The lung after trauma and shock--fine structure of the alveolar-capillary barrier in 23 autopsies.

We have examined the ultrastructure of the alveolar septa in the lungs of 23 victims of severe trauma and shock. In ten patients, who died within a week after trauma, protein-poor interstitial edema and fat emboli were the most constant ultrastructural change. The alveolar epithelium and the capillary endothelium were surprisingly devoid of morphologic evidence of injury. A high incidence of pneumonia and/or sepsis complicated the hospital course of patients surviving for longer periods of time. Ultrastructurally, the lungs of these patients showed variable degrees of injury to the alveolar epithelium and capillary endothelium and accumulation of protein-rich edema fluid in the extravascular spaces. The study suggests that most of the pulmonary pathologic lesions attributed to tissue trauma and shock are the consequence of systemic or local infections to which trauma patients are particularly susceptible.