Regional Citrate Anticoagulation for High Volume Continuous Venovenous Hemodialysis in Surgical Patients With High Bleeding Risk

Abstract

Acute kidney injury requiring renal replacement therapy occurs in up to 10% of all intensive care unit patients. Those who are hemodynamically unstable are often treated with continuous renal replacement therapy requiring continuous anticoagulation of the extracorporeal circuit. This is usually achieved by infusion of unfractionated heparin, which subsequently increases the risk of bleeding. To avoid systemic anticoagulation for continuous renal replacement therapy, regional anticoagulation with citrate has been introduced. We studied safety and efficacy of regional citrate anticoagulation for continuous venovenous hemodialysis in surgical patients requiring high dialysis doses. This was an observational prospective study in a 40-bed surgical intensive care unit at a university hospital. During a 12-month study period, all consecutive critically ill patients with high risk of bleeding requiring continuous renal replacement therapy continuous renal replacement therapy were treated with citrate anticoagulation for continuous venovenous hemodialysis. Prescribed dialysis dose was 45 mL/kg per h with a 10% increase for expected downtime. We studied filter lifetime, delivered dialysis dose, control of acid-base status, bleeding episodes, and adverse effects, that is, citrate intolerance. The total number of filters analyzed in 75 patients was 100. Mean (± standard deviation) filter running time was 78 ± 25 h. Fifty-one circuits had to be renewed because of extended filter running time (96 ± 18 h), 33 discontinued for reasons not related to renal replacement therapy (62 ± 19 h), and 13 due to filter clotting (58 ± 18 h). The mean dialysis dose during the first 72 h was 49 ± 14 mL/kg per h. Overall, acid-base status after 72 h was well controlled in 62% of patients, metabolic alkalosis (pH > 7.45) occurred in 29%, and metabolic acidosis (pH < 7.35) in 9%. In one patient, treatment was stopped because of citrate accumulation. Citrate intoxication or overt bleeding episodes were not observed. Regional citrate anticoagulation for continuous venovenous hemodialysis is a safe and effective method to deliver a high dialysis dose in critically ill patients with a high risk of bleeding. Filter patency was excellent, acid-base status was well controlled, and clinically relevant adverse effects were not observed. Therefore, citrate anticoagulated continuous venovenous hemodialysis is a useful treatment option for patients with acute kidney injury requiring high dialysis doses and at risk of bleeding.

Regional Citrate Anticoagulation for Continuous Renal Replacement Therapy in the Perioperative Care of Liver Transplant Recipients: A Single Center Experience

“…Here, 29% of patients developed metabolic alkalosis after 72 h of dialysis treatment. The authors argue, that beside citrate metabolism, also compensation of a pre‐existing metabolic acidosis related to renal failure could lead to subsequent alkalosis in this critically ill patient cohort and thus metabolic control should be monitored carefully . This would perfectly fit to our patient cohort: while on dialysis day 1 almost 32% of the patients suffered from metabolic acidosis, acid‐base status stabilized to normal values or mild alkalosis during the following days.…”

Regional Citrate Anticoagulation for RRTs in Critically Ill Patients with AKI

“…Conversely, as in the case of metabolic acidosis, an increase in the buffer supply to the patient can be achieved by increasing the citrate load throughout a parallel rise of blood and citrate flow rates (46). This approach permits flexibility in the management of acid-base status, but it may result in the development of metabolic acidosis if a high dialysis dose is required (high diffusive removal of buffers related to the increase of low-bicarbonate dialysate flow rate) (46,49). A different approach, using pharmacymade solutions, was adopted to perform RCA in continuous venovenous hemofiltration (CVVH).…”

“…Although the use of standard sodium concentration CRRT solutions has also been reported in RCA protocols adopting hypertonic citrate formulations (68,69), these solutions are usually combined with customized low-sodium dialysis/replacement fluids to prevent hypernatremia. As long as a well designed protocol is implemented, hypertonic citrate solutions can be used to perform RCA with all modalities of CRRT ( Figure 2, Table 1) (15,16,18,46,47,49). RCA protocols based on hypertonic citrate solutions use citrate as the primary buffer, regardless of CRRT modality.…”

“…Citrate accumulation represents the most common complication of RCA, with a reported incidence of 0%-12% of patients depending on the RCA protocol used and the patient case mix (14,16,18,19,(44)(45)(46)(47)(48)(49)(50)(51). Because hepatic clearance represents the main metabolic fate of endogenous and exogenous citrate, citrate metabolism may be significantly slowed in clinical conditions where liver function is impaired, with a higher risk of citrate accumulation and consequent acid-base and electrolyte complications.…”

Extracorporeal Membrane Oxygenation in Diffuse Alveolar Hemorrhage Secondary to Systemic Lupus Erythematosus

“…The use of regional citrate anticoagulation in critically ill patients at increased risk for bleeding requiring CVVH is a recognized alternative [8, 9]. This alternative to anticoagulation with an ECMO circuit has preliminarily been explored in animal studies [10] where no clot formation was noted in circuits after 24 h, but further studies are required in human subjects.…”