Acute Respiratory Distress Syndrome (ARDS) Treatment

Acute respiratory distress syndrome (ARDS) is a serious lung condition that develops when fluid builds up in the tiny air sacs (alveoli) of your lungs. This fluid buildup prevents the lungs from properly filling with air, making it difficult to breathe and get enough oxygen into the bloodstream. ARDS typically occurs as a response to various underlying conditions, such as pneumonia, sepsis, trauma, or aspiration of gastric contents into the lungs and can be life-threatening, thus requiring immediate medical attention.

Acute respiratory distress syndrome (ARDS) arises from injuries that damage the lungs. These injuries can come from various sources, broadly classified into two categories:

• Direct Lung Injury: This refers to a direct injury or trauma to the lungs themselves. Examples include:

○ Pneumonia (infection within the lungs)

○ Aspiration (inhaling foreign objects like vomit or food)

○ Inhalation of harmful substances (smoke, toxins)

○ Near drowning

○ Contusion (bruising) of the lungs

• Indirect Lung Injury: This occurs when a condition elsewhere in the body triggers a systemic inflammatory response that ultimately harms the lungs. Examples include:

○ Sepsis (severe infection anywhere in the body)

○ Severe pancreatitis (inflammation of the pancreas)

○ Severe COVID-19

○ Major trauma or surgery

○ Transfusion of a large amount of blood

○ Certain medications

These are some of the leading causes of ARDS. It's important to note that ARDS can also develop in some cases from less common causes or a combination of factors.

ARDS, or Acute Respiratory Distress Syndrome, can occur in anyone, but certain factors may increase the risk of developing the condition. Common risk factors for ARDS include:

• Age: Older adults are more susceptible to ARDS.
• Smoking: Damages lung function and increases ARDS risk.
• Substance abuse: Alcohol and certain drugs can weaken the lungs and raise ARDS risk.
• Obesity:Obesity may make breathing more difficult and worsen ARDS outcomes.
• Underlying medical conditions: People with pre-existing lung diseases like chronic obstructive pulmonary disease (COPD), asthma, Sepsis, and others are at higher risk.
• Blood transfusions: Receiving large volumes of blood can increase the risk of ARDS.

The symptoms of ARDS, or Acute Respiratory Distress Syndrome, typically develop rapidly and can vary in severity. Common symptoms include:

• Severe Shortness of Breath: Rapid onset of severe difficulty breathing, often described as feeling like "suffocating" or "drowning." Patients may struggle to catch their breath even at rest.
• Rapid Breathing: Increased respiratory rate (tachypnea) as the body attempts to compensate for the reduced oxygen levels in the blood.
• Bluish discoloration of the skin or lips: Hypoxemia, or low oxygen levels in the blood, leading to symptoms such as cyanosis (bluish discoloration of the skin or lips) and confusion.
• Rapid Heart Rate: Tachycardia, or a rapid heart rate, as the body tries to deliver oxygen to vital organs in response to hypoxemia.
• Fatigue and Weakness: Generalised weakness and fatigue due to the increased work of breathing and decreased oxygen delivery to tissues.
• Cough: Dry or productive cough may be present, often accompanied by frothy sputum.
• Chest Pain: Chest discomfort or pain may occur, particularly with severe respiratory distress or underlying chest trauma.
• Confusion or Altered Mental Status: Hypoxemia can lead to confusion, disorientation, or changes in consciousness due to inadequate oxygen delivery to the brain.
• Restlessness or Agitation: Patients may become agitated or restless as they struggle to breathe and experience feelings of suffocation.
• Increased Respiratory Effort: Use of accessory muscles of respiration, such as neck muscles or the muscles between the ribs (intercostal muscles), to assist with breathing.
• Decreased Urine Output: In severe cases of ARDS, decreased urine output (oliguria) may occur due to reduced blood flow to the kidneys.

It's important to note that the symptoms of ARDS can overlap with those of other respiratory conditions, making diagnosis challenging. If you or someone you know experiences sudden onset of severe difficulty breathing or any of the symptoms mentioned above, seek immediate medical attention as early intervention is crucial for improving outcomes in ARDS.

Diagnosing ARDS typically involves a combination of clinical evaluation, medical history review, physical examination, and various tests. Here's an overview of the diagnostic process:

Clinical Evaluation and History

The healthcare provider will ask about symptoms such as shortness of breath, rapid breathing, and low oxygen levels. They'll also inquire about any underlying conditions or recent events that may have triggered ARDS, such as pneumonia, sepsis, trauma, or aspiration.

Physical Examination

The doctor will listen to the lungs with a stethoscope to detect abnormal breath sounds such as crackles and diminished breath sounds, which are common findings in ARDS.

