title: 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.
abstract: 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-Ca(2+) (≤ 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-Ca(2+) 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-Ca(2+). The introduction of a phosphate-containing solution, in the setting of RCA, significantly reduced CRRT-related phosphate depletion.
authors.affiliation: Department of Nephrology and Urology, Hemodialysis Unit, Umberto I, Policlinico di Roma, "Sapienza" University, Rome, Italy. santo.morabito@uniroma1.it.
authors.forename: Santo
authors.initials: S
authors.lastname: Morabito
authors.forename: Valentina
authors.initials: V
authors.lastname: Pistolesi
authors.forename: Luigi
authors.initials: L
authors.lastname: Tritapepe
authors.forename: Elio
authors.initials: E
authors.lastname: Vitaliano
authors.forename: Laura
authors.initials: L
authors.lastname: Zeppilli
authors.forename: Francesca
authors.initials: F
authors.lastname: Polistena
authors.forename: Enrico
authors.initials: E
authors.lastname: Fiaccadori
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pierucci
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058186:Acute Kidney Injury / Q000150:complications / Q000534:rehabilitation; D000925:Anticoagulants / Q000008:administration & dosage; D019343:Citric Acid / Q000008:administration & dosage; D003131:Combined Modality Therapy; D006440:Hemofiltration / Q000009:adverse effects / Q000379:methods; D006470:Hemorrhage / Q000209:etiology / Q000517:prevention & control; D006863:Hydrogen-Ion Concentration; D017674:Hypophosphatemia / Q000209:etiology / Q000517:prevention & control; D007261:Infusions, Intra-Arterial / Q000379:methods; D010710:Phosphates / Q000008:administration & dosage; D011292:Premedication / Q000379:methods; D012996:Solutions; D002985:Clinical Protocols
chemical_list: D000925:Anticoagulants; D019343:Citric Acid; D010710:Phosphates; D012996:Solutions