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\begin{document}

\title{Outcomes of Extracorporeal Membrane Oxygenation in Influenza vs.
COVID-19 During the First Wave of COVID-19}



\author[1]{Cameron Blazoski}%
\author[1]{Michael Baram}%
\author[1]{Hitoshi Hirose}%
\affil[1]{Thomas Jefferson University Hospital}%


\vspace{-1em}



  
  \date{May 24, 2024}


\begingroup
\let\center\flushleft
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\selectlanguage{english}
\begin{abstract}
Purpose: Extracorporeal membrane oxygenation (ECMO) is a refractory
treatment for acute respiratory distress syndrome (ARDS) due to
influenza and severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2, also referred to as COVID-19). We conducted this study to
compare the outcomes of influenza patients treated with veno-venous-ECMO
(VV-ECMO) to COVID-19 patients treated with VV-ECMO, during the first
wave of COVID-19. Materials and Methods: Patients in our institution
with ARDS due to COVID-19 or influenza who were placed on ECMO between
August 1, 2010 and September 15, 2020 were included in this comparative,
retrospective study. To improve homogeneity, only VV -ECMO patients were
analyzed. The clinical characteristics and outcomes were extracted and
analyzed. Results: 28 COVID-19 patients and 17 influenza patients were
identified and included. ECMO survival rates were 68\% (19/28) in
COVID-19 patients and 94\% (16/17) in influenza patients (p=0.04).
30-day survival rates after ECMO decannulation were 54\% (15/28) in
COVID-19 patients and 76\% (13/17) in influenza patients (p=0.13).
COVID-19 patients spent a longer time on ECMO compared to flu patients
(21 days vs. 12 days, p=0.025), and more COVID-19 patients (26/28 vs.
2/17) were on immunomodulatory therapy prior to ECMO initiation
(p\textless{}0.001). COVID-19 patients had higher rates of new
infections during ECMO (50\% vs. 18\%, p=0.03) and bacterial pneumonia
(36\% vs 6\%, p=0.024). Conclusions: COVID-19 patients who were treated
in our institution with VV-ECMO had statistically lower ECMO survival
rates than influenza patients. It is possible that COVID-19
immunomodulation therapies may increase the risk of other superimposed
infections.%
\end{abstract}%



\sloppy


\textbf{Outcomes of Extracorporeal Membrane Oxygenation in Influenza vs.
COVID-19 During the First Wave of COVID-19.}

Cameron M. Blazoski, BA,\textsuperscript{1} Michael Baram,
MD,\textsuperscript{2} Hitoshi Hirose, MD, PhD. \textsuperscript{3}

\textsuperscript{1} Sidney Kimmel Medical College, Thomas Jefferson
University, Philadelphia, PA

\textsuperscript{2} Division of Pulmonary and Critical Care, Thomas
Jefferson University, Philadelphia, PA.

\textsuperscript{3} Department of Surgery, Thomas Jefferson University,
Philadelphia, PA

Running title: ECMO Influenza vs. COVID-19

Address for correspondence:

Hitoshi Hirose, MD.

Dept. Surgery, Thomas Jefferson University

1025 Walnut Street, Suite 605, Philadelphia, PA 19107, USA.

Tel: 215-955-5654, Fax: 215-955-6010, Email:
Hitoshi.Hirose@jefferson.edu

Word count: 2735

Conflict of Interests: None declared

Financial support: None.

Data: The data that support the findings of this study are available
from the corresponding author upon reasonable request

\textbf{Abstract}

\textbf{Purpose:} Extracorporeal membrane oxygenation (ECMO) is a
refractory treatment for acute respiratory distress syndrome (ARDS) due
to influenza and severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2, also referred to as COVID-19). We conducted this study to
compare the outcomes of influenza patients treated with veno-venous-ECMO
(VV-ECMO) to COVID-19 patients treated with VV-ECMO, during the first
wave of COVID-19.

