Mechanisms of pulmonary edema clearance

The mechanisms of pulmonary edema resolution are different from those regulating edema formation. Absorption of excess alveolar fluid is an active process that involves vectorial transport of [Na.sup.+] out of alveolar air spaces with water following the [Na.sup.+] osmotic gradient. Active [Na.sup.+] transport across the alveolar epithelium is regulated via apical [Na.sup.+] and chloride channels and basolateral Na-K-ATPase in normal and injured lungs. During lung injury, mechanisms regulating alveolar fluid reabsorption are inhibited by yet unclear pathways and can be upregulated by pharmacological means. Better understanding of the mechanisms that regulate edema clearance may lead to therapeutic interventions to improve the ability of lungs to clear fluid, which is of clinical significance. acute lung injury; acute respiratory distress syndrome; alveolar epithelium; alveoli lung