Use Of Regional Citrate Anticoagulation Research Articles

Management of regional citrate anticoagulation in pediatric high-flux dialysis: activated coagulation time versus post-filter ionized calcium

Recent years has seen an increasing use of regional citrate anticoagulation in pediatric dialysis. Several approaches have been described for monitoring anticoagulation in the extracorporeal circuit, such as serum citrate levels, post-filter ionized calcium (iCa), and activated coagulation time (ACT). However, no standard recommendations have yet been established for applying any of these parameters, especially for iCa. The objective of this retrospective analysis was to establish adequate coagulation management using post-filter iCa values. Normal values for ACTester-based ACT were established using a group of 64 children who were divided into two subgroups, with one subgroup comprising children without chronic kidney disease or coagulation disorder (age 1.2-17.5 years, median 9.7 years) and one consisting of 32 uremic patients (age 0.6-17.5 years, median 13.7 years). In a second group of 13 patients (aged 7-17 years), all of whom were undergoing high-flux dialysis (HD) with regional citrate anticoagulation (RCA), we assessed 73 post-filter blood samples for ionized calcium and ACT. A receiver operating characteristic graph was used to identify the iCa threshold needed to achieve adequate anticoagulation. Normal values for ACT were 90 s [2 standard deviations (SD) 72-109] in healthy children and 94 s (2 SD 75-113) in the uremic children. There was no statistically significant difference between the groups. In the children undergoing HD with RCA, the post-filter iCa level correlated with ACT (r = -0.94, p < 0.001). A post-filter iCa level of < or = 0.30 mmol/l reliably predicted an ACT >120 s. Our citrate protocol [citrate 3% rate (ml/h) approximately blood flow rate (ml/min) x 2] meets the established criteria with a high sensitivity. Based on these results, we conclude that the post-filter iCa level can be reliably used for the management of extracorporeal anticoagulation with citrate in pediatric HD. We recommend the application of our citrate prescription protocol in the setting of pediatric intermittent hemodialysis.

Regional Citrate Anticoagulation for PrismaFlex Continuous Renal Replacement Therapy

Since Mehta et al. reported the first successful use of regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) in 1990, RCA is increasingly used for CRRT because it provides filter patency with minimal risk of bleeding. However, RCA has been associated with significant metabolic complications including hypocalcemia, hypernatremia, metabolic alkalosis, and citrate toxicity. To describe our experience with a newly implemented RCA protocol with acid citrate dextrose formula A (ACD-A) and intravenous calcium gluconate, for use with PrismaFlex CRRT in critically ill patients with acute kidney injury. A retrospective chart review was conducted from May 1, 2006, until May 1, 2007, in a 16-bed medical-surgical university-affiliated intensive care unit. Data collected included dialysis filter life, patient and circuit metabolic parameters, and units of packed red blood cells transfused. Forty-eight patients received dialysis with citrate (n = 178 filters). Circuit clotting occurred in 24% of all filters. Mean +/- SD filter life was 38.4 +/- 25.9 hours, and filter survival at 48 hours was 38.2%. Persistent metabolic alkalosis while on CRRT was identified in 6 of 45 (13.3%) patients. Mild hypocalcemia (ionized calcium <3.6 mg/dL) occurred in 11 (23%) patients, but no patient had an ionized calcium level less than 2.8 mg/dL. Six patients, 3 with acute leukemia, required transfusion of 2 or more units of packed red blood cells in 24 hours. We found that anticoagulation of PrismaFlex CRRT with ACD-A and intravenous calcium gluconate provided reasonable filter patency, but with minor metabolic complications. Close monitoring of electrolyte and acid-base balance is required to minimize metabolic derangements.

