = 0.38), the duration of mechanical ventilat ion (23.1 +/- 20.2 versus 21.4 +/- 16.3 d, p = 0.85), the incidence of pneu mothorax (14% versus 12% p = 0.78), or the secondary occurrence of multiple organ failure (41% versus 41%, p = 1). We conclude that no benefit could b e observed with reduced V-T titrated to reach plateau pressures around 25 c m H2O compared with a more conventional approach in which normocapnia was a chieved with plateau pressures already below 35 cm H2O.