Clinical Efficacy of Extracorporeal Membrane Oxygenation in Cardiogenic Shock Patients: A Multi-Center Study
Cardiogenic shock (CS)—a life-threatening condition where the heart can’t pump enough blood to meet the body’s needs—is a leading cause of death in intensive care units. Even with advances in care, 60% to 80% of CS patients still die. For years, doctors have searched for better ways to save these patients—and extracorporeal membrane oxygenation (ECMO) has emerged as a promising tool.
ECMO is a short-term mechanical support system that takes over part or all of the heart’s and lungs’ work. It pumps blood outside the body, adds oxygen, and returns it to the circulation—buying time for the heart to recover, for surgery, or for a transplant. Observational studies have linked ECMO to better outcomes in CS patients with heart failure or cardiac arrest. But most research is small or retrospective, and large, randomized trials are missing. That’s why a team of Chinese researchers set out to conduct a multi-center study to test ECMO’s real-world efficacy.
The Study: How We Tested ECMO’s Efficacy
The team—led by Qing-Qing Dai and Hong-Liang Wang from Harbin Medical University’s affiliated hospitals—designed a cross-sectional study involving six hospitals in China. From January 2013 to January 2015, they enrolled 27 CS patients who received ECMO (the “ECMO group”) and 27 who got conventional therapy (the “control group”). Five control patients dropped out, leaving 22 for final analysis.
All procedures followed the 1975 Declaration of Helsinki, and the study was approved by the Ethics Committee of Harbin Medical University’s Second Affiliated Hospital (No. 2013-Research-06). Every patient (or their family) signed informed consent.
ECMO patients got standard ECMO care. Control patients received conventional treatments: drugs to boost heart function, diuretics, coronary artery dilation, and adjustments to heart “preload” (blood entering the heart) and “afterload” (resistance the heart pumps against). Both groups could get additional help like intra-aortic balloon pumps (another mechanical support), blood purification, or ventilators if needed.
Key Findings: Does ECMO Improve Outcomes?
At the start, the two groups were similar in age, gender, and other baseline traits. But there was one critical difference: the ECMO group had a higher Acute Physiology and Chronic Health Evaluation II (APACHE II) score—a tool that measures how sick a patient is. This meant ECMO patients were more severe than controls (Z = 3.64, P = 0.0008).
When it came to survival:
- 63% of ECMO patients died (17 of 27).
- 82% of control patients died (18 of 22).
While this difference wasn’t statistically significant (meaning it could have been due to chance), the trend matters: ECMO patients were sicker but had a lower mortality rate. For non-survivors, ECMO patients had even higher APACHE II scores than control non-survivors (t = 3.03, P = 0.0064)—hinting that ECMO might have kept sicker patients alive longer.
The team also found that APACHE II scores predicted survival time: higher scores meant shorter survival (rs = -0.43729, P = 0.0097). In fact, APACHE II was the only factor that significantly affected how long non-survivors lived (odds ratio = 0.0803; 95% confidence interval 0.0069–0.9309; P = 0.0437). This indirectly suggests ECMO worked better than conventional therapy: even in sicker patients, ECMO helped them live as long (or longer) than less sick control patients.
What the Numbers Tell Us About ECMO’s Impact
The real power of ECMO showed up in physiological markers—the numbers that reflect how well the body is working. Using repeated measures analysis (tracking changes over time), the team found:
- Mean Arterial Pressure (MAP): ECMO patients had bigger improvements in blood pressure than controls. This means ECMO helped get more blood to vital organs.
- Central Venous Pressure (CVP): ECMO reduced pressure in the heart’s veins more effectively—easing strain on the failing heart.
- PaO2/FiO2 Ratio: This measures how well the lungs are getting oxygen into the blood. ECMO patients saw much bigger gains here, meaning better oxygenation.
- Creatinine: ECMO patients started with higher creatinine (a kidney damage marker) than controls. But ECMO didn’t improve creatinine—likely because their kidneys were already too damaged to recover, even with better blood flow.
For ECMO patients, three markers predicted survival:
- Heart Rate (HR): Lower heart rates meant better chances.
- MAP: Higher blood pressure meant better survival.
- Central Venous Oxygen Saturation (ScvO2): Higher oxygen levels in the veins meant the body was getting enough oxygen.
If these markers didn’t improve within the first day of ECMO, the patient was far less likely to survive.
Takeaways: ECMO’s Role in Saving Lives
While the study didn’t show a statistically significant difference in mortality, it tells a clear clinical story: ECMO helps the sickest cardiogenic shock patients. Even though ECMO patients were more severe (higher APACHE II), their mortality rate was 20% lower than controls. And when it came to key functions—blood pressure, heart strain, oxygen levels—ECMO outperformed conventional therapy.
For doctors, this means ECMO isn’t just a “last resort”—it’s a critical tool for keeping patients alive while their hearts heal. For patients and families, it’s a sign of hope in a condition where hope is scarce.
The original study was published in the Chinese Medical Journal in 2020 by Qing-Qing Dai, Yan Liu, Yu-Dong Ren, Kai-Jiang Yu, and Hong-Liang Wang from Harbin Medical University’s affiliated hospitals.
doi:10.1097/CM9.0000000000001030
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