Adult respiratory distress syndrome: definition and historical perspective.

The adult respiratory distress syndrome is a reaction of the lung to a variety of severe direct or indirect pulmonary insults. It is characterized by acute respiratory distress, severe hypoxemia requiring high oxygen fractions, and "stiff lungs" requiring approaches to ventilatory management cited elsewhere in this issue of Clinics in Chest Medicine. Increased shunt fraction and dead space ventilation and airless lungs with debris and hyaline membranes are hallmarks of the syndrome, even though the final common pathway, i.e., the mechanism, is not known. The characterization of ARDS creates an important pathological concept for which there is an organized approach to physiologically oriented management. Details of management are cited elsewhere in this issue.