Added value of this systematic review and meta-analysis
This systematic review is the first in the current pandemic to perform a meta-analysis from all available cohort studies using venovenous ECMO for acute respiratory distress system caused by severe COVID 19 infection. Across low-to-moderate quality studies, we noted a reduction in short term mortality with venovenous ECMO in comparison to what is known about treatment with conventional mechanical ventilation in severe COVID 19. Given the current challenges of doing large clinical trials in this population of COVID 19 critically ill patients, a large well designed randomised controlled trial of ECMO treatment for COVID 19 is unlikely to happen. Therefore, the results of this meta-analysis represent the most comprehensive and up-to-date synthesis of the available evidence for clinicians on the use of venovenous ECMO in COVID 19 patients with severe acute respiratory distress syndrome.