Acute Respiratory Distress Syndrome (ARDS)

 Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury caused by sepsis, pneumonia, the coronavirus (COVID-19) and other conditions. ARDS tends to develop within few hours to few days of the event that caused it, and can worsen rapidly. ARDS patients may have to be put in an intensive care unit (ICU) and on a ventilator to help them breathe.

OVERVIEW

What is acute respiratory distress syndrome (ARDS)?

Acute respiratory distress syndrome, or ARDS, is an inflammatory lung injury that happens when fluids build up in small air sacs (called alveoli) in the lungs. ARDS prevents the lungs from filling up with air and causes dangerously low oxygen levels in the blood (hypoxemia).

This condition prevents other organs such as brain, heart, kidneys and stomach from getting the oxygen they need to function. ARDS is dangerous and can lead to a number of serious and life-threatening problems.

ARDS typically happens in hospital settings while the patient is being treated for infection or trauma. If you’re not hospitalized and experience symptoms of ARDS, get medical attention immediately.

The image on the left shows the location of the lungs, trachea, and bronchi within the body. The middle image shows the normal gas exchange of oxygen and carbon dioxide through the air sacs. The image on the right shows the fluid buildup in the air sacs of someone who has ARDS. The fluid buildup prevents gas exchange.

SYMPTOMS AND CAUSES

What causes acute respiratory distress syndrome (ARDS)?

ARDS is caused when fluids leak from small lung vessels into lung air sacs (alveoli). When the protective membrane between blood vessels and air sacs is compromised, levels of oxygen in the blood decrease.

Causes of ARDS include:

• Sepsis: The most common cause of ARDS, a serious infection in the lungs (pneumonia) or other organs with widespread inflammation.
• Aspiration pneumonia: Aspiration of stomach contents into the lungs may cause severe lung damage and ARDS.
• The coronavirus (COVID-19): The infection COVID-19 may develop into severe ARDS.
• Pancreatitis (severe inflammation in the pancreas), and massive blood transfusion.
• Major trauma and burns: Accidents and falls may directly damage the lungs or other organs in the body that trigger severe inflammation injury in the lungs.
• Inhalational injury: Breathing and exposure to high concentrations of chemical fumes or smoke.
• Drug overdose: An overdose on drugs like cocaine and opioids.

What are the symptoms of acute respiratory distress syndrome (ARDS)?

Symptoms of ARDS depend on the cause and severity of the case, as well as pre-existing lung or heart conditions. Symptoms include:

• Severe shortness of breath or breathlessness.
• Rapid and labored breathing.
• Extreme tiredness and muscle fatigue.
• Confusion.
• Rapid heart rate.
• Bluish color of fingernails and lips due to low oxygen level in the blood.
• Cough and chest pain.

If ARDS is caused by severe infection (sepsis), symptoms of sepsis may also be present (fever, low blood pressure).

How quickly can acute respiratory distress syndrome (ARDS) develop?

ARDS tends to develop within a few hours to a few days of the event that caused it. ARDS can worsen rapidly.

DIAGNOSIS AND TESTS

What tests are done to diagnose acute respiratory distress syndrome (ARDS)?

When symptoms of ARDS occur, a combinations of tests may be done:

• Chest X-ray to measure fluids in the lungs.
• A blood test to determine oxygen level in the blood to help determine the severity of ARDS.
• Echocardiogram (ultrasound of the heart) to evaluate heart function.

Sometimes, symptoms and signs of ARDS may require additional tests to diagnose other causes that are similar to ARDS.

• A computerized tomography (CT scan) may be done to gain detailed information about the lungs.
• Sampling of secretions from the airways may be taken to find the cause of infection.

MANAGEMENT AND TREATMENT

How is acute respiratory distress syndrome (ARDS) treated?

ARDS is usually treated in the intensive care unit (ICU) along with treatment of the underlying cause.

Mechanical ventilation (a ventilator) is often used in caring for patients with ARDS. For milder cases of ARDS, oxygen may be given through a fitted face mask or a cannula fitted over the nose.

Steps to minimize complications (see below) from ARDS are commonly used. These include:

• Sedation to manage pain.
• Breathing tests to determine when it’s safe to remove the tube and ventilator.
• Blood thinners to prevent clots.
• Minimizing fluid buildup in the lungs.
• Minimizing stress ulcers in the stomach.
• Active mobility and physical therapy to prevent muscle weakness.

No direct drug therapy has been shown to improve survival in ARDS, but researchers continue to work on finding treatment.

What complications can develop from acute respiratory distress syndrome (ARDS)?

Complications and problems from ARDS may develop while a patient is in the hospital or after discharge.

• Blood clots or deep vein thrombosis.
• Collapsed lung (pneumothorax). This may result from pressure applied by the ventilator to the injured stiff lungs.
• Confusion (delirium).
• Muscle weakness.
• Scarred lungs or lung fibrosis.
• Post traumatic stress disorder (PTSD).
• Anxiety and depression

What is the outlook for acute respiratory distress syndrome (ARDS)?

ARDS can be life-threatening and deadly. But improved care and ventilator treatments  including prone ventilation with patients lying face down to improve oxygen flow  are now helping more people survive and reduce risk of complications from ARDS.

Recovery from ARDS may take a long time. Most patients can be removed from the ventilator and breathe freely. Some recover completely, but others may develop chronic lung problems that require care by lung doctors (pulmonologists). Some patients may develop post-intensive care syndrome (PICS) and can experience post-traumatic stress disorder, physical weakness, and anxiety and depression.

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Time in the ICU can be traumatic and hard. People recovering from ARDS may not be able to go back to everyday life and work quickly, and need support. Getting professional help and advice is important along the road to recovery from ARDS. Ask your healthcare team about any post intensive care recovery programs in your area and online support groups that are available.

References :

• National Heart, Blood, and Lung Institute. Acute Respiratory Distress Syndrome.
• American Lung Association.
• Book:Acute Respiratory Distress Syndrome Advances in Diagnostic Tools and Disease Management... Editor: Sadatomo Tasaka