Anticoagulation Options for Pediatric Hemodialysis

Abstract

Blood coagulation in the extracorporeal hemodialysis circuit is one of the manifestations of bio-incompatibility that is related to the activation of monocytes, platelets, and the coagulation cascades. Compared to adults, in pediatric patients, the surface area of the extracorporeal circuit is increased relative to blood volume. This is due to the patient's smaller blood volume and the combination of the higher relative surface area of the dialyzer, smaller lumen lines, and small-bore vascular catheters, potentially increasing contact activation of coagulation proteins, platelets, and inflammatory cells. Although unfractionated heparin remains the most commonly used anticoagulant, low molecular weight heparin offers the advantages of a single bolus, less fibrin and platelet deposition in the dialyzer, and perhaps more importantly, less osteoporosis, hyperkalemia, and abnormal lipoprotein profile. Although regional anticoagulants are available, these are often prohibitively expensive or require increased complexity of the dialysis procedure (e.g., citrate), but have the advantage of reducing the risk of bleeding when compared to heparin. Thrombin inhibitors are now available, and with the advent of argatroban, which is metabolized in the liver, have become the anticoagulants of choice for the few patients who develop heparin-induced thrombocytopenia type II.

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

“…A receiver-operator characteristic graph calculated from our data showed that a post-filter iCa <0.30 mmol/l is needed to reliably achieve a post-filter ACT >120 s. In accordance with the published results of Calatzis et al [13], we found a hyperbolic relationship between post-filter coagulation time and postfilter iCa, with a high correlation between both parameters. We therefore recommend keeping the post-filter iCa <0.30 mmol/l for adequate anticoagulation in regional citrate anticoagulation, as supported by the recommendations of Ward and Davenport [11,20]. In our experience the post-filter iCa is a suitable parameter for monitoring anticoagulation of the extracorporeal circuit in RCA in iHD.…”

“…The ACT has also been advocated as a routine preoperative screening test for detecting coagulation disorders [18,19]. As a whole blood coagulation test, the ACT is affected by different anticoagulants and therefore can be used for monitoring the effects of unfractionated heparin, nafamostat, aprotinin, citrate, and hirudin [20]. It is also affected by certain congenital disorders of coagulation, warfarin, and liver failure [18,21,22].…”

“…As such, caution is recommended, and times relative to reference or baseline (pre-dialysis) ACT values are safer to use. In general, times of 1.4-to 2.3-fold the baseline ACT can be considered sufficient for anticoagulation [11,20]. The lower the blood flow rate, the longer the ACT should be.…”

“…81-133 s [11,18] or 96-152 s (Hemochron)]. This is easily explained by the different functional principles of ACT measurement and associated varying norm values and, in turn, may also explain the different recommendations for anticoagulation targets found in the literature [11,20,24].…”

“…Thus, calcium is not available for activation of the tenase complex and the prothrombinase complex of the coagulation cascade [20]. Fibrin generation is thereby inhibited.…”