The Impact of CRRT Modality on Filter Life
Lewis Mann, Iiro Honkanen, Rebecca L. Hegeman, Chou‐Long Huang, Prerna Kumar, Swe Zin Mar Winhtutoo, Christie P. Thomas, Melissa L. Swee, Benjamin Reed Griffin · Journal of the American Society of Nephrology · 2020
Background: Increasing CRRT filter lifespan would save money, decrease iatrogenic blood loss, increase the time CRRT is actively running, and waste less nursing time. Filter clotting is a common reason for filter loss that can potentially be reduced. CRRT can be performed using convective clearance as in CVVH or diffusive clearance as in CVVHD. Whether convection or diffusion prolongs filter life over the other is unknown, but there are plausible arguments for both. CVVHD has no significant hemoconcentration within the circuit, whereas CVVH is subject to hemoconcentration as fluid is removed across the filter. However, pre-filter CVVH results in hemodilution prior to entering the filter that may mitigate the effects of the filter hemoconcentration. We hypothesize that filter life is longer in patients treated with CVVHD than CVVH. Methods: In this unblinded prospective randomized trial, patients are assigned to either pre-filter CVVH or CVVHD. The standard treatment protocol at the University of Iowa is to use citrate anticoagulation with a blood flow rate of 200 mL/min and a dose of 25 mL/kg/hr. Using a power of 0.8 and an alpha of 5%, and historical filter loss attributable to clotting of 60%, a total of 1,010 filters are needed to show a hazard ratio of at least 1.3 for filter loss. The primary outcome is average filter life, and secondary outcomes are mortality, intensive care unit LOS, hospital LOS, and renal recovery. Results: Beginning March 25, 2020, we have enrolled 30 patients using a total of 90 filters (Table 1). The average filter life in CVVH filters is 36.8 ± 26.8, compared to 37.0 ± 31.9 hours in CVVHD filters (p=NS).Table 1:: Patient characteristicsConclusions: Data from 2 months of a planned 12-month prospective study comparing filter life in CVVH vs CVVHD shows no significant difference in filter life.