Monitoring alveolar epithelial function in acute lung injury

Objective. Identification of humoral markers of acute lung injury may lead to insights into pathologic mechanisms. In addition, specific markers may b e useful for predicting development of acute respiratory distress syndrome (ARDS) or for assessing prognosis. Ultimately, studies of lung injury marke rs may help define interventions that prevent or moderate ARDS. The alveola r epithelium is important both for the integrity of the blood-gas barrier a nd for repair of the barrier after lung injury. This article reviews marker s that derive from or relate to the alveolar epithelium and that might be u sed for monitoring alveolar epithelial function in acute lung injury. Surfa ctant apoproteins may be important markers of injury or for prognosis. Leve ls of surfactant apoprotein A (SP-A) fall 50-75% in patients with severe lu ng injury compared to normal patients. Serum levels of SP-A in patients dyi ng of acute respiratory distress syndrome are double serum levels of surviv ors.