Blood purification in a critically ill COVID-19 patient with cytokine storm: A case report

Introduction: Cytokine storm syndrome (CSS) is a common and severe cause of mortality among critically ill COVID-19 patients. BPTs, especially continuous renal replacement therapy (CRRT), may work by removing cytokines and blocking the cascade of inflammation and thus preventing the progression of CSS. However, the efficacy of Blood purification therapies (BPTs) in patients with complications of CSS but without AKI(Acute kidney injury) is still controversial. Case Description: We report the case of a 66-year-old female who had severe COVID-19 without AKI. After admission, the patient's condition progressed rapidly to severe respiratory failure and heart failure, and she had been treated with venousvenous extracorporeal membrane oxygenation (VV-ECMO). Meanwhile, the level of interleukin-6 (IL-6) increased rapidly and reached 304.8 pg/ml. Although there was no kidney impairment in our patient, CRRT was initiated to reduce the levels of cytokines in circulation, while the decrease in IL-6 in serum and dialysate was not significant. Oxiris-CRRT was then introduced and there was a significant decline in serum levels of IL-6 after 3 Oxiris-CRRT sessions. However, when we stopped Oxiris-CRRT after the third treatment, the serum levels of IL-6 were elevated again 12 hours after the suspension of Oxiris-CRRT Subsequently. Therefore, the patient received 6 additional Oxiris-CRRT sessions until the serum IL-6 levels of 2.67 pg/ml. After 144 days of hospitalization, including 2 CRRT sessions, 9 Oxiris-CRRT sessions and 2 therapeutic plasma exchange (TPE) sessions, she completely recovered (shown in Fig. 1). Discussion: In our patient, BPTs, especially Oxiris-CRRT, showed unique superiority and application value in the clearance of excess plasma cytokines, promoting a smooth recovery, which suggests that even if AKI does not occur, it is beneficial to use BPTs to prevent the progression of CSS in COVID-19 patients.