Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening condition where the lungs are unable to work properly. It is caused by injury to the capillary wall either from illness or a physical injury such as major trauma. This results in the wall becoming leaky, leading to a build-up of fluid and the eventual collapse of the air sacs, leaving the lungs unable to exchange oxygen and carbon dioxide. Acute respiratory failure (ARF) is a term often used alongside ARDS, but it is a broader term that refers to the failure of the lungs from any causes, such as chronic obstructive pulmonary disease (COPD).

Last Update 07/08/2023
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ARDS is unlikely to occur on its own and is usually the result of another health condition or serious accident or injury. People who experience ARDS are therefore likely to have already been admitted to hospital. Signs that a person could have developed ARDS include breathlessness or blue fingers or lips.


There are two types of events that can cause ARDS; direct injury to the lungs and indirect injury to other parts of the body.

Direct causes

  • Pneumonia
  • Contents of the stomach moving into the lung (known as gastric aspiration)
  • Near drowning
  • Severe trauma to the lungs
  • Smoke and toxic gas inhalation
  • A fat embolism – when fat from the body moves into the respiratory system and causes problems

Indirect causes

  • Widespread swelling in the body, caused by an overreaction of the immune system (known as severe sepsis)
  • Shock
  • Multiple blood transfusions
  • Inflammation in the pancreas (known as pancreatitis)
  • Blood clotting
  • Drug overdose


Doctors identify ARDS based on a number of criteria, including worsening lung symptoms, a chest x-ray showing fluid in the lungs, lung failure without a known cause, or the syndrome occurring within a week of a known injury.

The condition is treated in a number of ways:

  • Mechanical ventilation, which helps the lungs breathe artificially after they have stopped working.
  • Fluid management, either restricting fluid or supplying extra fluid depending on the patient’s needs.
  • Strategies which use the airways to access the injured lung could prove beneficial but there has been little research into the success of these treatments.
  • Techniques and devices that involve taking blood from a patient and either adding oxygen or removing carbon dioxide, to help support the lungs and heart (known as extracorporeal membrane oxygenation (ECMO).
  • Supportive measures such as turning the patient on their stomach and nutritional support may also help.
  • There have so far been no effective pharmacological treatments developed to help treat ARDS.

ARDS can cause death as multiple organs fail. The elderly and people with other conditions are most likely to die from ARDS.

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