Extracorporeal cardiopulmonary resuscitation for refractory out-of-hospital cardiac arrest: a systematic review and meta-analysis of randomized clinical trials

Does extracorporeal cardiopulmonary resuscitation improve survival with favorable neurological outcome in out-of-hospital cardiac arrest? A systematic review and meta-analysis

PURPOSE

Extracorporeal cardiopulmonary resuscitation (E-CPR) may improve survival with favorable neurological outcome in patients with refractory out-of-hospital cardiac arrest (OHCA). Unfortunately, recent results from randomized controlled trials were inconclusive. We performed a meta-analysis to investigate the impact of E-CPR on neurological outcome compared to conventional cardiopulmonary resuscitation (C-CPR).

METHODS

A systematic research for articles assessing outcomes of adult patients with OHCA either treated with E-CPR or C-CPR up to April 27, 2023 was performed. Primary outcome was survival with favorable neurological outcome at discharge or 30 days. Overall survival was also assessed.

RESULTS

Eighteen studies were included. E-CPR was associated with better survival with favorable neurological status at discharge or 30 days (14% vs 7%, OR 2.35, 95% CI 1.61-3.43, I2 = 80%, p < 0.001, NNT = 17) than C-CPR. Results were consistent if the analysis was restricted to RCTs. Overall survival to discharge or 30 days was also positively affected by treatment with E-CPR (OR = 1.71, 95% CI = 1.18-2.46, I2 = 81%, p = 0.004, NNT = 11).

CONCLUSIONS

In this meta-analysis, E-CPR had a positive effect on survival with favorable neurological outcome and, to a smaller extent, on overall mortality in patients with refractory OHCA.

Extracorporeal cardiopulmonary resuscitation versus standard treatment for refractory out-of-hospital cardiac arrest: a Bayesian meta-analysis

BACKGROUND

The outcomes of several randomized trials on extracorporeal cardiopulmonary resuscitation (ECPR) in patients with refractory out-of-hospital cardiac arrest were examined using frequentist methods, resulting in a dichotomous interpretation of results based on p-values rather than in the probability of clinically relevant treatment effects. To determine such a probability of a clinically relevant ECPR-based treatment effect on neurological outcomes, the authors of these trials performed a Bayesian meta-analysis of the totality of randomized ECPR evidence.

METHODS

A systematic search was applied to three electronic databases. Randomized trials that compared ECPR-based treatment with conventional CPR for refractory out-of-hospital cardiac arrest were included. The study was preregistered in INPLASY (INPLASY2023120060). The primary Bayesian hierarchical meta-analysis estimated the difference in 6-month neurologically favorable survival in patients with all rhythms, and a secondary analysis assessed this difference in patients with shockable rhythms (Bayesian hierarchical random-effects model). Primary Bayesian analyses were performed under vague priors. Outcomes were formulated as estimated median relative risks, mean absolute risk differences, and numbers needed to treat with corresponding 95% credible intervals (CrIs). The posterior probabilities of various clinically relevant absolute risk difference thresholds were estimated.

RESULTS

Three randomized trials were included in the analysis (ECPR, n = 209 patients; conventional CPR, n = 211 patients). The estimated median relative risk of ECPR for 6-month neurologically favorable survival was 1.47 (95%CrI 0.73-3.32) with a mean absolute risk difference of 8.7% (- 5.0; 42.7%) in patients with all rhythms, and the median relative risk was 1.54 (95%CrI 0.79-3.71) with a mean absolute risk difference of 10.8% (95%CrI - 4.2; 73.9%) in patients with shockable rhythms. The posterior probabilities of an absolute risk difference > 0% and > 5% were 91.0% and 71.1% in patients with all rhythms and 92.4% and 75.8% in patients with shockable rhythms, respectively.

CONCLUSION

The current Bayesian meta-analysis found a 71.1% and 75.8% posterior probability of a clinically relevant ECPR-based treatment effect on 6-month neurologically favorable survival in patients with all rhythms and shockable rhythms. These results must be interpreted within the context of the reported credible intervals and varying designs of the randomized trials.

REGISTRATION

INPLASY (INPLASY2023120060, December 14th, 2023, https://doi.org/10.37766/inplasy2023.12.0060 ).

Extracorporeal cardiopulmonary resuscitation for refractory out-of-hospital cardiac arrest: Lessons learned from recent clinical trials

Cardiac arrest is a leading contributor to morbidity and mortality in the United States. Survival has been historically dependent on high-quality cardiopulmonary resuscitation (CPR) and rapid defibrillation. However, a large percentage of patients remain in refractory cardiac arrest despite adherence to structured advanced cardiac life support algorithms in which these factors are emphasized. Veno-arterial extracorporeal membrane oxygenation is becoming an increasingly used rescue therapy for patients in refractory cardiac arrest to restore oxygen delivery by extracorporeal CPR (ECPR). Recently published clinical trials have provided new insights into ECPR for patients who sustain an outside hospital cardiac arrest (OHCA). In this narrative review, we summarize the rationale for, results of, and remaining questions from these recently published clinical trials. The existing observational data combined with the latest clinical trials suggest ECPR improves mortality in patients in refractory arrest. However, a mixed methods trial is essential to understand the complexity, context, and effectiveness of implementing an ECPR program.

Survival and neurological function in patients treated with extracorporeal membrane oxygenation and therapeutic hypothermia: a protocol for updating a systematic review

INTRODUCTION

The widespread application of extracorporeal membrane oxygenation (ECMO) has enhanced clinical outcomes for patients experiencing cardiac arrest. However, its effectiveness is still limited and falls short of the desired level. Therapeutic hypothermia, which maintains body temperatures between 32°C and 36°C in cardiac arrest patients treated with ECMO, has been proposed as a potential means of neuroprotection and increased survival rates. Nevertheless, it remains controversial, and its impact on patient complications has yet to be fully understood. Thus, this paper aims to update the protocol for a systematic review of patients treated with ECMO and therapeutic hypothermia, in order to explore its effects on survival and neurological function.

METHOD AND ANALYSIS

This protocol has been developed in compliance with the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols 2015. The following databases will be systematically searched: PubMed, Web of Science, Cochrane Library, Embase, Ovid, CNKI, Wanfang and China Biology Medicine Disc. The database search strategy will use a combination of subject terms and free-text keywords. The search will encompass articles from the inception of each database up to 15 June 2023. Inclusion criteria encompass randomised controlled trials, cohort studies, case-control studies and quasi-experimental studies. Two researchers will independently review articles and extract relevant data based on these criteria. Any disagreements will be resolved through discussion. Data analysis will be performed using Review Manager software.

ETHICS AND DISSEMINATION

Since no patient data were collected in this study, ethical approval was not required. Research findings will be released in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023435353.