Albumin Dialysis Molecular Adsorbents Recirculating System: Impact of Dialysate Albumin Concentration on Detoxification Efficacy

[Extracorporeal Support Strategies in Liver Failure - Focus on Albumin Dialysis and Therapeutic Plasma Exchange]

Combining albumin dialysis for the removal of hydrophobic substances with classical haemodialysis in the treatment of acute liver failure (ALF) and acute-on-chronic liver failure (ACLF) has a strong theoretical rational and clinical data showed a positive effect on laboratory and partly clinical characteristics of ALF and ACLF. However, neither the MARS nor the Prometheus System has so far been able to demonstrate a mortality benefit in ALF or ACLF patients. To date, only the use of therapeutic plasma exchange (TPE) has demonstrated significant removal of pathogen-associated (PAMPs), damage-associated molecular patterns (DAMPs) and pro-inflammatory cytokines. In addition, TPE also acts simultaneously by replacing protective but depleted mediators, thus improving multiple key pathophysiological principles of both ALF and ACLF. In ALF, both high-volume and standard-volume TPE showed a significant improvement in survival. The data on the use of TPE in ACLF is still sparse, with only two Chinese monocentric studies in patients with exclusively hepatitis B-associated ACLF suggesting potentially improved survival with TPE. The currently recruiting APACHE study will include patients with the modern EASL-CLIF definition of ACLF.

In vitro safety and efficacy evaluation of a novel hybrid bioartificial liver system with simulated liver failure serum

BACKGROUND

Acute liver failure (ALF), which can potentially be treated with an artificial liver, is a fatal condition. The purpose of this study was to evaluate the safety and effectiveness of a novel hybrid bioartificial liver system (NHBLS) using simulated liver failure serum in vitro.

METHODS

The bioreactor in experimental group was cultivated with primary porcine hepatocytes, whereas in control group was not. Next, the simulated liver failure serum was treated using the NHBLS for 10 h. Changes in albumin (ALB), total bilirubin (TBIL), ammonia (Amm), total bile acid (TBA), creatinine (Cr), and blood urea nitrogen (BUN) were measured before treatment (0 h) and every 2 h during treatment. In addition, changes in NHBLS pressures, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lidocaine metabolism were also recorded.

RESULTS

The NHBLS worked steadily without unexpected occurrences during the treatment. Blood culture showed no bacterial growth after 7 days, and the endotoxin level was less than 0.5 EU. The TBIL, TBA, Cr, and BUN levels in both groups were markedly lower than those at 0 h (p < 0.05). The Amm level in experimental group was significantly lower than that in control group (p < 0.05). NHBLS pressures were also stable, and the hepatocytes in the bioreactor functioned well.

CONCLUSIONS

The preparation method for the simulated liver failure serum was optimized successfully, and the safety and effectiveness of the NHBLS in vitro were verified. Furthermore, the NHBLS significantly reduced the levels of Amm which can lead to hepatic encephalopathy.

Extracorporeal Albumin Dialysis in Liver Failure with MARS and SPAD: A Randomized Crossover Trial

INTRODUCTION

Liver failure is associated with hepatic and extrahepatic organ failure leading to a high short-term mortality rate. Extracorporeal albumin dialysis (ECAD) aims to reduce albumin-bound toxins accumulated during liver failure. ECAD detoxifies blood using albumin dialysis through an artificial semipermeable membrane with recirculation (molecular adsorbent recirculating system, MARS) or without (single-pass albumin dialysis, SPAD).

METHODS

We performed a randomized crossover open trial in a surgical intensive care unit. The primary outcome of the study was total bilirubin reduction during MARS and during SPAD therapies. The secondary outcomes were conjugated bilirubin and bile acid level reduction during MARS and SPAD sessions and tolerance of dialysis system devices. Inclusion criteria were adult patients presenting liver failure with factor V activity <50% associated with bilirubin ≥250 μmol/L and a complication (either hepatic encephalopathy, severe pruritus, or hepatorenal syndrome). For MARS and SPAD, the dialysis flow rate was equal to 1,000 mL/h.

