Monitoring patients with ARDS, Part 1: How to measure respiratory mechanics. Strategies to enhance the benefits of mechanical ventilation and lessen complications

Large inspiratory tidal volume, rather than high peak airway pressure (Ppeak), may be responsible for ventilator-associated lung injury in patients with acute respiratory distress syndrome (ARDS). Sustained increases in Ppeak are, however, a nonspecific marker of airway complications and should be investigated. Plateau pressure (Pplat) is useful as an approximation of alveolar pressure; it should not exceed 35 cm H₂O. Limiting Pplat by using smaller tidal volumes appears to mitigate the potential for lung injury and may reduce ARDS-related mortality. Intrinsic positive end-expiratory pressure (PEEP) can cause hemodynamic compromise; to detect it, an end-expiratory hold maneuver is performed. Applying external PEEP according to the location of the lower inflection point of the pressure-volume curve may improve oxygenation while helping to avoid barotrauma.