How is the pathophysiology of ARDS?

Endothelial injury increases permeability, leading to protein-rich alveolar edema. Neutrophils play a role (but it may occur in neutropenic pt) Proinflammatory cytokines mediate cellular responses lead to microvascular injury Activation of coagulation system in sepsis can lead to inflammation and tissue ischemia Due to increased permeability, hydrostatic pressure is unopposed and any increase in pressure will increase the edema (depends on area of lungs affected) Increase in tissue/gas ratio leads to alveolar collapse and closure, exaggerated by reduction and damage of surfactant