\textbf{Materials and Methods:} Patients in our institution with ARDS
due to COVID-19 or influenza who were placed on ECMO between August 1,
2010 and September 15, 2020 were included in this comparative,
retrospective study. To improve homogeneity, only VV -ECMO patients were
analyzed. The clinical characteristics and outcomes were extracted and
analyzed.

\textbf{Results} : 28 COVID-19 patients and 17 influenza patients were
identified and included. ECMO survival rates were 68\% (19/28) in
COVID-19 patients and 94\% (16/17) in influenza patients (p=0.04).
30-day survival rates after ECMO decannulation were 54\% (15/28) in
COVID-19 patients and 76\% (13/17) in influenza patients (p=0.13).
COVID-19 patients spent a longer time on ECMO compared to flu patients
(21 days vs. 12 days, p=0.025), and more COVID-19 patients (26/28 vs.
2/17) were on immunomodulatory therapy prior to ECMO initiation
(p\textless{}0.001). COVID-19 patients had higher rates of new
infections during ECMO (50\% vs. 18\%, p=0.03) and bacterial pneumonia
(36\% vs 6\%, p=0.024).

\textbf{Conclusions} : COVID-19 patients who were treated in our
institution with VV-ECMO had statistically lower ECMO survival rates
than influenza patients. It is possible that COVID-19 immunomodulation
therapies may increase the risk of other superimposed infections.

\textbf{(Word count of abstract: 247)}

\textbf{Introduction}

One of the main concerns of coronavirus disease 2019 (COVID-19)
infection is development of acute respiratory distress syndrome (ARDS).
Although the definition of ARDS has changed over the decades, its
clinical context remains the same: a rapidly progressive inflammatory
syndrome that impairs oxygen transport in the
lungs.\textsuperscript{1--3} Historically, the most common viral cause
of adult ARDS prior to COVID-19 infection was influenza pneumonia, and
the complication of ARDS from influenza is known to be associated with
an increased mortality.\textsuperscript{4,5} The pulmonary injury in
ARDS due to COVID-19 has been shown to resemble other viral causes of
ARDS, and as expected, the severity of ARDS is associated with
significantly worsened mortality among COVID-19
patients.\textsuperscript{1,6,7}

Due to the high mortality rate of ARDS due to COVID-19, there has been a
high demand for refractory treatment options in patients who do not
improve upon standard ventilation and treatment. Thus, extracorporeal
membrane oxygenation (ECMO) was used in select cases of COVID-19 with
refractory ARDS and severe hypoxemia.\textsuperscript{7--10} ECMO is a
temporary form of mechanical cardiopulmonary support, used in patients
with severe cardiac and/or respiratory shock. ECMO was first clinically
used in 1972 and has been increasingly incorporated into standard
practice in the past two decades.\textsuperscript{11--13} Despite
controversial and conflicting evidence on its overall efficacy, ECMO has
become a common treatment for patients with refractory
ARDS.\textsuperscript{13--16}

In cases of influenza, ECMO can be used adjunctive support in cases
complicated by severe ARDS.\textsuperscript{17} With knowledge learned
from years of critical care and development of protocols, there is a
good understanding of how to properly care for patients with
influenza.\textsuperscript{18,19} It is known that in the setting of
influenza, immunosuppression with steroids increases the duration of
viral shedding and worsens mortality,\textsuperscript{20} so high dose
immunosuppression is usually avoided. If traditional therapies fail to
stabilize the patient, early initiation of ECMO in critically ill
patients with influenza can improve their chance of survival by
promoting lung protective ventilator strategies without compromising
required gas exchange. The amount of benefit provided by ECMO in
complement to anti-influenza agents is unclear, though outcomes have
been acceptable.\textsuperscript{17} In contrast, we have not identified
a specific, proven treatment protocol for COVID-19 infection despite the
widespread use of supportive measures such as remdesivir,
lung-protective ventilator strategies, anti-inflammatory agents, and
steroids.\textsuperscript{21} Despite initial support for some of these
agents, some subsequent research has been less
optimistic.\textsuperscript{21,22}

