What is ECMO?

ECMO stands for Extracorporeal Membrane Oxygenation. "Extracorporeal" simply means "outside the body." ECMO is a life-support machine that temporarily takes over the work of the heart, the lungs, or both when they are too sick or weak to function on their own.

The machine pulls blood out of the body, adds oxygen to it, removes carbon dioxide (the waste gas), and then pumps the cleaned, oxygen-rich blood back in. This gives the heart and lungs time to rest and recover from whatever is causing them to fail.

ECMO is also called Extracorporeal Life Support (ECLS). It is not a cure — it is a bridge. It keeps a person stable while the real problem is treated, whether that means waiting for an organ to recover, preparing for surgery, or finding a longer-term solution like a transplant.

Purpose of ECMO and Where It Is Used

ECMO is used in hospitals — specifically in Intensive Care Units (ICUs), Neonatal Intensive Care Units (NICUs), and Pediatric Intensive Care Units (PICUs) — when the heart, the lungs, or both are failing and standard treatments are not enough.

When ECMO is Needed

The conditions that may require ECMO include:

• Severe respiratory failure: Acute Respiratory Distress Syndrome (ARDS), severe pneumonia, meconium aspiration syndrome (in newborns), or congenital diaphragmatic hernia (CDH)
• Severe heart failure: After open-heart surgery, cardiogenic shock, myocarditis (infection of the heart muscle), or cardiomyopathy
• Cardiac arrest not responding to CPR: Known as ECPR (Extracorporeal Cardiopulmonary Resuscitation)
• Congenital heart defects: Before or after surgery for heart problems present at birth
• Bridge to transplant: Supporting the heart or lungs while waiting for a donor organ
• Drug overdose or poisoning causing heart or lung failure
• Pulmonary hypertension (high blood pressure in the lungs) that is not responding to other treatments
• Sepsis-related heart failure in children

Indications by Age Group

Contraindications

ECMO is generally not used in the following situations, because the risk is too high or recovery is unlikely:

• Premature newborns under 34 weeks of gestation (relative contraindication; evolving with newer technology)
• Newborns weighing less than 2 kg (relative contraindication)
• Severe, irreversible brain damage
• Active, uncontrolled bleeding or severe clotting disorders
• Very prolonged mechanical ventilation (generally more than 14 days in children) associated with poor outcomes
• Non-recoverable heart or lung disease with no bridge option
• Recent major brain surgery or significant intracranial bleed

Types of ECMO

There are three main configurations of ECMO, each chosen based on whether the heart, lungs, or both need support.

VV-ECMO vs VA-ECMO: Key Differences

Main Components of an ECMO Circuit

An ECMO system is made of several parts that work together continuously:

• Cannulas: Tubes inserted into blood vessels (veins or arteries) to carry blood out of and back into the body.
• Blood Pump: A centrifugal or roller pump that moves blood through the circuit. Modern ECMO systems use centrifugal pumps, which are gentler on blood cells and more reliable.
• Oxygenator (Membrane Lung): The heart of the ECMO machine. Blood flows across a thin membrane inside this device. Oxygen passes in and carbon dioxide passes out — just like breathing, but done artificially. Most modern oxygenators use a material called polymethylpentene (PMP).
• Heat Exchanger: Warms the blood back to normal body temperature before returning it to the patient.
• Gas Blender: Controls the mixture of oxygen and air delivered to the oxygenator, allowing fine adjustment of how much oxygen the blood receives.
• Monitoring Sensors: Continuously measure blood pressure, oxygen levels, blood flow rate, and the status of the circuit to detect any problems early.

How ECMO Is Used: Step-by-Step

Starting and running ECMO is a team effort. It involves surgeons, intensivists (ICU doctors), perfusionists (ECMO specialists), nurses, and respiratory therapists working closely together. The following steps outline the complete process from preparation to removal.

Phase 1: Decision and Preparation

1. Patient assessment: The medical team evaluates whether ECMO is appropriate based on the diagnosis, severity, reversibility, and the patient's overall condition. Standard guidelines (e.g., ELSO guidelines) help guide this decision.
2. Consent: The risks, benefits, and alternatives are explained to the patient or their family or legal guardian before proceeding.
3. Circuit preparation: The ECMO circuit (tubing, pump, oxygenator) is assembled, checked, and primed — filled with a sterile solution or blood to remove all air bubbles. Strict sterile technique is used throughout. All connection points are tightened and verified.
4. Patient preparation: The patient is given sedation, pain relief, and anticoagulation medication (usually heparin) to prevent blood from clotting inside the circuit. Imaging (ultrasound, X-ray) is used to guide cannula placement.

