Acute respiratory distress syndrome (ARDS) is caused by the increased permeability of alveolar capillaries leading to fluid accumulation in the alveoli, i.e. non-cardiogenic pulmonary oedema. It is a serious condition that has a mortality of around 40% and is associated with significant morbidity in those who survive.

Causes

• infection: sepsis, pneumonia
• massive blood transfusion
• trauma
• smoke inhalation
• acute pancreatitis
• Covid-19
• cardio-pulmonary bypass

Clinical features are typically of an acute onset and severe:

• dyspnoea
• elevated respiratory rate
• bilateral lung crackles
• low oxygen saturations

A chest x-ray and arterial blood gases are the key investigations.

Criteria (American-European Consensus Conference)

• acute onset (within 1 week of a known risk factor)