AACN and The Institute for Extracorporeal Life Support Present – The ECMO Course

Comprehensive knowledge and understanding of extracorporeal membrane oxygenation (ECMO) can contribute to optimal outcomes for critically ill patients with severe heart and lung failure due to a variety of conditions to include trauma, infection, cardiac arrest, acute respiratory distress syndrome or cardiogenic shock.

How ECMO Works

Extracorporeal life support (ECLS), also known as extracorporeal membrane oxygenation (ECMO), is advanced life support to provide temporary support for critical care patients whose heart and/or lungs are not functioning adequately. The term extracorporeal means outside the body and refers to the use of a circuit that takes over the functions of these organs outside the patient's body.

ECMO works by circulating a patient's blood through an external circuit that performs the gas exchange process typically handled by the heart and lungs. Blood is removed from the body via large tubes (cannulas), passed through an oxygenator where carbon dioxide is removed and oxygen is added, and then returned to the body. This support allows the heart and lungs to rest and recover when they are too damaged or weak to function on their own. ECMO is often used as a last-resort intervention for patients who have not responded to traditional treatments such as mechanical ventilation or medication.

The two main types of ECMO:

1. Veno-arterial (VA) ECMO: supports both heart and lung function
2. Veno-venous (VV) ECMO: supports lung function only, while the heart continues to pump blood

Components of the ECMO Machine

An ECMO circuit consists of several key components that work together to support heart and lung function:

1. Drainage and Return Cannulas: Large tubes that carry blood to and from the patient's body
2. Pump: mimics the heart by circulating blood through the machine; controls blood flow so that it is not pulsatile. There are two main types: roller and centrifugal.
3. Blender: provides fresh gas to the oxygenator, which is a mixture of oxygen and nitrogen, to ensure the oxygen fraction can be programmed from 21% (room air) to 100%
4. Oxygenator (membrane lung): adds oxygen to the blood and removes carbon dioxide, thus acting like the lungs
5. Heat Exchanger: regulates the temperature of the blood before it is returned to the body.
6. Controller: allows the operator to adjust RPM and sweep settings

Indications for ECMO: How do you know you need it?

Severe Respiratory Failure

ECMO is indicated for severe respiratory failure when conventional treatments are no longer effective. This situation can occur in conditions such as:

• Acute Respiratory Distress Syndrome (ARDS): It is a life-threatening condition where the lungs become severely inflamed and filled with fluid, making oxygenation difficult. ECMO helps by oxygenating the blood externally, giving the lungs time to heal.
• Pneumonia: In severe cases of bacterial or viral pneumonia, the infection can impair lung function. If mechanical ventilation fails, ECMO can oxygenate the blood while bypassing the damaged lungs.
• COVID-19 or Influenza: Viral infections such as COVID-19 or influenza can cause extreme lung inflammation and respiratory failure. In these cases, ECMO can support oxygenation when ventilators are insufficient.
• Pulmonary Embolism: A large blood clot in the lungs can block blood flow and lead to severe respiratory distress. ECMO can help maintain oxygenation and circulation while the patient with a clot is treated.
• Trauma: Severe chest trauma or injuries to the lungs can lead to respiratory failure. ECMO provides temporary support by oxygenating the blood and allowing time for healing.

Cardiac Dysfunction

Cardiac dysfunction is another key indication for ECMO, specifically for VA ECMO, which supports both the heart and lungs. It is used when the heart is unable to pump blood effectively due to conditions such as:

• Cardiogenic Shock: When the heart fails to pump enough blood to meet the body's needs, often due to a heart attack or heart failure
• Myocarditis: Severe inflammation of the heart muscle, leading to weakened heart function
• Post-Cardiac Surgery: can help the patient recover after surgery by resting the heart and supporting circulation temporarily
• Cardiac Arrest: If the patient does not respond to standard therapies; can improve survival and neurological outcomes
• Bridge to Transplant: can support patients waiting for heart and lung transplants

VA ECMO provides cardiac support by pumping oxygenated blood back into the arterial system, relieving the heart's workload while allowing time for recovery or for other treatments to take effect.