While ARDS due to COVID-19 has been compared to ARDS caused by
influenza, severe cases of COVID-19 continue to demonstrate high
mortality rates, and the similarities and differences between the two
diseases are not well understood. Similarly, despite recent studies on
the use of ECMO in COVID-19 patients,\textsuperscript{23--25} there
remains a lack of evidence documenting the overall efficacy of ECMO in
treating ARDS due to COVID-19. This paper will compare the outcomes and
efficacy of ECMO in treating patients with ARDS due to COVID-19 or
influenza to better understand the prognosis of ARDS due to COVID-19 and
the use of ECMO in treating it.

\textbf{Materials and Methods}

Patients were identified within an IRB-approved, prospectively
maintained ECMO database (IRB approval \# 11D.185) at our institution
from August 1, 2010 to September 15, 2020. Patients who were confirmed
to have influenza or COVID-19 who underwent ECMO were included in this
study. 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 those listed in our
previous paper,\textsuperscript{26} and Table 1 includes the list of
contraindications for ECMO placement in COVID-19 patients. The exclusion
criteria for COVID-19 patients may be more restrictive than in
non-COVID-19 patients, due to the limited resources available during the
first wave of the pandemic and challenges due to increased isolation
needs.

During the first wave, our institution did not utilize veno-arterial
ECMO (VA-ECMO) in patients with COVID-19, due to limited resources and
an unclear understanding of the reversibility of the disease. In
influenza patients, 7 patients were placed for VA-ECMO for cardiac
dysfunction. However, these VA-ECMO patients were excluded from this
study to ensure the appropriate comparisons.

Due to resource allocation and isolation concerns, COVID-19 and
influenza patients were treated differently. We traditionally used
single double-lumen cannula (Avalon\selectlanguage{ngerman}\textsuperscript{©} cannula, Avalon
Laboratories, Rancho Dominguez, CA) for VV- ECMO patients, but this had
to be modified for COVID-19. In COVID-19 patients, VV-ECMO was placed
using the femoral and internal jugular veins (Figure 1). This change in
insertion practice did not result in procedural complications, but it
did affect body mass index (BMI) restrictions. All cannulation was
performed in the ICU without transport to either the operating room or
catheterization lab unless an issue occurred during the bedside
cannulation. Since single 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\textsuperscript{©} cannula was
discouraged.\textsuperscript{26}

Due to the COVID-19 pandemic, our institution did not offer a mobile
ECMO program outside of our hospital network to avoid possible 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.\textsuperscript{28,29} Briefly, after placement of ECMO, the
ventilator was set to the ARDSnet protocol.\textsuperscript{18} The
typical setting was pressure controlled ventilation, rate 15 per minute,
PEEP 15 cm H\textsubscript{2}O, delta P 15 cm H\textsubscript{2}O, and
inspiratory time 1.5 seconds until recovery of the respiratory
function.\textsuperscript{30} Paralytics were discontinued within 24
hours of ECMO initiation, unless ventilatory desynchrony resulted in
hemodynamic instability. Sedatives were used to achieve a RAS score of
negative 1-2. Blood pressure was maintained at a mean arterial pressure
of at least 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 IU/ml. If
bleeding complications were observed, the anticoagulation was held and
then restarted at a lower anti-Xa goal of 0.1-0.3 IU/ml.

Timing of the decannulation was determined by chest x-ray findings, lung
mechanics, and gas exchange. 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
encouraged bed-side decannulation and discouraged transporting to
operating room to limit exposure to COVID-19.

For our primary comparison, all adult patients who met our inclusion
criteria were divided by their cause of ARDS, either influenza or
COVID-19. The baseline characteristics, clinical characteristics, and
outcomes were calculated and compared between the two groups. The
primary endpoints of this study were ECMO survival and 30-day survival.
ECMO survival was defined as surviving at least 24 hours post
decannulation.

