[Pathophysiology and Diagnosis of the acute respiratory distress syndrome]

We studied methods for diagnosing the acute respiratory distress syndrome (ARDS) based on its characteristic abnormalities. A gamma-ray external counting method with Tc-99m human serum albumin revealed that pulmonary microvascular permeability was abnormally high in patients with ARDS. With this method, ARDS could be distinguished from cardiogenic pulmonary edema. Levels of interleukin-8 in bronchoalveolar fluid from patients with septic ARDS, reexpansion pulmonary edema, and inhalation burn injury were abnormally high. In 21 patients with acute lung injury, 15 of whom had ARDS, plasma concentrations of three inflammatory markers were measured: thiobarbituric acid reactive material which reflects cell membrane lipid peroxidation; 7S collagen, a component of basement membrane; and the soluble form of P-selectin, an adhesion molecule. Levels of all three were abnormally high in patients with ARDS, and correlated with the degree of lung injury and with the outcome in these patients. We conclude that these measurements in plasma or bronchoalveolar lavage fluid may enable us to assess the severity of ARDS.