Comparative Analysis of Fixed Versus Variable Rates of Regional Citrate Anticoagulation in Critically Ill Adult Patients on Continuous Kidney Replacement Therapy

Abstract

Background:

The Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guideline recommends regional citrate anticoagulation during continuous kidney replacement therapy (CKRT) to prolong circuit lifespan. Limited data directly compare citrate dosing strategies.

Objective:

Evaluate effectiveness and safety of fixed (FIX) versus variable (VAR) citrate rates in CKRT.

Methods:

This single-center, retrospective study evaluated adult ICU patients (≥18 years) receiving CKRT with regional citrate anticoagulation for ≥24 hours between July 2018 and June 2024. Patients with COVID-19 or whose citrate rate was inconsistent with the prescribed order were excluded. FIX versus VAR groups were case-matched based on ICU service, citrate duration, and age. The primary outcome was time from citrate initiation to first filter change. Secondary outcomes included hyper- and hypocalcemia, citrate toxicity, bleeding, and thrombosis.

Results:

Of 534 patients screened, 48 (24 FIX, 24 VAR) met inclusion criteria and matched closely in ICU service, citrate duration, and age. Time to first CKRT filter change was similar, 1.5 [0.7, 3.0] FIX versus 1.9 [0.5, 3.1] VAR, days, P = 0.89. Fewer hypocalcemia episodes were associated with FIX (72 vs 141 VAR, episodes, P < 0.0001), as was less calcium supplementation (36 FIX vs 142 VAR, grams, P = 0.0113). Bleeding and thrombosis events were similar between groups, 33% FIX vs 50% VAR (P = 0.19) and 25% FIX vs 13% VAR (P = 0.46), respectively.

Conclusion and Relevance:

Fixed and variable citrate rates showed similar effectiveness in CKRT. However, the fixed rate was associated with less hypocalcemia and calcium supplementation without a significant increase in bleeding or thrombosis. These findings contribute new comparative data to help guide citrate anticoagulation strategies and suggest that a fixed rate may help minimize electrolyte disturbances and simplify supplementation needs. Given that the study was potentially underpowered, further studies are needed to validate these findings and guide the development of optimal citrate rate guidelines.