Extracorporeal cardiopulmonary resuscitation for refractory OHCA: lessons from three randomized controlled trials-the trialists' view

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 ).

Physiology-Guided Resuscitation: Monitoring and Augmenting Perfusion during Cardiopulmonary Arrest

Given the high morbidity and mortality associated with cardiopulmonary arrest, there have been multiple trials aimed at better monitoring and augmenting coronary, cerebral, and systemic perfusion. This article aims to elucidate these interventions, first by detailing the physiology of cardiopulmonary resuscitation and the available tools for managing cardiopulmonary arrest, followed by an in-depth examination of the newest advances in the monitoring and delivery of advanced cardiac life support.

Favorable resuscitation characteristics in patients undergoing extracorporeal cardiopulmonary resuscitation: A secondary analysis of the INCEPTION-trial

Introduction

Extracorporeal cardiopulmonary resuscitation (ECPR) is increasingly used as a supportive treatment for refractory out-of-hospital cardiac arrest (OHCA). Still, there is a paucity of data evaluating favorable and unfavorable prognostic characteristics in patients considered for ECPR.

Methods

We performed a previously unplanned post-hoc analysis of the multicenter randomized controlled INCEPTION-trial. The study group consisted of patients receiving ECPR, irrespective of initial group randomization. The patients were divided into favorable survivors (cerebral performance category [CPC] 1-2) and unfavorable or non-survivors (CPC 3-5).

Results

In the initial INCEPTION-trial, 134 patients were randomized. ECPR treatment was started in 46 (66%) of 70 patients in the ECPR treatment arm and 3 (4%) of 74 patients in the conventional treatment arm. No statistically significant differences in baseline characteristics, medical history, or causes of arrest were observed between survivors (n = 5) and non-survivors (n = 44). More patients in the surviving group had a shockable rhythm at the time of cannulation (60% vs. 14%, p = 0.037), underwent more defibrillation attempts (13 vs. 6, p = 0.002), and received higher dosages of amiodarone (450 mg vs 375 mg, p = 0.047) despite similar durations of resuscitation maneuvers. Furthermore, non-survivors more frequently had post-ECPR implantation adverse events.

Conclusion

The persistence of ventricular arrhythmia is a favorable prognostic factor in patients with refractory OHCA undergoing an ECPR-based treatment. Future studies are warranted to confirm this finding and to establish additional prognostic factors.Clinical trial Registration:clinicaltrials.gov registration number NCT03101787.

Extracorporeal life support in cardiac arrest: a post hoc Bayesian re-analysis of the INCEPTION trial

AIMS

Previously, we performed the multicentre INCEPTION trial, randomizing patients with refractory out-of-hospital cardiac arrest (OHCA) to extracorporeal cardiopulmonary resuscitation (ECPR) or conventional cardiopulmonary resuscitation (CCPR). Frequentist analysis showed no statistically significant treatment effect for the primary outcome; 30-day survival with a favourable neurologic outcome (cerebral performance category score of 1-2). To facilitate a probabilistic interpretation of the results, we present a Bayesian re-analysis of the INCEPTION trial.

METHODS AND RESULTS

We analysed survival with a favourable neurologic outcome at 30 days and 6 months under a minimally informative prior in the intention-to-treat population. Effect sizes are presented as absolute risk differences (ARDs) and relative risks (RRs), with 95% credible intervals (CrIs). We estimated posterior probabilities at various thresholds, including the minimal clinically important difference (MCID) (5% ARD), based on expert consensus, and performed sensitivity analyses under sceptical and literature-based priors. The mean ARD for 30-day survival with a favourable neurologic outcome was 3.6% (95% CrI -9.5-16.7%), favouring ECPR, with a median RR of 1.22 (95% CrI 0.59-2.51). The posterior probability of an MCID was 42% at 30 days and 42% at 6 months, in favour of ECPR.

CONCLUSION

Bayesian re-analysis of the INCEPTION trial estimated a 42% probability of an MCID between ECPR and CCPR in refractory OHCA in terms of 30-day survival with a favourable neurologic outcome.

TRIAL REGISTRATION

Clinicaltrials.gov (NCT03101787, registered 5 April 2017).

Implementation of Extracorporeal CPR Programs for Out-of-Hospital Cardiac Arrest: Another Tale of Two County Hospitals

Extracorporeal cardiopulmonary resuscitation (ECPR) is a form of intensive life support that has seen increasing use globally to improve outcomes for patients who experience out-of-hospital cardiac arrest (OHCA). Hospitals with advanced critical care capabilities may be interested in launching an ECPR program to offer this support to the patients they serve; however, to do so, they must first consider the significant investment of resources necessary to start and sustain the program. The existing literature describes many single-center ECPR programs and often focuses on inpatient care and patient outcomes in hospitals with cardiac surgery capabilities. However, building a successful ECPR program and using this technology to support an individual patient experiencing refractory cardiac arrest secondary to a shockable rhythm depends on efficient out-of-hospital and emergency department (ED) management. This article describes the process of implementing 2 intensivist-led ECPR programs with limited cardiac surgery capability. We focus on emergency medical services and ED clinician roles in identifying patients, mobilizing resources, initiation and management of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in the ED, and ongoing efforts to improve ECPR program quality. Each center experienced a significant learning curve to reach goals of arrest-to-flow times of cannulation for ECPR. Building consensus from multidisciplinary stakeholders, including out-of-hospital stakeholders; establishing shared expectations of ECPR outcomes; and ensuring adequate resource support for ECPR activation were all key lessons in improving our ECPR programs.

