Cardiac arrest is a life-threatening medical emergency that occurs when the heart suddenly stops beating. If not treated immediately via cardiopulmonary resuscitation (CPR) and defibrillation with a shock from an AED or defibrillator, it can lead to death within minutes. For patients who do not respond to standard resuscitation efforts, extracorporeal cardiopulmonary resuscitation (ECPR) has emerged as a promising salvage therapy. In this article, we explore the growing importance of ECPR in the management of cardiac arrest and the roles it plays in improving survival outcomes.
What is ECPR?
ECPR, also known as extracorporeal membrane oxygenation (ECMO), is an advanced form of cardiopulmonary bypass that takes over the function of the heart and lungs. It works by diverting blood from the body to an artificial lung that oxygenates the blood before pumping it back into circulation. This provides circulatory support and allows oxygenated blood to continue circulating throughout the body while standard CPR efforts or more advanced therapies like targeted temperature management take effect.
ECPR provides a “bridge to recovery” by gaining valuable time for the heart to recover its natural function after a cardiac arrest. It allows for prolonged resuscitation efforts beyond what would traditionally be possible with standard CPR alone. The goal is to prevent further damage from prolonged lack of oxygen and give the heart the best chance to restart on its own or with additional therapies.
Expanding Indications for Its Use
Initially considered only for “salvage” cases who failed standard resuscitation, ECPR is now being used more routinely in selected cardiac arrest patients. Recent studies and guidelines have expanded the accepted indications for its use based on growing evidence of improved survival rates compared to conventional CPR alone:
- In-hospital cardiac arrests: Several studies have found ECPR may double or triple survival rates to discharge compared to standard CPR for in-hospital cardiac arrests, even among those with a non-shockable initial rhythm.
- Out-of-hospital cardiac arrests: While outcomes are still lower than in-hospital arrests, ECPR is showing promise for select out-of-hospital cardiac arrest patients transported rapidly to ECPR-capable hospitals.
- Younger patients: Younger patients (typically defined as less than 65 years old) tend to have the best outcomes with ECPR compared to older patients. However, some centers are having success even in older adult populations.
- Longer down-times: ECPR may be considered even in patients with longer “no-flow” times (time from collapse to initiation of CPR) than previously believed salvageable by conventional CPR alone. One study found a benefit for down-times up to 60 minutes.
As more data emerges supporting its use in carefully selected populations, ECPR is playing a larger role earlier in refractory cardiac arrest resuscitation protocols rather than only as a last resort salvage therapy. However, patient selection remains important for achieving optimal outcomes.
Improving Survival Rates and Neurological Outcomes Post-Cardiac Arrest
Several large observational studies and meta-analyses have demonstrated ECPR’s ability to substantially improve survival rates for cardiac arrest when compared to conventional CPR alone:
- A meta-analysis of 36 studies found an overall survival to hospital discharge rate of 24.4% with ECPR, significantly higher than the 13.7% rate observed with conventional CPR.
- An international registry study of 973 cardiac arrest patients found a survival to discharge rate of 29.8% with ECPR compared to 13.7% for conventional CPR alone.
- A Japanese study of 500 IHCA patients reported 1-month and 1-year survival rates of 44.7% and 34.1% with ECPR versus 24.8% and 17.8% with conventional CPR alone.
In addition, there is emerging evidence ECPR may lead to better neurological outcomes and quality of life in survivors compared to standard resuscitation. One study found 85% of ECPR survivors were able to fully regain independent neurological function versus only 50-60% of conventional CPR survivors. Larger studies continue to research long-term outcomes and life quality post-ECPR.
Important Role in Special Cardiac Arrest Scenarios
ECPR is also playing a pivotal role in resuscitation of certain high-risk cardiac arrest scenarios where outcomes are traditionally very poor with conventional CPR alone:
Refractory VF/VT: For in-hospital cardiac arrests with an initial non-shockable rhythm that is refractory to escalating anti-arrhythmic drugs and ablation attempts, ECPR provides a bridge to more definitive rhythm control therapies or transplant.
Pulmonary Embolism: Massive pulmonary embolism is a leading cause of cardiac arrest with survival near zero using conventional CPR. ECPR can effectively oxygenate patients while clot removal therapies take effect.
Cardiotoxic Drug Overdose: Poisonings from drugs like calcium channel blockers carry a dismal prognosis with standard resuscitation due to cardiovascular collapse. ECPR support while antidotes work has shown promise.
Trauma: Patients suffering traumatic out-of-hospital cardiac arrests, especially from hemorrhagic shock, may benefit from rapid ECPR initiation to support circulation until bleeding is controlled.
The unique ability of ECPR to provide prolonged cardiac and respiratory support makes it uniquely suited to improve outcomes in these catastrophic scenarios that currently have little to no viable options with conventional CPR alone.
Factors Impacting ECPR Outcomes
While ECPR clearly improves overall survival from cardiac arrest compared to conventional CPR, certain patient- and hospital-related factors can impact whether an individual survives the intervention:
Comorbidities: Advanced age, end-stage renal or liver disease, metastatic cancer, severe depression lower chances of survival. Charlson Comorbidity Index can help assess risk.
First monitored rhythm: Non-shockable rhythms (PEA, asystole) fare worse than initial shockable rhythms (VT, VF). The duration of CPR also affects outcomes.
Time to ECMO initiation: Faster times (<120 minutes) from arrest to ECMO yields better results. Delays weaken the heart and brain.
Hospital ECPR experience: Higher-volume centers (≥20 cases annually) achieve stronger outcomes thanks to coordinated protocols and well-trained teams.
Post-resuscitation care: Targeted temperature management, hemodynamic support, coronary reperfusion if indicated, and advanced heart failure therapies all interplay with ECPR’s effect.
By thoroughly assessing individual risk profiles, working to minimize time to ECMO initiation, and providing intensive post-resuscitation care, ECPR centers focus on optimizing each patient’s chances of survival. However, outcomes remain imperfect due to the severity of illness.
Common Misconceptions about ECPR
Despite evidence supporting its efficacy when used properly, several misconceptions still surround the use of ECPR. Understanding the facts is important for guiding appropriate utilization and management of appropriate patient and family expectations:
ECPR is too risky: While it is more complex than standard CPR, multinational data demonstrates ECPR has an acceptable risk profile when used in select patients at experienced centers.
Only the young may benefit: While younger patients tend to have better outcomes, some centers report success even in older age groups (60s-70s) with good pre-arrest health when other factors are optimized.
Survivors always have brain damage: Emerging evidence shows majority of ECPR survivors regain good neurological function equivalent to standard CPR. Proper post-resuscitation care is pivotal to mitigating brain injury.
ECPR is too expensive: When factoring in continued ICU costs of prolonged conventional CPR, studies show ECPR produces higher quality adjusted survival and may even provide cost savings in the long run compared to standard CPR alone.
Conclusion
In conclusion, ECPR has transformed the management of refractory cardiac arrest over the past decade by providing an unprecedented ability to support the heart, lungs, and circulation beyond what conventional CPR can offer. While further research continues, high-quality evidence shows ECPR substantially increases survival and neurological recovery rates when used for carefully selected cardiac arrest patients. By expanding access to this life-saving therapy through coordinated resuscitation protocols and educating providers/public alike, many more lives stand to benefit in the years ahead. ECPR is filling a critical niche between reversible cardiac arrest etiologies and inevitable death.
