It’s Not Over Till It’s Over – ECMO Resuscitation in the ED: A Medical Student Clinical Pearl

Ryan Buyting

Med III, Class of 2022

Dalhousie Medicine New Brunswick (DMNB)

Reviewed by Dr. Luke Taylor

Copyedited by Dr. Mandy Peach

Extracorporeal Membrane Oxygenation (ECMO), also sometimes referred to as extracorporeal life support (ECLS), employs components from traditional cardiopulmonary bypass machines to augment a patient’s heart and/or lung capacity for a prolonged duration of days to weeks. Importantly, ECMO is not a treatment but a bridge to native heart/lung recovery or durable organ replacement. ¹

ECMO has been a hot topic of discussion over the past year based on its role in supporting patients with severe COVID-19 infections. The Extracorporeal Life Support Organization (ELSO), the World Health Organization and the Surviving Sepsis Campaign (SSC) Guidelines recommend considering ECMO, in specialized centers, for patients with COVID-19 who develop severe acute respiratory distress syndrome (ARDS). ² Many of these cases made use of veno-venous ECMO, which exclusively provides pulmonary bypass for severe respiratory failure.

This article will focus on veno-arterial ECMO (which provides both cardiac and pulmonary bypass) and seeks to provide readers with an overview of the following:

• What is an Extracorporeal Cardiopulmonary Resuscitation (ECPR) code?
• Which patients should be considered for acute ECMO initiation?
• What care will patients need in the ED post-circuit initiation?
• What is the evidence for the use of ECPR?

Calling an ECPR Code and Patient Selection

An ECPR code essentially mobilizes the cannulation team to initiate an ECMO circuit in a previously high-functioning patient. The goal is to restore end-organ perfusion, buying time to investigate the underlying causative pathology, with hopes of improving long-term survival and neurological outcomes. Emergency physicians should consider calling an ECPR code for severe cardiac and/or pulmonary failure deemed refractory to conventional therapies. ³ Patients in cardiac arrest are potential candidates for ECPR if they meet the following:

• reversible cause of arrest
• witnessed arrest with bystander CPR
• total chest compression time < 60 minutes
• no known preexisting terminal illnesses

Review the reversible causes of cardiac arrest or see the image below outlining the “Hs and Ts” mnemonic.

Figure 1: The Hs and Ts / Reversible Causes of Cardiac Arrest ⁴

The timing at which an ECPR code should be initiated is (at present) left to physician discretion, but often depends on the availability of the cannulation team. ECMO as an option for a given patient should be anticipated and considered early amid a code to allow the team and equipment to be assembled. Most often the procedure is performed by a cardiac surgeon, however there is growing interest and involvement from vascular, general, and trauma surgeons. ⁵

The initiation of ECMO is divided into 3 stages:

(1) vascular access,

(2) insertion of ECMO cannulas and connection to the circuit once the patient is determined to be an ECMO candidate,

(3) pump initiation.

In emergent situations, unilateral peripheral cannulation is the preferred and most expedient method. ⁶ This approach also allows for the continuation of high-quality CPR while access is obtained. Either through surgical exposure or under ultrasound guidance, a venous drainage cannula is placed in the femoral vein. Blood is returned from the machine through a similarly placed cannula in the adjacent femoral artery. Several alternative circuits are possible in extenuating circumstances depending upon patient injuries or characteristics. ¹

Figure 2: Veno-arterial peripheral ECMO via unilateral femoral-arterial and femoral-venous cannulation. ⁷

Post-Circuit Initiation Critical Care

After the circuit has been initiated, the lines should be closely examined; the venous drainage blood should be dark red and the arterial return blood should be bright red. Given the proximity of the vessels and the fact that these procedures are often done with ongoing CPR, this confirmation of placement is crucial.

Next, it is important to reassess the patient’s rhythm; if the patient is in VFIB, defibrillation should be repeated after a few minutes on circuit as it is important to have an ejecting left ventricle on ECMO to prevent distention. ⁸

At this point, the team should obtain a right radial arterial line (for accurate measurement of the MAP) and an ABG (to assess for adequate oxygenation and the need for setting adjustments). Vasopressors and/or inotropes should be initiated as required to meet a target MAP of 60-80mmHg. If LV distention (as assessed based on arterial line pulsatility >10mmHg or POCUS) is not improved with these medications on board, an LV vent (such as an Impella or intra-aortic balloon pump) may be needed. ⁸

Important next steps in the process include the initiation of therapeutic hypothermia, planning for the placement of a distal perfusion catheter to prevent leg ischemia, and, based on the etiology of the arrest, any other appropriate treatment (such as transfer to the cardiac catheterization laboratory for acute coronary syndrome).

