The outcome of patients after out-of-hospital cardiac arrest (OHCA) is poor and only worsens after prolonged resuscitation. There is growing interest in utilizing extracorporeal membrane oxygenation (ECMO) assisted cardiopulmonary resuscitation in the management of refractory cardiac arrest. ECMO is technology that has been used since the 1970’s as a way of providing cardiac and respiratory support to patients who have potentially reversible causes of respiratory/cardiac failure.
ECMO used in the emergent setting is more appropriately titled Extracorporeal Life Support (ECLS). Alternatively, ECMO used in the arresting patient has been termed Extracorporeal Cardiopulmonary Resuscitation (ECPR).
The focus of this article will be on the initiation of ECLS and ECPR in the Emergency Department patient and recent publications that have shown possible promise when the correct patient population can be quickly identified…
While there are two types of ECMO circuits, venous-arterial ECMO is the modality used for ECPR in the ED. Venous-Arterial ECMO (VA ECMO) provides cardiovascular support during cardiac failure or shock.
- Bridge to therapy (PCI, LVAD)
- Refractory shock
- Cardiac Arrest
- Hypothermia w/ arrhythmias
Cannulation of a femoral vein and femoral artery are needed for this procedure.
Traditional approach (ACLS w/ CPR) is highly unsuccessful
- Return of spontaneous circulation (ROSC) – 26.3% (1)
- Discharged from hospital – 9.6% (1)
Associations with improved outcomes: (1-3)
- Rapid initiation of bystander CPR
- Rapid defibrillation
- Rapid PCI after ROSC
- Therapeutic hypothermia after ROSC
ECPR for OHCA
Currently there is mounting evidence that patients started on ECPR have better outcomes than those patients who receive traditional CPR for OHCA. Although a large RCT is lacking from the literature, recent evidence demonstrates that ECPR is effective. These articles help establish the when and who, certain clinical questions and possible concerns.
Which Cardiac Arrest patients are the candidates for ECPR?
This seems to be the most crucial part of a successful ECPR program for OHCA. While inclusion criteria differ among centers and studies, the general trend is outlined below. (5-9)
- Witnessed arrest
- VF or VT as initial rhythm
- Age (18-70)
- Presumed cardiac cause
- Minimal interruptions in CPR
- Irreversible causes
- Prolonged CPR/EMS transport
- Known cognitive impairment
- Evidence of multi-organ dysfunction
How is ECPR initiated?
Traditionally, ECMO has been initiated by cardiothoracic surgeons in the Operating Room (OR). The advent of newer more mobile ECMO equipment has allowed ECMO implementation to be a common out-of-OR procedure. While most studies do not describe the exact method of ECMO implementation on OHCA patients, there is literature supporting the role of non-surgical physicians initiating ECMO cannulation. (5,7)
The most known ED ECPR algorithm is published by Dr. Shinar and Dr. Bellezzo who are strong advocates of ECPR and authors of the podcast/blog EDECMO.org. (5) An algorithm is being considered for local practice, but has yet to be established…
What has been identified in the literature leading to successful outcomes?
The key to good outcomes is largely rooted in the inclusion criteria. Greater success has been demonstrated in the following situations: (5-12)
- Shorter time from arrest to ECLS initiation
- Cardiac cause with rapid catheterization
- ECLS combined with hypothermia protocols
- VT/VF as presenting rhythm
- Younger age at time of arrest
What types of outcomes?
Le Guen, M. et al. Extracorporeal life support following out-of-hospital refractory cardiac arrest was a single center prospective observational study with the primary outcome – survival at 28 days after OHCA with ECLS. 51 consecutive patients who experienced witnessed OH refractory cardiac arrest and received automated chest compression and ECLS upon arrival in the hospital. 2 patients (4%) were alive at 28 days. (4)
The poor outcomes suggested that the use of ECPR should be more restricted following cardiac arrest.
Bellezzo, JM. Emergency Physician-Initiated Extracorporeal Cardiopulmonary Resuscitation was a single center prospective observational study over 1 year (included 42 out of hospital cardiac arrests). The primary outcome was survival to hospital discharge neurologically intact. 18 patients met inclusion criteria for ECMO, of these only 8 patients were started on ECMO. 5 patients survived to hospital discharge neurologically intact. Only 12% of all OHCA, however, 63% of those receiving ECPR had favorable outcome. (5)
In the appropriate patient population, excellent outcomes are achievable. Yet, the quantity of patients that would qualify for ECPR will be small.
SAVE-J Study Group. Extracorporeal cardiopulmonary resuscitation versus conventional cardiopulmonary resuscitation in adults with out-of-hospital cardiac arrest was a multicenter prospective observational study. Primary outcome was to examine the neurological difference at 1 & 6 months in patients who had VF/VT arrest out of hospital. Patients were divided into two groups: ECPR versus conventional CPR. 454 total patients were enrolled (234 in ECPR group, 159 in CPR group). Patients that were neurologically intact at 1 month, 12.3% ECPR vs. 1.5% CPR (P < 0.0001),. At 6 months, 11.2% ECPR vs. 2.6% CPR (P = 0.001). (6)
In OHCA patients with VF/VT on the initial ECG, a treatment bundle including ECPR, therapeutic hypothermia and IABP was associated with improved neurological outcome at 1 and 6 months after OHCA.
