Introduction:
Dialysis adequacy is crucial for improving survival in patients with acute kidney injury (AKI) requiring dialysis. This can be achieved by using anticoagulants to extend hemofilter lifespan and ensure sufficient clearance. However, many patients on continuous renal replacement therapy (CRRT) are not prescribed anticoagulants due to various contraindications, and there is still limited evidence on the factors associated with hemofilter clotting in these patients.
Methods:
We conducted a prospective study to evaluate the relationships between various factors and filter clotting in non-anticoagulant CRRT, including CRRT downtime, conventional filtration fraction (FF), filtration fraction calculated form pre- and post-filter hematocrit (FFHct) and post-filter hematocrit. Factors related to hemofilter clotting were documented at baseline and every 8 hours for up to 72 hours or until filter loss.
Results:
We enrolled 80 patients, using a total 172 filters over 212 patient-days. The average age of the patients was 67.4 ± 16.3 years, with 47.5% being female. Acute tubular necrosis was the leading cause of AKI (86.3%), and septic shock was the predominant diagnosis (87.5%). The right common femoral vein was the most commonly used access site (52.5%). The median lifespan of the hemofilter was 18.5 hours (IQR 11.8-30.1). There was no significant difference between continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodiafiltration (CVVHDF), with lifespans of 15.75 hours (IQR 11.25-25.67) and 21.08 hours (IQR 13.67-30.42), respectively (P=0.095). Of the 172 hemofilters, 152 clotted before reaching 72 hours of use. Hemofilter changes due to clotting were the primary cause of CRRT downtime exceeding one hour per day. Univariate analysis identified baseline factors significantly associated with reduced hemofilter lifespan, including conventional FF, platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT). Factors significantly associated with hemofilter clotting closest to the time of occurrence included FFHct and transmembrane pressure (TMP). In contrast, baseline FFHct, CRRT mode and dose, vascular access site, arterial and venous circuit pressures during CRRT, and post-filter Hct were not significantly associated with hemofilter survival. However, after multivariate analysis, the factors that remained independently associated with a decreased hemofilter lifespan were baseline platelet count >100,000/µl (HR 2.08, 95%CI 1.37-3.16, P=0.001), baseline PT < 20 seconds (HR 2.08, 95%CI 1.37-3.17, P=0.001), and TMP > 200 mmHg at time nearest to hemofilter clotting (HR 1.52, 95%CI 1.05-2.19, P=0.03).
Conclusions:
In AKI patients undergoing CRRT without anticoagulants, those with low baseline platelet counts and prolonged PT/aPTT shows a significant association with longer hemofilter lifespan. Monitoring TMP during CRRT is essential, as filter clotting is likely if TMP exceeds 200 mmHg. Conventional FF may not effectively identify premature hemofilter clotting, tracking post-filter hematocrit and FFHct may also be unnecessary in populations similar to ours.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.