ECMO: Extra Corporeal Membrane Oxygenation

Let’s start off with the basics. ECMO is the medical abbreviation for Extra Corporeal Membrane Oxygenation. This means that the system takes blood out of your body run its through a circuit, and puts oxygen into it. It can obviously do other things which I will cover below. There are two types of ECMO, VA (venoarterial) and VV (venovenous).

Many of you have heard the term “ECMO” being flung around and do not really know what it is. I remember the first time I heard of the concept. I was thinking, “wow, this is wild”. It is now becoming quite common place, though. More facilities are picking up this technology to care for their critically ill patients who need a little more help staying alive than what is offered. Still, ECMO centers are a not predominant in our healthcare system. This page is a work in progress where I plan to constantly update it with new ECMO papers. Right now it is short. It will get loooong with lots of citations. Last updated 01/25/22.

The VA stands for veno-arterial meaning that both an artery and a vein are cannulated while VV means that either one or two veins are cannulated. I’ll explain this a bit more in depth later. In VV-ECMO the patient typically has stable hemodynamics and does not need the heart help that VA-ECMO provides.

Table of Contents

  • Indications for ECMO
    • Veno-venous ECMO
    • Veno-arterial ECMO
  • Deciding who gets put on ECMO
    • How many days on mechanical ventilation prior to cannulation?
    • What are the ethics involved in patient selection?
  • Who cannulates ECMO Patients?
  • Where are the cannulas placed?
  • Anticoagulation Strategies (Updated 1/23/22)
  • Contraindications
  • Complications
    • Refractory Hypoxemia on ECMO?
  • What are the outcomes of ECMO in certain patient populations?
    • COVID-19
    • Sepsis-induced cardiogenic shock

Veno-Venous (VV) Indications

The indications for VV ECMO are, to make something complex easy, those where the lungs on a ventilator simply won’t cut it. It can be used in situations where you cannot oxygenate the patients as well as situations where you cannot ventilate the patients. We’re heading much about VV-ECMO these days (it’s Summer 2020 right now) due to COVID induced acute respiratory distress syndrome (ARDS).

  • Acute Respiratory Distress Syndrome
    • Bacterial pneumonia
    • Viral pneumonias (such as influenza and COVID)
    • Alveolar proteinosis
    • Aspiration pneumonia
  • Rest the lungs
    • This may need to be performed in cases like major traumas where there are contusions that negatively affect the lung function
  • Pre and Post Lung Transplant
    • Sometimes the only way to keep a patient alive to survive up to transplant is ECMO. At the same time, sometimes the lungs fail after transplantation, unfortunately, and those people need ECMO as well.
  • Status Asthmaticus
    • There are unfortunate times where you’re throwing the kitchen sink and every single ventilator strategy you know at asthmatics and you still can’t ventilate them. Time to call your friendly ECMO center for a transfer.
  • Bleeding of the lung
    • pulmonary hemorrhage
    • massive hemoptysis

Veno-Arterial Indications

VA ECMO for Acute Pulmonary Embolism (updated 1/25/22)

When a patient has an acute pulmonary embolism with hemodynamic compromise, it is second nature to quickly pull the trigger and provide them with tPA. This is clearly the management in all the algorithms. It remained a question, however, whether placing a patient on VA ECMO “as a bridging therapy during pharmacological or mechanical thrombolysis or embolectomy might improve outcomes”. To at least begin to answer the question, Hobohm et al. published a retrospective look at these patients in Resuscitation.

The team analyzed data from 2005 to 2018 from a database looking at ICD-10 codes in Germany. Over a million patients were hospitalized in that time with PE’s and over 2000 were placed on ECMO for this indication. They looked at all-cause in-hospital mortality and intracranial bleeding as their outcomes. Comparing the two groups who received ECMO and those who didn’t, as one could expect, the patients who were cannulated were far sicker.

A takeaway from this paper is that the teams in Germany seem to place more patients on ECMO than they do in the US. They found a bleeding rate of 35% of their patients. All in all, they concluded that “the use of VA-ECMO alone or as part of a multi-pronged reperfusion strategy compared to thrombolysis alone might be associated with a survival benefit in patients with high-risk PE deteriorating to cardiac arrest”.

Hobohm L, Sagoschen I, Habertheuer A, Barco S, Valerio L, Wild J, Schmidt FP, Gori T, Münzel T, Konstantinides S, Keller K. Clinical use and outcome of extracorporeal membrane oxygenation in patients with pulmonary embolism. Resuscitation. 2021 Oct 12:S0300-9572(21)00403-2. doi: 10.1016/j.resuscitation.2021.10.007. Epub ahead of print. PMID: 34653550.
Link to Article
Link to FULL FREE PDF

How do you decide who needs VV-ECMO?