Data was expressed as the number with percentage, mean +/- standard
deviation, or median (quantile) as appropriate. The two groups were
compared using chi-squared tests for categorical variables and standard
t-tests for continuous variables as appropriate, with significance
accepted at a P-value less than 0.05.

\textbf{Results}

45 patients with ARDS who underwent VV-ECMO placement met our inclusion
criteria and were included in this study. Of those patients, 28 had ARDS
due to COVID-19 and 17 had ARDS due to influenza. 64\% of COVID-19
patients (n=18) and 65\% of influenza patients (n=11) were transferred
from an outside of hospital to our institution, with a significantly
higher percentage of COVID-19 patients having ECMO initiated outside of
our hospital (50\% vs. 12\%, p=0.01). Avalon
cannula\textsuperscript{©}was used more often in influenza patients than
COVID-19 patients (88\% vs. 7\%, p\textless{}0.01). The average duration
of ECMO utilization in COVID-19 patients was 21.4 days, which was
significantly longer than the average duration of influenza patients
(12.2 days) (p=0.03).

COVID-19 patients had lower incidence of pre-ECMO comorbidities
including history of coronary artery disease (p=0.02) and acute kidney
injury (p=0.05). They also had a lower body surface area (p=0.04). There
were no statistically significant differences in the vital signs before
ECMO placement. Patient demographics and pre-ECMO characteristics are
displayed in Table 2.

Patients with ARDS due to COVID-19 had a significantly decreased ECMO
survival rate (p=0.04). Of the COVID-19 patients, 19 (68\%) survived
ECMO and 15 (54\%) survived to 30 days after decannulation. Among
influenza patients, 16 (94\%) survived ECMO and 13 (76\%) survived to 30
days after decannulation.

The most common complication among COVID-19 patients was the development
of a new infection during ECMO, with 14 patients (50\%) developing a new
infection after the placement of ECMO. Among influenza patients, the
most common complications were renal failure, GI bleeds, and new
infections, all of which occurred in 3 patients (18\%). COVID-19
patients had significantly higher rates of bacterial pneumonia (p=0.03),
any new infections (p=0.03), and blood culture-positive sepsis (p=0.04),
as displayed in Table 3.

\textbf{Discussion}

The primary findings of this study relate to the survival rate and
complications associated with patients with ARDS due to COVID-19 who are
treated with VV-ECMO. Patients with ARDS due to COVID-19, compared to
patients with ARDS due to influenza, had a significantly higher ECMO
mortality, with less patients surviving to ECMO decannulation. At the
same time, patients with COVID-19 had an increased risk for developing
new infections, with significantly higher rates of pneumonia and sepsis
among COVID-19 patients.

The treatment of ARDS with ECMO remains disputed, despite its increased
use in treating ARDS in the past decade.\textsuperscript{13,14} While
the exact mortality rate of treating ARDS with ECMO varies by research
study, it is typically accepted to range between
34-39\%.\textsuperscript{13,15,16} This mortality rate is still better
on ECMO than was reported by the ARDS definition task force, which
highlights the importance of patient selection.\textsuperscript{3} Thus,
it is generally recognized that ECMO should be primarily used for
refractory cases of ARDS, in which a patient remains severely hypoxic
despite aggressive treatment.\textsuperscript{15}

A 2020 study by Acosta and Singer suggests that the pathogenesis and
clinical course of ARDS due to influenza resembles ARDS due to
COVID-19.\textsuperscript{32} However, differences in patient outcomes
illustrates that there must be an difference between the two. The paper
speculated that these severe cases may be due to SARS-CoV-2's ability to
dampen the inflammatory response to severe infection and impede normal
pulmonary recovery to damage, which would exacerbate ARDS and lead to
the observed increased mortality rate among patients with COVID-19. This
again brings to question the treatment protocols that utilize potent and
high dose immunosuppressants.\textsuperscript{21,22}

