Regional citrate anticoagulation in continuous venovenous hemofiltration in critically ill patients with a high risk of bleeding

Background. Systemic heparinization is associated with a high rate of bleed ing when used to maintain patency of the extracorporeal circuit during cont inuous renal replacement therapy (CRRT) in critically ill patients. Regiona l anticoagulation can be achieved with citrate, but previously described te chniques are cumbersome and associated with metabolic complications. Methods. We designed a simplified system for delivering regional citrate an ticoagulation during continuous venovenous hemofiltration (CVVH). We evalua ted filter life and hemorrhagic complications in the first 17 consecutive p atients who received this therapy at our institution. Blood flow rate was s et at 180 ml/min. Ultrafiltration rate was maintained at 2.0 liters/hr and citrate-based replacement fluid (trisodium citrate 13.3 mM, sodium chloride 100 mM, magnesium chloride 0.75 mM, dextrose 0.2%) was infused proximal to the filter to maintain the desired fluid balance. Calcium gluconate was in fused through a separate line to maintain a serum-ionized calcium level of 1.0 to 1.1 mM. Results. All patients were critically ill and required mechanical ventilati on and vasopressor therapy. Systemic heparin anticoagulation was judged to be contraindicated in all of the patients. A total of 85 filters were used, of which 64 were lost because of clotting, with a mean life span of 29.5 /- 17.9 hours. The remaining 21 filters were discontinued for other reasons . Control of fluid and electrolyte balance and azotemia was excellent (mean serum creatinine after 48 to 72 hr of treatment was 2.4 +/- 1.2 mg/dl). No bleeding episodes occurred. Two patients, one with septic shock and the ot her with fulminant hepatic failure, developed evidence for citrate toxicity without a significant alteration in clinical status. Nine patients survive d (52.9%). Conclusion. Our simplified technique of regional anticoagulation with citra te is an effective and safe form of anticoagulation for CVVH in critically ill patients with a high risk of bleeding.