A Practical Citrate Anticoagulation Continuous Venovenous Hemodiafiltration Protocol for Metabolic Control and High Solute Clearance

Abstract

Obstacles to the widespread use of continuous renal replacement therapy (CRRT) include the need for anticoagulation, customized solutions, and complex protocols that carry an attendant risk for error, raise cost, and increase pharmacy and nursing workload. However, high solute clearance using CRRT with an effluent rate of 35 ml/kg per h has also recently been associated with improved survival in critically ill patients with acute renal failure. No published CRRT protocols using dilute regional citrate anticoagulation have achieved adequate metabolic control, effective anticoagulation, and high solute clearance in a practical, user-friendly, and economical manner. The safety and the efficacy of continuous venovenous hemodiafiltration at effluent rates of 35 ml/kg per h in critically ill acute renal failure patients were evaluated prospectively using a standardized bicarbonate-based dialysate; a systemic calcium infusion; and two separate trisodium citrate replacement solutions, a 0.67% solution and a 0.5% solution. All patients achieved adequate metabolic control, the desired effluent rate of 35 ml/kg per h, and high solute clearance. Use of the 0.67% citrate replacement solution resulted in mild alkalosis, whereas the 0.5% solution maintained appropriate acid-base balance. There was no difference in dialyzer survival between the 0.67 and 0.5% citrate groups (80 versus 82%; P ‫؍‬ 0.60, Kaplan-Meier analysis). Dilute regional citrate as part of a CRRT protocol with a standard 25-mmol/L bicarbonate dialysate provides adequate metabolic control, high diffusive and convective clearance, and excellent dialyzer patency in a practical and cost-effective manner.

Regional Citrate Anticoagulation for RRTs in Critically Ill Patients with AKI

“…with exposure of patients to different electrolyte and buffer combinations, significantly affecting acid-base status and electrolyte balance during RCA (46,62,65,66). For the sake of simplicity, RCA solutions may be classified on the basis of citrate concentration as high-and lowconcentration solutions, with high citrate concentrations corresponding to hypertonicity with regard to sodium.…”

“…The physiologic sodium content of isotonic solutions allows RCA CVVH or RCA CVVHDF without the need of a low-sodium replacement fluid and/ or dialysate (Table 1). In protocols using citrate-buffered replacement solutions, the buffer supply derives from citrate (predilution CVVH) or citrate and bicarbonate in various proportions (predilution and postdilution CVVH and CVVHDF) in relation to the composition and the combination of the solutions that are used (14,19,50,62,(64)(65)(66)(67). A simplification on the basis of the use of solutions with an appropriately low citrate concentration allows RCA CRRT as CVVH in the predilution-only modality (19,50).…”

Renal replacement therapy review

“…Citrate is metabolized by the liver to ~3 moles of bicarbonate, and hence, the infusion may induce hypernatremic alkalosis. Low concentration citrate protocols have been developed to prevent these complications 137 as have protocols for other modalities, such as high-flux hemodialysis and SLED. [138][139][140] In patients with liver disease, citrate may accumulate if citrate infusion is greater than total clearance (filter and liver combined), and this complication may have significant effects in pediatric patients who often experience hypotension with hypocalcaemia.…”

Profound hypocalcaemia in a patient being anticoagulated with citrate for continuous renal replacement therapy

“…Continuous renal replacement therapy was commenced using citrate to provide regional anticoagulation of the extracorporeal circuit because the patient deemed to be at high risk of bleeding. Our protocol is modelled on the original description by Tolwani et al [6] (Fig. 1).…”