Re-expansion, Re-oxygenation, and Rethinking

In a 1902 American Journal of the Medical Sciences case report, Riesman described "albuminous expectoration" following thoracentesis, a phenomenon that is now recognized as re-expansion pulmonary edema (RPE). Both cellular and biochemical mechanisms that produce lung injury in RPE have been described recently. Pathophysiologically, this unilateral edematous lung injury resembles the adult respiratory distress syndrome (ARDS) because both are characterized by intra-alveolar-activated neutrophils and markedly increased lung capillary permeability. Biochemical mechanisms that operate in RPE are analogous to those in diverse re-oxygenation (reperfusion) injuries that have been described recently in the heart, kidney, brain, and intestine. Re-oxygenated lung tissue appears to produce excess superoxide and other cytotoxic oxygen metabolites, although lung xanthine oxidase, the commonly recognized source of these oxidants, is exceedingly low. Riesman's critical analyses of the re-expansion edema fluid in his case provided an impetus for others to hypothesize that increased permeability pulmonary edema in RPE represented re-oxygenation injury of the lung microvasculature.