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

Abstract

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.

A Target-Oriented Algorithm for Citrate-Calcium Anticoagulation in Clinical Practice

“…Figure 7 shows that a Ca 2+ level of about 0.2 mmol/l inhibits coagulation, whereas a Ca 2+ concentration of <0.4 mmol/l might not suppress coagulation sufficiently. These findings are in accordance with those of Kreuzer et al [40] and Opatrny et al [43]. The latter found no prolonged ACT at a post-filter Ca 2+ level slightly lower than 0.4 mmol/l compared to the patient Ca 2+ .…”

“…In agreement with Kreuzer et al [40] and our in vitro study [41,42], we could show that Ca 2+ predicts the anticoagulation status determined by ACT, which reflects the entire plasmatic coagulation cascade as well as platelet function. Therefore, we used samples of the patients from the extracorporeal circuit pre-filter as well as after calcium infusion.…”

Regional citrate anticoagulation—a safe and effective procedure in pediatric apheresis therapy

“…In all patients, the citrate (3%) to blood flow ratio was started at 1:25 (= 4.0% of blood flow) and subsequently adapted during the course of the session to match post-filter ionized calcium levels ≤0.30 mmol/l. The rate was calculated to achieve a citrate plasma level of about 6 mmol/l, which is needed for sufficient anticoagulation [12,13]. The patients' ionized calcium levels were monitored closely.…”

A Target-Orientated Algorithm for Regional Citrate-Calcium Anticoagulation in Extracorporeal Therapies

“…For sufficient anticoagulation, iCa levels of 0.2–0.4 mmol/l are necessary in the extracorporeal circuit [8,9,10,11,12]. Kreuzer et al [13] found that a postfilter iCa of <0.3 mmol/l corresponds to an activated clotting time of >120 s. Our own investigations confirmed a highly significant correlation between iCa and activated clotting time in vitro, which clearly demonstrates the importance of focusing on iCa as a target in regional citrate anticoagulation [14]. The use of calcium-free dialysate prevents an increase in iCa within the filter.…”

“…Since the reduction in iCa concentration is limited to the extracorporeal circuit, this type of anticoagulation is called regional anticoagulation. The rate of calcium infusion depends on the systemic iCa level in the patient as well as on the calcium clearance of the dialyzer [13]. The target range for a patient’s systemic blood iCa level is generally 1.1–1.3 mmol/l [15,16].…”