title: Pathobiology of acute respiratory distress syndrome.
abstract: The unique characteristics of pulmonary circulation and alveolar-epithelial capillary-endothelial barrier allow for maintenance of the air-filled, fluid-free status of the alveoli essential for facilitating gas exchange, maintaining alveolar stability, and defending the lung against inhaled pathogens. The hallmark of pathophysiology in acute respiratory distress syndrome is the loss of the alveolar capillary permeability barrier and the presence of protein-rich edema fluid in the alveoli. This alteration in permeability and accumulation of fluid in the alveoli accompanies damage to the lung epithelium and vascular endothelium along with dysregulated inflammation and inappropriate activity of leukocytes and platelets. In addition, there is uncontrolled activation of coagulation along with suppression of fibrinolysis and loss of surfactant. These pathophysiological changes result in the clinical manifestations of acute respiratory distress syndrome, which include hypoxemia, radiographic opacities, decreased functional residual capacity, increased physiologic deadspace, and decreased lung compliance. Resolution of acute respiratory distress syndrome involves the migration of cells to the site of injury and re-establishment of the epithelium and endothelium with or without the development of fibrosis. Most of the data related to acute respiratory distress syndrome, however, originate from studies in adults or in mature animals with very few studies performed in children or juvenile animals. The lack of studies in children is particularly problematic because the lungs and immune system are still developing during childhood and consequently the pathophysiology of pediatric acute respiratory distress syndrome may differ in significant ways from that seen in acute respiratory distress syndrome in adults. This article describes what is known of the pathophysiologic processes of pediatric acute respiratory distress syndrome as we know it today while also presenting the much greater body of evidence on these processes as elucidated by adult and animal studies. It is also our expressed intent to generate enthusiasm for larger and more in-depth investigations of the mechanisms of disease and repair specific to children in the years to come.
authors.affiliation: 1Division of Critical Care, Department of Pediatrics, University of California, San Francisco, San Francisco, CA. 2Pediatric Intensive Care Unit, Department of Medicine, Children's Hospital, Oakland, CA. 3Division of Pediatric Critical Care, Research Center Oakland, Oakland, CA. 4Division of Pediatric Critical Care, Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI.
authors.forename: Anil
authors.initials: A
authors.lastname: Sapru
authors.forename: Heidi
authors.initials: H
authors.lastname: Flori
authors.forename: Michael W
authors.initials: MW
authors.lastname: Quasney
authors.forename: Mary K
authors.initials: MK
authors.lastname: Dahmer
mesh_terms: D000208:Acute Disease; D004730:Endothelium, Vascular / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism; D011652:Pulmonary Circulation / Q000502:physiology; D011654:Pulmonary Edema / Q000503:physiopathology; D011663:Pulmonary Surfactants / Q000378:metabolism; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology* / Q000628:therapy; D020545:Respiratory Mucosa / Q000378:metabolism; D013927:Thrombosis / Q000503:physiopathology
chemical_list: D011663:Pulmonary Surfactants