Methods
Adult patients positive for COVID-19 who underwent ECMO at our
institution from April 1, 2020 to June 11, 2020 were included in this
study. Patients were identified by an IRB-approved, prospectively
maintained ECMO database (IRB approval # 11D.185). The data from these
patients was retrospectively extracted and details were further studied
by reviewing medical records. Inclusion criteria included a positive
COVID-19 test and a diagnosis of ARDS. ECMO placement was determined by
a multidisciplinary team that included a cardiac surgeon, a pulmonary
critical care physician, and a cardiovascular intensivist.
The indications for ECMO placement were the same as our previous
paper,(18) and contraindications for ECMO placement in treating COVID-19
patients are listed in Table 1. The exclusion criteria may be more
restricted than in non-COVID-19 patients, due to the limitations of
resources during this pandemic.
The primary mode of ECMO in COVID-19 ARDS was veno-venous ECMO (VV-ECMO)
using the femoral and internal jugular veins (Figure 1). All cannulation
was performed in the ICU without transport to either the operating room
or catheterization lab unless an issue occurred during bedside
cannulation. Since Avalon dual lumen ECMO cannula placement always
requires fluoroscopy and echocardiography, which requires additional
personnel including radiology technicians and an echocardiography
technician, the utilization of the Avalon cannula was discouraged.(18)
Veno-arterial ECMO (VA-ECMO) should be reserved for only those who had
severe but reversible cardiac dysfunction, such as COVID-19 related
myocarditis. ECMO assisted cardiopulmonary resuscitation (ECPR) for
patients with COVID-19 was discouraged due to its known poor outcomes.
Due to the COVID-19 pandemic, we no longer offer a mobile ECMO program
outside of our institutional network due to the concern of exposure of
required personnel including the ECMO surgeon, perfusionist, and
transfer nurses at the local site. Instead of activating mobile ECMO
cannulation teams, we encouraged local cardiac surgeons to place ECMO at
their institutions and then transport the patient to our facility.
The general management of ECMO has been described in one of our prior
papers.(19) Briefly, after placement of ECMO, the ventilator was set to
the ARDSnet protocol. The typical setting was pressure controlled
ventilation, rate 15, PEEP 15, delta P 15 until recovery of the
respiratory function. Paralytics were discontinued within 24 hours of
ECMO initiation, unless respiratory function was deetiolated. Sedatives
were used if a RAS score was negative 1-2. Blood pressure was maintained
at least mean arterial pressure of 60 mm Hg with vasopressors and/or
fluid as appropriate. A heparin drip was started once PTT fell below 50
seconds after cannulation and maintained at an anti-Xa level of 0.3-0.5.
If bleeding complications were observed, the anticoagulation was held
and then restarted at a lower anti-Xa goal of 0.1-0.3.
Timing of the decannulation was determined by chest x-ray findings and
lung mechanics. Before decannulation, the sweep gas was discontinued for
at least 24 hours to ensure the lungs were able to exchange oxygen and
carbon dioxide appropriately. For COVID-19 cases, we encourage bed-side
decannulation rather than transporting to operating room to limit
exposure to COVID-19.
The primary endpoints of this study were ECMO survival and hospital
survival. ECMO survival was defined by withdrawal of care or death
within 24 hours of decannulation. All patients who survived to hospital
discharge were classified as “Survivors” and all patients who did not
survive to hospital discharge were classified as “Non-Survivors.” The
baseline characteristics, clinical characteristics, and outcomes were
calculated and compared between the two groups.
Data was expressed as the number with percentage, mean +/- standard
deviation, or median (quantile) as appropriate. Two groups were compared
using chi-squared tests for categorical variables and standard t-tests
for continuous variables as appropriate. Significance was accepted at a
P-value less than 0.05.