RESULTS

Twenty crossovers have been performed. Baseline biochemical characteristics (bilirubin, ammonia, bile acids, creatinine, and urea) were not statistically different between MARS and SPAD. Both ECAD have led to a significant reduction in total bilirubin (-83 ± 67 μmol/L after MARS; -122 ± 118 μmol/L after SPAD session), conjugated bilirubin (-82 ± 61 μmol/L after MARS; -105 ± 96 μmol/L after SPAD session), and bile acid levels (-64 ± 75 μmol/L after MARS; -56 ± 56 μmol/L after SPAD session), all nondifferent comparing MARS to SPAD.

CONCLUSION

A simple-to-perform SPAD therapy with equal to MARS dialysate flow parameters provides the same efficacy in bilirubin and bile acid removal. However, clinically relevant endpoints have to be evaluated in randomized trials to compare MARS and SPAD therapies and to define the place of SPAD in the liver failure care program.

Case Report: Enhanced Diazepam Elimination With the Molecular Adsorbents Recirculating System (MARS) in Severe Autointoxication: A Survival Case Report

Objective: Due to the extensive use of diazepam worldwide, self-induced intoxication is very common, yet rarely fatal. Nevertheless, the management of intoxication caused by extremely high doses of diazepam is not known, as well as the effectiveness of flumazenil, a specific benzodiazepine (BDZ) antagonist. Here we present the first report on the enhanced elimination (clearance) of diazepam using the Molecular Adsorbents Recirculating System (MARS) following autointoxication with an extremely high dose as part of a suicide attempt. Case: A 44-year-old male patient was admitted to the ICU because of impaired consciousness following the ingestion of 20 g of diazepam. Blood and urine samples revealed high benzodiazepine levels. Repeated doses of flumazenil were without effect on consciousness. Following deterioration of the patient's clinical condition, including unconsciousness, hypoventilation, and decreased SpO2 (88%), the patient was intubated and mechanically ventilated. On the fourth day after admission, the patient was unresponsive, with no attempt to breath spontaneously. The plasma level of benzodiazepines was 1,772 μg/l. The elimination of benzodiazepines by MARS was attempted, continuing for 5 days, with one session per day. Five sessions of MARS effectively enhanced benzodiazepine elimination. After the first MARS treatment, the plasma level of benzodiazepines dropped from 1,772 to 780 μg/l. After the final MARS treatment on the eighth day, the patient was weaned from mechanical ventilation and extubated. Two days later, the patient was discharged to the internal medicine department and subsequently to the psychiatry department. Conclusions: To the best of our knowledge, this is the first case reporting successful treatment of diazepam intoxication using MARS. In severe cases of diazepam intoxication, with prolonged unconsciousness and the necessity of mechanical ventilation, we suggest considering the use of MARS elimination therapy together with the monitoring of the BDZ plasma level.

Molecular adsorbent recirculating system (MARS) and continuous veno-venous hemodiafiltration (CVVHDF) for diltiazem removal: An in vitro study

The objective of the present study was to evaluate the efficacy of the molecular adsorbent recirculating system (MARS) vs continuous veno-venous hemodiafiltration (CVVHDF). Diltiazem poisoning was simulated in a central compartment consisting in a 5L dialysis solute spiked with diltiazem at two different toxic concentrations: 750 and 5000 µg/L. For CVVHDF, mean extraction coefficients (EC = (in concentration - out concentration)/in concentration) were concentration-dependent with a decrease all along the dialysis. At the end of the sessions the mean amounts remaining in the central compartment were 8% and 7% of the initial dose at 750 and 5000 µg/L, respectively. The mean cumulative amounts found in the effluent were 60% and 75% of the initial dose, respectively. The missing amounts accounted for 32% and 18% of the initial dose, respectively, corresponding to an adsorption to the dialysis membrane. In contrast, the different compartments of the MARS resulted in undetectable output concentration earlier that the end of the session. The mean concentrations of diltiazem remaining in the central compartment were <1 µg/L at the end of the sessions. Global ECs were around 50% all along the experiment at both concentrations, and the average charcoal cartridge ECs was 80% throughout the experiments.CVVHDF system in the developed model was efficient for diltiazem removal, mainly by diffusion, convection and to a lesser extent by adsorption to the dialysis membrane. In MARS system, resin cartridge and hemodialysis components are ineffective, charcoal cartridge is responsible for almost all drug removal.

