[Mediators and ARDS].

The symptoms of adult respiratory distress syndrome (ARDS) include dyspnea, tachypnea, hypoxemia refractory to supplemental oxygen and bilateral infiltrations in the chest X-ray. Neutrophils are implicated in the pathogenesis as important effector cells acting by release of mediators. Activation of the complement system has been shown in several studies and can induce lung damage directly in animal models. Proteases and collagenase have been found in elevated concentration in bronchoalveolar lavage fluid, while the amount of protease-inhibitors has been found to be reduced. Arachidonic acid metabolites of the cyclooxygenase and lipoxygenase pathway, such as prostaglandins and leukotrienes, may play a role in the pathogenesis or perpetuation of the disease process. The same holds true for cytokines such as interleukin-1 or tumor necrosis factor. All of them have been found to be elevated either in plasma or bronchoalveolar lavage fluid of ARDS patients. Several lines of evidence implicate oxygen radicals as important mediators of lung damage in ARDS. The therapeutic implications of these new insights into the pathogenesis of ARDS are briefly discussed.