Acute respiratory distress syndrome (ARDS), sometimes called “wet lung,” is a serious and potentially life-threatening condition in which the lungs become severely inflamed and the tiny air sacs (alveoli) fill with fluid. This prevents the lungs from exchanging oxygen properly, causing dangerously low levels of oxygen in the blood. As a result, vital organs such as the brain, heart, kidneys and liver may not receive enough oxygen. ARDS can develop suddenly, often within hours to a few days after a serious illness or injury. It requires prompt medical attention and is usually treated in a hospital, often in an intensive care unit (ICU).
ARDS occurs when inflammation damages the lungs and the blood vessels surrounding the alveoli. The damaged blood vessels may allow fluid to leak into the air sacs, interfering with oxygen exchange. Common causes and risk factors include:
Severe bacterial or viral pneumonia can cause extensive inflammation and lung injury. Severe influenza and other respiratory infections may also trigger ARDS.
Sepsis, a life-threatening response to an infection, is one of the most common causes of ARDS. Widespread inflammation caused by sepsis can damage lung tissue.
In some cases, particularly after large-volume or multiple blood transfusions, a person may develop a type of acute lung injury associated with transfusion.
ARDS may also occur following certain severe infections, aspiration of stomach contents, near-drowning and other conditions that cause significant lung or systemic inflammation. Sometimes, despite extensive investigation, a specific cause cannot be identified.
Severe illness and prolonged immobility can increase the risk of blood clots. Abnormal blood clotting may also occur as part of the body’s response to severe infection or inflammation.
People with severe ARDS may be more susceptible to infections, particularly when mechanical ventilation is required. Ventilator-associated pneumonia is one possible complication.
Severe lung injury may result in scarring of lung tissue, known as pulmonary fibrosis. This can cause persistent breathing difficulties and reduced lung function in some people.
Severe lack of oxygen and widespread inflammation can impair the function of the kidneys, heart, brain and other organs. Multiple-organ failure can occur in severe cases.
There is no single test that confirms ARDS. Doctors generally make the diagnosis using a combination of medical history, physical examination and investigations. Tests may include:
Pulse oximetry: Measures oxygen saturation in the blood.
Arterial blood gas test: Measures oxygen and carbon dioxide levels and the blood’s acid-base balance.
Chest X-ray: May show widespread areas of inflammation and fluid in both lungs.
Chest CT scan: Can provide more detailed images of the lungs when necessary.
Blood tests: May help identify infections, inflammation and other underlying causes.
Echocardiogram: May be performed to assess heart function and help distinguish ARDS from fluid accumulation caused by certain heart conditions.
Other tests: Additional investigations may be performed to identify the illness or injury responsible for ARDS.
Doctors also assess how severely oxygen exchange is impaired and whether other organs are affected.
There is currently no single medication that cures ARDS. Treatment focuses on improving oxygen levels, supporting breathing, treating the underlying cause and preventing complications.
Supplemental oxygen is commonly given to improve blood oxygen levels. Depending on the severity of respiratory failure, oxygen may be delivered through different devices.
People with severe ARDS may need a ventilator to help them breathe. Doctors generally use lung-protective ventilation strategies designed to provide adequate oxygen while reducing additional injury to the lungs.
If ARDS is caused by a bacterial infection or sepsis, appropriate treatment such as antibiotics and other supportive measures may be required. Other causes, such as aspiration, pancreatitis or trauma, are treated according to the underlying condition.
ARDS is a medical emergency. Severe or rapidly worsening difficulty breathing, bluish or grayish skin or lips, confusion, fainting, or severe weakness requires immediate emergency medical attention. A person with a serious infection, pneumonia, major injury or another known risk factor who suddenly develops significant breathing difficulty should be evaluated urgently.
Because ARDS is usually an emergency requiring hospital treatment, care is often provided by a multidisciplinary medical team. Specialists may include:
Pulmonologist: Specializes in diseases and disorders of the lungs and respiratory system.
Critical Care Specialist (Intensivist): Manages patients with severe, life-threatening illnesses, particularly those requiring intensive care or mechanical ventilation.
Infectious Disease Specialist:May be involved when ARDS is caused by a severe infection, pneumonia or sepsis.
Emergency Medicine Specialist:Provides initial assessment and stabilization during an acute respiratory emergency.
Other specialists may be involved depending on the underlying cause and complications.
Recovery from ARDS varies considerably from person to person. Some people recover relatively quickly, while others may experience fatigue, shortness of breath, reduced physical strength or other problems for weeks or months. The outcome depends on factors such as:
The underlying cause of ARDS
Severity of lung injury
Age and general health
Presence of other medical conditions
Degree of oxygen deprivation
Whether other organs are affected
How quickly appropriate treatment is started
Early recognition and appropriate intensive care can be important in improving outcomes.
No. Pneumonia is an infection or inflammation of the lungs and is one of the conditions that can cause ARDS. ARDS is a severe form of lung injury that can result from pneumonia as well as several other causes.
Many people recover from ARDS, although recovery can take time. Treatment focuses on supporting breathing and oxygenation while treating the underlying cause and preventing complications.
Not everyone with ARDS requires mechanical ventilation. However, people with severe respiratory failure may need a ventilator to maintain adequate oxygenation and support breathing.
Severe ARDS can sometimes result in long-term changes in lung function or lung scarring. However, some people recover much of their lung function after the acute illness.
Medical Disclaimer: This article is intended for general educational and informational purposes only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. ARDS is a potentially life-threatening condition that requires urgent medical evaluation and hospital-based care when suspected.
