Regional Citrate Anticoagulation for Continuous Venovenous Hemodiafiltration in Critically Ill Children with Acute Renal Failure † 1807

INTRODUCTION: Continuous renal replacement therapy (CRRT) is an important advance for the treatment of critically ill patients. A major problem with CRRT is the need for systemic anticoagulation with heparin. Recently we have adapted a new form of regional citrate anticoagulation for children requiring CRRT. This procedure uses continuous venovenous hemodiafiltration (CVVHDF). Anticoagulation is achieved in the extracorporeal circuit by infusing citrate directly into the blood as it leaves the patient. The citrate acts as an anticoagulant by chelating calcium. The effect of citrate is reversed in the patient's circulation by infusing calcium chloride, so that the patient's coagulation system is unaffected by the procedure.

METHODS: Twenty children received CVVHDF with regional citrate anticoagulation. All patients had acute renal failure. The ages of the patients ranged from one to 18 years. CVVHDF was performed with a Hospal Multiflow-60 hemofilter and a Cobe-Hospal BSM-222 machine. Four percent trisodium citrate was infused ino the blood as it left the patient; the infusion rate was adjusted to keep the post filter activated clotting time between 180 and 220 seconds. The patient's ionized calcium level was maintained in the normal range with a separate infusion of calcium chloride. A special dialysate was used to remove the calcium-citrate chelate and to offset the sodium given as trisodium citrate. The composition of the dialysate was sodium 117 meq/L, magnesium 1.5 meq/L, potassium 4 meq/L, chloride 122.5 meq/L and glucose 25 gm/L. Blood flow was 150 ml/minute/1.7 M².

RESULTS: Mean patient partial thromboplastin time (PTT) was 31.8 seconds(normal 25-35 seconds) indicating that the patients were not systemically anticoagulated by the procedure. Average patient serum ionized calcium was 1.19 mmol/L (normal 1.09 - 1.32). Mean hemofilter life was 3.5 days including elective changes. Mean dialyzer sieving coefficient was well maintained at 0.96. Ultrafiltration rate for the CVVHDF was 14 ml/minute/1.7 M². Mean urea clearance was 36 ml/minute/1.7 M². During CVVHDF the mean patient arterial pH was 7.38 and base excess 0.22.

CONCLUSION: Continuous venovenous hemodiafiltration can be performed in children with citrate anticoagulation. Citrate anticoagulation does not affect the patient's clotting system.