Acute lung injury (ALI) and th

f****2

Acute lung injury (ALI) and the acute respiratory distress syndrome (**S) are a major cause of acute respiratory failure inthe critically ill patient. ALI and **S are characterized by the acute onset of severe hypoxemia and bilateral pulmonaryinfiltrates in the absence of clinical evidence for left atrial hypertension. These conditions are differentiated from one anotherby the ratio of the partial pressure of oxygen in the arterial blood to the inspired fraction of oxygen; **S requires a moresevere oxygenation defect. ALI and **S may occur in association with a number of clinical disorders, including sepsis,pneumonia, aspiration, trauma including inhalational injury, and blood transfusions. The mortality rate remains high, in therange of 25% to 40%. The pathophysiology of ALI/**S involves resident lung cells, including endothelial and epithelialcells, as well as neutrophils, monocytes/macrophages, and platelets. When ALI/**S is complicated by acute kidney injury,mortality increases substantially. Several supportive and pharmacologic therapies have been tested in clinical trials. Of these,a low tidal volume, lung protective ventilation strategy is the only strategy that has been demonstrated in a large, multicenterrandomized clinical trial to reduce mortality for patients with ALI/**S. Based on a recent randomized trial, a conservativefluid management strategy reduces the duration of mechanical ventilation without increasing the incidence of renal failure.Pharmacologic strategies and other ventilator management strategies have not been successful to date; however, severalrandomized, placebo controlled treatment trials are ongoing.