Pediatric Heart Conditions

ECMO is often used for children with severe congenital or acquired heart conditions that lead to cardiac failure. Some pediatric heart conditions where ECMO may be indicated include:

• Congenital Heart Defects (CHDs): Conditions such as hypoplastic left heart syndrome or transposition of the great arteries can cause life-threatening heart failure, requiring ECMO to support circulation and oxygenation.
• Post-Cardiac Surgery: Children undergoing heart surgery may need ECMO if their heart cannot maintain adequate function immediately postoperatively.
• Myocarditis or Cardiomyopathy: Severe heart muscle inflammation or weakening can cause heart failure, and ECMO provides crucial support.

In these cases, ECMO helps maintain blood circulation and oxygen delivery, buying time for the heart to heal or for further surgical interventions.

COVID-19 and ECMO

During the COVID-19 pandemic, ECMO became a critical life-saving treatment for patients experiencing severe respiratory failure when mechanical ventilation alone was insufficient. COVID-19 can cause ARDS, where the lungs are too damaged to oxygenate the blood effectively.

Patient Eligibility and Preparation

Criteria for ECMO Candidates

1. Severe Respiratory Failure: Conditions such as ARDS or pneumonia where oxygenation cannot be maintained with mechanical ventilation alone
2. Cardiac Failure: Cardiogenic shock, myocarditis or post-cardiac surgery complications that impair the heart's ability to pump blood effectively
3. Age and Overall Health: Patients should ideally be younger and without significant comorbidities to improve the chances of recovery.
4. Reversible Condition: ECMO is often used when the underlying condition has the potential to improve with time and support.

Eligibility also depends on the resources and expertise available at the treating facility.

Preparation Process for ECMO

Preparing for ECMO requires a coordinated, highly specialized approach to ensure the patient and the ECMO circuit are ready for safe initiation. The preparation process involves a multidisciplinary team, including critical care nurses and/or ECMO specialists, an anesthesiologist, perfusionists, respiratory therapists and intensivists. Cannulation can occur in the operating room (OR), intensive care unit (ICU) or in the field, en route to the hospital under strict sterile protocols.

First, pre-ECMO assessments determine whether the patient is a suitable candidate. This process includes evaluating the severity of cardiac or respiratory failure, potential contraindications (such as uncontrolled bleeding) and the patient's overall stability. Once eligibility is confirmed, vascular access sites are identified, central veins or arteries, depending on whether veno-venous (VV) or veno-arterial (VA) ECMO is planned. The right internal jugular (RIJ) is often ideal for cannulation. Ideally, a patient will also have an arterial line placed for invasive hemodynamic monitoring.

While cannulation sites are meticulously prepped and sterilized, the ECMO circuit is primed and anticoagulated to ensure proper function and sterility. The medical team prepares to administer anesthesia and sedation to the patient prior to cannulation. Adequate monitoring equipment should be available, including hemodynamic, oxygen saturation monitors and ultrasound imaging.

Critical care nurses support ECMO setup by monitoring vital signs, managing sedation and preparing for possible complications during initiation. With the circuit primed, the patient is then connected to ECMO, with nurses observing closely for stability, adjusting settings and troubleshooting as needed. This comprehensive preparation enhances ECMO success and patient safety.

Risks and Complications of ECMO

While ECMO can be lifesaving, it also involves certain risks and potential complications that require vigilant, expert monitoring and management by the critical care team. Awareness of these risks allows the team to take proactive steps in minimizing adverse outcomes and promoting patient safety throughout ECMO support.

Risks to watch for include bleeding, which is the most common risk, blood clots in ECMO tubing, infections, circuit failure, limb ischemia, pulmonary embolisms, transfusion-related issues, and neurological injuries, including stroke, seizures and brain injuries.

Mechanical Failures

The ECMO circuit is a complex system, and even minor mechanical failures can have significant implications for patient outcomes. Common mechanical issues include pump malfunctions, oxygenator failures and tubing leaks, which can all disrupt oxygenation or circulation. Regular equipment checks and prompt troubleshooting by ECMO specialists and critical care nurses are essential to identify and resolve these issues quickly, ensuring uninterrupted support for the patient.

Stroke Risks

Patients on ECMO face an increased risk of stroke, primarily due to clot formation within the circuit or vascular access sites. These clots can embolize, leading to ischemic strokes. Preventing stroke in ECMO patients requires careful anticoagulation management, with the nursing team closely monitoring clotting parameters and adjusting medications as needed to maintain a safe balance between bleeding and clot prevention.

Kidney Complications

Kidney complications, including acute kidney injury (AKI), are common in ECMO patients, often resulting from low blood flow, inflammation or the patient's underlying critical illness. These issues can lead to fluid imbalance, waste accumulation and electrolyte disturbances. Early detection through routine lab monitoring and assessments enables the critical care team to intervene with appropriate therapies, such as renal replacement therapy, to support kidney function and manage fluid balance effectively.

