By Dr Lui Mei Sze, Macy, ICU of QMH
Introduction: Regional citrate anticoagulation (RCA) is effective in prolonging filter function, and confers less risk of bleeding. In recent years, commercial preparation of citrate-containingreplacement solution is available which facilitates wider use of RCA in critically ill patientswith improved metabolic profile.
Objectives: To assess thefeasibility andsafety of a protocol using Prismocitrate 18/0(GambroDasco, Sondalo, Italy),a new formulation of pre-dilution replacement solution with altered citrate content,coupled with calcium-free dialysate (Prism0cal B22) for continuous venovenoushemodiafiltration in patients admitted to the Adult Intensive Care Unit (AICU)
Methods: Asian medical patients admitted to the AICUof Queen Mary Hospital who were indicated for continuous renal replacement therapy were invited. Those with significant liver impairment, history of advanced cirrhosis, septic shock refractory to high dose vasopressor, were excluded. The protocol adopted fixed flow rates of blood and Prismocitrate 18/0 (pre-dilution replacement) at 120ml/minute and 1000ml/hourrespectively. Dialysate (Prism0cal B22) flow rate was adjusted according to body weight to achieve the ultrafiltration dose of 25-35 ml/kg/hour. Normal saline ran at 100ml/hour as the post-dilution solution. CVVHDF is performed using Prismaflex machine with AN69 ST 100filter (GambroIndustries). Pre-filter and post-filter calcium levels targeted between 0.3-0.5 mmol/l. Calcium chloride 10% was infused to keep serum ionized calcium level between 1.0-1.2mmol/l.
Results: 31 eligible subjects (16 males, 15 females, age 26-85) with 32 sessions were analysed. Five sessions were withdrawn. The pre and post-filter ionized calcium were consistent between 0.3-0.5mmol/l. 23 sessions completed the CVVHDF therapy without filter clotting, with median filter lifespan 29.5 hours (interquartile range 14-39). Filter clotting was reported in 3 subjects, after CVVHDF for 26, 38, 53 hours respectively. Catheter malfunction were found in 2 of the cases with filter clotted. Among the cohort, no disturbance in sodium level was reported. No adverse events related to hypocalcemia, hypophosphatemia, hypomagnesemia or citrate accumulation were reported in the study subjects. Mild hypophosphatemia and hypomagnesemia developed mainly after prolonged CVVHDF (>24 hours). Baseline lactate level ≥ 4.5 mmol/l was found to be a sensitive marker of intolerance to the citrate CVVHDF regimen with acidemia. Metformin-associated lactic acidosis (MALA) was an exception.
Conclusion: The current CVVHDF protocol using Prismocitrate 18/0 as replacement solutionand Prism0cal B22 dialysateis feasible and safe.