Extracorporeal Membrane Oxygenation (ECMO) System

A comprehensive guide to ECMO life-support technology at Apollo Hospitals

Overview

Extracorporeal Membrane Oxygenation (ECMO) is a life-support technology that provides prolonged cardiac and respiratory support to patients whose heart and lungs are unable to function adequately. This advanced medical intervention is used in critical care settings, particularly intensive care units (ICUs), for patients suffering from severe respiratory or cardiac failure. The ECMO system stands out due to its ability to oxygenate blood outside the body, allowing the heart and lungs time to heal or recover.

The ECMO system consists of a pump that circulates blood through an artificial lung (membrane oxygenator) where carbon dioxide is removed and oxygen is added before the blood is returned to the patient. This process mimics the natural functions of the heart and lungs, providing essential support during life-threatening conditions.

Nature of the Procedure

ECMO is a highly invasive, resource-intensive life-support system used in intensive care units for patients with severe, potentially reversible respiratory or cardiac failure that does not respond to conventional treatment. It is not a routine procedure and is not comparable to less invasive diagnostic or therapeutic interventions.

ECMO involves:

• Large-bore vascular cannulation: Insertion of large cannulas into major blood vessels, often requiring surgical cut-down of the neck, groin, or chest vessels. The size and placement of these cannulas carry inherent procedural risks.
• Full systemic anticoagulation with heparin: This is required to prevent clotting in the extracorporeal circuit. This anticoagulation increases the risk of bleeding throughout the body.
• Continuous ICU-level monitoring: ECMO requires monitoring by a specialised ECMO team, including perfusionists, intensivists, cardiac surgeons, and critical care nurses. Patients on ECMO require round-the-clock bedside monitoring.
• Significant risks: These include major bleeding, thrombosis, limb ischaemia, stroke, infection, haemolysis, renal failure, and mechanical circuit complications such as oxygenator failure or tubing rupture.

ECMO is initiated by intensivists and ECMO-trained teams as an emergency or urgent intervention. It is not a procedure that patients or families schedule. The decision to place a patient on ECMO is made by the treating medical team based on the severity of the clinical situation and the likelihood of recovery.

Purpose

The primary purpose of the ECMO system is to provide temporary mechanical support when the heart, lungs, or both are failing and not responding to conventional treatments. ECMO allows these organs to rest and recover while the underlying condition is treated.

The system is used in the following clinical contexts:

• Severe respiratory failure: Including acute respiratory distress syndrome (ARDS), severe pneumonia, and respiratory failure from COVID-19 or other infections, when mechanical ventilation alone is insufficient.
• Cardiac failure: Including cardiogenic shock, refractory cardiac arrest, and failure to wean from cardiopulmonary bypass after cardiac surgery.
• Bridge to transplant: ECMO can support patients while they await a heart or lung transplant.
• Bridge to recovery: Providing time for the heart or lungs to heal from acute injury or illness.
• Bridge to decision: Maintaining organ perfusion while the medical team assesses whether further treatment options are available.

How It Works

The ECMO system works by drawing blood from the patient through a large cannula, passing it through a membrane oxygenator where oxygen is added and carbon dioxide is removed, warming the blood to body temperature, and then returning it to the patient through another cannula. A pump drives the blood through the circuit.

There are two main configurations:

Veno-Venous (VV) ECMO

In VV-ECMO, blood is drawn from and returned to the venous system. This configuration provides respiratory support only, including oxygenation and carbon dioxide removal. It is used when the lungs are failing but the heart is functioning adequately. The patient’s own heart continues to pump blood through the body.

Veno-Arterial (VA) ECMO

In VA-ECMO, blood is drawn from the venous system and returned to the arterial system. This configuration provides both cardiac and respiratory support. It is used when both the heart and lungs are failing, or when the heart alone is failing, such as in cardiogenic shock or cardiac arrest.

Key components of the ECMO circuit include:

• Cannulas: Large-bore tubes inserted into major blood vessels to drain and return blood
• Blood pump: A centrifugal or roller pump that drives blood flow through the circuit
• Membrane oxygenator: An artificial lung that adds oxygen and removes carbon dioxide
• Heat exchanger: Warms the blood to body temperature before it is returned to the patient
• Monitoring systems: Continuous monitoring of blood flow, pressures, oxygenation levels, and circuit function

Who Can Benefit from ECMO?

ECMO may be considered for patients with:

• Severe ARDS (acute respiratory distress syndrome) not responding to optimal ventilator management
• Severe pneumonia caused by bacterial, viral, or fungal infection causing refractory hypoxaemia
• Cardiogenic shock not responding to medical therapy or mechanical circulatory support
• Refractory cardiac arrest, as extracorporeal cardiopulmonary resuscitation or eCPR
• Failure to wean from cardiopulmonary bypass after cardiac surgery
• Acute myocarditis with haemodynamic compromise
• Massive pulmonary embolism
• As a bridge to heart or lung transplant, or bridge to a ventricular assist device (VAD)

The decision to initiate ECMO is made by the treating intensive care and ECMO team. It is reserved for patients with severe, potentially reversible conditions who have not responded to all conventional therapies.

ECMO is not appropriate for all critically ill patients, and the team will assess factors including the underlying diagnosis, likelihood of recovery, patient age, comorbidities, and the duration of illness before initiation.

Benefits

When indicated, ECMO can offer the following benefits:

• Life-saving support: ECMO can sustain life in patients who would otherwise not survive severe cardiac or respiratory failure.
• Organ rest and recovery: By taking over the work of the heart and lungs, ECMO allows these organs to rest and heal, potentially enabling recovery.
• Improved oxygenation: ECMO provides adequate oxygenation to the body, allowing vital organs to function while the underlying condition is treated.
• Reduced ventilator-induced lung injury: In respiratory failure, ECMO can allow the ventilator settings to be reduced, minimising further damage to the lungs.
• Improved survival rates: Studies have shown that patients who receive timely ECMO support for appropriate indications have improved survival compared with conventional treatment alone.
• Versatility: ECMO can be configured for respiratory support, cardiac support, or both, depending on the patient’s needs.