The state of emergency department extracorporeal cardiopulmonary resuscitation: Where are we now, and where are we going?

Extracorporeal cardiopulmonary resuscitation (ECPR) has emerged in the context of the emergency department as a life-saving therapy for patients with refractory cardiac arrest. This review examines the utility of ECPR based on current evidence gleaned from three pivotal trials: the ARREST trial, the Prague study, and the INCEPTION trial. We also discuss several considerations in the care of these complex patients, including prehospital strategy, patient selection, and postcardiac arrest management. Collectively, the evidence from these trials emphasizes the growing significance of ECPR as a viable intervention, highlighting its potential for improved outcomes and survival rates in patients with refractory cardiac arrest when employed judiciously. As such, these findings advocate the need for further research and protocol development to optimize its use in diverse clinical scenarios.

Early extracorporeal CPR for refractory out-of-hospital cardiac arrest - A pre-planned per-protocol analysis of the INCEPTION-trial

BACKGROUND

Evidence for extracorporeal cardiopulmonary resuscitation (CPR) in refractory out-of-hospital cardiac arrest (OHCA) remains inconclusive. Recently, the INCEPTION-trial, comparing extracorporeal with conventional CPR, found no statistically significant difference in neurologically favorable survival. Since protocol deviations were anticipated, a pre-specified per-protocol analysis was foreseen.

METHODS

The per-protocol analysis of the INCEPTION trial excluded patients not meeting inclusion or exclusion criteria, amongst which time-to-cannulation of >60 minutes, and achieving a return of spontaneous circulation before hospital arrival. Crossovers were excluded as well. The primary outcome (30-day survival in a neurologically favorable condition; cerebral performance category [CPC] 1-2) was primarily analyzed under a frequentist statistical framework. In addition, Bayesian analysis under a minimally informative prior was performed.

RESULTS

Eighty-one patients were included in the per-protocol analysis (extracorporeal CPR n = 33, conventional CPR n = 48). Thirty-day survival with CPC1-2 was 15% in the extracorporeal CPR group versus 9% in the conventional CPR group (adjusted OR 1.9; 95% CI 0.4-9.3; p-value 0.393). Bayesian analysis showed an 84% posterior probability of any ECPR benefit and a 61% posterior probability of a 5% absolute risk reduction for the primary outcome.

CONCLUSION

A pre-planned, pre-specified per-protocol analysis of the INCEPTION-trial, found a higher survival with favorable neurological in patients undergoing ECPR versus CCPR for refractory shockable OHCA. This difference did not reach statistical significance, but results should be interpreted with care, in the light of the small remaining sample size.

Treatment of Refractory Cardiac Arrest by Controlled Reperfusion of the Whole Body: A Multicenter, Prospective Observational Study

Background: Survival following cardiac arrest (CA) remains poor after conventional cardiopulmonary resuscitation (CCPR) (6-26%), and the outcomes after extracorporeal cardiopulmonary resuscitation (ECPR) are often inconsistent. Poor survival is a consequence of CA, low-flow states during CCPR, multi-organ injury, insufficient monitoring, and delayed treatment of the causative condition. We developed a new strategy to address these issues. Methods: This all-comers, multicenter, prospective observational study (69 patients with in- and out-of-hospital CA (IHCA and OHCA) after prolonged refractory CCPR) focused on extracorporeal cardiopulmonary support, comprehensive monitoring, multi-organ repair, and the potential for out-of-hospital cannulation and treatment. Result: The overall survival rate at hospital discharge was 42.0%, and a favorable neurological outcome (CPC 1+2) at 90 days was achieved for 79.3% of survivors (CPC 1+2 survival 33%). IHCA survival was very favorable (51.7%), as was CPC 1+2 survival at 90 days (41%). Survival of OHCA patients was 35% and CPC 1+2 survival at 90 days was 28%. The subgroup of OHCA patients with pre-hospital cannulation showed a superior survival rate of 57.1%. Conclusions: This new strategy focusing on repairing damage to multiple organs appears to improve outcomes after CA, and these findings should provide a sound basis for further research in this area.

[Extracorporeal cardiopulmonary resuscitation-When the heart no longer functions]

Extracorporeal cardiopulmonary resuscitation (ECPR) is an option for restoring blood circulation in patients with refractory circulatory failure. While conventional resuscitation measures are being continued, venoarterial extracorporeal membrane oxygenation (VA ECMO) is established in patients with cardiac arrest. This bypass can compensate for the functions of the heart and lungs until recovery of organ function. The benefit of ECPR compared to conventional resuscitation appears to be evident, especially after a prolonged resuscitation period; however, in three prospective randomized controlled studies an advantage has not yet been conclusively proven for widespread use in clinical routine. ECPR systems are complex and resource-intensive and should therefore be limited to specialized centers where sufficient numbers of patients are treated to ensure a high level of expertise in the teams.