Acute Respiratory Distress Syndrome (ARDS): Causes, Treatment & Recovery

What is Acute Respiratory Distress Syndrome (ARDS)?

Acute Respiratory Distress Syndrome (ARDS) is a life-threatening lung condition that prevents oxygen from properly entering the bloodstream. It occurs when the tiny air sacs (alveoli) in the lungs become inflamed and filled with fluid due to severe infection, injury, or illness.

ARDS causes sudden and severe shortness of breath that usually requires admission to an intensive care unit (ICU) for respiratory support. ARDS is not a disease itself but a clinical syndrome that develops secondary to other conditions such as pneumonia, sepsis, or trauma.

Causes of ARDS

Acute Respiratory Distress Syndrome (ARDS) occurs when the tiny air sacs (alveoli) in the lungs are damaged due to severe illness or injury, causing them to fill with fluid instead of air. This leads to poor oxygen exchange and rapid breathing difficulty. ARDS, sometimes colloquially called “wet lung,” can result from direct lung injury or indirect systemic inflammation.

1. Severe Pneumonia

Bacterial, viral, or fungal pneumonia can inflame and damage the lung tissue, allowing fluid to leak into the alveoli. Bilateral pneumonia is a major direct cause of ARDS.

2. Sepsis (Severe Blood Infection)

A body-wide infection triggers massive inflammation that increases lung capillary permeability, allowing fluid buildup and impairing oxygen transfer.

3. Aspiration of Stomach Contents

Inhaling vomit, food, or acid can cause chemical injury to the lungs, leading to inflammation and fluid accumulation — a common cause in unconscious or sedated patients.

4. Major Trauma or Injury

Severe accidents, burns, or multiple fractures can trigger systemic inflammation that indirectly damages lung tissues and leads to acute lung injury.

5. COVID-19 and Other Viral Infections

Severe COVID-19, influenza, or SARS can cause a “cytokine storm,” leading to widespread lung inflammation and oxygen deprivation.

6. Acute Pancreatitis

Inflammation in the pancreas releases enzymes and inflammatory mediators that damage distant organs, including the lungs.

7. Inhalation of Harmful Substances

Exposure to toxic fumes, smoke, or near-drowning can directly injure the alveoli and strip away surfactant, reducing lung elasticity.

8. Blood Transfusion–Related Acute Lung Injury (TRALI)

A rare reaction following blood transfusion, TRALI occurs when immune antibodies damage lung capillaries, causing sudden respiratory distress.

Risk Factors

While Acute Respiratory Distress Syndrome (ARDS) can affect anyone following a severe illness or injury, certain individuals are at a higher risk due to underlying health conditions or external factors that compromise lung function or immune response. Recognising these risk factors is vital for early diagnosis and prevention.

1. Chronic Lung Disease

People with pre-existing lung conditions like Chronic Obstructive Pulmonary Disease (COPD), asthma, or pulmonary fibrosis already have inflamed or damaged airways. When exposed to infection, trauma, or surgery, their lungs are less able to tolerate further injury, increasing ARDS risk.

2. Older Age (65+ Years)

According to the National Institutes of Health, ageing weakens lung elasticity and immune response. Elderly individuals are more prone to pneumonia, sepsis, and reduced respiratory muscle strength — all contributing to higher ARDS vulnerability and slower recovery.

3. Sepsis or Severe Systemic Infection

Patients with sepsis face widespread inflammation that affects multiple organs, including the lungs. It remains one of the leading ARDS causes, accounting for up to 40% of cases in critical care settings.

4. Alcohol or Tobacco Use

Chronic alcohol consumption impairs the immune system and weakens the protective barrier of lung tissue, while long-term smoking damages alveoli and cilia, making the lungs more susceptible to infection and inflammation like ARDS.

5. Major Surgery or Trauma

Extensive surgical procedures, burns, or multiple fractures can trigger systemic inflammatory responses. Blood loss and shock during trauma also reduce oxygen supply, making the lungs more prone to secondary injury and fluid buildup.

6. Pre-existing Heart Disease or Diabetes

Conditions like congestive heart failure and uncontrolled diabetes impair oxygen delivery and weaken immune defense, increasing susceptibility to infection and fluid accumulation in the lungs — both of which heighten ARDS risk.

7. Prolonged Mechanical Ventilation or ICU Stay

Patients already on ventilators for other conditions can develop ventilator-induced lung injury (VILI) if pressures are not carefully managed. Extended ICU stays also increase the risk of hospital-acquired infections that can precipitate ARDS.