Risks and Complications

ECMO is a high-risk intervention. While it can be life-saving, patients and families should be aware of the significant risks involved:

• Major bleeding: Reported in up to 30–40% of ECMO patients, due to the systemic anticoagulation required to prevent clotting in the circuit. Bleeding can occur at the cannulation sites, in the lungs, gastrointestinal tract, or brain.
• Thrombosis: Blood clots can form in the circuit or in the patient, potentially leading to stroke, pulmonary embolism, or limb ischaemia.
• Limb ischaemia: Particularly with femoral arterial cannulation in VA-ECMO, reduced blood flow to the leg can cause tissue damage. Distal perfusion cannulas may be used to mitigate this risk.
• Stroke: Both ischaemic and haemorrhagic strokes can occur during ECMO support.
• Infection: Prolonged vascular access and ICU stay increase the risk of bloodstream and surgical site infections.
• Haemolysis: Mechanical destruction of red blood cells as they pass through the pump and circuit.
• Renal failure: May occur due to the underlying illness, haemodynamic instability, or ECMO-related factors. Some patients require dialysis during ECMO support.
• Mechanical complications: Including oxygenator failure, air embolism, tubing rupture, and pump malfunction. These require immediate intervention by the ECMO team.

The overall mortality rate for patients requiring ECMO remains significant, as these patients are by definition critically ill. Survival rates vary based on the indication: approximately 50–60% for respiratory ECMO and 30–45% for cardiac ECMO, according to data from the Extracorporeal Life Support Organization (ELSO).

Recovery

Recovery from ECMO depends on the underlying condition that necessitated the treatment:

• The duration of ECMO support varies widely, from days to weeks, depending on the patient’s clinical course and response to treatment
• When the heart and lungs have recovered sufficiently, the ECMO team will gradually reduce support and assess the patient’s ability to function independently, a process called weaning
• Decannulation, or removal of the cannulas, is performed once the patient has been successfully weaned from ECMO support
• Patients typically remain in the ICU for continued monitoring after ECMO is discontinued
• Rehabilitation, including physiotherapy and respiratory therapy, is an important part of recovery after ECMO
• Full recovery may take weeks to months, depending on the severity of the illness and the patient’s overall health

Frequently Asked Questions

1. How does ECMO work?

ECMO works by drawing blood from the patient, oxygenating it through an artificial lung (membrane oxygenator), and then returning it to the body. This process supports patients whose heart and lungs are not functioning adequately.

2. Who is eligible for ECMO?

Eligibility for ECMO typically includes patients with severe respiratory or cardiac failure who have not responded to conventional treatments. The decision is made by the treating intensive care and ECMO team based on the clinical situation. ECMO is not a procedure that patients or families request or schedule; it is initiated as an emergency or urgent intervention by the medical team.

3. Is the procedure painful or uncomfortable?

Patients on ECMO are usually sedated and in the intensive care unit. While the cannulation process is an invasive procedure that involves inserting large tubes into major blood vessels, patients are sedated during this and throughout ECMO treatment. Continuous monitoring ensures patient comfort and safety.

4. How long does ECMO treatment last?

The duration of ECMO varies from days to weeks, depending on the underlying condition and the patient’s response to treatment. The ECMO team continuously assesses whether the patient’s heart and lungs are recovering sufficiently to allow weaning from support.

5. What are the risks of ECMO?

ECMO carries significant risks including major bleeding, thrombosis, stroke, limb ischaemia, infection, haemolysis, renal failure, and mechanical circuit complications. These risks are weighed against the life-threatening nature of the conditions for which ECMO is used.

6. Can ECMO cure the underlying condition?

No. ECMO does not treat the underlying disease. It provides temporary support for the heart and lungs while the medical team treats the underlying condition. ECMO buys time for the organs to rest and recover, or serves as a bridge to further interventions such as transplantation.

7. What is the survival rate for patients on ECMO?

Survival rates vary based on the indication. According to the Extracorporeal Life Support Organization (ELSO), survival is approximately 50–60% for respiratory ECMO and 30–45% for cardiac ECMO. Individual outcomes depend on the underlying diagnosis, patient age, comorbidities, and the timeliness of ECMO initiation.

8. Is ECMO available at all hospitals?

No. ECMO requires specialised equipment, trained personnel including perfusionists, intensivists, and cardiac surgeons, and dedicated ICU infrastructure. It is available only at select hospitals with established ECMO programmes.

9. Can family members visit a patient on ECMO?

ICU visiting policies vary by hospital and clinical situation. In most cases, family members can visit patients on ECMO, though visiting hours and the number of visitors may be restricted. The ECMO and ICU team will provide guidance on visitation.

10. How can I learn more about ECMO at Apollo Hospitals?

ECMO is available at select Apollo Hospitals with dedicated ECMO programmes. For information, contact your nearest Apollo Hospitals centre. For emergencies, contact your nearest Apollo emergency department or call 1066.

Emergency Contact Information

ECMO is available at select Apollo Hospitals with dedicated ECMO programmes. ECMO is initiated as an emergency or urgent intervention by the treating medical team and is not a procedure that patients or families schedule.

For emergencies, contact your nearest Apollo emergency department or call 1066 (Apollo Hospitals emergency helpline).

If a family member is critically ill and you wish to understand whether ECMO may be available or appropriate, speak directly with the treating intensivist or critical care team at the hospital where the patient is being cared for.