Clinical features

Patients with ARDS show a gradually worsening picture of respiratory disturbance which may rapidly become life threatening.

Usually, there is a latent period of hours or days after the insult with the patient hospitalised for one of the known aetiologic conditions.

This is then followed by stages of:

• respiratory distress - dyspnoea, tachypnoea - but with a normal chest radiograph
• increasing cyanosis, arterial hypoxaemia, and respiratory failure; the chest x-ray now shows diffuse bilateral shadowing which may be asymmetric depending on cause and recent posture
• hypoxaemia becomes refractory to high inspired oxygen and respiratory acidosis develops
• there may be death from hypoxic cardiac arrest

Not all stages are observed in all patients and some recover completely.