Signs & Symptoms of Acute Respiratory Distress Syndrome (ARDS)

Acute Respiratory Distress Syndrome or ARDS symptoms typically appear within 6 to 72 hours after a known clinical insult or trigger such as infection, trauma, or aspiration and worsen quickly as lung function deteriorates.

Common ARDS symptoms include:

• Sudden shortness of breath: Rapid onset breathing difficulty that worsens with minimal activity.
• Rapid, shallow breathing: The body attempts to compensate for low oxygen levels.
• Low blood oxygen (hypoxaemia): Despite oxygen therapy, oxygen levels remain dangerously low.
• Bluish skin, lips, or fingernails (cyanosis): Indicates oxygen deprivation in the bloodstream.
• Cough (with or without frothy sputum): Fluid accumulation in the lungs may produce pink, frothy mucus.
• Severe fatigue and confusion: Result from inadequate oxygen reaching vital organs, including the brain.
• Low blood pressure (hypotension): Can occur due to reduced oxygen supply and systemic inflammation.

Why early detection matters: ARDS progresses rapidly — timely medical intervention with oxygen therapy or ventilation can prevent respiratory failure and reduce the risk of multi-organ damage.

How Acute Respiratory Distress Syndrome (ARDS) is Diagnosed

Diagnosing ARDS (Acute Respiratory Distress Syndrome) requires a careful combination of clinical evaluation, imaging, and laboratory testing to confirm lung injury and exclude other causes of respiratory failure, such as heart disease or pneumonia.

Here are the key ARDS diagnostic steps:

1. Clinical Examination
   Doctors assess symptoms such as breathing difficulty, rapid respiration, and oxygen saturation, while reviewing the patient’s medical history and any triggering event (like trauma, sepsis, or pneumonia).
2. Chest X-ray or CT Scan
   Imaging typically shows diffuse bilateral opacities, often described as “ground-glass” or consolidative changes, indicating alveolar flooding and reduced aeration — a hallmark feature of ARDS.
3. Blood Oxygen Measurement (Arterial Blood Gas Test)
   The ABG test measures oxygen (PaO₂) and carbon dioxide (PaCO₂) levels in arterial blood to assess the degree of hypoxaemia and determine the need for oxygen therapy or mechanical ventilation.
4. Echocardiogram
   This ultrasound of the heart helps rule out cardiac failure or fluid overload as alternative causes of lung congestion and breathlessness.
5. Bronchoscopy or Lung Ultrasound
   These advanced procedures detect infection, aspiration, or inflammation, and may help collect fluid samples for microbial testing.

Accurate and timely diagnosis is critical, as early management of ARDS can prevent complications like multi-organ failure and improve recovery outcomes.

Tests to Diagnose ARDS

Specialists use advanced diagnostic tools to confirm ARDS, determine its severity, and identify underlying causes such as infection, inflammation, or organ dysfunction.

Key ARDS tests include:

• Arterial Blood Gas (ABG) Analysis
  Measures oxygen (PaO₂) and carbon dioxide (PaCO₂) levels in arterial blood to evaluate oxygen deficiency (hypoxaemia) and respiratory function.
• Chest X-Ray / High-Resolution CT (HRCT) Scan
  Detects characteristic “ground-glass opacities” or diffuse lung infiltrates that indicate fluid buildup and alveolar injury.
• Complete Blood Count (CBC)
  Helps identify infection, inflammation, or anaemia that may worsen respiratory distress.
• C-Reactive Protein (CRP) and D-Dimer Tests
  Elevated CRP indicates inflammation, while D-Dimer helps detect blood clots (a potential complication in severe ARDS or COVID-19–related lung injury).
• Blood Culture
  Used to detect bacterial or fungal sepsis, one of the most common underlying causes of ARDS.
• Liver and Kidney Function Tests (LFT & KFT)
  Evaluate organ function, as severe ARDS can impact multiple organs and alter drug metabolism.

Together, these tests help clinicians confirm diagnosis, guide treatment, and monitor recovery, ensuring a comprehensive approach to managing ARDS.

Treatment of Acute Respiratory Distress Syndrome (ARDS)

ARDS treatment focuses on restoring oxygen levels, managing the underlying cause, and preventing complications. ARDS treatment typically requires hospitalisation in an ICU.

