Ventilatory strategies in severe acute respiratory failure

Lung-protective ventilator strategies are considered standard practice in the care of patients with the acute respiratory distress syndrome (ARDS). To minimize ventilator-induced lung injury, attention is directed at avoidance of alveolar overdistention and cyclical opening and closing. The lowest possible plateau pressure and tidal volume (V(T)) should be selected. A reasonable target V(T) in all mechanically ventilated patients is 6 mL/kg. A topic of much controversy is the optimal setting of positive end-expiratory pressure (PEEP). Results of a meta-analysis using individual patient data from three randomized controlled trials suggest that higher PEEP should be used for moderate and severe ARDS, whereas lower PEEP may be more appropriate in patients with mild ARDS. PEEP should be set to maximize alveolar recruitment while avoiding overdistention. Volume and pressure limitation during mechanical ventilation can be described in terms of stress and strain. Fraction of inspired oxygen (Fio(2)) and PEEP are typically titrated to maintain arterial oxygen saturation (Spo(2)) of 88 to 95% (Pao(2) 55-80 mm Hg). There is currently no clear proven benefit for advanced modes.