Definition

Acute Respiratory Distress Syndrome (ARDS) is a condition characterized by the filling of fluid in the alveoli, the air sacs in the lungs. The term "acute" indicates that the condition has recently occurred rather than being long-standing.

ARDS is a severe lung disorder where the presence of fluid in the lungs obstructs the exchange of oxygen and carbon dioxide in the alveoli. This leads to a decrease in oxygen levels and an increase in carbon dioxide throughout the body. ARDS impedes the flow of oxygen to organs necessary for their functions, ultimately resulting in organ failure.

Individuals with severe illnesses hospitalized in intensive care units are most commonly affected by ARDS. Trauma or severe injury can also trigger ARDS. Symptoms typically manifest within one or two days after the onset of the underlying illness or injury. The most common symptoms include severe shortness of breath and visible signs of labored breathing. ARDS is a medical emergency and is a potentially life-threatening condition.

Causes

ARDS is caused by damage to the small blood vessels in the lungs. Fluid from the damaged blood vessels enters the air sacs of the lungs, where the exchange of oxygen and carbon dioxide occurs in the body. Oxygen entering the lungs is carried into the bloodstream to be circulated throughout the body. When the air sacs become filled with fluid, less oxygen can enter the bloodstream.

Some causes of ARDS include:

• Inhalation of toxic substances, such as saltwater, chemicals, smoke, or vomit
• Severe bloodstream infections
• Severe lung infections, including severe cases of COVID-19 infection
• Chest or head injuries, such as those from car accidents or certain contact sports
• Overdose of sedative medications or antidepressants

Risk Factor

ARDS typically develops as a complications of other conditions. The following factors can increase the risk of ARDS:

• Age over 65 years
• Chronic lung diseases (long-term)
• History of alcohol abuse or smoking

ARDS can be a more serious condition for individuals who:

• Experience toxic shock
• Are older
• Have liver disease
• Have a history of alcohol abuse

Symptoms

The symptoms of ARDS typically appear between one and three days after injury or trauma to the lungs. Common symptoms and signs of ARDS include:

• Shortness of breath and rapid breathing
• General fatigue and weakness
• Decreased blood pressure
• Changes in skin color or nails
• Dry cough
• Fever
• Headache
• Increased heart rate
• Confusion or disorientation regarding surroundings

Diagnosis

If you suspect someone is experiencing ARDS, you should call emergency services or take them to the emergency department. ARDS is a medical emergency, so early diagnosis can help the patient survive this condition.

Doctors diagnose ARDS through several methods. The doctor will inquire about the patient's complaints and medical history briefly, perform a physical examination, and may recommend one of the following tests:

• Blood tests: Indicate signs of anemia and infection.
• Throat and nose swabs to detect bacteria causing lung infections.
• Chest X-ray: shows which part of the lungs is affected, the amount of fluid present, and lung swelling.
• CT scan: Provides detailed images of the heart and lungs.
• Electrocardiogram (EKG): Records the heart's electrical activity.
• Echocardiogram: ultrasound of the heart.
• Examination of the airways.

Low blood pressure and low oxygen levels are signs of ARDS. Doctors may use ECGs and echocardiograms to rule out heart conditions. If chest X-rays or CT scans show fluid-filled air sacs, a diagnosis of ARDS can be made. A lung biopsy may also be performed to rule out other lung diseases, although this is rarely done.

Management

Treatment and therapy for ARDS include:

Oxygen

The primary goal of ARDS treatment is to maintain normal oxygen levels in the patient's body to prevent organ failure. Doctors will provide oxygen therapy through a mask. Mechanical ventilators can also be used to deliver air into the lungs and reduce fluid in the alveoli.

Fluid therapy

Fluid therapy will maintain the patient's body fluid balance. Too much fluid in the body can cause fluid buildup in the lungs. However, too little fluid will cause dehydration of the heart and other organs, leading to suboptimal function.

Medications

People with ARDS are often given medications to address symptoms. These medications may include:

• Pain relievers to alleviate pain
• Antibiotics to treat infections
• Blood thinners to prevent clot formation in the lungs or legs

Pulmonary rehabilitation

Individuals recovering from ARDS may require pulmonary rehabilitation to strengthen their respiratory system and improve their lung capacity. The program may include exercise training, lifestyle classes, and a support team to aid in ARDS recovery.

Complications

If you're experiencing ARDS, there's a risk of developing or contracting other diseases while in the hospital. These conditions include:

• Blood clots. Lying in the hospital for an extended period of time while on a ventilator increases the risk of blood clots, particularly in the deep veins of the legs. If a clot forms in the leg, some of it may break off and go to one or both lungs, blocking blood flow there (pulmonary embolism).
• Collapsed lung or pneumothorax. Most cases of ARDS include the use of breathing equipment known as a ventilator to improve oxygen levels in the body and drive fluid out of the lungs. However, the pressure and volume of air from the ventilator can cause gas to leak through small holes in the lungs' outermost part and accumulate in the pleural cavity, which is the space between the lungs and the membrane that covers them. This disorder, known as pneumothorax, causes the lungs to become smaller or collapse.
• Infection. Ventilators are a common cause of infection in hospitals. The device is attached to a tube that is placed straight into the neck. Using a ventilator can increase the risk of lung infection and further damage the lungs.
• Lung scarring or fibrosis. Scarring between the alveoli can develop within weeks of the onset of ARDS. Scar tissue stiffens the lungs, resulting in more difficulty for oxygen to pass from the alveoli to the bloodstream.

Prevention

While there's no guaranteed way to prevent ARDS, its risk can be reduced by:

• Seeking immediate medical help for injuries, infections, or illnesses.
• Quitting smoking and avoiding secondhand smoke exposure.
• Limiting alcohol intake, as long-term use can increase ARDS risk and impair lung function.
• Getting routine flu vaccinations yearly and pneumonia vaccinations every five years to reduce lung infection risk.

When to See a Doctor? 

ARDS typically follows an underlying disease or injury, often necessitating hospitalization. If experiencing symptoms or signs of ARDS outside the hospital, seek immediate medical assistance from emergency services or visit the emergency unit. Prompt diagnosis and management can prevent worsening symptoms and complications.

If you have risk factors for ARDS, see a doctor and follow his or her advice regarding treatment or routine medical visits.

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