ECMO vs. Other Supportive Therapies

ECMO stands out among supportive therapies for its ability to temporarily take over the function of the heart, lungs or both, allowing these vital organs time to rest and heal. Unlike other therapies, ECMO provides full support for severe cardiac or respiratory failure by directly oxygenating the blood and removing carbon dioxide outside the body. This unique feature makes ECMO a critical option for patients who are unresponsive to conventional treatments such as mechanical ventilation or medications alone. However, ECMO is typically considered when other less invasive interventions have been exhausted, given its complexity and the intensive resources required for monitoring and management.

Invasive vs. Noninvasive Ventilation

In cases of respiratory failure, noninvasive ventilation (NIV) is often the first line of support, delivering positive pressure ventilation through a mask to help improve oxygen levels without intubation. NIV can be highly effective in cases of mild to moderate respiratory distress but may not provide adequate support for patients with severe respiratory failure. Invasive ventilation, involving intubation and mechanical ventilation, becomes necessary when higher oxygen levels and greater control over the breathing process are required.

ECMO, as a step beyond both noninvasive and invasive ventilation, provides oxygenation without relying on the lungs, effectively bypassing the respiratory system. It makes ECMO a valuable option when other forms of ventilation no longer sustain adequate oxygenation or carbon dioxide removal.

Comparison With Other Heart and Lung Support Systems

Compared with other heart and lung support systems, ECMO offers the most comprehensive support. Traditional therapies, such as inotropic medications and intra-aortic balloon pumps (IABPs), can help improve heart function and support blood flow in cases of cardiac failure but do not oxygenate the blood. Left ventricular assist devices (LVADs) are another option for patients with severe heart failure, providing continuous blood flow but also lacking respiratory support. ECMO, particularly VA ECMO, provides both circulatory and respiratory support, making it a great option for patients with combined heart and lung failure. Its ability to function as an artificial heart and lung distinguishes ECMO from other therapies and underscores its importance in advanced critical care.

Current Trends and Advancements in ECMO

As ECMO technology and clinical knowledge have advanced, application in critical care has expanded. Once used predominantly for newborns with respiratory failure, ECMO is now commonly applied for adults facing severe cardiac and respiratory conditions, including during recent COVID-19 surges. New protocols and interdisciplinary care models emphasize a team-based approach, where nurses, ECMO specialists, respiratory therapists and intensivists work in unison, optimizing patient outcomes through coordinated care. Additionally, shortened cannulation times and more sophisticated patient-selection criteria are improving ECMO's safety and effectiveness, enabling more successful weaning and recovery.

Technological Innovation

Technological innovations have played a key role in enhancing ECMO safety and efficacy. Recent advancements include miniaturized, portable ECMO devices that make transport and bedside care more feasible in emergency settings, along with biocompatible materials that reduce the risk of clot formation and infection. Integrated monitoring systems now allow for real-time assessments of oxygen levels, blood flow and other critical parameters, providing clinicians with the data needed to make rapid, informed adjustments. These innovations help reduce complications and improve survival rates, making ECMO a more viable option for high-risk patients.

Clinical Trials and Research Updates

Ongoing clinical trials and research continue to shape ECMO practices and expand the therapeutic boundaries. Current studies are investigating optimal anticoagulation strategies, exploring the effectiveness of ECMO in patients with severe pulmonary hypertension and assessing its potential role in treating sepsis. These trials aim to refine protocols, identify the patient populations most likely to benefit, and reduce the risks associated with ECMO. This evidence-based approach not only informs best practices but also helps solidify ECMO's place as an advanced lifesaving therapy in critical care.

Conclusion: The Role of ECMO in Modern Medicine

ECMO has emerged as a powerful tool in modern medicine, offering critical support when traditional therapies are insufficient. Technological advancements, a growing body of research and expanding applications are enhancing its accessibility and efficacy across diverse patient populations. By providing a bridge to recovery for those in severe cardiac or respiratory failure, ECMO represents a vital component of critical care that will continue to evolve alongside medical innovation. The expanding use of ECMO not only reflects advancements in lifesaving technology but also underscores a commitment in the critical care field to adapt and respond to complex patient needs, ensuring that even patients with the most challenging cases have access to hope and healing.