Continuous Renal Replacement Therapy among Patients with COVID-19 and Acute Kidney Injury

Abstract

Background and objectives: Acute kidney injury (AKI) is a common complication among patients with COVID-19 and acute respiratory distress syndrome. Reports suggest that COVID-19 confers a pro-thrombotic state, which presents challenges in maintaining hemofilter patency and delivering continuous renal replacement therapy (CRRT). We present our initial experience with CRRT in critically ill patients with COVID-19, emphasizing circuit patency and the association between fluid balance during CRRT and respiratory parameters.

Design, setting, participants, and measurements: Retrospective chart review of 32 consecutive patients with COVID-19 and AKI managed with continuous venovenous hemodiafiltration with regional citrate anticoagulation (CVVHDF-RCA) according to the University of Michigan protocol. Primary outcome was mean CRRT circuit life per patient during the first 7 days of CRRT. We used simple linear regression to assess the relationship between patient characteristics and filter life. We also explored the relationship between fluid balance on CRRT and respiratory parameters using repeated measures modeling.

Results: Patients' mean age was 54.8 years and majority were Black (75%). Comorbidities included hypertension (90.6%), obesity (70.9%) diabetes (56.2%), and chronic kidney disease (40.6%). Median CRRT circuit life was 53.5 [interquartile range 39.1-77.6] hours. There was no association between circuit life and inflammatory or pro-thrombotic laboratory values (ferritin p = 0.92, C-reactive protein p = 0.29, D-dimer p = 0.24), or with systemic anticoagulation (p = 0.37). Net daily fluid removal during the first 7 days of CRRT was not associated with daily (closest recorded values to 20:00) PaO2/FIO2 ratio (p = 0.21) or positive end-expiratory pressure requirements (p = 0.47).

Conclusions: We achieved adequate CRRT circuit life in COVID-19 patients using an established CVVHDF-RCA protocol. During the first 7 days of CRRT therapy, cumulative fluid balance was not associated with improvements in respiratory parameters, even after accounting for baseline fluid balance.

Keywords: Acute kidney injury; Acute respiratory distress syndrome; Continuous renal replacement therapy; Coronavirus disease 2019.