Acute Respiratory Distress Syndrome [ARDS] is an acute condition characterized by bilateral pulmonary infiltrates and severe hypoxemia in the absence of evidence for cardiogenic pulmonary edema.
In this condition, the small blood vessels leak leading to fluid bluid up in the alveoli. This is described as diffuse alveolar damage (DAD) and lung capillary endothelial injury. This fluid prevents effective oxygen to carbon dioxide transfer into and out of the body respectively. Therefore carbon dioxide is not cleared and oxygen uptake is impaired.
The early phase is described as being exudative, whereas the later phase is fibroproliferative in character.
ARDS was recognized as the most severe form of acute lung injury (ALI), a form of diffuse alveolar injury. As this condition is life-threatening; many patients with ARDS require life support with a ventilator in an intensive care unit to assist with breathing.
Pathophysiology of ARDs
Medscape & Stevens et. al 2018