Acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a life-threatening condition where the lungs can't provide the body's vital organs with enough oxygen.

It's usually a complication of a serious existing health condition. Most people have therefore already been admitted to hospital by the time they develop ARDS.

Symptoms of ARDS

Symptoms of ARDS can include:

• severe shortness of breath
• rapid, shallow breathing
• tiredness, drowsiness or confusion
• feeling faint

When to get urgent medical help

Although most people develop ARDS when they're already in hospital, this isn't always the case. It can develop quickly as a result of an infection such as pneumonia, or if someone accidentally inhales their vomit.

Dial 999 immediately to ask for an ambulance if a child or adult is having breathing problems.

What causes ARDS?

ARDS occurs when the lungs become severely inflamed due to an infection or injury. The inflammation causes fluid from nearby blood vessels to leak into the tiny air sacs in your lungs, making breathing increasingly difficult.

The lungs can become inflamed following:

• pneumonia or severe flu
• blood poisoning 
• a severe chest injury  
• accidental inhalation of vomit, smoke or toxic chemicals
• near drowning
• acute pancreatitis – a serious condition where the pancreas becomes inflamed over a short period of time 
• an adverse reaction to a blood transfusion

Diagnosing ARDS

There's no specific test to diagnose ARDS. A full assessment is needed to identify the underlying cause and rule out other conditions.

The assessment is likely to include:

• a physical examination
• blood tests – to measure the amount of oxygen in the blood and check for an infection
• a pulse oximetry test – where a sensor attached to the fingertip, ear or toe is used to measure how much oxygen the blood is absorbing
• a chest X-ray and a computerised tomography (CT) scan – to look for evidence of ARDS
• an echocardiogram – a type of ultrasound scan that's used to look at the heart and nearby blood vessels

Treating ARDS

If you develop ARDS, you'll probably be admitted to an intensive care unit (ICU) and put on a breathing machine (ventilator) to help your breathing.

This involves breathing through a mask attached to the machine. In severe cases, a breathing tube may be inserted down your throat and into your lungs.

Fluids and nutrients will be supplied through a feeding tube (nasogastric tube) that's passed through your nose and into your stomach.

The underlying cause of ARDS should also be treated. For example, if it's caused by a bacterial infection, you may need antibiotics.

How long you'll need to stay in hospital depends on your individual circumstances and the cause of ARDS. Most people respond well to treatment, but it may be several weeks or months before you're well enough to leave hospital.

Complications of ARDS

As ARDS is often caused by a serious health condition, about one in three people who develop it will die. However, most deaths are caused by the underlying illness, rather than ARDS itself.

For people who survive, the main complications are associated with nerve and muscle damage, which causes pain and weakness. Some people also develop psychological problems, such as post-traumatic stress disorder (PTSD) and depression.

The lungs usually recover and long-term lung failure after ARDS is rare.