Efficient removal of serum bilirubin by a novel artificial liver support system using albumin convection: a pilot study

Tailoring the Colloidal Stability, Magnetic Separability, and Cytocompatibility of High-Capacity Magnetic Anion Exchangers

Extracorporeal blood purification has been applied to artificially support kidney or liver function. However, convection and diffusion based blood purification systems have limited removal rates for high molecular weight and hydrophobic molecules. This limitation is due to the finite volume of infusion and limited membrane permeability, respectively. Adsorption provides an attractive alternative for the removal of higher molecular weight compounds. The use of adsorption resins containing ion exchanging groups to capture specific molecules has become well-established. Instead of stationary adsorption resins, however, ion exchanging polymers may be immobilized on magnetic particles and serve as freely diffusing, mobile, high capacity solid phase of ion exchange chromatography. While small beads with high surface area are attractive in terms of mass transfer and binding, unifying high capturing capacity with rapid and quantitative bead recovery remains an issue. Therefore, most of the current magnetic ion exchangers are based on micron-sized beads or require long times to separate. In addition to unfavorable magnetic recovery rates, the usually poor cytocompatibility limits their applicability in biomedicine. Here, we report on the synthesis and performance of polycationic polymer coated magnetic nanoflowers (MNF) for highly efficacious anion capturing. We demonstrate accurate control over the polymer content and composition on the beads and show its direct influence on colloidal stability, capturing capacity and magnetic separability. We present the removal of clinically relevant targets by capturing bilirubin with capacities 2-fold higher than previous work as well as quantitative heparin removal. Additionally, we illustrate how copolymerization of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) with poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) leads to improved cytocompatibility of the polymer-coated MNF capturing agents while retaining high capturing capacities. Taken together, we present a nanoparticle/polymer material, which upon future in vivo validation, unifies high binding capacities and magnetic separability for rapid toxin capturing and hence fulfills key requirements of clinical utility.

Prometheus therapy for the treatment of acute liver failure in patients after cardiac surgery

Introduction

Acute liver failure usually develops in multiple organ dysfunction syndrome and significantly increases the mortality risk in patients after cardiac surgery.

Aim

To assess the safety and efficacy of extracorporeal liver support in patients with acute liver failure after cardiac surgery.

Material and methods

We studied 39 adult patients with multiple organ dysfunction syndrome and acute liver failure as postoperative complication, treated with Prometheus therapy. Inclusion criteria comprised clinical and laboratory signs of acute liver failure. Criteria to start Prometheus therapies were: serum bilirubin above 180 µmol/l (reference values: 3-17 µmol/l), hepatocyte cytolysis syndrome (at least 2-fold increase in aspartate aminotranspherase and alanine aminotranspherase concentrations; reference values 10-40 U/l) and decrease in plasma cholinesterase (reference values 4490-13 320 U/l).

Results

Extracorporeal therapy provided stabilization of hemodynamics, decrease in serum total bilirubin and unconjugated bilirubin levels, decrease in cytolysis syndrome severity and positive effect on the synthetic function of the liver. The 28-day survival rate in the group treated with Prometheus therapy was 23%.

Conclusions

Prometheus procedures could be recommended as a part of combined intensive care in patients with acute liver failure after cardiac and major vessel surgery. The efficiency of this method could be improved by a multi-factor evaluation of patient condition in order to determine indications for its use.

Severe Acute Valproic Acid Intoxication Successfully Treated with Liver Support Therapy

Valproic acid (VPA) is widely used for the treatment of epilepsy. However, its overdose can cause intoxication and could be life-threatening. Due to the lack of specific antidote and poorness of endogenous clearance, extracorporeal treatment for severe intoxication cases is indicated. Here, we report a case of severe intoxication of VPA which was successfully treated with liver support therapy. A previously healthy woman was admitted due to coma and hypotension after intentional ingestion of 20 g of sodium valproate. Her serum concentration of VPA measured on admission was 420.84 mg/L. In addition to standard therapy, she received two sessions of extracorporeal blood purification using a system based on fractionated plasma separation and adsorption mode integrated with continuous veno-venous haemofiltration (FPSA-CVVH), which is usually used for liver support therapy at our hospital. Her serum concentration of VPA decreased dramatically to 40.18 mg/L and her consciousness recovered completely within 24 hr after admission. Therefore, although haemodialysis has been reported to be effective in the treatment for VPA poisoning, FPSA-CVVH may provide an option for patients who require bedside therapy but have an unstable haemodynamic status or other conditions that result in inability to endure haemodialysis.

Severe Hemolysis in a Patient With Erythrocytosis During Coupled Plasma Filtration Adsorption Therapy Was Prevented by Changing From Membrane-Based Technique to a Centrifuge-Based One

Coupled plasma filtration adsorption (CPFA) usually adopts membrane to separate plasma from blood. Here, we reported a case with erythrocytosis experienced severe hemolysis and membrane rupture during CPFA, which was avoided by changing from membrane-based technique to a centrifuge-based one. A 66-year-old man was to receive CPFA for severe hyperbilirubinemia (total bilirubin 922 μmol/L, direct bilirubin 638 μmol/L) caused by obstruction of biliary tract. He had erythrocytosis (hemoglobin 230 g/L, hematocrit 0.634) for years because of untreated tetralogy of Fallot. Severe hemolysis and membrane rupture occurred immediately after blood entering into the plasma separator even at a low flow rate (50 mL/min) and persisted after changing a new separator. Finally, centrifugal plasma separation technique was used for CPFA in this patient, and no hemolysis occurred. After 3 sessions of CPFA, total bilirubin level decreased to 199 μmol/L with an average decline by 35% per session. Thereafter, the patient received endoscopic biliary stent implantation, and total bilirubin level returned to nearly normal. Therefore, centrifugal-based plasma separation can also be used in CPFA and may be superior to a membrane-based one in patients with hyperviscosity.