The use of regional citrate anticoagulation for continuous venovenous hemodiafiltration in acute kidney injury

Continuous renal replacement therapy is commonly used in the treatment of acute kidney injury. Although the optimal anticoagulation system is not well defined, citrate has emerged as the most promising method. We evaluated the data of 143 patients with acute kidney injury subjected to citrate-based continuous venovenous hemodiafiltration. Retrospective cohort study. Intensive care unit of tertiary care private hospital. Patients with acute kidney injury treated from February 2004 to July 2006. None. The main cause of acute kidney injury was sepsis (58%). The mean dialysis dose was 36.6 mL/kg/hr allowing for excellent metabolic control (last tests: creatinine, 1.1 mg/dL; urea, 46 mg/dL). No significant bleeding, severe electrolyte, or calcium disorders were observed. Of the 418 filters used, almost 28,000 hrs of treatment, hemofilter patency was 68% at 72 hrs. Hospital mortality was 59%, and 22% of survivors were dialysis-dependent at the time of discharge. Within our sample, we identified 21 patients with liver failure (mean prothrombin time index, 21% vs. 67%, p < 0.001). This group presented with a lesser median systemic ionized calcium level (1.06 vs. 1.12 mmol/L, p < 0.001) and similar mean total calcium level (8.5 vs. 8.6 mg/dL, not significant), compared with patients without liver failure. These subjects also showed acidemia (median pH, 7.31 vs. 7.40, p < 0.001); however, they exhibited higher levels of lactate (median 29 vs. 16 mg/dL, p < 0.001), chloride (mean 109 vs. 107 mEq/L, p = 0.045) and had a trend to higher mortality rate (76% vs. 56%). Besides a trend toward higher mortality rate observed in the group with liver failure, we found that citrate-based continuous venovenous hemodiafiltration allowed an effective dialysis dose and reasonable filter patency.

Choice of replacement solution and anticoagulant in continuous venovenous hemofiltration

Several types of replacement fluid and methods of anticoagulation have been employed for continuous renal replacement therapy, but there is no consensus on a preferred approach. We evaluated the indications for the selection of replacement fluid and anticoagulant among critically ill patients receiving continuous venovenous hemofiltration (CVVH) and assessed the effect of the selection on the efficacy of anticoagulation and complications. We retrospectively studied 29 consecutive patients who received CVVH in the Medical Intensive Care Unit at Massachusetts General Hospital. There were 3 types of replacement solution available, an isotonic citrate solution which was also used for regional anticoagulation of the extracorporeal circuit, and bicarbonate and lactate solutions which were used with low-dose heparin or no anticoagulant. Blood flow rate was set at 120 ml/min when citrate replacement fluid was used and at 200 ml/min with bicarbonate or lactate. The replacement fluid was administered proximal to the hemofilter at a constant rate of 1,600 ml/h. There were 22 patients who received citrate replacement fluid which was mainly chosen for the purpose of anticoagulation in the setting of contraindications to heparin. 12 patients received bicarbonate, predominantly when citrate was considered contraindicated due to liver failure or high-anion gap metabolic acidosis, and 2 received lactate; 8 of these 14 patients were anticoagulated with heparin and 6 were managed without anticoagulation. There were 44 filters used in the patients receiving citrate with a median filter life of 42.0 (interquartile range 22.2 - 70.7) hours. Only 8 of the 44 filters were lost due to clotting. Heparin was used for anticoagulation of 17 filters and no anticoagulation was used in the case of 15 filters, resulting in a median filter life of 43.0 (13.5 - 75.0) and 12.0 (4.0 - 33.0) hours, respectively. Clinically significant bleeding occurred in 2 patients, 1 receiving citrate and another receiving heparin. No patient had evidence for citrate toxicity, metabolic alkalosis or hypernatremia. 14 (48.3%) patients survived. The use of regional citrate anticoagulation of the CVVH circuit appears advantageous in patients with increased risk of bleeding and bicarbonate-based replacement fluid seems desirable in patients with lactic acidosis due to shock and/or severe liver failure. Tailoring the type of replacement fluid and method of anticoagulation to the individual patient leads to long filter lives, excellent metabolic control and minimal complications.