Lung protection ventilation: Pressure goal

ARDSNET

Patients with ARDS (PaO₂/FiO₂ < 300, bilateral pulmonary infiltrates on a CXR, no clinical evidence of left atrial hypertension or if measured a wedge < 18 mm Hg, excluding all patients with elevated ICP, neuromuscular, sickle cell, or severe chronic respiratory disease, obesity > 1 kg/cm height, or burns > 30% of BSA) given AC ventilation at either 12 ml/kg (average plateau pressure 33 cm H₂O) or 6 ml/kg, subsequently reduced stepwise by 1 ml/kg of PBW if necessary tomaintain Pplateau at a level of no more than 30 cm of water, if Pplateau dropped below 25 cm of water, tidal volume was increased in steps of 1 ml/kg of PBW until the Pplateau was at least 25 cm of water or theTV was 6 ml/kgof PBW. (average plateau pressure 25 cm H₂O) Results showed improvements in death before discharge (39.8 vs 31.0%, p = 0.007),% of patients breathing without the vent at 28 days (55.0 vs 65.7%, p < 0.001), number of ventilator-free days (10 vs 12, p 0.007), and days free of non-pulmonary organ failure (12 vs 15,p = 0.006, see [NEJM 342: 1301, 2000])

ARDSNET-2

8.3 vs. 13.2 cm H₂O PEEP in patients with acute lung injury and ARDS who receive mechanical ventilation with a tidal-volume goal of 6 ml per kilogram of predicted body weight and an end-inspiratory plateau-pressure limit of 30 cm of water, clinical outcomes are similar whether lower or higher PEEP levels are used [NEJM 351: 327, 2004]

Lung Protective Pressure Strategy

Set PEEP slightly above the LIP (Lower Inflection Point on inspiratory volume pressure curve to avoid end-expiratory alveolar collapse), and tidal volume to obtain end-inspiratory plateau pressure just below the UIP (Upper Inflection Point, where hyperinflation occurs). may be better to set PEEP based on expiratory limb of volume-pressure loop. requires vital capacity maneuver and decremental PEEP.