Continuous venovenous hemodiafiltration with a low citrate dose anticoagulation protocol

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#IVTEAM #Intravenous literature: Morabito, S., Pistolesi, V., Tritapepe, L., Vitaliano, E., Zeppilli, L., Polistena, F., Fiaccadori, E. and Pierucci, A. (2013) Continuous venovenous hemodiafiltration with a low citrate dose regional anticoagulation protocol and a phosphate-containing solution: effects on acid–base status and phosphate supplementation needs. BMC Nephrology. 14.

Abstract (provisional):

Background: Recent guidelines suggest the adoption of regional citrate anticoagulation (RCA) as first choice CRRT anticoagulation modality in patients without contraindications for citrate. Regardless of the anticoagulation protocol, hypophosphatemia represents a potential drawback of CRRT which could be prevented by the adoption of phosphate-containing CRRT solutions. The aim was to evaluate the effects on acid–base status and phosphate supplementation needs of a new RCA protocol for Continuous Venovenous Hemodiafiltration (CVVHDF) combining the use of citrate with a phosphate-containing CRRT solution.

Methods: To refine our routine RCA-CVVH protocol (12 mmol/l citrate, HCO3- 32 mmol/l replacement fluid) (protocol A) and to prevent CRRT-related hypophosphatemia, we introduced a new RCA-CVVHDF protocol (protocol B) combining an 18 mmol/l citrate solution with a phosphate-containing dialysate/replacement fluid (HCO3- 30 mmol/l, Phosphate 1.2). A low citrate dose (2.5–3 mmol/l) and a higher than usual target circuit-Ca2+ (<=0.5 mmol/l) have been adopted.

Results: Two historical groups of heart surgery patients (n = 40) underwent RCA-CRRT with protocol A (n = 20, 102 circuits, total running time 5283 hours) or protocol B (n = 20, 138 circuits, total running time 7308 hours). Despite higher circuit-Ca2+ in protocol B (0.37 vs 0.42 mmol/l, p < 0.001), circuit life was comparable (51.8 +/- 36.5 vs 53 +/- 32.6 hours). Protocol A required additional bicarbonate supplementation (6 +/- 6.4 mmol/h) in 90% of patients while protocol B ensured appropriate acid–base balance without additional interventions: pH 7.43 (7.40–7.46), Bicarbonate 25.3 (23.8–26.6) mmol/l, BE 0.9 (-0.8 to +2.4); median (IQR). No episodes of clinically relevant metabolic alkalosis, requiring modifications of RCA-CRRT settings, were observed. Phosphate supplementation was needed in all group A patients (3.4 +/- 2.4 g/day) and in only 30% of group B patients (0.5 +/- 1.5 g/day). Hypophosphatemia developed in 75% and 30% of group A and group B patients, respectively. Serum phosphate was significantly higher in protocol B patients (P < 0.001) and, differently to protocol A, appeared to be steadily maintained in near normal range (0.97–1.45 mmol/l, IQR).

Conclusions: The proposed RCA-CVVHDF protocol ensured appropriate acid–base balance without additional interventions, providing prolonged filter life despite adoption of a higher target circuit-Ca2+. The introduction of a phosphate-containing solution, in the setting of RCA, significantly reduced CRRT-related phosphate depletion.

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