Evolution of continuous renal replacement therapy scenarios and the rise of anticoagulant-free continuous veno-venous hemodiafiltration

PURPOSE OF REVIEW: Continuous renal replacement therapy (CRRT) is an essential support modality for patients with acute kidney injury (AKI) and hemodynamic instability. Circuit clotting remains a major limitation to efficacy. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend regional citrate anticoagulation (RCA) as the preferred method of anticoagulation in CRRT for patients without contraindications. The guidelines also emphasize tailoring anticoagulation strategies to individual patient needs and institutional capabilities. RECENT FINDINGS: Strategies to prevent CRRT circuit clotting can be broadly categorized into nonpharmacological and pharmacological approaches after optimization of blood flow rate, catheter function and CRRT modality. Nonpharmacological methods include prefilter dilution and intermittent saline flushes. Pharmacological strategies include systemic heparin and RCA. Heparin remains the most widely used anticoagulant globally due to its availability and low cost; however, citrate is favored for its safety profile, including use in patients with liver failure in the absence of shock.Despite KDIGO recommendations, utilization of RCA remains limited in the United States. In a recent survey, only 28% of patients received citrate during CRRT, while 29% received no anticoagulation. Notably, U.S. nephrologists reported managing approximately 41% of CRRT patients without anticoagulation. Within our hospital network, prefilter dilution is the most common strategy for anticoagulation. We present case-based scenarios to illustrate practice variation and to support efficient decision-making when managing critically ill patients requiring urgent CRRT initiation. SUMMARY: Both heparin and RCA are effective anticoagulation strategies in CRRT, with RCA preferred for its favorable safety profile. Nonetheless, nearly half of U.S. nephrologists report providing CRRT without anticoagulation. In our practice, we typically initiate CRRT without anticoagulation and reserve pharmacological agents for cases complicated by frequent filter clotting.