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:
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.