Imaging Tests

• Chest X-ray: This is often the initial imaging test performed. It can show characteristic findings such as bilateral infiltrates (opacity or "whiteness" in both lungs), but it may not be sensitive enough to detect early ARDS.
• CT Scan: In some cases, a CT scan may be done to provide more detailed images of the lungs and to rule out other conditions.

Blood Tests

Blood tests are done to assess oxygen levels, carbon dioxide levels, and other markers of inflammation or organ dysfunction.

Pulmonary Function Tests (PFTs)

These tests measure lung function and capacity, but they are not typically performed during the acute phase of ARDS.

Other Tests

Depending on the suspected underlying cause of ARDS, additional tests such as blood cultures, sputum cultures, and tests for specific infections may be ordered.

The diagnosis of ARDS is based on specific criteria, including the degree of hypoxemia (low oxygen levels), bilateral infiltrates on chest imaging, absence of heart failure as the primary cause, and certain physiological criteria related to respiratory function.

Treatment for ARDS typically involves a combination of supportive care measures aimed at maintaining adequate oxygenation and ventilation, addressing the underlying cause, and preventing complications. Here's an overview of the treatment approach for ARDS:

Mechanical Ventilation

Most patients with ARDS require mechanical ventilation to support their breathing. Ventilator settings are adjusted to maintain adequate oxygenation while minimising ventilator-induced lung injury. Strategies such as low tidal volume ventilation and prone positioning may be used to optimise lung protection and improve oxygenation.

Oxygen Therapy

Supplemental oxygen is provided to maintain adequate oxygen levels in the blood. Oxygen delivery may be titrated based on arterial blood gas measurements and pulse oximetry readings.

Fluid Management

Fluid balance is carefully monitored and maintained to avoid fluid overload, which can worsen lung function and lead to complications such as pulmonary edema. Diuretics may be used to help manage fluid balance in some cases.

Prone Positioning

Placing patients in the prone (face-down) position can improve oxygenation by redistributing blood flow and reducing pressure on the lungs. Prone positioning is often used as a supportive therapy in patients with moderate to severe ARDS.

Medications

• Bronchodilators: These may be used to help improve airflow in patients with bronchospasm or underlying airway disease.
• Corticosteroids: While controversial, corticosteroids may be considered in some cases of ARDS, especially if there is evidence of an underlying inflammatory component.
• Vasopressors: These medications may be used to support blood pressure and improve tissue perfusion in patients with septic shock or hemodynamic instability.

Treatment for ARDS is often provided in an intensive care unit (ICU) setting, and management is individualised based on the severity of the condition, underlying cause, and patient's overall health status. Close monitoring and multidisciplinary care are essential for optimising outcomes in patients with ARDS.

ARDS itself is a serious condition, and complications can arise from the condition or its treatment. Here are some potential complications of ARDS:

• Multiple organ failure: When ARDS is severe, organs like the kidneys, heart, and liver may not receive enough oxygen-rich blood and begin to malfunction.
• Pulmonary hypertension: Increased pressure in the blood vessels of the lungs due to inflammation and injury.
• Blood clots: ARDS can increase the risk of blood clots forming in the legs (deep vein thrombosis) or lungs (pulmonary embolism) due to reduced mobility and inflammation.
• Collapsed lung (pneumothorax): This can occur from the pressure of mechanical ventilation or injury to the lung tissue.
• Muscle weakness: Being on a ventilator for a long period can lead to muscle weakness from inactivity.
• Lung scarring (fibrosis): In some cases, ARDS can cause permanent scarring of the lung tissue, which can impair breathing function.
• Mental health issues: Experiencing a critical illness like ARDS can lead to anxiety, depression, or post-traumatic stress disorder (PTSD).

Unfortunately, there's no guaranteed way to prevent ARDS entirely. However, some strategies can help reduce the risk of developing severe ARDS:

• Treat underlying conditions promptly: Early and effective treatment of conditions like pneumonia or sepsis that can lead to ARDS can minimise lung damage.
• Manage chronic health conditions: Maintaining good control of chronic conditions like heart failure or chronic obstructive pulmonary disease (COPD) can reduce the risk of complications that might trigger ARDS.
• Safe lung ventilation practices: In critical care situations, using lung-protective ventilation strategies with lower pressures and tidal volumes helps minimise further lung injury.
• Avoidance of harmful substances: Smoking and excessive alcohol intake can damage the lungs and increase the risk of respiratory infections that could lead to ARDS.
• Infection prevention: Frequent hand washing and taking precautions to avoid getting sick, especially with respiratory illnesses, can help.