Poppe, M. et al. The Incidence of “load & go” out-of-hospital cardiac arrest candidates for emergency department utilization of emergency extracorporeal life support, A one-year review.
Load & Go Criteria
- Shockable Rhythm
- < 75 y/o
- Witnessed Collapse
- Bystander CPR
- No ROSC after 15 min of ALS
Of 948 OCHA, only 6% of these cases fulfilled the Load & Go Criteria, with only 12 patients, 1.2% being treated with ECPR. (13)
Patients whom would potentially beneﬁt from a transport with on-going CPR and the use of ECPR were identified. Yet, the study would suggest a very low number of eligible candidates exist.
Stub D, et al. Refractory Cardiac arrest treated with mechanical CPR, hypothermia, ECMO and early reperfusion (the Cheer trial) was a single center prospective pilot observational study. Data was collected over a 32 month period.
o Out of hospital cardiac arrest (OHCA)
- refractory cardiac arrest (> 30min)
- aged 18-65 years
- cardiac arrest due to suspected cardiac etiology
- chest compressions commenced within 10 min by bystander or Emergency Medical Service (EMS)
- initial cardiac arrest rhythm of ventricular fibrillation (VF)
- mechanical CPR machines available
o In hospital cardiac arrest (IHCA)
- At the discretion of the attending physician providing that cause of cardiac arrest considered to be reversible and ECMO immediately available
o known significant pre-existing neurological disability, non-cardiac co-morbidities that cause limitations in activities of daily living
o 26 patients
- 11 OHCA
- 15 IHCA
- Mechanical Chest compressions using the Autopulse
- Rapid intravenous administration of 30mL/kg of ice-cold saline to induce Hypothermia.
- Early Reperfusion with urgent percutaneous coronary intervention
- Primary outcome survival with good neurological recovery (CPC 1-2) 14/26 (54%)
- Secondary outcomes
o ROSC achieved in 25/26 (92%) of patients
o Survival to hospital discharge 14/26 (54%)
- 2 patients died primarily of major bleeding
- Vascular injury
o Surgical intervention was required in 10/24 (42%) patients who underwent cannulation
Of the 24 patients that received ECMO
- 3/9 (33%) of the OHCA patients survived
- 9/15 (60%) of the IHCA patients survived
- Survival rates with CPC 1-2 of 54% in a group of patients with prolonged periods of cardiac arrest.
- Protocol driven resuscitation therapy driven by clinical teams and with engagement of pre-hospital Emergency Medical Services sounds sensible and based on this data correlates to outcome benefits
- Historically, pre-hospital Emergency Medical Services were authorized to cease resuscitation after 30 minutes of CPR unless compelling reasons to continue such as hypothermia were present. 5 patients therefore survived with good neurological recovery who would have otherwise been pronounced dead
- This is a pilot observational study. It included very small numbers of selected patients in a single and specialist ECMO center. (11)
The CHEER protocol has been shown to improve survival with favorable neurological outcome following cardiac arrest compared with historical data. In an experienced ECMO center, with engagement of pre-hospital services and as part of a bundle, ECMO is effective.
Yannopoulos, D. et al Minnesota Resuscitation Consortium’s Advanced Perfusion and Reperfusion Cardiac Life Support Strategy for Out-of-Hospital Refractory Ventricular Fibrillation, in 2015, the Minnesota Resuscitation Consortium (MRC) implemented an advanced perfusion and reperfusion life support strategy designed to improve outcome for patients with out-of-hospital refractory ventricular ﬁbrillation/ventricular tachycardia (VF/VT). They reported the outcomes of the initial 3-month period of operations.
- Three emergency medical services systems serving the Minneapolis–St. Paul metro area participated in the protocol.
- Age 18 to 75 years
- Body habitus accommodating automated Lund University Cardiac Arrest System (LUCAS) cardiopulmonary resuscitation (CPR)
- Estimated transfer time from the scene to the cardiac catheterization laboratory of ≤30 minutes.
- Included known terminal illness
- Do Not Resuscitate/Do Not Intubate status
- Traumatic arrest
- Signiﬁcant bleeding.
Refractory VF/VT arrest
- Defined as failure to achieve sustained return of spontaneous circulation after treatment with 3 direct current shocks and administration of IV/IO amiodarone.
- 27 patients were transported with ongoing mechanical CPR.
- 18 patients met the inclusion and exclusion criteria.
o ECMO was placed in 83%.
- Seventy-eight percent of patients had signiﬁcant coronary artery disease with a high degree of complexity
o 67% received PCI.
- Seventy-eight percent of patients survived to hospital admission
- 55% (10 of 18) survived to hospital discharge
- 50% (9 of 18) achieving good neurological function (cerebral performance categories 1 and 2).
No signiﬁcant ECMO-related complications were encountered. (12)
The MRC refractory VF/VT protocol is feasible and led to a high functionally favorable survival rate with few complications.
OCHA is a serious disabling condition, resulting in a great deal of cost and poor outcomes every year. This decade may witness advances in outcomes, utilizing appropriate inclusion and exclusion criteria, patients could leave the hospital with good neurological recovery that would have otherwise been pronounced dead! There are still further trials to run and as we begin to expand our local ECMO program, comes hope…
Hijinio Carreon DO, FACEP