Acosta and Singer emphasize that while mild to moderate cases of
influenza and COVID-19 may present similarly, their prognoses diverge in
severe cases. This idea is supported by a body of evidence which
indicate that severe cases of COVID-19 have a higher mortality rate than
severe cases of influenza. For example, one study found that patients
who are admitted to the ICU for COVID-19 have a 3.7 times higher risk of
death than patients treated in the ICU for
influenza.\textsuperscript{6}Similarly, another study detailed that
hospitalized patients in the Veteran's Health Administration had a 5
times higher risk for death than hospitalized patients with
influenza.\textsuperscript{33} These studies are consistent with the
trends at our institution.

In our study, we also discovered that while COVID-19 patients had lower
rates of certain pre-existing conditions, they still had a higher
mortality rate. Influenza patients had significantly higher rates of
pre-ECMO acute kidney injury and coronary artery disease, as well as a
higher body surface area. However, this is likely due to our restricted
inclusion criteria for ECMO placement in COVID-19 patients and should
not be used to make any definite conclusions on the impact of
pre-existing conditions on mortality rate between influenza and COVID-19
patients.

An important finding of our study was the significantly higher rates of
secondary bacterial infection in COVID-19 patients. Of the 28 COVID-19
patients, 14 (50\%) developed a new infection during ECMO placement,
with 10 (36\%) developing bacterial pneumonia and 9 (32\%) developing
blood culture-positive sepsis. It is important to note that bacterial
infection is a common complication for any patient who undergoes ECMO
placement, and infections can lead to pneumonia and sepsis, both of
which significantly increase these patients' mortality
rate.\textsuperscript{11} However, our research indicates that
comparatively, patients with ARDS due to COVID-19 develop new infections
more commonly when on ECMO than patients with ARDS due to influenza.
This finding is backed by recent research on cases of COVID-19. COVID-19
has been statistically linked with cases of bacterial superinfection,
especially in critically ill patients, which has been documented to lead
to bacterial pneumonia and sepsis.\textsuperscript{34--36} Secondary
bacterial infection in COVID-19 patients has also been significantly
associated with poor outcomes and an increased mortality rate, even when
patients are treated with aggressive antimicrobial
therapies.\textsuperscript{37}

The increased risk of infection may be a result of immunomodulation
therapy in treating COVID-19. While immunomodulation therapy has been
shown to decrease the mortality rate of
COVID-19,\textsuperscript{38,39}it has also been associated with an
increased infection rate. In our study, 93\% of COVID-19 patients were
on some form of immunotherapy -- either steroids, interleukin
inhibitors, or both -- while only 12\% of influenza patients were
immunosuppressed prior to ECMO initiation (p\textless{}0.001).
Ultimately, it is possible -- and even likely -- that the decreased ECMO
survival rate among our COVID-19 patients is partially caused by the
increased incidence of bacterial superinfections.

Our study is limited by its small sample size and being based in one
hospital center that provided ECMO support for a twelve hospital health
system. It is also possible that there was selection bias in this study,
even though ECMO placement was determined by a multidisciplinary team of
physicians. Moreover, influenza patients dated back to 2010, while all
COVID-19 patients were treated in 2020; it is possible that changes in
ECMO protocol due to COVID-19 and associated treatment protocols with
ECMO could impact patient outcomes and complication rates.

Despite its limitations, this study provides significant data on 28
patients with COVID-19 and effectively compares patients with ARDS due
to COVID-19 to patients with ARDS due to influenza. This paper is one of
a growing number of studies on COVID-19, and we hope that our findings
contribute to a better understanding of how to effectively treat
COVID-19.

\textbf{Conclusion}

Based on our results, we conclude that there are significant differences
in the use of VV-ECMO in treating ARDS due to COVID-19 to treating ARDS
due to influenza. COVID-19 patients appear to be at a higher risk of
bacterial superinfection, and prevention and control of bacterial
infections may be critical in improving survival. More research is
needed to understand the efficacy and risks of using ECMO to treat cases
of COVID-19.