Early recognition of risk factors and prompt medical attention are crucial in preventing ARDS from progressing to a severe stage.

What position is best for ARDS?

The prone position, where patients lie on their stomachs, is often utilised in managing ARDS as it can improve oxygenation by optimising ventilation-perfusion matching in the lungs.

How do lungs heal from ARDS?

Lung healing from ARDS typically involves resolution of inflammation, repair of damaged tissue, and restoration of normal lung function. This process may take weeks to months and can involve therapies to support lung recovery, such as mechanical ventilation, oxygen therapy, and supportive care.

How common is ARDS?

ARDS is relatively uncommon but can occur in critically ill patients with severe infections, trauma, or other underlying medical conditions. It is more prevalent in intensive care unit (ICU) settings, especially among patients with pneumonia, sepsis, or aspiration.

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

ARDS can develop rapidly, often within hours to days after the onset of the underlying illness or injury. It is characterised by sudden onset of severe respiratory distress and hypoxemia, requiring prompt medical attention and intervention.

How long does ARDS take to resolve?

The resolution time for ARDS varies depending on factors such as the underlying cause, severity of lung injury, and effectiveness of treatment. While some patients may recover within a few days to weeks, others may experience a more prolonged course requiring weeks to months for resolution.

What is the ARDS survival rate?

The survival rate for ARDS varies depending on factors such as the severity of lung injury, presence of underlying medical conditions, and response to treatment. Overall, the mortality rate for ARDS is significant, with reported rates ranging from 20% to 40% or higher in some cases.

Can one prevent acute respiratory distress syndrome (ARDS)?

While ARDS cannot always be prevented, measures to reduce the risk of predisposing conditions, such as avoiding smoking, preventing infections, managing chronic medical conditions, and optimising perioperative care, may help minimise the risk of developing ARDS.

Can the lungs recover from ARDS?

Yes, the lungs can recover from ARDS with appropriate treatment and supportive care. Many patients experience improvement in lung function and resolution of symptoms over time, although some may experience persistent respiratory impairment or long-term complications.

Are ARDS and COVID-19 the same?

ARDS and COVID-19 are not the same, but COVID-19 can lead to ARDS in severe cases. ARDS is a syndrome characterised by acute, diffuse lung injury resulting in severe respiratory distress and hypoxemia, whereas COVID-19 is a viral respiratory illness caused by the novel coronavirus SARS-CoV-2.

What is the survival rate for ARDS in people with COVID-19?

The survival rate for ARDS in people with COVID-19 varies depending on factors such as age, underlying health conditions, severity of illness, and access to medical care. While some patients with COVID-19-associated ARDS recover with supportive care, others may experience significant morbidity and mortality, especially in cases of severe illness requiring mechanical ventilation and intensive care.

Who treats acute respiratory distress syndrome?

ARDS is typically managed by a multidisciplinary team of healthcare professionals, including pulmonologists, intensivists, critical care nurses, respiratory therapists, and other specialists. Treatment may be provided in intensive care units (ICUs) or specialised respiratory care units.

What is the target oxygen level for ARDS?

The target oxygen level for ARDS is typically to maintain arterial oxygen saturation (SaO2) between 88% and 95% or partial pressure of arterial oxygen (PaO2) between 55 and 80 mm Hg. Oxygen therapy is titrated to achieve adequate oxygenation while avoiding oxygen toxicity.

Can a pulse oximeter detect ARDS?

A pulse oximeter can detect hypoxemia, which is a characteristic feature of ARDS. However, the diagnosis of ARDS requires comprehensive clinical assessment, including evaluation of respiratory symptoms, chest imaging, and laboratory tests, in addition to monitoring oxygen saturation levels.

What are the three stages of ARDS?

The stages of ARDS are not universally agreed upon by medical professionals, but some healthcare providers describe ARDS as progressing through three overlapping phases:

• Exudative: Fluid leaks from blood vessels into lung airspaces, reducing oxygen exchange.
• Proliferative: Cells attempt repair, but can thicken airspace walls and worsen oxygen exchange.
• Fibrotic: Scarring (fibrosis) reduces lung function permanently (may not occur in all cases).

What is the Prognosis/Outlook for ARDS?

The outlook for acute respiratory distress syndrome (ARDS) can vary depending on factors such as the underlying cause and severity of lung injury. While ARDS can be life-threatening, many individuals recover with prompt and appropriate medical care. However, some may experience long-term complications, and mortality rates remain significant. Early recognition, aggressive supportive care, and addressing the underlying cause are essential for improving outcomes.

Reviewed By Dr. Vivek Nangia, Principal Director & Head, Pulmonology on 21 May 2024.