What is Extracorporeal Membrane Oxygenation (ECMO)? Purpose, Procedure & Results

Extracorporeal membrane oxygenation, or ECMO, is a life-support machine that temporarily takes over the work of your heart and lungs when they're too sick to function properly. Think of it as giving your vital organs a chance to rest and heal while a specialized device keeps oxygen flowing through your body.

This advanced medical technology has helped thousands of people survive critical illnesses that might otherwise be fatal. While ECMO is reserved for the most serious situations, understanding how it works can help you feel more informed if you or a loved one ever needs this treatment.

What is ECMO?

ECMO is a machine that acts like an artificial heart and lung system outside your body. It removes blood from your body, adds oxygen to it, removes carbon dioxide, and then pumps the freshly oxygenated blood back into your circulation.

The system works through tubes called cannulas that are surgically placed in large blood vessels. Your blood travels through these tubes to the ECMO machine, where it passes over a special membrane that does the gas exchange your lungs normally handle. Meanwhile, a pump does the work your heart usually does.

There are two main types of ECMO support. Veno-venous (VV) ECMO helps when your lungs aren't working but your heart is still strong. Veno-arterial (VA) ECMO supports both your heart and lungs when both organs need help.

Why is ECMO done?

ECMO is used when your heart or lungs are so severely damaged that they can't keep you alive on their own, even with other treatments. It's typically considered when conventional therapies like ventilators and medications aren't enough to maintain safe oxygen levels in your blood.

Your medical team might recommend ECMO if you have severe pneumonia, COVID-19 complications, or acute respiratory distress syndrome (ARDS) that isn't responding to maximum ventilator support. These conditions can make your lungs so inflamed and damaged that they can't transfer oxygen into your bloodstream effectively.

For heart-related problems, ECMO might be needed during massive heart attacks, severe heart failure, or after certain heart surgeries when your heart muscle is too weak to pump blood effectively. It can also serve as a bridge treatment while you wait for a heart transplant.

Sometimes ECMO is used during cardiac arrest when standard resuscitation efforts haven't restored normal heart function. In these cases, the machine can maintain circulation while doctors work to address the underlying problem that caused the arrest.

What is the procedure for ECMO?

The ECMO procedure begins with your medical team placing you under general anesthesia or deep sedation. A surgeon or specially trained doctor will then insert the cannulas into large blood vessels, typically in your neck, groin, or chest area.

For VV ECMO, doctors usually place one large cannula in a vein in your neck or groin area. This single cannula can both remove blood from your body and return oxygenated blood, though sometimes two separate cannulas are used.

VA ECMO requires placing cannulas in both an artery and a vein. The venous cannula removes blood from your body, while the arterial cannula returns oxygenated blood directly to your arterial circulation, bypassing your heart entirely.

Once the cannulas are in place, your medical team connects them to the ECMO circuit. The system includes a pump, an oxygenator (artificial lung), and various monitoring devices. Blood thinning medication is given to prevent clots from forming in the circuit.

Throughout the procedure, your vital signs are continuously monitored. The entire setup process typically takes one to two hours, depending on the complexity of your condition and which type of ECMO support you need.

How to prepare for ECMO?

ECMO is almost always an emergency treatment, so there's usually no time for traditional preparation. However, if you're being considered for ECMO, your medical team will quickly assess whether you're a good candidate for this intensive therapy.

Your doctors will review your medical history, current medications, and overall health status. They'll also perform blood tests to check your clotting function, kidney function, and other vital parameters that affect how well you might tolerate ECMO.

If you're conscious, your medical team will explain the procedure and its risks to you or your family members. They'll discuss alternative treatments and help you understand why ECMO is being recommended in your specific situation.

Your care team will also ensure you have adequate IV access and may place additional monitoring devices like arterial lines to track your blood pressure continuously. If you're not already on a ventilator, one will likely be placed to help protect your airway during the procedure.

How to read your ECMO results?

ECMO doesn't produce test results in the traditional sense, but your medical team continuously monitors several important numbers to ensure the system is working properly. These measurements tell doctors how well the machine is supporting your body's needs.

Blood flow rates are measured in liters per minute and show how much blood is moving through the ECMO circuit. Higher flow rates generally mean more support, but the exact numbers depend on your body size and medical condition.

Oxygen levels in your blood are tracked through regular blood gas measurements. Your team looks for oxygen saturation levels above 88-90% and carbon dioxide levels in the normal range, which indicates the artificial lung is working effectively.

Your medical team also monitors pump speeds, which are measured in revolutions per minute (RPMs). These speeds are adjusted based on how much support your heart and lungs need as your condition changes.

Laboratory tests are performed frequently to check for signs of bleeding, clotting, kidney function, and other complications. Your doctors use all these measurements together to adjust your ECMO settings and plan your overall treatment.