Plant protein modified natural cellulose with multiple adsorption effects used for bilirubin removal

In this study, bacterial cellulose (BC)/soy protein isolate (SPI) composite membranes were prepared by in situ cross-linked polymerization, and used as efficient blood compatible adsorbents to remove bilirubin. The obtained composite membranes were successively characterized by FTIR, SEM, AFM, contact angle test and hemolysis assay, which exhibited unique protein coated 3D fibrous network structures, hydrophobic surfaces and outstanding blood compatibility due to the incorporation of SPI. The BC/SPI membranes with high SPI content showed high adsorption efficiency, short adsorption equilibrium time (2 h) and multiple adsorption effects on bilirubin. The adsorption rate for free bilirubin of BC/SPI5 membrane could reach 78.8% when the bilirubin concentration was 100 mg L^-1, while it increased to over 96.5% when the initial bilirubin concentration exceeded 400 mg L^-1. More importantly, the BC/SPI5 membrane still exhibited high adsorption rate (over 70%) in presence of albumin. Furthermore, the composite membrane could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This novel naturally-derived membrane is an economical and efficient absorbent for the remove of bilirubin, and will provide new ideas for therapy of hemoperfusion without plasma separation process.

Molecular adsorbent recirculating system and single-pass albumin dialysis in liver failure--a prospective, randomised crossover study

Background

The aim of extracorporeal albumin dialysis (ECAD) is to reduce endogenous toxins accumulating in liver failure. To date, ECAD is conducted mainly with the Molecular Adsorbents Recirculating System (MARS). However, single-pass albumin dialysis (SPAD) has been proposed as an alternative. The aim of this study was to compare the two devices with a prospective, single-centre, non-inferiority crossover study design with particular focus on reduction of bilirubin levels (primary endpoint) and influence on paraclinical and clinical parameters (secondary endpoints) associated with liver failure.

Methods

Patients presenting with liver failure were screened for eligibility and after inclusion were randomly assigned to be started on either conventional MARS or SPAD (with 4 % albumin and a dialysis flow rate of 700 ml/h). Statistical analyses were based on a linear mixed-effects model.

Results

Sixty-nine crossover cycles of ECAD in 32 patients were completed. Both systems significantly reduced plasma bilirubin levels to a similar extent (MARS: median −68 μmol/L, interquartile range [IQR] −107.5 to −33.5, p = 0.001; SPAD: −59 μmol/L, −84.5 to +36.5, p = 0.001). However, bile acids (MARS: −39 μmol/L, −105.6 to −8.3, p < 0.001; SPAD: −9 μmol/L, −36.9 to +11.4, p = 0.131), creatinine (MARS: −24 μmol/L, −46.5 to −8.0, p < 0.001; SPAD: −2 μmol/L, −9.0 to +7.0/L, p = 0.314) and urea (MARS: −0.9 mmol/L, −1.93 to −0.10, p = 0.024; SPAD: −0.1 mmol/L, −1.0 to +0.68, p = 0.523) were reduced and albumin-binding capacity was increased (MARS: +10 %, −0.8 to +20.9 %, p < 0.001; SPAD: +7 %, −7.5 to +15.5 %, p = 0.137) only by MARS. Cytokine levels of interleukin (IL)-6 and IL-8 and hepatic encephalopathy were altered by neither MARS nor SPAD.

Conclusions

Both procedures were safe for temporary extracorporeal liver support. While in clinical practice routinely assessed plasma bilirubin levels were reduced by both systems, only MARS affected other paraclinical parameters (i.e., serum bile acids, albumin-binding capacity, and creatinine and urea levels). Caution should be taken with regard to metabolic derangements and electrolyte disturbances, particularly in SPAD using regional citrate anti-coagulation.

Trial registration

German Clinical Trials Register (www.drks.de) DRKS00000371. Registered 8 April 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1159-3) contains supplementary material, which is available to authorized users.

