ADVANCES IN EM
Dr WONG Kwun Bun
Associate Consultant, PWH, A&E
Extracorporeal Membrane Oxygenation (ECMO) also known as extracorporeal life support (ECLS). The primary indication for ECLS is acute severe heart or lung failure with high mortality risk despite optimal conventional therapy (1).
There are two types of ECMO – venoarterial (VA) and venovenous (VV). Both provide respiratory support, but only VA ECMO provides hemodynamic support. The use VA-ECMO in the setting of in-hospital or out-of-hospital cardiac arrest, or so-called extracorporeal cardiopulmonary resuscitation (E-CPR).
Other specific indications for VA-ECMO include refractory circulatory shock attributable to myocarditis, acute MI, acute cor pulmonale from massive pulmonary embolism, primary transplant graft failure, acute exacerbation of chronic heart failure, toxic ingestions, and intractable arrhythmias
Picture from Mark Dennis. Journal of the American Heart Association. In-Depth Extracorporeal Cardiopulmonary Resuscitation in Adult Out-of-Hospital Cardiac Arrest, Volume: 9, Issue: 10, DOI: 10.1161/JAHA.120.016521
Trend and Rationale of ECMO-CPR
High-quality CPR, defibrillation when appropriate, vasopressors and/or antiarrhythmics, and airway management remain the cornerstones of cardiac arrest resuscitation. The use of E‐CPR has increased 10‐fold in the past 10 years, from 35 to over 400 per year (2). ELSO registry of ECPR for refractory OHCA reveals a survival rate of 27.6%, demonstrates association of male gender with mortality, and highlights regional differences in PCI utilization (3)
Even with optimal technique, Conventional CPR (C-CPR) delivers only 15% to 25% of normal cardiac output (4). It produces a “low-flow” state that can temporarily sustain organ function. EMCO‐CPR can provide near‐normal levels of cerebral and end organ perfusion (5)
The inclusion criteria for published E‐CPR studies are variable, but most commonly include witnessed arrest, immediate bystander CPR, an initial shockable rhythm, and an estimated time from CPR start to establishment of E‐CPR (low‐flow time) of <60 minutes.
The major complications of ECMO are bleeding and thromboembolism. (6,7,8) Other complications including infection, renal failure, hyperbilirubinemia, and oxygenator mechanical failure, air emoblism and and limb ischemia
Latest evidence of E-CPR
Recently, a single-center open-label phase 2 clinical trial was conducted between Aug 8, 2019, and June 14, 2020 in University of Minnesota Medical Center, USA.(9) It is the first randomized trial of ECMO in refractory OHCA in the United States. The primary outcome of survival to hospital discharge occurred in 6 of 14 patients (43%) in the ECMO group, compared with 1 of 15 patients (7%) in the ACLS group. The study was terminated because of the encouraging results. However, the results may not be validated externally. Yannopoulos et al were able to initiate venoarterial ECMO a mean 7 minutes from patient arrival to the cardiac catheterization laboratory. This may not be responsible in other centers. Secondly, the size of the study included 30 patients only.
Some systematic reviews and meta‐analyses suggested that E‐CPR may improve survival or neurological outcome (10-14). A systematic review of 15 OHCA studies and 7 IHCA studies concluded that evidence did not support or refute the use of E-CPR for either group (15).
All systematic reviews of E‐CPR have rated the quality of evidence as very low. Most reviewed studies were small, single‐center, and from diverse locations with different EMS systems. The cases are mixed with OHCA and IHCA. It will be difficult to draw a robust conclusion of the ECPR and OHCA.
According to the ACLS guideline, ECMO may be used as rescue therapy during CPR in adult setting. While there is insufficient evidence to recommend for or against the use of extracorporeal CPR for pediatric patients in OHCA(16). Optimal patient selection, timing of initiation, post-ECPR patient management, and logistical feasibility of providing an ECPR service remain ongoing challenges to securing good outcomes. The cost of ECPR and availability of expertise should also be addressed.
Richardson AS, Schmidt M, Bailey M, Pellegrino VA, Rycus PT, Pilcher DV. ECMO cardio‐pulmonary resuscitation (ECPR), trends in survival from an international multicentre cohort study over 12‐years. Resuscitation. 2017; 112:34–40.
