NEW YORK, June 23 (Praxis Press) Acute chest syndrome is the leading cause of death among patients with sickle cell disease, but its cause is largely unknown. To determine the cause of acute chest syndrome and its response to therapy, Vichinsky and colleagues performed a study of 671 episodes of the acute chest syndrome in 538 patients with sickle cell disease. They found that among patients with sickle cell disease, acute chest syndrome is commonly precipitated by fat embolism and infection, especially community-acquired pneumonia. Among older patients and those with neurologic symptoms, the syndrome often progresses to respiratory failure. Treatment with transfusions and bronchodilators improves oxygenation, and with aggressive treatment, most patients who have respiratory failure recover. Acute chest syndrome is commonly precipitated by fat embolism and infection and most patients with respiratory failure can recover with aggressive treatment.