Not everyone can go on VV-ECMO. Resources are not infinite. The cited paper here was published a few days ago in CHEST. It describes how a particular team selects the best patients to be placed on VV-ECMO for ARDS. 

Please download the paper for yourself and don’t trust me. The other thing is that much of the stuff listed in the article has some wiggle room and practical variation. They may do things a bit differently at your shop.

I digress. In this day of “do everything” Medicine, we run into the conundrum of having insufficient ECMO machines and beds at facilities. 

The authors looked at eligibility criteria such as vent settings as well as whether the patient has been proned, paralyzed, etc. 

They discuss the contraindications which are relative. Things such as profound distributive shock and the inability to tolerate anticoagulation. 
Then, they looked at short term outcomes. Patients need to be stratified to see if the short term prognosis is going to be catastrophic regardless of being placed on ECMO. An example of this is anoxic brain injury. 
Premorbid conditions also need to be explored. After all, to use these limited resources we don’t want to place a patient with stage IV metastatic cancer with persistent encephalopathy due to brain metastasis on ECMO. 

Last comes informed consent. Patients (if able to understand) and their families need to be made aware that this is a marathon and not a sprint. Patients on VV ECMO spend prolonged periods of time on the machine in excess of several weeks. It’s not a cute but rather a band-aid until their underlying process (hopefully) resolves. 

Then comes the call to either your ECMO team or your friendly neighborhood ECMO center. Don’t bullshit these folks. Their decisions to accept or not accept the patient is riding mostly on your word. Don’t trash your reputation by dumping on someone. Make sure the patient is going to be safe for transport and that all your ducks are in a row. Get an echo prior to transfer to help the receiving team assess whether VA ECMO May be a better option than VV. 

There’s more to it. This is a quick review.

Bullen EC, Teijeiro-Paradis R, Fan E. How I Select Which Patients With ARDS Should Be Treated With Venovenous Extracorporeal Membrane Oxygenation. Chest. 2020 Sep;158(3):1036-1045. doi: 10.1016/j.chest.2020.04.016. Epub 2020 Apr 21. PMID: 32330459.
Link to Abstract
Link to FULL FREE PDF

Role of ECMO in COVID (Article Shared 1/9/22)

MacLaren G, Fisher D, Brodie D. Treating the Most Critically Ill Patients With COVID-19: The Evolving Role of Extracorporeal Membrane Oxygenation. JAMA. 2022 Jan 4;327(1):31-32. doi: 10.1001/jama.2021.22580. PMID: 34919122.
Link to Article and FULL FREE PDF

The Ethics of ECMO (Article Shared on 7/26/21)

Schou A, Mølgaard J, Andersen LW, Holm S, Sørensen M. Ethics in extracorporeal life support: a narrative review. Crit Care. 2021 Jul 21;25(1):256. doi: 10.1186/s13054-021-03689-0. PMID: 34289885; PMCID: PMC8293515.
Link to Article
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How many days on mechanical ventilation prior to ECMO? (Updated 1/14/22)

During my fellowship, we had a criteria that the mortality of a patient skyrockets if they’ve been on mechanical ventilation for 7 days or greater prior to cannulation for ECMO. Hermann et al. stated that “ECMO initiation within 7 days following intubation is considered optimal as longer pre-ECMO IMV durations increase mortality in general ARDS populations”. This has been my practice during the pandemic when it comes to referring patients out. Currently, I do not work at an ECMO facility. Well, it may be time to throw that criteria out the window.

Hermann et al. looked at 101 patients retrospectively over the prior of a year and a half in Vienna, Austria. The team crunched a ton of numbers and criteria trying to tease out a number of parameters. To be frank their demographic data as well as all their ventilation parameters (table 1 and table 2) have a ton of detail which I recommend you take a look at for yourself.

60 of the 101 patients survived. The median length of stay was 41 days in the ICU in survivors. This means that you have to really commit to the course. 12 of the 60 survivors ended up needing lung transplants. One better have an exit strategy or a good relationship with a lung transplant facility. I can keep going on and on about other details that can be teased out of this paper. When they compared the outcomes of patients who were on the vent for less than 7 days versus those on the vent for 10 days, there was no difference. They did not extend this out further than 10 days from what I am seeing. All in all, I interpret this data as 10 days being a potential cutoff rather than 7.

ECMO Cannulation: Who does it?

Generally speaking, the cannulation for ECMO is performed by someone who has received substantial training at it. For the most part the specialists who perform this are: cardiothoracic surgeons, interventional cardiologists, vascular surgeons, and intensivists. There others who perform it as well that you can let me know in the comments section below if I have missed anything.

VV Cannulation Sites

The different cannulation sites for VV-ECMO include the a single catheter in the right internal jugular (called the avalon cannula) and there are also two two cannula approaches: femoral-internal jugular and femoral-femoral.