Thiagarajan RR, Barbaro RP, Rycus PT, et al. Extracorporeal Life Support Organization registry international report 2016.
Lurie KG, Nemergut EC, Yannopoulos D, Sweeney M. The physiology of cardiopulmonary resuscitation. Anesth Analg. 2016; 122:767–783.
Moller‐Helgestad OK, Hyldebrandt JA, Banke A, Rud CS, Udesen NLJ, Linde L, Okkels‐Jensen L, Schmidt H, Ravn HB, Moller JE. Impella CP or VA‐ECMO in profound cardiogenic shock: left ventricular unloading and organ perfusion in a large animal model. EuroIntervention. 2019; 14:e1585–e1592.
Sklar MC, Sy E, Lequier L, Fan E, Kanji HD Anticoagulation Practices during Venovenous Extracorporeal Membrane Oxygenation for Respiratory Failure. A Systematic Review. Ann Am Thorac Soc. 2016 Dec;13(12):2242-2250.
Michael Mazzeffi , John Greenwood , Kenichi Tanaka etc Bleeding, Transfusion, and Mortality on Extracorporeal Life Support: ECLS Working Group on Thrombosis and Hemostasis Ann Thorac Surg . 2016 Feb;101(2):682-9. doi: 10.1016/j.athoracsur.2015.07.046. Epub 2015 Oct 9.
Nathan L. Haas,a, Ryan A. Descriptive analysis of extracorporeal cardiopulmonary resuscitation following out-of-hospital cardiac arrest—An ELSO registry study’ Nathan L. Haas,a, Ryan A. Resuscitation. 2017 Oct; 119: 56–62.
Yannopoulos D, Bartos J, Raveendran G, Walser E, et al. Advanced reperfusion strategies for patients with out-of-hospital cardiac arrest and refractory ventricular fibrillation (ARREST): a phase 2, single centre, open-label, randomised controlled trial. Lancet. 2020 Nov 12:S0140-6736(20)32338-2. doi: 10.1016/S0140-6736(20)32338-2.
Dennis M, McCanny P, D’Souza M, Forrest P, Burns B, Lowe DA, Gattas D, Scott S, Bannon P, Granger E, Pye R, Totaro R; Sydney ECMO Research Interest Group. Extracorporeal cardiopulmonary resuscitation for refractory cardiac arrest: A multicentre experience. Int J Cardiol. 2017 Mar 15;231:131-136. doi:10.1016/j.ijcard.2016.12.003. Epub 2016 Dec 6. PubMed PMID: 27986281
Wang GN, Chen XF, Qiao L, Mei Y, Lv JR, Huang XH, Shen B, Zhang JS. Comparison of extracorporeal and conventional cardiopulmonary resuscitation: A meta-analysis of 2 260 patients with cardiac arrest. World J Emerg Med. 2017;8(1):5-11. Doi: 10.5847/wjem.j.1920-8642.2017.01.001. PubMed PMID: 28123613
Chih-Hsien Wang , Nai-Kuan Chou , Lance B Becker etc Improved outcome of extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest--a comparison with that for extracorporeal rescue for in-hospital cardiac arrest Resuscitation 2014 Sep;85(9):1219-24.
Bartos JA, Carlson K, Carlson C, Raveendran G, John R, Aufderheide TP, Yannopoulos D. Surviving refractory out‐of‐hospital ventricular fibrillation cardiac arrest: critical care and extracorporeal membrane oxygenation management. Resuscitation. 2018; 132:47–55.
Hutin A, Abu‐Habsa M, Burns B, Bernard S, Bellezzo J, Shinar Z, Torres EC, Gueugniaud PY, Carli P, Lamhaut L. Early ECPR for out‐of‐hospital cardiac arrest: best practice in 2018. Resuscitation. 2018; 130:44–48.
Holmberg MJ, Geri G, Wiberg S, et al. Extracorporeal cardiopulmonary resuscitation for cardiac arrest: a systematic review. Resuscitation. 2018;131:91–100. doi: 10.1016/j.resuscitation.2018.07.029.