Principles and operational parameters to optimize poison removal with extracorporeal treatments

A role for nephrologists in the management of a poisoned patient involves evaluating the indications for, and methods of, enhancing the elimination of a poison. Nephrologists are familiar with the various extracorporeal treatments (ECTRs) used in the management of impaired kidney function, and their respective advantages and disadvantages. However, these same skills and knowledge may not always be considered, or applicable, when prescribing ECTR for the treatment of a poisoned patient. Maximizing solute elimination is a key aim of such treatments, perhaps more so than in the treatment of uremia, because ECTR has the potential to reverse clinical toxicity and shorten the duration of poisoning. This manuscript reviews the various principles that govern poison elimination by ECTR (diffusion, convection, adsorption, and centrifugation) and how components of the ECTR can be adjusted to maximize clearance. Data supporting these recommendations will be presented, whenever available.

Available extracorporeal treatments for poisoning: overview and limitations

Poisoning is a significant public health problem. In severe cases, extracorporeal treatments (ECTRs) may be required to prevent or reverse major toxicity. Available ECTRs include intermittent hemodialysis, sustained low-efficiency dialysis, intermittent hemofiltration and hemodiafiltration, continuous renal replacement therapy, hemoperfusion, therapeutic plasma exchange, exchange transfusion, peritoneal dialysis, albumin dialysis, cerebrospinal fluid exchange, and extracorporeal life support. The aim of this article was to provide an overview of the technical aspects, as well as the potential indications and limitations of the different ECTRs used for poisoned patients.

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

BACKGROUND/AIMS

To compare the efficacy of a new artificial liver support system, fractionated plasma separation and adsorption integrated with hemofiltration, with the old system, plasma adsorption.

METHODS

Sixteen patients with acute liver failure each received a first session of treatment using the old system, in which plasma was perfused through an adsorber. They then received a second session using the new system, in which albumin-rich plasma separated using a fraction plasma separator was ultrafiltrated using a hemofilter and perfused through an adsorber before being returned to blood.

RESULTS

The new system had a higher clearance of bilirubin and slower decline of clearance over time. There was a lower reduction ratio of bilirubin, bile acid, urea, and creatinine; longer prolongation of coagulation parameters; and greater decline in albumin level using the old system compared with the new one.

CONCLUSIONS

Use of the novel system results in more efficient removal of toxins and fewer deterious effects than the old system.

Use of an in vitro model of renal replacement therapy systems to estimate extracorporeal drug removal

The use of in vitro modeling to predict in vivo drug and solute clearance during renal replacement therapy has evolved to reflect the different dialytic therapies available in clinical practice. This area of renal replacement therapy research is representative of translational research that demonstrates a correlation from bench to bedside where results generated in the laboratory can assist with clinical decisions in the absence of in vivo studies. This review describes in vitro renal replacement therapy models and compares the findings of several in vitro and in vivo studies.

Human serum albumin: from bench to bedside

Human serum albumin (HSA), the most abundant protein in plasma, is a monomeric multi-domain macromolecule, representing the main determinant of plasma oncotic pressure and the main modulator of fluid distribution between body compartments. HSA displays an extraordinary ligand binding capacity, providing a depot and carrier for many endogenous and exogenous compounds. Indeed, HSA represents the main carrier for fatty acids, affects pharmacokinetics of many drugs, provides the metabolic modification of some ligands, renders potential toxins harmless, accounts for most of the anti-oxidant capacity of human plasma, and displays (pseudo-)enzymatic properties. HSA is a valuable biomarker of many diseases, including cancer, rheumatoid arthritis, ischemia, post-menopausal obesity, severe acute graft-versus-host disease, and diseases that need monitoring of the glycemic control. Moreover, HSA is widely used clinically to treat several diseases, including hypovolemia, shock, burns, surgical blood loss, trauma, hemorrhage, cardiopulmonary bypass, acute respiratory distress syndrome, hemodialysis, acute liver failure, chronic liver disease, nutrition support, resuscitation, and hypoalbuminemia. Recently, biotechnological applications of HSA, including implantable biomaterials, surgical adhesives and sealants, biochromatography, ligand trapping, and fusion proteins, have been reported. Here, genetic, biochemical, biomedical, and biotechnological aspects of HSA are reviewed.