Published: 18 Jun 2025

ICD9: 518.82      ICD10: J80      ICD11: CB00

Acute Respiratory Distress Syndrome (ARDS), also sometimes referred to as Acute Lung Injury (ALI), is a severe and life-threatening lung condition that occurs when the lungs become severely inflamed and filled with fluid.
This fluid prevents the lungs from properly transferring oxygen to the blood, leading to a lack of oxygen in the body.

Here's a breakdown of key aspects:

What happens in ARDS:

Inflammation: ARDS is triggered by an inflammatory response, often due to a serious illness, injury, or infection. This inflammation damages the lining of the tiny air sacs in the lungs (alveoli) and the capillaries (small blood vessels) surrounding them.
Fluid Leakage: The damaged capillaries leak fluid into the alveoli, filling them with fluid.
Impaired Gas Exchange: The fluid in the alveoli makes it difficult for oxygen to pass from the air into the blood, and for carbon dioxide to pass from the blood into the air to be exhaled.
Reduced Lung Compliance: The lungs become stiff and less able to expand and contract properly, making breathing difficult.

Causes of ARDS:

ARDS is usually a complication of another serious medical condition. Common causes include:

Sepsis: A severe bloodstream infection. This is the most common cause.
Pneumonia: Lung infection.
Aspiration: Breathing vomit or other foreign substances into the lungs.
Trauma: Significant injury, especially to the chest or lungs.
Pancreatitis: Inflammation of the pancreas.
Burns: Extensive burns.
Blood Transfusions: (Transfusion-related acute lung injury, or TRALI)
Drug Overdose: Certain medications can trigger ARDS.
Inhalation of toxic substances: Smoke, chemicals, or fumes.
COVID-19: A significant number of COVID-19 patients develop ARDS.

Symptoms of ARDS:

Symptoms typically develop rapidly, usually within 24 to 72 hours of the initial injury or illness. They can include:

Severe shortness of breath: This is the most prominent symptom.
Rapid breathing (tachypnea)
Cough
Fatigue and weakness
Confusion and disorientation
Bluish discoloration of the skin, lips, and nail beds (cyanosis) - this indicates a lack of oxygen in the blood.
Low blood pressure

Diagnosis:

Diagnosis usually involves:

Physical Exam: Listening to the lungs with a stethoscope can reveal abnormal sounds, such as crackles or wheezing.
Chest X-ray or CT Scan: These imaging tests can show fluid in the lungs and other signs of lung damage.
Blood Tests: To measure oxygen and carbon dioxide levels in the blood (arterial blood gas analysis) and to look for signs of infection or inflammation.
Exclusion of other causes: Doctors need to rule out other conditions that can cause similar symptoms, such as heart failure.

Treatment:

ARDS is a medical emergency requiring intensive care. Treatment focuses on:

Oxygen Therapy: Providing supplemental oxygen, often through a ventilator (breathing machine), to increase oxygen levels in the blood. Positive End-Expiratory Pressure (PEEP) is often used to keep the alveoli open.
Mechanical Ventilation: A ventilator is often necessary to assist or take over breathing. Specific ventilation strategies are used to minimize further lung injury (lung-protective ventilation).
Treatment of the Underlying Cause: Addressing the underlying illness or injury that triggered ARDS. For example, antibiotics for pneumonia, surgery for trauma, or treatment for sepsis.
Fluid Management: Carefully managing fluid intake to prevent further fluid buildup in the lungs. Diuretics may be used.
Medications: Various medications may be used to reduce inflammation, prevent blood clots, or treat infections.
Prone Positioning: Placing the patient on their stomach (prone positioning) can sometimes improve oxygenation by improving blood flow to different areas of the lungs.
Extracorporeal Membrane Oxygenation (ECMO): In severe cases, ECMO may be used. This is a life-support system that pumps blood outside the body, oxygenates it, and returns it to the body, bypassing the lungs.

Prognosis:

ARDS is a serious condition with a significant mortality rate, ranging from 30% to 50%, depending on the severity of the condition and the underlying cause. Survivors may experience long-term lung damage, physical weakness, and cognitive problems. Early diagnosis and treatment are crucial for improving the chances of survival and minimizing long-term complications.

Important Considerations:

Prevention: Preventing the underlying causes of ARDS, such as pneumonia and sepsis, is crucial.
Research: Ongoing research is focused on developing new and improved treatments for ARDS.
ALI vs. ARDS: Acute Lung Injury (ALI) was previously used as a less severe form of ARDS, but the distinction is now less commonly used in favor of defining ARDS based on severity scales.

In summary, ARDS is a severe lung condition that requires immediate medical attention. It is characterized by inflammation, fluid buildup in the lungs, and impaired oxygen exchange. Treatment focuses on supporting breathing, addressing the underlying cause, and minimizing further lung damage.