1. Oxygen Therapy

Supplemental oxygen through a face mask or nasal cannula helps improve oxygen delivery. In moderate cases, a high-flow oxygen system or non-invasive ventilation may be used.

2. Mechanical Ventilation

In severe ARDS, patients are placed on a ventilator to assist breathing. The machine delivers oxygen-rich air while maintaining low lung pressures to prevent further injury.

3. Medications

• Antibiotics: To treat underlying infections like pneumonia or sepsis.
• Diuretics: Reduce fluid accumulation in the lungs.
• Corticosteroids: Help reduce lung inflammation and may improve oxygenation in selected patients with moderate to severe ARDS.
• Anticoagulants: Prevent blood clots due to prolonged immobility.
• Pain and Sedation Management: To reduce stress and aid ventilation comfort.

4. Prone Positioning

Lying patients face down improves oxygenation by redistributing lung fluids and enhancing alveolar expansion. It is a widely used supportive therapy for ARDS management.

5. Extracorporeal Membrane Oxygenation (ECMO)

In critical cases where conventional ventilation fails, ECMO (Extracorporeal Membrane Oxygenation) functions as an external artificial lung, oxygenating the blood outside the body and allowing the lungs to rest and recover.

Recovery from Acute Respiratory Distress Syndrome (ARDS)

Recovery varies depending on severity and patient health. Most survivors begin to show improvement within 2–4 weeks; however, full lung recovery and return to normal activity levels may take several months.

Post-treatment rehabilitation involves breathing exercises, physiotherapy, and nutritional support to restore lung capacity and muscle strength.

Follow-up care is essential, as up to 10–15% of patients may experience residual lung stiffness or reduced exercise tolerance.

Complications of Acute Respiratory Distress Syndrome (ARDS)

• Lung scarring (fibrosis) leading to long-term breathing difficulty
• Barotrauma (due to ventilator pressure)
• Infections like ventilator-associated pneumonia
• Muscle weakness or fatigue
• Post-traumatic stress or anxiety after prolonged ICU stay
• Multi-organ failure in severe, untreated cases

Prevention & Early Detection

While not always preventable, you can reduce your risk of ARDS with healthy habits and timely care:

• Avoid smoking and second-hand smoke exposure.
• Manage chronic diseases such as diabetes and hypertension.
• Practice infection control: wash hands regularly, get vaccinated for flu and COVID-19.
• Seek early treatment for pneumonia, sepsis, or lung injury.
• Use protective gear when working with chemicals or pollutants.
• Maintain good nutrition and hydration to support overall immunity and recovery.

Early recognition and intervention can significantly reduce complications and mortality.

Conclusion

Acute Respiratory Distress Syndrome (ARDS) is a critical condition requiring immediate care and careful monitoring. With timely diagnosis, oxygen therapy, and proper treatment of the underlying cause, recovery is possible for most patients.

If you or your loved one experiences persistent shortness of breath or worsening respiratory symptoms after an infection or injury, seek medical help immediately.

For accurate diagnostic tests and home sample collection, visit Metropolis Healthcare — your trusted partner for comprehensive lung health and early disease detection.

FAQs

What is the main cause of ARDS?

The most common cause of ARDS is severe infection, especially pneumonia or sepsis, which triggers inflammation and fluid buildup in the lungs.

Can ARDS be fatal?

Yes, ARDS can be fatal in severe cases if not treated promptly. However, survival rates have improved significantly with modern ICU care and early oxygen therapy.

How long does it take to recover from ARDS?

Recovery can range from a few weeks to several months. Mild cases resolve faster, while severe cases may require long-term pulmonary rehabilitation.

Is ARDS contagious?

No, ARDS itself is not contagious, but underlying infections such as COVID-19 or pneumonia may spread from person to person.

Can healthy people get ARDS?

Yes. Even healthy individuals can develop ARDS after major trauma, aspiration, or severe infection. Early medical attention is vital to prevent complications.

References

1. https://www.lung.org/lung-health-diseases/lung-disease-lookup/ards
2. https://www.nhlbi.nih.gov/health-topics/acute-respiratory-distress-syndrome
3. https://emedicine.medscape.com/article/165139-overview
4. https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(21)00439-6/fulltext
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC11096524/
6. https://www.mayoclinic.org/diseases-conditions/ards/symptoms-causes/syc-20355576
7. https://my.clevelandclinic.org/health/diseases/15283-acute-respiratory-distress-syndrome-ards
8. https://www.who.int/news-room/fact-sheets/detail/acute-respiratory-distress-syndrome