Extracorporeal cardiopulmonary resuscitation (ECPR)
Extracorporeal Life Support (ECLS) and ECMO (Extracorporeal Membrane Oxygenation)
Survival after cardiac arrest depends on the restoration of spontaneous cardiac rhythm. The likelihood of achieving spontaneous cardiac activity is a function of the duration of circulatory standstill and the underlying cause, as elaborated in earlier chapters (see The 3-Phase Model of Cardiac Arrest). Both chest compressions and defibrillation are paramount in restoring cardiac electrical activity, hence rhythm and contractility. Yet, in a significant number of cases, the rhythm is non-shockable, as seen in certain causes of cardiac arrest (e.g. pulmonary embolism) or in case of long no-flow or low-flow periods. Under such circumstances, the efficacy of compressions and defibrillation diminishes considerably. Extracorporeal Life Support (ECLS) emerges as the sole therapeutic alternative for such situations. Presently, this treatment is confined to well-equipped centers and is generally reserved for meticulously selected cases.
Extracorporeal Life Support (ECLS) encompasses several extracorporeal systems designed to assist in cases of cardiac or respiratory failure by means of an extracorporeal pump and oxygenator. ECMO (Extracorporeal Membrane Oxygenation), a type of ECLS, operates by drawing venous blood from the patient to an oxygenator (gas-exchanger), where it undergoes oxygenation and carbon dioxide removal, and then reintroducing the oxygenated blood into the circulation.
ECMO use during cardiac arrest (referred to as ECPR [extracorporeal CPR]) requires the immediate establishment of veno-arterial ECMO (VA-ECMO). A peripheral artery (typically femoral artery) and vein (typically femoral vein) are cannulated, and blood is drawn from the vein, oxygenated and depleted from carbon dioxide, and then pushed into the circulation via the artery.
ECPR is indicated when conventional cardiopulmonary resuscitation (CPR) fails to achieve a stable return of spontaneous circulation (ROSC). Stable ROSC is when spontaneous circulation is maintained for 20 consecutive minutes, without the need for chest compressions.
ECMO is considered in individuals who can survive with satisfactory quality of life if the circulation is temporarily supported by ECMO. Furthermore, ECMO might be required to facilitate procedures such as percutaneous coronary intervention (PCI) or pulmonary embolectomy. Thus ECMO acts as a bridge, offering support until a definitive or interim therapeutic solution can be reached.
There is no consensus regarding the criteria for ECMO initiation. However, frequently used criteria include the following:
- A witnessed cardiac arrest attended by immediate bystander CPR.
- Cannulation should be completed within 60 minutes following the collapse.
- Preferential consideration is often given to younger patients, typically those below 65 years of age, who lack significant comorbidities.
- The underlying etiology of the cardiac arrest should be amenable to reversal.
- The indication is stronger in younger individuals.
Individual patient circumstances and clinical judgment are paramount in determining the appropriateness and feasibility of ECMO initiation.
Efficacy of ECMO (ECPR) in refractory out-of-hospital cardiac arrest
Several studies have investigated the efficacy of ECMO (ECPR). The results of these studies are as follows:
- Suverein et al (2023): In a multicenter, randomized trial, the effects of extracorporeal cardiopulmonary resuscitation (ECPR) was compared to conventional CPR in patients with refractory out-of-hospital cardiac arrest. Patients aged 18 to 70, who received bystander CPR and initially presented with a ventricular arrhythmia without return of spontaneous circulation within 15 minutes, were included. At 30 days, 20% of those in the extracorporeal CPR group and 16% in the conventional CPR group had a favorable neurologic outcome. This difference was not statistically significant.
- Yannopoulos et al (2020): In a randomized trial, extracorporeal membrane oxygenation (ECMO) was compared to conventional CPR among patients experiencing out-of-hospital cardiac arrest (OHCA) with refractory ventricular fibrillation. Of the 30 patients who participated (15 in each group), survival to hospital discharge was 7% in the standard ACLS group and 43% in the ECMO-facilitated resuscitation group. The study was terminated early due to the significant superiority of ECMO. This research indicates that early ECMO-facilitated resuscitation significantly enhances survival to hospital discharge for these patients when compared to conventional CPR.
- Napp et al (2020): This randomized trial compared a hyperinvasive approach to standard care. The hyperinvasive approach combined prehospital intraarrest hypothermia, mechanical chest compression, in-hospital extracorporeal life support (ECLS), and early invasive procedures for all OHCA patients presumed of cardiac origin. Eligible patients were those who did not achieve a return of spontaneous circulation (ROSC) after at least 5 minutes of advanced cardiac life support (ACLS) procedures by emergency teams. The trial concluded that a hyperinvasive approach did not significantly improve survival with neurologically favorable outcomes at 180 days compared with conventional CPR. The author noted, however, that the trial was possibly underpowered.
Early Extracorporeal CPR for Refractory Out-of-Hospital Cardiac Arrest List of authors. Martje M. Suverein, M.D., Thijs S.R. Delnoij, M.D., Roberto Lorusso, M.D., Ph.D., George J. Brandon Bravo Bruinsma, M.D., Ph.D., Luuk Otterspoor, M.D., Ph.D., Carlos V. Elzo Kraemer, M.D., Alexander P.J. Vlaar, M.D., Ph.D., Joris J. van der Heijden, M.D., Erik Scholten, M.D., Corstiaan den Uil, M.D., Ph.D., Tim Jansen, M.D., Ph.D., Bas van den Bogaard, M.D., Ph.D., Marijn Kuijpers, M.D., Ka Yan Lam, M.D., José M. Montero Cabezas, M.D., Antoine H.G. Driessen, M.D., Ph.D., Saskia Z.H. Rittersma, M.D., Ph.D., Bram G. Heijnen, M.D., Dinis Dos Reis Miranda, M.D., Ph.D., Gabe Bleeker, M.D., Ph.D., Jesse de Metz, M.D., Ph.D., Renicus S. Hermanides, M.D., Ph.D., Jorge Lopez Matta, M.D., Susanne Eberl, M.D., Ph.D., Dirk W. Donker, M.D., Ph.D., Robert J. van Thiel, M.D., Sakir Akin, M.D., Ph.D., Oene van Meer, M.D., José Henriques, M.D., Ph.D., Karen C. Bokhoven, M.D., Loes Mandigers, M.D., Jeroen J.H. Bunge, M.D., Martine E. Bol, M.Sc., Bjorn Winkens, Ph.D., Brigitte Essers, Ph.D., Patrick W. Weerwind, Ph.D., Jos G. Maessen, M.D., Ph.D., and Marcel C.G. van de Poll, M.D., Ph.D. N Engl J Med 2023; 388:299-309 DOI: 10.1056/NEJMoa2204511
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