\textbf{Table 1} : Contraindications for ECMO in COVID-19\selectlanguage{english}
\begin{longtable}[]{@{}l@{}}
\toprule
\textbf{Standard contraindications}\tabularnewline
\midrule
\endhead
Age \textgreater{} 70 y.o.\tabularnewline
Body mass index \textgreater{}45 with high risk of vascular
access\tabularnewline
Mechanical ventilation \textgreater{}7 days\tabularnewline
Multiorgan failure\tabularnewline
End stage liver disease\tabularnewline
Irreversible neurological damage\tabularnewline
Contraindications of anticoagulation\tabularnewline
Cardiac arrest without ROSC\tabularnewline
\textbf{Relative contraindications}\tabularnewline
Age \textgreater{} 65 y.o.\tabularnewline
Body mass index \textgreater{}35\tabularnewline
Mechanical ventilation \textgreater{}5 days\tabularnewline
Active bacterial blood stream infection\tabularnewline
Severe COPD Cirrhosis Chronic heart failure\tabularnewline
Inability of access neuro status\tabularnewline
High lactate related to low perfusion status\tabularnewline
Limited activity at home\tabularnewline
No family or appropriate power of attorney Outside of institutional
network\tabularnewline
\bottomrule
\end{longtable}

\textbf{Table 2} : Demographics and baseline characteristics of studied
patients. Data is expressed with number (percentage) or mean \selectlanguage{ngerman}± standard
deviation.\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
& All patients & Influenza & COVID-19 &\tabularnewline
\midrule
\endhead
Number of patients & n = 45 & n =17 & n = 28 & P-value\tabularnewline
Characteristics & & & &\tabularnewline
Age (years) & 51.9 \selectlanguage{ngerman}± 11.2 & 49.5 \selectlanguage{ngerman}± 13.2 & 53.3 \selectlanguage{ngerman}± 9.8 &
0.314\tabularnewline
Male & 28 (62\%) & 9 (53\%) & 19 (68\%) & 0.317\tabularnewline
Body surface area (cm\textsuperscript{2}) & 2.11 \selectlanguage{ngerman}± 0.27 & 2.24 \selectlanguage{ngerman}± 0.27 &
2.04 \selectlanguage{ngerman}± 0.35 & 0.036\tabularnewline
Body mass index & 34.95 \selectlanguage{ngerman}± 7.82 & 37.58 \selectlanguage{ngerman}± 9.06 & 33.36 \selectlanguage{ngerman}± 6.63 &
0.107\tabularnewline
Underlying Conditions & & & &\tabularnewline
Pre-ECMO positive blood culture & 10 (22\%) & 4 (24\%) & 6 (0\%) &
0.869\tabularnewline
Smoking & 10 (22\%) & 5 (29\%) & 5 (18\%) & 0.366\tabularnewline
Coronary artery disease & 3 (7\%) & 3 (18\%) & 0 (0\%) &
0.021\tabularnewline
Chronic lung disease & 5 (11\%) & 3 (18\%) & 2 (7\%) &
0.277\tabularnewline
Diabetes & 13 (29\%) & 5 (29\%) & 8 (29\%) & 0.952\tabularnewline
Pre-ECMO acute renal injury & 18 (40\%) & 10 (59\%) & 8 (29\%) &
0.045\tabularnewline
Pre-ECMO Immunotherapy & 28 (62\%) & 2 (12\%) & 26 (93\%) &
\textless{}0.001\tabularnewline
Pre-ECMO Vital Signs & & & &\tabularnewline
Temperature (\selectlanguage{ngerman}°F) & 99.7 \selectlanguage{ngerman}± 1.8 & 100.1 \selectlanguage{ngerman}± 2.0 & 99.04 \selectlanguage{ngerman}± 1.6 &
0.074\tabularnewline
Heart Rate & 107.2 \selectlanguage{ngerman}± 25.5 & 115.8 \selectlanguage{ngerman}± 26.5 & 102.0 \selectlanguage{ngerman}± 23.9 &
0.089\tabularnewline
Respiratory rate & 27.4 \selectlanguage{ngerman}± 4.7 & 26.9 \selectlanguage{ngerman}± 4.6 & 27.7 \selectlanguage{ngerman}± 4.8 &
0.581\tabularnewline
Mean arterial pressure (mm Hg) & 82.3 \selectlanguage{ngerman}± 15.7 & 78.1 \selectlanguage{ngerman}± 12.8 & 84.9 \selectlanguage{ngerman}± 15.1
& 0.115\tabularnewline
FiO2 (\%) & 95.3 \selectlanguage{ngerman}± 13.1 & 96.6 \selectlanguage{ngerman}± 14.6 & 94.6 \selectlanguage{ngerman}± 12.3 &
0.640\tabularnewline
PEEP (cm) & 15.2 \selectlanguage{ngerman}± 5.4 & 15.6 \selectlanguage{ngerman}± 6.8 & 15.0 \selectlanguage{ngerman}± 4.6 & 0.750\tabularnewline
Other & & & &\tabularnewline
Transfer from outside hospital & 29 (64\%) & 11 (65\%) & 18 (64\%) &
0.977\tabularnewline
ECMO initiated other than our hospital & 16 (36\%) & 2 (12\%) & 14
(50\%) & 0.009\tabularnewline
Use of Avalon cannula & 15 (38\%) & 15 (88\%) & 2 (7\%) &
\textless{}0.001\tabularnewline
\bottomrule
\end{longtable}

