Extracorporeal blood purification with Oxiris® filter in critically ill patients with COVID-19 requiring continuous renal replacement therapy.

Introduction: Severe COVID-19 is associated with a dysregulated immune response that usually leads to cytokine release syndrome. This study aimed to compare the use of extracorporeal blood purification therapy (Oxiris^®) versus standard continuous renal replacement therapy (CRRT) in critically-ill patients with severe COVID-19.

Methods: This was a national, multicenter, retrospective study of patients with COVID-19 admitted to the intensive care unit (ICU) between March and October 2020 who required CRRT. Patients were categorized into two groups: Oxiris^® CRRT and standard CRRT. The primary outcome was the number of patients alive and ventilator-free at 30-days post-CRRT treatment. Key secondary endpoints included change in inflammatory markers, Sequential Organ Failure Assessment (SOFA) scores, and PaO₂/FiO₂ ratio at 24- and 72-h post Oxiris^® initiation.

Results: Thirty-five patients received Oxiris^® CRRT and 23 patients received standard CRRT. The primary outcome was 31.4% in the Oxiris^® group versus 4.3% in the standard CRRT group (adjusted odds ratio 5.97, 95% confidence interval [CI], 0.64-55.6; p = 0.117). In the Oxiris^® group, interleukin-6 (IL-6) concentrations significantly decreased at 24 and 72-h (p = 0.033) and PaO₂/FiO₂ ratio significantly increased at 24 and 72 h after Oxiris^® initiation (p = 0.001). There was no significant change in SOFA scores at 24- and 72-h after Oxiris^® initiation.

Conclusion: The number of patients alive and ventilator-free at 30-days was higher in the Oxiris^® group than that in the standard CRRT group; however, the difference did not reach statistical significance after adjusting for the baseline severity of illness. There was a significant reduction in IL-6 and significant improvement in PaO₂/FiO₂ ratio after Oxiris^® CRRT initiation.