Key characteristics impacting survival of COVID-19 extracorporeal membrane oxygenation
Authors: Herrmann Johannes , Lotz Christopher , Karagiannidis Christian , Weber-Carstens Steffen , Kluge Stefan , Putensen Christian , Wehrfritz Andreas , Schmidt Karsten , Ellerkmann Richard K. , Oswald Daniel , Lotz Gösta , Zotzmann Viviane , Moerer Onnen , Kühn Christian , Kochanek Matthias , Muellenbach Ralf , Gaertner Matthias , Fichtner Falk , Brettner Florian , Findeisen Michael , Heim Markus , Lahmer Tobias , Rosenow Felix , Haake Nils , Lepper Philipp M. , Rosenberger Peter , Braune Stephan , Kohls Mirjam , Heuschmann Peter , Meybohm Patrick ,   for the German ECMO COVID Study Group, Hübsch Martha E. , Notz Quirin , Röder Daniel , Kranke Peter , Merten Michaela L. , Jarczak Dominik , Roedl Kevin , Schewe Jens-Christian , Ehrentraut Stefan F. , Kreyer Stefan , Castellanos Ixchel , Brenner Thorsten , Herbstreit Frank , Espeter Florian , Wiefhoff Jan , Ellger Björn , Raimann Florian J. , Sonntagbauer Michael , Wengenmayer Tobias , Staudacher Dawid , Natanov Ruslan , Rolfes Caroline , Reyher Christian , Torje Iuliu-Emilian , Glaser Patricia , Rembold Vanessa , Haseneder Rainer , Sackarnd Jan , Lepper Johannes , Becker Andre , Danziger Guy , Metz Carlos , Mirakaj Valbona , Calov Stefanie , Grau Anna , Haas Kirsten , Ungethüm Katrin , Bihlmaier Karl 
Published: June 2022

Abstract
Background
Severe COVID-19 induced acute respiratory distress syndrome (ARDS) often requires extracorporeal membrane oxygenation (ECMO). Recent German health insurance data revealed low ICU survival rates. Patient characteristics and experience of the ECMO center may determine intensive care unit (ICU) survival. The current study aimed to identify factors affecting ICU survival of COVID-19 ECMO patients.

Methods
673 COVID-19 ARDS ECMO patients treated in 26 centers between January 1st 2020 and March 22nd 2021 were included. Data on clinical characteristics, adjunct therapies, complications, and outcome were documented. Block wise logistic regression analysis was applied to identify variables associated with ICU-survival.

Results
Most patients were between 50 and 70 years of age. PaO2/FiO2 ratio prior to ECMO was 72 mmHg (IQR: 58–99). ICU survival was 31.4%. Survival was significantly lower during the 2nd wave of the COVID-19 pandemic. A subgroup of 284 (42%) patients fulfilling modified EOLIA criteria had a higher survival (38%) (p = 0.0014, OR 0.64 (CI 0.41–0.99)). Survival differed between low, intermediate, and high-volume centers with 20%, 30%, and 38%, respectively (p = 0.0024). Treatment in high volume centers resulted in an odds ratio of 0.55 (CI 0.28–1.02) compared to low volume centers. Additional factors associated with survival were younger age, shorter time between intubation and ECMO initiation, BMI > 35 (compared to < 25), absence of renal replacement therapy or major bleeding/thromboembolic events.

Conclusions
Structural and patient-related factors, including age, comorbidities and ECMO case volume, determined the survival of COVID-19 ECMO. These factors combined with a more liberal ECMO indication during the 2nd wave may explain the reasonably overall low survival rate. Careful selection of patients and treatment in high volume ECMO centers was associated with higher odds of ICU survival.

Trial registration

Registered in the German Clinical Trials Register (study ID: DRKS00022964, retrospectively registered, September 7th 2020, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00022964.

Graphical abstract