Background Coronavirus disease 2019 (COVID-19) patients who are admitted to intensive care units (ICU) have a high risk of requiring renal replacement therapy (RRT) due to acute kidney injury (AKI). Concomitantly, COVID-19 patients exhibit a state of hypercoagulability that can affect circuit lifespan. An optimal anticoagulation strategy is therefore needed in order to maintain circuit patency and therapeutic efficiency of RRT. Methods Retrospective single-centre cohort study on 71 critically ill COVID-19 patients at the University of Freiburg Medical Center. Included were all patients aged 18 years and older with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection that were admitted to ICU between February 26 and May 21, 2020. We collected data on the COVID-19 disease course, AKI, RRT, thromboembolic events and anticoagulation. Primary outcome of the study was the effect of different anticoagulation strategies during RRT on extracorporeal circuit lifespans. Results Anticoagulation during continuous veno-venous haemodialysis (CVVHD) was performed with unfractionated heparin (UFH) or citrate. Mean treatment time in the UFH group was 21.3h (SEM: {+/-}5.6h). Mean treatment time in the citrate group was 45.6h (SEM: {+/-}2.7h). Citrate anticoagulation prolonged treatment duration significantly by 24.4h (p=0.0014). Anticoagulation during sustained low-efficiency daily dialysis (SLEDD) was performed with UFH, argatroban or low molecular weight heparin (LMWH). Mean dialysis time with UFH was 8.1h (SEM: {+/-}1.3h), argatroban 8.0h (SEM: {+/-}0.9h) and LMWH 11.8h (SEM: {+/-}0.5h). Compared to UFH and argatroban, LMWH significantly prolonged treatment times by 3.7h (p=0.0082) and 3.8h (p=0.0024), respectively. Conclusions UFH fails to prevent early clotting events in dialysis circuits. For patients, who do not require an effective systemic anticoagulation, regional citrate dialysis is the most effective strategy in our cohort. For patients, who require an effective systemic anticoagulation treatment, the usage of LMWH results in the longest circuit life spans.
Superior anticoagulation strategies for renal replacement therapy in critically ill patients with COVID-19: a cohort study