Phase 2: Cannulation (Inserting the Tubes)

1. Site selection: The type of ECMO (VV or VA) determines which blood vessels are used. Common sites include the neck (internal jugular vein), groin (femoral vein and artery), or chest (via open surgery for central cannulation in newborns and post-cardiac surgery patients).
2. Ultrasound-guided access: A specially trained clinician (usually a surgeon or interventionalist) uses real-time ultrasound to safely insert the cannulas into the correct blood vessels with minimal risk of injury.
3. Cannula positioning: The drainage cannula tip is positioned correctly (usually near or inside the right atrium of the heart for optimal blood flow). The return cannula is placed at its designated site. Position is confirmed with imaging (echocardiogram or chest X-ray).
4. Connecting to the circuit: The cannulas are connected to the ECMO circuit tubing. The ECMO pump is then slowly started. Blood begins to flow through the external circuit.

Phase 3: Running ECMO (Maintenance)

1. Flow adjustment: The blood flow rate through the circuit is set based on the patient's body weight and needs. The oxygen delivered and carbon dioxide removed are adjusted using the gas blender and sweep gas flow through the oxygenator.
2. Anticoagulation management: Heparin (or, in some cases, direct thrombin inhibitors like bivalirudin) is continuously given to prevent blood clots forming in the circuit. The level of anticoagulation is checked regularly using blood tests (ACT or aPTT).
3. Continuous monitoring: The patient is monitored around the clock — vital signs, blood oxygen levels, circuit pressures, blood flow rates, and blood tests. The ECMO circuit itself (tubing, oxygenator, connections) is also checked frequently for any clots, air, or leaks.
4. Ventilator settings reduced: Once on ECMO, the ventilator (breathing machine) settings are reduced to "rest" levels to allow the lungs to recover without being further damaged by high pressures or oxygen concentrations.
5. Treating the underlying cause: ECMO buys time. The medical team continues to treat the problem that caused the heart or lung failure in the first place (e.g., antibiotics for infection, surgery for a heart defect).

Phase 4: Weaning (Reducing Support Gradually)

1. Monitoring for recovery: As the heart or lungs begin to improve, signs of recovery are tracked closely. For VV-ECMO, the oxygen sweep gas is gradually reduced. For VA-ECMO, the blood flow through the machine is slowly turned down.
2. Trial off ECMO: When the patient appears stable enough, a brief trial of 1 to 6 hours with minimal or no ECMO support is done to confirm that the heart and lungs can manage on their own before the machine is removed.
3. Decision to decannulate or continue: If the patient remains stable during the trial, the team plans to remove the ECMO. If not, support is continued and reassessed. When recovery is not expected to happen, the team and family discuss the next steps, which may include other mechanical support devices or organ transplantation.

Phase 5: Decannulation (Removing the Cannulas)

1. Increasing flow before removal: Just before removing the cannulas, ECMO flow is briefly increased and anticoagulation is maintained to prevent clots forming in the circuit during the removal process.
2. Surgical or bedside removal: The cannulas are removed by a trained surgeon or physician. Pressure is applied to stop bleeding from the insertion sites. Vessels may be repaired surgically if needed.
3. Post-decannulation monitoring: After the cannulas are removed, the patient is monitored very closely for several hours to ensure the heart and lungs continue to function independently. Ultrasound checks for blood clots are routine after removal.

Precautions and Potential Risks

ECMO is a powerful but complex life-support system. It carries significant risks. These are well-recognized by medical teams and are actively managed throughout the ECMO run.

Risks to the Patient

• Bleeding: The most common complication. Anticoagulant medication needed to prevent circuit clotting also increases the risk of bleeding anywhere in the body, including the brain. Brain bleeding is especially serious in newborns.
• Blood clots (thrombosis): Clots can form inside the circuit or within the patient's blood vessels, potentially causing stroke, organ damage, or blockage of the return cannula.
• Stroke and brain injury: Can result from clots, air entering the circulation, or unstable blood oxygen levels, particularly with VA-ECMO.
• Infection: Long-term indwelling cannulas and the need for multiple procedures increase the risk of serious bloodstream infections.
• Limb ischemia (reduced blood supply to a limb): With femoral (groin) arterial cannulas in VA-ECMO, the leg on the same side can receive reduced blood flow, potentially causing tissue damage. A small additional tube (distal perfusion cannula) is sometimes placed to prevent this.
• Kidney and other organ injury: Reduced blood flow during critical illness, combined with ECMO-related effects, can impair kidney function. Continuous kidney replacement therapy (dialysis) is often needed alongside ECMO.
• Heart distension (LV overload): In VA-ECMO, the increased pressure on the left ventricle from the ECMO return flow can cause the heart to swell if it is not monitored carefully. Venting procedures may be needed.

