ABSTRACT
Background: Severe coronavirus disease 2019 (COVID-19) not only causes acute pulmonary pathology leading to acute respiratory distress syndrome needing intubation, but also leads to acute kidney injury (AKI) requiring renal replacement therapy (RRT). Due to hemodynamic instability, these patients (pts) often need either continuous RRT (CRRT) or prolonged intermittent RRT (PIRRT). Accelerated Veno-Venous Hemodialysis (AVVHD), a form of PIRRT with typically 40-50 liter of dialysate used over 8-10 hours has been successfully used to treat hemodynamically unstable pts. In the past, we have published extracorporeal circuit clotting (ECC) to be low (5%) even without anticoagulation. However as hypercoagulability is extreme with COVID-19, we noticed a marked increase in ECC. Unfractionated heparin (UFH) was the initial anticoagulation of choice during the early phase of the pandemic but was ineffective in preventing ECC, prompting a trial of low molecular weight heparin (LMWH). Methods: We conducted a single-center retrospective study to evaluate the efficacy and safety of LMWH vs UFH in preventing ECC in pts with AKI due to COVID-19 who received AVVHD from 3/25/20 through 4/30/20 at a large academic medical center. Data collected included pt demographics, type of anticoagulation and thrombolytic use, treatment characteristics including clotting frequency as well as bleeding complications. ECC was defined as any event that required an unexpected interruption in treatment or the use of thrombolytics. Results: A total of 58 pts received 408 AVVHD treatments. The average pt age was 58 years, 65% were male, 66% were black and 69% were obese with body mass index >;30 kg/m2. 188/408 (46%) of AVVHD treatments received anticoagulation with UFH while 165/408 (40%) of treatments received LMWH. ECC occurred in 30% of AVVHD treatments who received UFH vs 15% in the LMWH group, a relative risk reduction of 50% (P = 0.001). 47.1% pts who were on UFH had ECC on the first RRT treatment compared to 13.6% on LMWH (P = 0.01). Only 1 pt experienced a major bleeding event in the UFH group and none with LMWH. Conclusions: Anticoagulation with LMWH is superior to UFH in reducing ECC in pts receiving AVVHD for AKI due to COVID-19 without an increased risk of bleeding.