Extracorporeal Membrane Oxygenation (ECMO) is the highest tier of life support for patients experiencing catastrophic heart or lung failure. This technology circulates the patient’s blood outside the body, adding oxygen and removing carbon dioxide before returning it. Initiating ECMO means the patient is in profound organ failure, where conventional treatments are insufficient to sustain life. Given the severity of the underlying condition, the question of survival is complex and involves significant risks associated with the support system.
ECMO as a Bridge to Recovery
The core function of ECMO is to serve as a bridge, allowing the patient’s native organs time to rest and heal while the underlying illness is treated. The machine uses a pump and an oxygenator to perform gas exchange and provide circulatory support, reducing the strain on failing cardiopulmonary function.
There are two primary configurations. Veno-Venous (VV) ECMO is used for severe lung failure (e.g., ARDS) when the heart is functioning effectively; blood is drawn from a vein and returned to a vein after oxygenation. Veno-Arterial (VA) ECMO supports both the heart and lungs, draining blood from a vein and returning it to an artery. This configuration provides full circulatory support, necessary when the heart is too weak to pump blood, such as in cardiogenic shock.
Survival depends on the recovery of the failing organ. If the heart or lungs cannot regain sufficient function during support, the patient cannot be successfully weaned from the circuit. ECMO provides a borrowed window of time, but the patient remains critically ill.
Understanding Mortality Rates
Patients on ECMO frequently die, reflecting the severity of their condition upon initiation of support. The Extracorporeal Life Support Organization (ELSO) registry tracks international outcomes, showing that survival rates vary significantly based on the patient’s age and the type of organ failure treated.
Overall survival to hospital discharge for adults receiving ECMO is typically 50 to 60%. Survival rates are higher for patients with isolated respiratory failure (VV-ECMO) compared to those requiring support for combined heart and lung failure (VA-ECMO). Outcomes are lowest for patients requiring ECMO following cardiac arrest (ECPR), with adult survival to discharge reported around 29.5% in recent ELSO data.
Survival is also influenced by the underlying reason for organ failure, such as a reversible infection versus severe trauma or chronic disease. Neonatal respiratory support generally shows the highest survival rates, sometimes exceeding 68%.
Major Complications Leading to Death
Death on ECMO often results from catastrophic complications related to the circuit or the intense medical support. Continuous exposure of blood to artificial surfaces requires aggressive anticoagulation, creating a risk of severe bleeding. Hemorrhage is the most common complication.
The most fatal bleeding complication is intracranial hemorrhage (bleeding in the brain), which is strongly linked to mortality due to required blood thinners. Bleeding can also occur at the cannula insertion site, in the gastrointestinal tract, or in the chest and abdomen.
Thrombosis and Circuit Failure
The constant contact of blood with the circuit can also trigger a pro-clotting state, leading to thrombosis. Clots can form within the ECMO circuit, causing the oxygenator to fail and requiring an emergency exchange of equipment. Patient-related clots, such as pulmonary or arterial thromboembolism, can occur despite anticoagulation efforts.
Infection and Sepsis
Patients on ECMO are highly susceptible to serious infections. The presence of multiple large lines and cannulas, combined with a compromised immune system, increases the risk of bloodstream and ventilator-associated infections. The development of severe sepsis or septic shock can overwhelm the body’s remaining organ systems, leading to irreversible multi-organ failure.
Prognostic Indicators for Survival
Survival likelihood is determined by factors present before and during support. Prognostic scoring systems, such as the Respiratory ECMO Survival Prediction (RESP) score for respiratory failure and the Survival After Veno-Arterial ECMO (SAVE) score for cardiac failure, help clinicians estimate outcomes. These scores incorporate variables like patient age, pre-existing conditions, and the severity of organ dysfunction before ECMO initiation.
Older age is associated with lower survival rates. Pre-existing comorbidities, such as chronic renal failure or severe immunosuppression, reduce the body’s capacity to recover. Indicators of multi-organ failure, particularly acute kidney injury or severe neurological injury at the time of cannulation, also suggest a lower chance of recovery.
The duration of the ECMO run is a strong prognostic indicator, as longer periods of support correlate with decreased survival. Death on ECMO usually results from the underlying disease progressing or the native organs failing to recover sufficiently. If the heart or lungs do not heal enough to sustain the patient independently, the machine must eventually be withdrawn, or the patient succumbs to complications.