Plasma exchange in the treatment of complex COVID-19-related critical illness: controversies and perspectives.

COVID-19 (coronavirus disease 2019), caused by the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), emerged in Wuhan, China, and has spread worldwide, resulting in over 73 million cases and more than 1 600 000 deaths as of December 2020. Although the disease is asymptomatic in most cases, some patients develop life-threatening disease characterised by acute respiratory distress syndrome, sepsis, multisystem organ failure (MSOF), extrapulmonary manifestations, thromboembolic disease and associated cytokine release syndrome. The rationale for applying therapeutic plasma exchange (TPE) early in the course of fulminant COVID-19 is the suppression of thromboinflammation and amelioration of microangiopathy, thus preventing the ensuing MSOF. In the course of complicated critical illness due to COVID-19, immune dysregulation may be as important as viral replication itself. Moreover, the natural course of SARS-CoV-2 infection remains obscure, as re-infections and/or recurrently positive real-time PCR results have been reported. Although concerns still exist regarding its potential immunosuppressive effects and safety, TPE shows promise in the management of life-threatening COVID-19 as documented by various pilot studies, which remain to be confirmed by future randomised controlled trials. However, current data suggest that TPE could be an adjunctive rescue therapy in complex COVID-19 critical illness.