ECMO Therapy
Background :
The need to treat critical COVID-19 patients has forced cardiovascular
surgeons to decide whether or not to implant an ECMO system. As there is
only scant and unsubstantiated evidence available hitherto, with only
minor experiments conducted, limited to a few published cases from
China2-4 and some literature reviews, such as that of
Savarimuthu et al .5, the benefits of ECMO
system implantation are not clear.
To add some confusion to the issue, doubts were raised about the
possible deleterious effect of ECMO in this disease. Patients who die of
COVID-19 have significantly lower lymphocyte counts and significantly
higher interleukin-6 (IL-6) levels than survivors. It is a well-known
fact, that during ECMO support there are substantial decreases in the
number and function of some lymphocyte populations, as well as
consistently high IL-6 levels, which are inversely correlated with
survival6. Elevated concentrations of IL-6 in the
lungs, induced by starting ECMO, have also been shown to be associated
with parenchymal damage in porcine models of veno-venous (VV)
ECMO7.
In this context, it would be considered prudent to evaluate the immune
status of ECMO candidate patients and seriously consider monitoring
lymphocyte count and IL-6 during support, while the pressure of care and
the number of critical patients that cannot be ventilated conventionally
grew uncontrollably.
Official regulation of the Government of Spain:
On February 28, the Ministry of Health published a technical
document8 entitled “Clinical management of COVID-19:
intensive care units”, with the participation of numerous scientific
societies and medical organizations and with successive updates, in line
with the evolution of the health crisis.
The April 27 version reviews and updates the section on ECMO and advises
starting care in patients with Acute Respiratory Distress Syndrome
(ARDS) who, despite the outlined protocols having been followed, have
persistent severe respiratory failure meeting the criteria indicated by
that document8. It establishes that support must be
offered in centers with proven experience, with well-structured
programs, and with an annual minimum of cases >15. As
stated in the document, “if the guidelines of this protocol are
followed, both in relation to the measures to be applied before
assistance, and in relation to the indications and contraindications of
their initiation, it is calculated that the need for ECMO will range
from 4 to 7 %”.
SECCE’s corporate recommendations1:
The SECCE established that cardiovascular surgery services, in
conjunction with those of Intensive Care Medicine, could offer
specialized last-level care through the use of temporary circulatory
mechanical support systems (veno-venous and veno-arterial ECMO) in
COVID-19 patients with severe ARDS or cardiomyopathy refractory to
treatment. With this official position, the care of the critically ill
patient in a moment of national emergency took precedence over possible
formal doubts about the suitability of ECMO therapy in this
disease9,10. The recommendations established a series
of key points as main lines of action against the pandemic:
- Adapting the ECMO programs of the different hospital centers for their
priority use in the pandemic, also guaranteeing adequate health care
in the reference area (first- and second-tier hospitals) and without
neglecting other non-COVID patients who are possible candidates for
the therapy.
- Specifically establishing the ECMO (VA and VV) entry criteria, with
some parameters quite similar to those defined somewhat later by the
ELSO Guidelines for ECMO in COVID-1911, and the
exclusion and contraindication criteria for the ECMO therapy in
COVID-19 patients (Figure 1, in Spanish).
- Limiting the number of professionals participating in the procedure to
the minimum necessary; the number of professionals involved at each
moment of the implantation, the inflow and outflow of each one of them
from the ICU room in which the implantation was made, as well as the
level of protection required for each person was precisely detailed,
depending on their specific role in each phase of the process.
- Enrolling the patient in the COVID-19 ECMO Registry that the SECCE
created for this purpose.
The different services were organized to offer the assistance required
at all times according to the impact of the pandemic, and a map of
device use was established, with a progressive restriction of the entry
criteria based on the availability of resources and each center’s own
clinical experience.
Records of ECMO implantation in COVID-19 patients:
EuroECMO-COVID Survey :
This is a direct initiative of the Steering Committee of the European
Chapter of the ELSO (Extracorporeal Life Support Organization) in order
to obtain information on the use of ECMO in European and Israeli centers
in patients with COVID-19. Data collection began on March 15, 2020, and
there was a first online publication with 333 patients in late
April12. As of July 17, and with 1,387 patients
collected, the survey reflected 160 ECMO implants in 26 centers for
Spain, which placed us in 3rd place in Europe in number of implants,
behind France (367 devices) and Germany (165 devices).
Spanish Registry of ECMO Implants in COVID-19:
The foreseeable increase in the use of ECMO devices caused by the very
high incidence of cases in our country led to the creation of a Registry
of Implants in patients with COVID-19 (coordinator: Dr. Mario Castaño,
León, Spain) managed by the SECCE and its Mechanical Circulatory Support
Working Group.
It is based on the EuroECMO-COVID Survey and allows direct exportation
to it, although the Spanish registry is more ambitious when
incorporating evolution variables, analytical-prognostic parameters, and
severity markers (D-dimers, procalcitonin, C-reactive protein, ferritin,
etc.) collected during the entire support period. Altogether 100
variables are collected in a secure database accessible online.
The registry was launched in early April and, at the time of writing
this manuscript, it is still open and there are no preliminary analyses
or provisional data. In the near future the definitive results will be
published and that is why here we can only give a partial and incomplete
view of the information collected, not in the form of scientific
communication or official publication. In the first week of July, the
registry collected more than 110 patients from 24 different centers with
accumulated experience, logically, in the areas with the highest
incidence of cases (Madrid and Catalonia); ECMO VV (90%) was
fundamentally implanted in the femoral-jugular configuration in two
thirds of the cases, and in up to 10% of patients it was changed to a
VA configuration or a third cannula was associated (V-VA or VV- A) due
to oxygenation problems or the appearance of ventricular failure. In
almost 90% of patients, the indication was ARDS and/or pneumonia (in
critical COVID-19 patients, differentiating between the two concepts is
difficult due to the similarity in symptoms) and the rest corresponded
to myocarditis, heart failure, barotrauma, or an association of several
of these.
Today, more than 50% of patients have been successfully disconnected
from ECMO and almost 20% more are still in support. Of all those who
have completed the follow-up, 55% were discharged from the hospital,
although the final data for each patient is not available at the present
time, in the expectation of later seeing the evolution of the pandemic
and deciding on the date of definitive closing of the registry.