Inflammatory response of the lungs to severe disease or injury
Acute respiratory distress syndrome (ARDS) is a serious lung disorder that develops suddenly as a result of severe damage either to the lungs or elsewhere in the body. In ARDS, the tiny blood vessels (capillaries) in the lungs leak fluid into the alveoli (air sacs), reducing the amount of oxygen that reaches the blood and preventing the lungs from expanding fully. This in turn can lead to the failure of other vital organs, including the kidneys and liver. ARDS is a life-threatening disorder that requires emergency medical treatment.
ARDS can develop after any serious illness or injury. A third of cases result from widespread bacterial infection of the blood (see Septicaemia). In other cases, major trauma such as multiple fractures, crushed internal organs, or severe burns are the cause. Less commonly, ARDS results from pneumonia, obstetric emergencies, inhaling vomit, or an overdose of an opioid drug such as heroin. How these conditions and emergencies cause leakage in the lungs remains unclear.
The symptoms of ARDS usually begin 24–48 hours after the injury or onset of the disease that brings about the condition and may include the following:
Severe shortness of breath.
Mottled blue skin.
Confusion or unconsciousness.
These symptoms develop in addition to those related to the underlying disorder that has caused the lung damage. As well as being a possible cause of ARDS, pneumonia may develop as a complication. Other complications, such as acute kidney failure, may also occur.
A doctor will probably suspect ARDS if a person who is already seriously ill develops sudden, unexpected breathing difficulties. The diagnosis can often be confirmed by a chest X-ray, which is used to look for evidence of fluid in the alveoli, and analysis of the oxygen levels in the blood (see Measuring blood gases).
People with ARDS are usually treated in an intensive therapy unit. High concentrations of oxygen are given using artificial ventilation in order to increase the amount of oxygen that passes from the lungs into the blood. Diuretic drugs may be given to reduce the amount of fluid in the lungs. The underlying cause and any complications are treated, and the condition of major organs is monitored.
Only 1 in 2 people who develop ARDS survive. In those who recover, symptoms usually improve over 7–10 days. There is often little or no permanent damage to the lungs, and the majority of people who do make a recovery experience no further problems.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.