Acute Kidney Injury and Blood Purification Techniques in Severe COVID-19 Patients.

Although most patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) experience respiratory manifestations, multi-organ dysfunction is frequent. Almost 20% of hospitalized patients with SARS-CoV-2 infection develop acute kidney injury (AKI). The pathophysiology of AKI is a result of both the direct and indirect effects of SARS-CoV-2 infection, including systemic inflammatory responses, the activation of the renin-angiotensin-aldosterone system (RAAS), and endothelial and coagulative dysfunction. Underlying SARS-CoV-2 infection-associated AKI, an immunological hyper-response with an unbalanced innate and adaptative response defined as a "cytokine storm" has emerged. Numerous agents have been tested in an effort to mitigate the cytokine storm, and a range of extracorporeal cytokine removal techniques have been proposed as potential therapeutic options. In the present review, we summarize the main pathogenetic mechanisms underlying COVID-19-related AKI in order to provide an appropriate individual therapeutic strategy to improve clinical outcomes and limit the progression of early disease.