Risks to the Circuit

• Oxygenator failure: The membrane lung can stop working if clots build up inside it. The entire oxygenator may need emergency replacement.
• Pump failure: Equipment malfunction requires immediate backup or circuit changeout.
• Air in the circuit: Air entering the blood circuit can cause air emboli (air bubbles in the blood), which can be fatal. Circuits must be checked constantly for any air entry points.
• Accidental decannulation: If a cannula is accidentally dislodged, life-threatening bleeding or air entry can occur immediately. Secure cannula fixation and constant vigilance are essential.
• Circuit tubing rupture or disconnection: All connection points are checked regularly. Emergency clamps must always be immediately available at the bedside.

Safety Measures Always in Place

• Trained ECMO specialist present at the bedside or immediately available at all times
• Emergency clamps, backup circuit components, and replacement oxygenators readily available
• Regular interdisciplinary team reviews and simulated emergency drills
• Strict aseptic technique for all circuit and cannula care
• Continuous alarm monitoring for circuit pressures, flows, and oxygenation

Frequently Asked Questions (FAQ)

Keeping ECMO Safe: Maintenance and Best Practices

ECMO circuit safety is a shared responsibility of the entire team involved in care. The following are established best practices:

Circuit and Equipment Safety

• Inspect all tubing, connectors, and the oxygenator at regular intervals (typically every 2 to 4 hours) for clots, discoloration, or air
• Ensure all circuit connections are tight and secured — loose connections are a major risk for air entry and bleeding
• Keep emergency clamps at the bedside at all times — these can be applied immediately if a cannula accidentally disconnects
• Monitor oxygenator performance regularly; if resistance increases or gas exchange worsens, oxygenator change may be needed
• Replace the circuit (tubing, pump head, oxygenator) if there are persistent clots, infection, or equipment degradation

Cannula Site Care

• Secure cannulas firmly with sutures and dressings to prevent accidental movement or dislodgement
• Change dressings aseptically at regular intervals and inspect the skin around the insertion site for signs of infection
• In VA-ECMO with femoral artery cannulation, monitor the limb continuously for color, temperature, and pulse to detect reduced blood supply early

Patient Monitoring

• Continuous monitoring of heart rate, blood pressure, oxygen saturation, and ECMO circuit pressures and flows
• Regular blood tests: complete blood count, clotting studies, blood gases, electrolytes, kidney and liver function
• Regular echocardiography (heart ultrasound) to assess heart function and cannula position
• Head ultrasounds in newborns to detect early brain bleeding
• Neurological assessments for all patients

Anticoagulation Management

• Anticoagulation levels must be checked frequently using ACT (Activated Clotting Time) or aPTT blood tests
• Dose adjustments are made promptly to stay within the therapeutic range — too little causes circuit clotting; too much causes bleeding
• Platelet counts are monitored and low platelets are replaced with transfusions as needed

Team and Institutional Requirements

• Only institutions with trained ECMO programs, regular case volume, and 24-hour specialist availability should offer ECMO
• Regular simulation drills for emergencies (pump failure, air entry, accidental decannulation) are mandatory for all ECMO team members
• Case reviews and quality improvement processes, as recommended by ELSO, improve outcomes over time

After ECMO: Follow-Up and Recovery

Recovery after ECMO depends on the underlying illness, age, and how long ECMO was required. After decannulation, the focus shifts to rehabilitation and monitoring for delayed complications.

• Patients typically remain in the ICU for observation after ECMO removal before moving to a general ward
• Limb blood flow and clotting complications are monitored with imaging after decannulation
• Neurodevelopmental follow-up is recommended for all neonates and children who have been on ECMO, ideally through dedicated multidisciplinary follow-up clinics
• Hearing assessment is important, particularly for neonates who received aminoglycoside antibiotics alongside ECMO
• Psychological support for families is an important part of recovery, given the emotional intensity of an ECMO admission