How to optimize your ECMO support?

While you're on ECMO, your medical team works continuously to optimize the support you're receiving. This involves carefully balancing the machine's settings with your body's changing needs as your underlying condition improves or worsens.

Your doctors will adjust blood flow rates and oxygen levels based on your lab results and clinical condition. They might increase support if your organs need more help, or gradually decrease it as your heart and lungs begin to recover.

Preventing complications is a crucial part of ECMO management. Your team monitors you closely for bleeding, clotting, and infection. They'll adjust your blood thinning medications and may perform procedures to address any issues that arise.

Physical therapy often begins while you're on ECMO, even if you're sedated. This helps prevent muscle weakness and blood clots. Your respiratory therapist will also work with your lungs to promote healing and prevent further damage.

The goal is always to wean you off ECMO support as quickly and safely as possible. Your medical team will gradually reduce the machine's assistance as your own heart and lungs recover their function.

What are the risk factors for needing ECMO?

Several medical conditions can increase your likelihood of needing ECMO support. Understanding these risk factors can help you recognize when someone might be at higher risk for severe heart or lung problems.

Severe respiratory conditions that might progress to ECMO include:

• Severe pneumonia that doesn't respond to antibiotics and ventilator support
• COVID-19 with severe lung complications
• Acute respiratory distress syndrome (ARDS) from various causes
• Severe asthma attacks that don't respond to maximum medical therapy
• Drowning or smoke inhalation injuries

These conditions can cause such severe lung damage that even high-pressure ventilators can't maintain adequate oxygen levels in your blood.

Heart-related conditions that might require ECMO support include:

• Massive heart attacks that damage large portions of heart muscle
• Severe heart failure that doesn't respond to medications
• Complications after heart surgery
• Cardiogenic shock where the heart can't pump enough blood
• Severe heart rhythm problems that cause cardiac arrest

Certain patient factors can also increase ECMO risk, including advanced age, multiple chronic medical conditions, and previous heart or lung disease. However, ECMO decisions are always made based on your individual situation rather than these general risk factors alone.

Is ECMO better for heart support or lung support?

ECMO can effectively support both heart and lung function, but the type of support depends on which organs need help. VV ECMO is specifically designed for lung support, while VA ECMO can support both heart and lung function simultaneously.

For pure lung problems, VV ECMO is often preferred because it allows your heart to continue working normally while giving your lungs time to heal. This approach preserves your heart's natural function and may lead to better long-term outcomes.

When your heart is failing, VA ECMO provides more comprehensive support by taking over both pumping and oxygenation functions. This gives both your heart and lungs a chance to recover from whatever condition caused the crisis.

The choice between types of ECMO depends on your specific medical condition, how well your heart is functioning, and your overall health status. Your medical team will select the approach that gives you the best chance of recovery.

What are the possible complications of ECMO?

While ECMO can be lifesaving, it does carry significant risks that your medical team will monitor closely. Understanding these potential complications can help you and your family know what to expect during treatment.

Bleeding is one of the most common complications because ECMO requires blood thinning medications to prevent clots in the circuit. This can lead to bleeding around the cannula sites, in your brain, or in other parts of your body.

Blood clots can form despite blood thinning medications, potentially blocking blood flow to vital organs. Your medical team performs regular tests to balance the risk of bleeding against the risk of clotting.

Infection is another serious concern, particularly around the cannula insertion sites or in your bloodstream. The longer you're on ECMO, the higher this risk becomes, which is why doctors work to wean you off support as quickly as possible.

Kidney problems can develop due to the stress of critical illness and the ECMO procedure itself. Some patients may need temporary dialysis to support their kidney function during recovery.

Less common but serious complications include:

• Stroke from blood clots or bleeding in the brain
• Damage to blood vessels from the cannulas
• Problems with the ECMO circuit requiring emergency repairs
• Complications from prolonged sedation and immobility

Your medical team monitors you continuously for these complications and has protocols in place to manage them quickly if they occur.

When should I see a doctor about ECMO?

ECMO is typically initiated in hospital settings during medical emergencies, so the decision usually isn't something you make independently. However, there are situations where you might want to discuss ECMO with your healthcare providers.

If you have severe heart or lung disease, you might want to ask your doctor about ECMO as a potential treatment option during a serious flare-up. This conversation can help you understand whether you'd be a candidate for this therapy.

Families of patients currently on ECMO should maintain regular communication with the medical team about goals of care, progress markers, and realistic expectations for recovery. These conversations help ensure everyone understands the treatment plan.

If you're considering ECMO as a bridge to heart or lung transplant, discuss this option with your transplant team early in your care. They can help you understand how ECMO might fit into your overall treatment strategy.

For patients with advance directives, it's important to discuss your preferences about intensive treatments like ECMO with your healthcare providers and family members before a crisis occurs.