Fig. 4: Potential extracorporeal blood purification treatment options based on underlying COVID-19 pathophysiology.

Extracorporeal blood purification (EBP) has been proposed as a possible adjuvant therapy for critically ill patients with COVID-19 on the basis that removal of circulating immunomodulatory factors, that might contribute to disease processes and/or the development of multiple organ failure, might improve outcomes. Of note, the efficacy of EBP in patients with COVID-19 and/or COVID-19 AKI has not been tested, and all therapeutic options must therefore be tested in clinical trials in the context of COVID-19. EBP therapies should be considered complementary to pharmacological support. EBP therapies may also be considered in sequence or as separate entities according to current evidence or pathophysiological rationale, as changes in pathophysiology over the disease course might indicate different treatment approaches. AKI, acute kidney injury; ARDS, acute respiratory distress syndrome; COVID-19, coronavirus disease 2019; DAMPs, damage-associated molecular patterns; HCO, high cut-off; HP, haemoperfusion; MCO, medium cut-off; PAMPs, pathogen-associated molecular patterns; RRT, renal replacement therapy; TPE, therapeutic plasma exchange. Adapted from Acute Disease Quality Initiative 25, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).