Acute respiratory distress syndrome, commonly known as ARDS, is a life-threatening inflammatory condition of the lungs. It presents with the hallmark findings of acute hypoxic respiratory failure, including dyspnea, tachypnea, tachycardia, confusion, diaphoresis, and cyanosis as well as lung crackles, and a chest radiograph showing bilateral patchy pulmonary infiltrates that are not due to a cardiac cause or volume overload. It is usually seen after exposure to a clinical stressor or within 1 week of such a stressor.

Clinically, ARDS is characterized by decreased compliance in the lungs ("stiff lungs"). On a microscopic level, it involves alveolar edema due to increased permeability from membrane destruction ("leaky capillaries") as well as neutrophil infiltration, which can lead to activation of a localized inflammatory response. Once the alveoli are damaged, they will start to collapse, leading to atelectasis derecruitment of the lung. Although mechanical ventilation is the mainstay of treatment, it can be challenging and must be done carefully and within specific parameters, as repetitive re-expansion and collapse of the alveoli can lead to mechanical injury known as atelectrauma and the elevated mean airway pressures or excess tidal volumes in the setting of decreased lung compliance result in alveolar barotrauma / volutrauma.

The Berlin Definition of ARDS was published in 2012, identifying specific criteria for diagnosis.

Related topics: respiratory distress syndrome in the newborn, respiratory failure