Lung-protective ventilation strategies in acute lung injury

Objectives. To review the challenges of providing mechanical ventilatory support for respiratory failure while avoiding ventilator-associated lung injury in patients with acute lung injury. To review the results of several randomized clinical trials of lung-protective ventilation strategies using conventional mechanical ventilators. Data Sources. Published reports of clinical trials comparing clinical outcomes of patients with acute lung injury, randomized to mechanical ventilation with either a lung-protective or a control, conventional, standard, or traditional approach. Data Extraction and Synthesis: Lung-protective mechanical ventilation strategies are designed to prevent injury from overdistention by using lower tidal volumes and lower inspiratory pressures (volume- and pressure-limited ventilation) or injury from ventilation with atelectasis and alveolar flooding at end-expiration (open-lung ventilation). In one trial, clinical outcomes were better in the study group that received combined volume- and pressure-limited and open-lung strategies compared with the study group that received a conventional approach. Of four trials focusing on volume- and pressure-limited ventilation alone, three did not demonstrate improvements in clinical outcomes, whereas one demonstrated a substantial reduction in mortality and an increase in ventilator-free days. The different results in these four trials may be attributable to differences in tidal volumes between the study groups, chance variation, or differences in the management of respiratory acidosis. Conclusions: Evidence supports the use of a volume- and pressure-limited approach to mechanical ventilation in patients with acute lung injury. It is not yet clear whether the open-lung approach will further reduce mortality in patients receiving volume- and pressure-limited ventilation support.