VA Cannulation Sites

The different cannulation sites for VA-ECMO include the central sites and three peripheral veno-arterial configurations. The central cannulation is completed in the operating room when the patient has an open chest. There may be exceptions to this, like all things in medicine, but it is not common.
Those configurations include femoral-femoral, axillary artery-femoral, and carotid artery-femoral. I’ve never seen the latter of the three, personally. Sounds like a bad vessel to stick a large cannula into.

Anticoagulation for ECMO Patients

ELSO released guidelines in January 2022 regarding anticoagulation in these patients. In these guidelines they tackle the anticoagulation agents, therapeutic monitoring, management of bleeding and thrombotic complications, blood product goals and replacements. Definitely a paper to have in our back pockets as a reference guide.

McMichael ABV, Ryerson LM, Ratano D, Fan E, Faraoni D, Annich GM. 2021 ELSO Adult and Pediatric Anticoagulation Guidelines. ASAIO J. 2022 Mar 1;68(3):303-310. doi: 10.1097/MAT.0000000000001652. PMID: 35080509.
Link to Article and FULL FREE PDF

Complications of ECMO (last updated 02.09.22)

In the January issue of Intensive Care Medicine, Nunez et al. published a paper analyzing the ELSO registry looking for bleeding and thrombotic events. In particular, the focus was on VV-ECMO. The block of time analyzed was from 2010-2017. From their review, although we are getting better at preventing these complications with time and experience, they still take place and are associated with in-hospital mortality. ECMO is not, and will never be benign. Families need to be provided with data such as these as we’re seeing way too often that ECMO is thought of as the greatest thing in the world when in fact it needs to be greatly respected.

Nunez JI, Gosling AF, O’Gara B, Kennedy KF, Rycus P, Abrams D, Brodie D, Shaefi S, Garan AR, Grandin EW. Bleeding and thrombotic events in adults supported with venovenous extracorporeal membrane oxygenation: an ELSO registry analysis. Intensive Care Med. 2022 Feb;48(2):213-224. doi: 10.1007/s00134-021-06593-x. Epub 2021 Dec 18. Erratum in: Intensive Care Med. 2022 Jan 18;: PMID: 34921625.
Link to Article
Link to FULL FREE PDF

Refractory Hypoxemia in ECMO Patients? (Updated 05.09.22)

Persistent Hypoxemia in COVID-19 Patients on ECMO: Keep Your Eyes on the Prize. Rafal Kopanczyk, DO*,1 Amar Bhatt, MD* Nicolas Kumar, BSy Christopher Patrick Henson, DO. Updated Citation coming soon once this is listed on PubMed.
Link to Article
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ECMO Outcomes in COVID-19 (Article Shared on 09.30.21)

Barbaro RP, MacLaren G, Boonstra PS, Combes A, Agerstrand C, Annich G, Diaz R, Fan E, Hryniewicz K, Lorusso R, Paden ML, Stead CM, Swol J, Iwashyna TJ, Slutsky AS, Brodie D; Extracorporeal Life Support Organization. Extracorporeal membrane oxygenation for COVID-19: evolving outcomes from the international Extracorporeal Life Support Organization Registry. Lancet. 2021 Oct 2;398(10307):1230-1238. doi: 10.1016/S0140-6736(21)01960-7. Epub 2021 Sep 29. PMID: 34599878; PMCID: PMC8480964.
Link to Article
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VA-ECMO for Sepsis-Induced Cardiogenic Shock

Sato and Kuriyama published a systematic review in June 2020 in Critical Care Medicine looking at in-hospital mortality and complication rates of patients who underwent VA-ECMO for Sepsis-induced cardiogenic shock. The outcomes are just not good, but then again, no one expected it to be a magic cure when the mortality rates of septic shock are 20-40% anyway. The paper cites a mortality rate in septic shock of 30-40% but I wanted to tip my cap to the ProCESS, ProMISe, and ARISE trials which had under 21, 30, and 19% mortality respectively. We need to continue shooting for the stars. Those looking for robust RCT data here are setting themselves up for disappointment. Take a step back and think about what it would take to conduct such a study. Okay now welcome back to reality.

Generally speaking, clinicians aren’t too enthusiastic to place septic shock patients on VA-ECMO due to the risk of the circuit in uncontrollable infections. Indwelling catheters are an infection risk. Something I would have liked to have seen in this paper but doesn’t exist is commentary on the incidence and theoretical risk factors for cardiac involvement in sepsis. The most frequent source of infections in these patients was respiratory (53.1%). Gram negative rods (43.1%) were the most common microorganism. Perhaps that can help you tease out when to look for this.

