Acute respiratory distress syndrome (ARDS)

Abstract

ARDS is diagnosed clinically on the basis of the acute development of hypoxaemic respiratory failure, CXR changes and non-cardiogenic pulmonary oedema, on the background of a pulmonary or non-pulmonary precipitating condition.  ARDS may affect one in ten intensive care unit patients, and it carries a mortality of 30-40%.

Pathologically ARDS is characterised by an inflammatory phase involving neutrophils and cytokines, followed by a reparative process that may end in fibrosis.  

Patients exhibit the signs and symptoms of pulmonary oedema, though features of the underlying condition may influence the picture.  

Management consists of treating the underlying condition, providing support for failing systems and early invasive ventilation.  Limiting the Fi02 may help to prevent further lung damage, while limiting tidal volumes to 6-8 ml.kg-1 has been shown to reduce mortality.  In cases of refractory hypoxaemia PC-IRV or ventilation in the prone position may improve blood gases, but have not been proven to influence survival.  In addition there are many advanced techniques but many are only available in specialist centres, and none convincingly reduce mortality.