It is undoubtedly true that identification of
novel coronavirus-2019 (COVID-19) infection,
announcement of pandemic, and its social and economic
effects, and reflections to the healthcare system are
expected to be the subject to many researches for next
years. It is a rightful interest with the actual numbers
of over seven million diagnosed cases and over 400,000
deaths.[
1] Debatable subjects among the healthcare
professionals include diagnosis and treatment methods,
epidemiological observations, and future predictions.
There are many case reports and different therapy
strategies of COVID-19 in recent papers about the
pandemic. The relationship between COVID-19
and cardiovascular surgery is the management of
surgical strategies during pandemic and extracorporeal
membrane oxygenation (ECMO) use which is, itself,
a subject of debate in terms of efficacy and outcomes.
The special interest of healthcare professionals other
than cardiovascular surgeons is, somehow, noteworthy.
The number of ECMO used for COVID-19 all over
the world is only 1,371 according to the Extracorporeal
Life Support Organization (ELSO), which is one of
the most important organizations recording ECMO
data.[
2] This number is quite insignificant, compared
to over seven million patients. However, ECMO
deserves this attention, as it can be the last option for
COVID-19 patients who do not have a chance of cure
with any other therapy modality.
Before discussing this subject in detail, one should
know what ECMO is and is not. In particular,
venoarterial ECMO (VA-ECMO) is used as the
left ventricular support system for postcardiotomy
cardiogenic shock, although it does not provide a left
ventricular support at all. This is most probably due
to easy insertion and old habits. The VA-ECMO
does not help ventricular improvement, as it does not
decompress left ventricle at all. On the contrary, it worsens the situation due to the increase of afterload
because of the arterial cannula in such patients.[3]
For sure, VA-ECMO should be used for only very
serious oxygenation problems or to maintain tissue
perfusion in patients with cardiogenic shock. On the
other hand, there is no debate on the conditions in
which venovenous ECMO (VV-ECMO) is used. It is
indicated in severe hypoxic cases of severe pulmonary
infections such as COVID-19.[4,5] The VA-ECMO
can be used in a small number of COVID-19 patients
with respiratory problems and severe circulatory
disturbances.
Which COVID-19 patients should receive ECMO
support? As mentioned previously, it can be used as
the last option for severe hypoxia in acute respiratory
distress. However, due to the limited number of
data, it still remains unclear whether conventional
respiratory support machines or ECMO would be more
appropriate for these patients. Some reports revealed
that patients who did not receive ECMO support
had higher survival rates than patients receiving
ECMO support.[6] As a result of this controversy,
clinicians attempted to support the indication, severe
respiratory distress, as mentioned above, with clinical
and respiratory parameters. For instance, the ELSO
has provided selection criteria needed for ECMO
referral. If despite optimal ventilation strategies,
neuromuscular blockade, appropriate positive end
expiratory pressure, prone positioning, and the use of pulmonary vasodilators, patients who meet the
following criteria can be referred for ECMO referral:
partial pressure of oxygen (PaO2)/fraction of inspired
oxygen (FiO2) less than 60 mmHg for longer than
6 h, PaO2/FiO2 less than 50 mmHg for less than 3 h
or pH less than 7.20 + PaCO2 greater than 80 mmHg
for less than 6 h, and having no contraindications.[2]
In addition, some risk scoring systems can be used for
the definition of indications.[7] For instance, patients
having severe respiratory distress with a Murrey score
of 3 to 4, it is reasonable to use ECMO.[7] Beside all
these experiences, even if limited, and parameters,
choosing the right patient is of utmost importance, as
the results are still obscure and sources should be used
very carefully. In this regard, it seems to be reasonable
to use ECMO for young patients without comorbidity,
and healthcare professionals who provide the greatest
support in the breakthrough of pandemic.
Unfortunately, very few data are available on
ECMO use for COVID-19, which are rarely used,
but widely known. Recent reports demonstrated that
ECMO use was not as helpful, as it was thought
regardless of COVID-19 pandemic.[8-11] Based on this
information, the results of COVID-19 patients with
ECMO support are not very good, as well. Studies
about ECMO use in small numbers of COVID-19
patients, survival was reported as ranging between
0 and 16%.[12-15] It should be kept in mind that patients
who received ECMO support were in seriously poor
hemodynamic conditions than the other group.
Additionally, case reports of successful ECMO use led
to confusion. However, it is ironic that the reason why
these papers were accepted by the editors was the small
number of successful ECMO use.
While debates about ECMO use for COVID-19
continue, there are also social, economic, and ethical
problems particularly on this subject. The most
important problem is the obligation of effective use
of resources in a pandemic which puts so much
burden on the healthcare system. There is an unmet
need for a large organization, when it is decided
to use ECMO, to protect healthcare professionals
in the first place. The ECMO is more expensive
than other conventional systems such as ventilators,
which poses another problem. Less developed and
developing countries should be more careful while
using ECMO in terms of cost-saving. Another point
is the necessity of a professional team to cope with
the setup and complications of ECMO. This team is
expected to handle these problems and get out of the system in pandemic circumstances, which is likely to
reduce the number of healthcare professionals in the
field. There are two other specific problems about the
ECMO use. The first one is the coagulation problems
commonly seen in COVID-19 patients. Many reports
showed that COVID-19 patients had a tendency
to thrombosis.[16-18] This makes management of
anticoagulation process more difficult than it already
is. The second problem is cardiomyopathy which
was accounted for one-third of critical COVID-19
patients.[14,19] This is explained as myocardial damage
and microvascular thrombosis caused by the cytokine
storm.[5] Myocardial problems with a wide spectrum
including simple electrocardiographic changes to
severe cardiac insufficiency can occur in COVID-19
patients. These problems obviously make ECMO
use more complicated than it is during pandemic.
If such kind of myocardial damage is skipped while
the VV-ECMO is inserted to a COVID-19 patient
with severe respiratory distress, the results would
be catastrophic. As aforementioned, choosing the
VA-ECMO in such circumstances would not yield
better results, particularly if there is left ventricular
insufficiency due to myocardial damage.
In conclusion, the ECMO use for COVID-19
patients should be assessed in the light of these
data. Regarding confusing problems and uncertain
results, the most important point in this process is
to choose the right patient who will benefit most. If
this cannot be achieved, both waste of resources and
disappointment of healthcare workers are inevitable.
Declaration of conflicting interests
The author declared no conflicts of interest with respect
to the authorship and/or publication of this article.
Funding
The author received no financial support for the research
and/or authorship of this article.
