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

Impact of anion exchange adsorbents on regional citrate anticoagulation

INTRODUCTION

Heparin and citrate are commonly used anticoagulants in membrane/adsorption based extracorporeal liver support systems. However, anion exchange resins employed for the removal of negatively charged target molecules including bilirubin may also deplete these anticoagulants due to their negative charge. The aim of this study was to evaluate the adsorption of citrate by anion exchange resins and the impact on extracorporeal Ca²⁺ concentrations.

METHODS

Liver support treatments were simulated in vitro. Citrate and Ca²⁺ concentrations were measured pre and post albumin filter as well as pre and post adsorbents. In addition, batch experiments were performed to quantify citrate adsorption.

RESULTS

Pre albumin filter target Ca²⁺ concentrations were reached well with only minor deviations. Citrate was adsorbed by anion exchange resins, resulting in a higher Ca²⁺ concentration downstream of the adsorbent cartridges during the first hour of treatment.

CONCLUSIONS

The anion exchange resin depletes citrate, leading to an increased Ca²⁺ concentration in the extracorporeal circuit, which may cause an increased risk of clotting during the first hour of treatment. An increase of citrate infusion during the first hour of treatment should therefore be considered to compensate for the adsorption of citrate.

The role of ionized calcium and magnesium in regional citrate anticoagulation and its impact on inflammatory parameters

INTRODUCTION

Regional anticoagulation with citrate has been found to be superior to heparin in terms of biocompatibility, and numerous protocols for regional citrate anticoagulation have been published, while a consensus on the target concentration of ionized calcium (Ca2+) in the extracorporeal circuit has not been reached so far.

METHODS

The aim of this in vitro study was to assess the impact of different citrate concentrations on coagulation as well as on complement activation and cytokine secretion and to investigate the impact of ionized magnesium (Mg2+) on these parameters.

RESULTS

We found that citrate effectively reduced coagulation, complement activation, and cytokine secretion in a dose-dependent manner and that a target Ca2+ concentration of 0.2-0.25 mM was required for efficient anticoagulation. Mg2+ triggered complement activation as well as interleukin (IL)-1β secretion in lipopolysaccharide (LPS)-stimulated whole blood in a dose-dependent manner and independently of Ca2+. Additionally, it was found to reduce activated clotting time (ACT) in samples with low Ca2+ levels, but not at physiological Ca2+.

CONCLUSIONS

Taken together, our data support the notion that regional citrate anticoagulation results in decreased release of inflammatory mediators in the extracorporeal circuit, requiring the depletion of both, Ca2+ and Mg2+.

Therapeutic Plasma Exchange in Children with Acute Autoimmune Central Nervous System Disorders

Background

There is a growing evidence for autoimmunity in acute central nervous system (CNS) disorders and treatment with therapeutic plasma exchange (TPE) may be considered. The aim was to share our experience on the clinical application of TPE in these disorders and to present a reproducible protocol which can be used even in small children.

Methods

We present a series of 8 children aged 2-12 years with transverse myelitis, Bickerstaff's brainstem encephalitis, neuromyelitis optica, and acute paraneoplastic or unspecified encephalitis in whom TPE was used as a second-line or rescue treatment.

Results

A total of 104 TPE sessions were performed where 80–110 ml/kg of plasma was exchanged using 4% albumin solution and fresh frozen plasma. Six episodes of TPE-related adverse events were documented. Fibrinogen concentrations decreased after the first TPE, whereas platelets decreased gradually. One patient died in the course of the acute illness. Three children achieved a complete resolution of symptoms, 2 children have mild sequelae; whereas 2 children remain paraplegic after a follow-up of 3 to 17 months.

Conclusions

We report 8 children with presumably autoimmune-mediated, acute CNS disorders treated with TPE as a rescue therapy. Although the effect of TPE can only be inferred, 5 children had a good clinical outcome. TPE is feasible even in small children with acute autoimmune CNS disorders.

Regional Citrate Anticoagulation in Therapeutic Plasma Exchange with Fresh Frozen Plasma - a Modified Protocol

Purpose

In membrane-based therapeutic plasma exchange (TPE), regional citrate anticoagulation (RCA) is associated with difficulties because of citrate accumulation and consequent, potentially significant, metabolic complications, especially when using fresh frozen plasma (FFP) as replacement fluid. We modified the technical setup of a commercially available continuous veno-venous hemodi-alysis RCA module (multiFiltrate Ci-Ca®) to establish an RCA-protocol for TPE.

Methods

Description of the modified technical setup and retrospective analysis of the feasibility of the RCA-protocol for TPE in all patients treated between 2009 and 2010.

Results

411 consecutive TPE with RCA were performed in 42 patients, all using FFP as replacement fluid. Median procedure characteristics were: blood flow 160 ml/min, filtrate flow 36 ml/min, duration 93 min, processed total plasma volume 3600 mL. Trisodium citrate was infused at a rate of 0.43 mmol/min to achieve post-filter ionized calcium levels of ≤0.4 mmol/l. Calcium substitution rate was 0.19 mmol/min to maintain physiologic iCa levels. RCA was well tolerated with no significant differences in pH, iCa, bicarbonate or potassium after repeated sessions. Clotting events complicated 7.3% of the procedures. Adverse events occurred in 3.4% of TPE procedures; none was severe or fatal. No significant differences were observed comparing the rate of adverse events to those observed in TPE using standard anticoagulation at our center (4.8%).

Conclusions

We describe for the first time a modified protocol for RCA in TPE using an integrated citrate module. Based on our experience, this RCA protocol is a feasible alternative for anticoagulation in TPE with FFP, especially in patients with a high risk of bleeding.