Outcomes of patients placed on VA-ECMO for Sepsis-Induced Cardiogenic Shock

In-hospital mortality: 76.7%. Ouch. Then again, I am not surprised. This is clearly a last ditch effort. Keep in mind that the mortality of cardiogenic shock alone, without sepsis is around 50% (not including the currently cooking Impella data from the Detroit Cardiogenic Shock Initiative). Adding sepsis to it adds some extra oomph. Six studies held the weight of this systematic review. In two of them, the mortality was < 30%. The other four are >75% mortality. Seems like these six centers need to get on the phone with each other and see what they’re doing differently. The complications are those expected in ECMO. Hemorrhage is obviously the most common one. All in all, the authors are unable to conclude a reasonable risk/benefit to VA-ECMO in sepsis-induced cardiogenic shock. Understandable at this time. But that doesn’t mean it can’t be done in the right patient.

Don’t forget to sign up for the FREE ELSO course teaching the basics of ECMO HERE.

This paper is part of the bibliography of my lecture titled “Cardiogenic Shock: Rise of the Machines”. If you want to learn more about other papers I have referenced in that lecture click here.

Recent JAMA image: check out their PDF here for free. Unfortunately, you have to jump through hoops to get to it. I used my standard google account to log in.

Citations of ECMO Studies:

Hobohm L, Sagoschen I, Habertheuer A, Barco S, Valerio L, Wild J, Schmidt FP, Gori T, Münzel T, Konstantinides S, Keller K. Clinical use and outcome of extracorporeal membrane oxygenation in patients with pulmonary embolism. Resuscitation. 2021 Oct 12:S0300-9572(21)00403-2. doi: 10.1016/j.resuscitation.2021.10.007. Epub ahead of print. PMID: 34653550.
Link to Article
Link to FULL FREE PDF

Schou A, Mølgaard J, Andersen LW, Holm S, Sørensen M. Ethics in extracorporeal life support: a narrative review. Crit Care. 2021 Jul 21;25(1):256. doi: 10.1186/s13054-021-03689-0. PMID: 34289885; PMCID: PMC8293515.
Link to Article
Link to FULL FREE PDF

Makdisi G, Wang IW. Extra Corporeal Membrane Oxygenation (ECMO) review of a lifesaving technology. J Thorac Dis. 2015 Jul;7(7):E166-76. doi: 10.3978/j.issn.2072-1439.2015.07.17. PMID: 26380745; PMCID: PMC4522501.
Link to FULL FREE ARTICLE

Sato R, Kuriyama A. Venoarterial Extracorporeal Membranous Oxygenation: Treatment Option for Sepsis-Induced Cardiogenic Shock? A Systematic Review. Crit Care Med. 2020 Aug;48(8):e722-e729. doi: 10.1097/CCM.0000000000004432. PMID: 32697514.
Link to Abstract

Bullen EC, Teijeiro-Paradis R, Fan E. How I Select Which Patients With ARDS Should Be Treated With Venovenous Extracorporeal Membrane Oxygenation. Chest. 2020 Sep;158(3):1036-1045. doi: 10.1016/j.chest.2020.04.016. Epub 2020 Apr 21. PMID: 32330459.
Link to Abstract
Link to FULL FREE PDF

Hermann M, Laxar D, Krall C, Hafner C, Herzog O, Kimberger O, Koenig S, Kraft F, Maleczek M, Markstaller K, Robak O, Rössler B, Schaden E, Schellongowski P, Schneeweiss-Gleixner M, Staudinger T, Ullrich R, Wiegele M, Willschke H, Zauner C, Hermann A. Duration of invasive mechanical ventilation prior to extracorporeal membrane oxygenation is not associated with survival in acute respiratory distress syndrome caused by coronavirus disease 2019. Ann Intensive Care. 2022 Jan 13;12(1):6. doi: 10.1186/s13613-022-00980-3. PMID: 35024972; PMCID: PMC8755897.
Link to Article
Link to FULL FREE PDF

McMichael ABV, Ryerson LM, Ratano D, Fan E, Faraoni D, Annich GM. 2021 ELSO Adult and Pediatric Anticoagulation Guidelines. ASAIO J. 2022 Jan 19. doi: 10.1097/MAT.0000000000001652. Epub ahead of print. PMID: 35080509.
Link to Article and FULL FREE PDF

Nunez JI, Gosling AF, O’Gara B, Kennedy KF, Rycus P, Abrams D, Brodie D, Shaefi S, Garan AR, Grandin EW. Bleeding and thrombotic events in adults supported with venovenous extracorporeal membrane oxygenation: an ELSO registry analysis. Intensive Care Med. 2022 Feb;48(2):213-224. doi: 10.1007/s00134-021-06593-x. Epub 2021 Dec 18. Erratum in: Intensive Care Med. 2022 Jan 18;: PMID: 34921625.
Link to Article
Link to FULL FREE PDF

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