\textbf{Table 3} : Rates of ECMO complications. Data is expressed with
number (percentage).\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
& All patients & Influenza & COVID-19 &\tabularnewline
\midrule
\endhead
Number of patients & n = 45 & n =17 & n = 28 & P-value\tabularnewline
Length on ECMO (days) & 17.8 \selectlanguage{ngerman}± 16.1 & 12.2 \selectlanguage{ngerman}± 5.7 & 21.4 \selectlanguage{ngerman}± 19.4 &
0.025\tabularnewline
ECMO survival & 35 (78\%) & 16 (94\%) & 19 (68\%) & 0.040\tabularnewline
30 days after decannulation survival & 28 (62\%) & 13 (76\%) & 15 (54\%)
& 0.130\tabularnewline
Complications & & & &\tabularnewline
Renal failure & 10 (22\%) & 3 (18\%) & 7 (25\%) & 0.565\tabularnewline
Liver failure & 3 (7\%) & 1 (6\%) & 2 (7\%) & 0.869\tabularnewline
Stroke & 2 (4\%) & 1 (6\%) & 1 (4\%) & 0.715\tabularnewline
Brain bleed & 2 (4\%) & 1 (6\%) & 1 (4\%) & 0.715\tabularnewline
Cannula site bleed & 5 (11\%) & 1 (6\%) & 4 (14\%) &
0.384\tabularnewline
GI bleed & 9 (20\%) & 3 (18\%) & 6 (21\%) & 0.758\tabularnewline
Any new infection during ECMO & 17 (38\%) & 3 (18\%) & 14 (50\%) &
0.030\tabularnewline
Bacterial pneumonia & 11 (24\%) & 1 (6\%) & 10 (36\%) &
0.024\tabularnewline
Blood culture-positive sepsis & 10 (22\%) & 1 (6\%) & 9 (32\%) &
0.040\tabularnewline
\bottomrule
\end{longtable}



\textbf{Ledends of Figure}

\textbf{Figure 1} : Typical veno-venous cannulation in COVID-19 case.
Patients were primarily cannulated via the right internal jugular vein
and right femoral vein due to anatomical preference.

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\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/FIg-VV-COVID/FIg-VV-COVID}

\end{center}
\end{figure}

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