Current Evidence for ECPR

No randomized trials concerning the use of ECPR have been published to date. Sonneville and Schmidt recently summarized the four most robust observational studies comparing the use of ECPR versus conventional CPR in patients with out-of-hospital cardiac arrest. ⁹ They describe a large study that reported similar low survival rates between 525 patients managed with ECPR and 12,666 patients with conventional CPR, with no significant effect of ECPR on outcomes after adjusting for confounders. ¹⁰ However, more recently, after instituting very strict patient selection criteria, Bartos et al. reported a relative risk reduction of 29% for death or poor neurological outcome (95% CI, 18%–41%) for patients receiving between 20 and 59 minutes of CPR and 19% (95% CI, 10%–27%) for patients receiving more than 60 minutes of CPR. ¹¹ This group has since published the University of Minnesota ECPR Protocol here. ¹²

Until results from randomized trials become available, it is likely that difficult continuation decisions will need to be made on a case-by-case basis at physician discretion. Protocols requiring objective data input such as specific time periods, lactate level and oxygenation status upon arrival, may help ease this burden in the meantime, if only marginally.

References

1. Badulak JH, Shinar Z. Extracorporeal Membrane Oxygenation in the Emergency Department. Emerg Med Clin North Am. 2020;38(4):945-959. doi:10.1016/j.emc.2020.06.015
2. Ramanathan K, Shekar K, Ling RR, et al. Extracorporeal membrane oxygenation for COVID-19: a systematic review and meta-analysis. Crit Care. 2021;25(1):211. doi:10.1186/s13054-021-03634-1
3. Extracorporeal Life Support Organization (ELSO). Guidelines. Accessed August 29, 2021. https://www.elso.org/Portals/0/ELSO%20Guidelines%20General%20All%20ECLS%20Version%201_4.pdf
4. @lightssirensaction. Hs and Ts. Accessed August 28, 2021. https://www.instagram.com/p/CA4MMdVBy8V/
5. McCallister D, Pilon L, Forrester J, et al. Clinical and Administrative Steps to the ECMO Program Development. IntechOpen; 2019. doi:10.5772/intechopen.84838
6. Stoecklein H, Slack S, Tonna JE, Youngquist ST. ECMO & ECPR. JEMS. Published December 2, 2017. Accessed August 28, 2021. https://www.jems.com/patient-care/ecmo-ecpr/
7. Lawler PR, Silver DA, Scirica BM, Couper GS, Weinhouse GL, Camp PC. Extracorporeal Membrane Oxygenation in Adults With Cardiogenic Shock. Circulation. 2015;131(7):676-680. doi:10.1161/CIRCULATIONAHA.114.006647
8. Cevasco M, Takayama H, Ando M, Garan AR, Naka Y, Takeda K. Left ventricular distension and venting strategies for patients on venoarterial extracorporeal membrane oxygenation. J Thorac Dis. 2019;11(4):1676-1683. doi:10.21037/jtd.2019.03.29
9. Sonneville R, Schmidt M. Extracorporeal Cardiopulmonary Resuscitation for Adults With Refractory Out-of-Hospital Cardiac Arrest. Circulation. 2020;141(11):887-890. doi:10.1161/CIRCULATIONAHA.119.044969
10. Bougouin W, Dumas F, Lamhaut L, et al. Extracorporeal cardiopulmonary resuscitation in out-of-hospital cardiac arrest: a registry study. Eur Heart J. 2020;41(21):1961-1971. doi:10.1093/eurheartj/ehz753
11. Bartos JA, Grunau B, Carlson C, et al. Improved Survival With Extracorporeal Cardiopulmonary Resuscitation Despite Progressive Metabolic Derangement Associated With Prolonged Resuscitation. Circulation. 2020;141(11):877-886. doi:10.1161/CIRCULATIONAHA.119.042173
12. Yannopoulos D, Bartos JA, Martin C, et al. Minnesota Resuscitation Consortium’s Advanced Perfusion and Reperfusion Cardiac Life Support Strategy for Out‐of‐Hospital Refractory Ventricular Fibrillation. J Am Heart Assoc. 5(6):e003732. doi:10.1161/JAHA.116.003732