Clinical Efficacy of Extracorporeal Membrane Oxygenation in Cardiogenic Shock Patients: A Multi-Center Study
Cardiogenic shock (CS) is a critical condition often encountered in intensive care units, characterized by a severe reduction in cardiac output leading to inadequate tissue perfusion. Despite advancements in medical care, CS continues to carry a poor prognosis, with mortality rates ranging from 60% to 80%. Extracorporeal membrane oxygenation (ECMO) has emerged as a promising therapeutic option for patients with CS, offering both circulatory and respiratory support. This multi-center study aimed to evaluate the clinical efficacy of ECMO in CS patients and compare its outcomes with conventional therapy.
Study Design and Methodology
This study was designed as a multi-center cross-sectional investigation involving six hospitals in China. The study period spanned from January 2013 to January 2015. A total of 27 CS patients who received ECMO were included in the ECMO group. For comparison, a control group of 27 CS patients who received conventional therapy was randomly selected from the same period. However, five patients in the control group abandoned treatment after initiation, resulting in a final control group size of 22 patients.
The study adhered to the ethical guidelines of the 1975 Declaration of Helsinki and received approval from the Ethics Committee of the Second Affiliated Hospital of Harbin Medical University. All participants provided written informed consent.
Treatment Protocols
Patients in the ECMO group received standard ECMO treatment, which involved partial or full circulatory support. The control group received conventional therapy, including inotropes, diuresis, coronary artery dilation, and measures to improve heart preload and afterload. Additionally, both groups received intra-aortic balloon pump counterpulsation, blood purification, or mechanical ventilation when necessary.
Statistical Analysis
Statistical analyses were performed using the Statistical Analysis System (SAS) version 9.1.3. Spearman rank correlation coefficient was used to analyze the correlation between Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) score and survival outcomes. Logistic regression analysis was employed to assess the influence of treatment, age, gender, and APACHE II score on survival time. Repeated measures analysis of variance (ANOVA) was used to analyze the dynamic changes of various clinical parameters. A P-value of less than 0.05 was considered statistically significant.
Results
Baseline characteristics were comparable between the ECMO and control groups. However, the APACHE II score in the ECMO group was significantly higher than that in the control group (Z = 3.64, P = 0.0008), indicating that ECMO patients were more severely ill. The mortality rate in the ECMO group was 62.96% (17/27), compared to 81.82% (18/22) in the control group. Although the mortality rates and survival times did not differ significantly between the two groups, the APACHE II score in non-survivors of the ECMO group was higher than that in non-survivors of the control group (t = 3.03, P = 0.0064).
Spearman rank correlation analysis revealed a negative correlation between APACHE II score and survival time in non-survivors (rs = -0.43729, P = 0.0097), suggesting that higher APACHE II scores were associated with shorter survival times. Multivariant logistic regression analysis identified APACHE II score as a significant risk factor for shorter survival time (odds ratio = 0.0803; 95% confidence interval 0.0069–0.9309; P = 0.0437).
Dynamic Changes in Clinical Parameters
Repeated measures ANOVA demonstrated significant differences in the dynamic changes of mean arterial pressure (MAP), central venous pressure (CVP), PaO2/FiO2, and creatinine levels between the ECMO and control groups. Improvements in MAP, PaO2/FiO2, and CVP indicated that ECMO was more effective than conventional therapy. Although baseline creatinine levels were higher in the ECMO group (P < 0.05), ECMO did not significantly improve creatinine levels, likely due to pre-existing severe kidney dysfunction.
Heart rate (HR), MAP, central venous oxygen saturation (ScvO2), and hemoglobin (Hb) levels were significantly different between survivors and non-survivors in the ECMO group. The generalized linear model for repeated measurement analysis of HR, MAP, and ScvO2 suggested that these factors could predict the outcome of ECMO patients. Specifically, if these parameters did not improve within the first day of ECMO initiation, the patient was less likely to survive.
Discussion
The findings of this study suggest that ECMO can improve the survival of CS patients compared to conventional therapy. The dynamic changes in MAP, PaO2/FiO2, and CVP demonstrated the superior efficacy of ECMO in enhancing systemic circulation and gas exchange. Additionally, the early improvement in HR, MAP, and ScvO2 levels served as valuable indicators for assessing clinical efficacy and predicting prognosis following ECMO application.
Despite the promising results, it is important to acknowledge the limitations of this study. The small sample size and the non-randomized design may limit the generalizability of the findings. Furthermore, the higher baseline severity of illness in the ECMO group may have influenced the outcomes. Future studies with larger sample sizes and randomized designs are needed to confirm these findings and further explore the potential benefits of ECMO in CS patients.
Conclusion
In conclusion, this multi-center study highlights the clinical efficacy of ECMO in improving the survival of CS patients compared to conventional therapy. The dynamic changes in key clinical parameters such as MAP, PaO2/FiO2, and CVP provide valuable insights into the therapeutic benefits of ECMO. Early improvements in HR, MAP, and ScvO2 levels are crucial for assessing the clinical efficacy and prognosis of ECMO treatment. These findings underscore the importance of ECMO as a viable therapeutic option for critically ill CS patients.
doi.org/10.1097/CM9.0000000000001030
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