Dialysis circuit clotting in critically ill patients with COVID-19 infection

Background Coronavirus Disease 2019 (COVID-19) infection has been associated with a hypercoagulable state with increased reports of thrombotic events. Acute kidney injury requiring dialysis is common in critically ill patients and circuit clotting compromises efficacy of treatment. This study aims to analyze the circuit life and circuit clotting during continuous kidney replacement therapy (CKRT) and intermittent hemodialysis in patients with and without COVID-19. Methods This is a single-center, retrospective cohort study in critically ill patients undergoing CKRT or intermittent hemodialysis between 1 February 2020 to 22 May 2020. Patients in the intensive care unit (ICU) with COVID-19 infection and contemporary controls who tested negative were included. Co-primary outcomes were functional circuit life for patients on CKRT and all circuit clotting events for patients on CKRT and/or intermittent hemodialysis. Results Seventy CKRT circuits and 32 intermittent hemodialysis sessions for 12 COVID-19 cases and 22 CKRT circuits and 18 intermittent hemodialysis sessions for 15 controls were analyzed. CKRT circuit clotting was more common in the COVID-19 group compared to the control group (64% vs 36%, p = 0.02), despite higher anticoagulation use in the COVID-19 group (41% vs 14%, p = 0.02). Functional CKRT circuit life was similar in COVID-19 patients and controls (median 11 vs 12 h, p = 0.69). On Cox regression analysis, circuit clotting was similar with hazard ratio (HR) 1.90 [95% confidence interval (CI): 0.89-4.04]; however, clotting was increased in COVID-19 patients after adjustment for anticoagulation use (HR: 3.31 [95% CI 1.49-7.33]). In patients with COVID-19, CKRT circuits with anticoagulation had a longer circuit life compared to CKRT circuits without anticoagulation (median 22 versus 7 h respectively, p < 0.001). Circuit clotting was similar in both groups undergoing intermittent hemodialysis. Conclusion Dialysis clotting amongst COVID-19 patients is increased despite more anticoagulation use and the hazard for clotting is greater especially after adjusting for anticoagulation use. Circuit life was suboptimal in COVID-19 patients on circuits without anticoagulation and therefore routine use of anticoagulation amongst COVID-19 patients should be considered whenever possible.