Adult Respiratory Distress Syndrome
Debra H. Fiser MD1
1 Associate Professor, Departments of Pediatrics, Anesthesiology, and Psychiatry, University of Arkansas for Medical Sciences, and Arkansas Children's Hospital, Little Rock, AR.
Definition
The adult respiratory distress syndrome (ARDS) was first defined by Ashbaugh et al in 1967. It is a syndrome of acute parenchymal lung dysfunction characterized by the following clinical presentation: 1) a major antecedent precipitating event, 2) the sudden onset of tachypnea and hypoxemia refractory to high concentrations of inspired oxygen, 3) the presence of diffuse patchy infiltrates on the chest radiograph, 4) a decrease in static lung compliance, and 5) the exclusion of cardiogenic pulmonary edema and chronic pulmonary disease as the sole causes of pulmonary dysfunction.
Etiology
A wide variety of major antecedent events may precipitate ARDS. Common triggering events include trauma, sepsis, shock, pulmonary aspiration of gastric contents, near-drowning, diffuse intravascular coagulation, pulmonary contusion, severe pneumonia, massive transfusion of blood products, fat embolism, burns, and cardiopulmonary bypass surgery. Despite the diversity of these predisposing conditions, the similarity in pulmonary pathology and physiology among patients who have ARDS implicates a final common pathway for alveolar injury.
Pathogenesis
ARDS is characterized histologically by diffuse alveolar epithelial and endothelial damage. Subsequently, water, solutes, protein, cellular elements, and collagen may be deposited in the interstitium and air spaces, resulting in decreased compliance and hypoxemia.
Large gaps remain in our knowledge of the pathophysiologic alterations at the cellular and molecular levels, and many mediators have been suspected of playing a role in causing ARDS.
