Jun 8, 2020
In the swan song of ERcast Lite, we speak with Scott Weingart
about the truths, misunderstandings, and physiology of ECMO.
To subscribe to ERcast and get 2.5 hours of high yield monthly
content, CME, and all sorts of goodies, use the code 'bacon' for a
3 month free trial. https://www.hippoed.com/em/ercast/
ECMO takes over lung function and is used for those with severe
lung disease (ie. ARDS, pneumonia, severe asthma).
ECMO takes over the heart and lung. Ideal candidates are patients
with massive PE or cardiogenic shock.
- Intubated patients who you can’t oxygenate
despite rapidly escalating PEEP and a high FiO2 should be
considered for VV ECMO.
There are 2 primary types of extracorporeal membrane
oxygenation (ECMO): veno-venous (VV) and veno-arterial
ECMO takes over lung function.
drains blood from the IVC or SVC, sends it through a pump which
delivers it to an oxygenator (a membrane which allows the influx of
oxygen and removes CO2), and then pumps the oxygenated blood back
into the right heart system (returning it to the IVC or
- Useful for those with severe lung disease but decent
Examples: pneumonia, ARDS,
severe asthma with CO2 retention, immunologic lung diseases, cystic fibrosis
awaiting lung transplant
- Limited by its complications, cost, and
ECMO takes over lung AND heart function.
drains blood from the IVC/SVC, pumps it out and sends it to an
oxygenator, and then returns the blood retrograde up the aorta so
it can perfuse the abdominal viscera, brain, and possibly even the
For patients with cardiogenic shock or massive
Does not yield as much benefit for patients with septic shock or
other vasodilatory states (unless they had a sepsis-induced
Shares the same limitations as VV ECMO, with the addition that the
physiology induced by the VA ECMO itself can be
Which patients might benefit from transfer to an ECMO
threshold for transfer depends in part on the capabilities at your
institution for advanced ventilatory modalities (ie. airway
pressure release ventilation, proning patients, nitric
large percentage of patients transferred for ECMO never end up
receiving or needing it. However, they still greatly benefit from
moving to a facility that has the ability to provide other nuanced
critical care options.
general, transfer young patients who are on very high vent settings
and not getting better.
- At a
community hospital with few vent resources, these patients should
be transferred within hours.
bigger institutions, transfer within 48 hours. Often people wait
too long (5-7 days) to initiate the transfer.
the ARDSnet Mechanical Ventilation Protocol
Score to help decide if a patient would be a
good VV ECMO candidate.
ARDSnet protocol is evidence-based and communicates where the
patient is on their vent settings. It gives receiving centers a
clean way to evaluate patients for potential transfer.
- Patients should be <65 years old (though
physiologic age is taken into consideration)
patient should have a reversible cause of respiratory failure and
no severe comorbidities (no past history of cirrhosis, end-stage
improving despite maximal adjunctive ventilatory
- Varies based on the capability of your
patients at small community hospitals could benefit from transfer
to a bigger medical ICU, not necessarily to an ECMO
should be <150 on high FiO2 of >0.6.
Murray Score ≥2.5 is a standard cutoff for ECMO
- Murray Score considers:
much consolidation there is on CXR
- PaO2/FiO2 ratio
- Amount of PEEP
When should we begin thinking about VV ECMO or advanced
ventilatory measures for an intubated ED patient?
ECMO if you can’t oxygenate a patient despite rapidly escalating
the PEEP and a high FiO2.
- Example: a patient whose PEEP = 20 and
FiO2 = 100%, yet oxygen saturation hovers in the 80s and CXR shows
What is the tipping point for VA ECMO in patients with
- Consider ECMO for patients who:
- have contraindications to
not improving/getting worse despite thrombolysis,
- require high vasopressor doses.
ECMO “solves the problem” for massive PE.
VA ECMO referrals for cardiomyopathy are typically for
post-viral CM or post-myocardial infarction CM (since these
patients tend to be younger with few comorbidities).
considering transfer for a patient in cardiogenic shock, if you
have an interventional cath lab capable of placing a mechanical
circulatory support device (ie. an Impella or left ventricular
assist device), contact them first.
criteria for patients in cardiogenic shock includes lack of
improvement with an Impella.
Who tends to recover well from ECMO?
- Patients with an acute indication for ECMO and
minimal comorbid disease have the best outcomes.
What is the minimal infrastructure and training level
needed to start an ECMO program?
- Starting a program is complicated. And VV ECMO
is more complex than VA ECMO (due to using bigger cannulae,
positioning requirements, etc).
possible for small facilities to initiate VA ECMO for cardiac
arrest or PE patients in the ED/ICU while awaiting an ECMO
retrieval team from a major center. This requires that all the
details be worked out between the facilities ahead of
- What’s more realistic is for the receiving ECMO
center to retrieve those patients and decide whether they want to
initiate ECMO with their own equipment and then take the patient
back to their facility.