Artificial and bioartificial support systems for acute and acute-on-chronic liver failure: a systematic review

Hemodynamic improvement as an additional parameter to evaluate the safety and tolerability of the molecular adsorbent recirculating system in liver failure patients

BACKGROUND

The molecular adsorbent recirculating system (MARS) is an extracorporeal acute liver failure (ALF) support system method using albumin-enriched dialysate to remove albumin-bound toxins.

PATIENTS AND METHODS

Since 1999 we performed 2027 MARS treatments in 191 patients: 39 fulminant hepatic failure (FHF), 16 primary nonfunction (PNF), 21 delayed function (DF), 94 acute-on-chronic liver failure (AoCHF), 7 post-hepatic resection, and 14 intractable pruritus.

RESULTS

We divided the complications by the AoCHF versus the ALF populations. Among 83 ALF patients, we observed worsening of hemodynamic parameters in 16 patients: 3 with PNF, 2 with DF without retransplantation, 9 with FHF, and 2 after hepatic resection. Among 94 AoCHF patients, 42 showed hemodynamic instability requiring intensive care unit support. Our study did not note significant adverse effects (1.8%), except for infections and hemorrhage from the central venous catheter not due to MARS treatment. The thrombocytopenia was controlled through administration of platelets before the start of treatment when a patient showed a level under 30,000 mm(3).

CONCLUSION

Our results confirmed that nonbiological hepatic support by MARS was safe and tolerable.

Prediction value of model for end-stage liver disease scoring system on prognosis in patients with acute-on-chronic hepatitis B liver failure after plasma exchange and lamivudine treatment

BACKGROUND AND AIM

We used the model for end-stage liver disease (MELD) scoring system to predict the 3-month prognosis of patients with acute-on-chronic liver failure (ACLF) after plasma exchange (PE) and lamivudine treatment, and studied the predictive factors on the prognosis of patients.

METHODS

A total of 280 patients treated with lamivudine were randomly divided into PE and control groups. The relationship between mortality and influential factors of patients was studied by univariate and multivariate analysis.

RESULTS

The mortality (49.4%) of patients in the PE group with a MELD score from 30 to 40 was lower than that (86.1%) of the control group (chi(2) = 24.546, P < 0.01). The total bilirubin (TBIL) rebound rate of the dead group was significantly higher than that of the survival group (P < 0.01). Univariate analysis showed that mortality was significantly related to age (P = 0.003), treatment method (P = 0.000), TBIL (P = 0.010), MELD score (P = 0.001), international normalised ratio (P = 0.014), pretreatment HBV-DNA load (P = 0.000), decline of hepatitis B virus (HBV)-DNA load during therapy (P = 0.013), encephalopathy (P = 0.019), and hepatorenal syndrome (P = 0.026). In multivariate analysis, MELD scores of 30-40, treatment method (P = 0.003), pretreatment HBV-DNA load (P = 0.009), decline of HBV-DNA load during therapy (P = 0.016), and encephalopathy (P = 0.015) were independent predictors of mortality; for MELD scores above 40, only the MELD score (P = 0.012) was an independent predictive.

CONCLUSIONS

PE significantly decreased the mortality of patients with a MELD score of 30-40. For ACLF patients with a MELD score of 30-40, a low viral load pretreatment and quick decline of HBV-DNA load are good predictors for the survival with PE and lamivudine treatment.

Intensive care management of acute liver failure

PURPOSE OF REVIEW

The mortality of acute liver failure remains unacceptably high and liver transplantation is the only effective treatment available to date. This review focuses on new research developments in the field and aims to provide a pragmatic organ-based treatment approach for liver failure patients requiring intensive care support.

RECENT FINDINGS

The pathophysiological basis for cerebral edema formation in acute liver failure continued to be the focus of various investigations. In-vivo observations confirmed the link between ammonia, cerebral glutamine content and intracranial hypertension. The role of arterial ammonia as an important prognostic indicator formed the basis of prospective, observational studies. Reduced monocytic HLA-DR expression linked acute liver failure with poor prognosis, and the cerebral effects and side effects of vasoactive therapy with terlipressin were investigated with two studies showing contradictory results.

SUMMARY

Despite increased knowledge of the pathophysiological events leading to organ dysfunction in acute liver failure, supportive treatment options remain limited in their efficacy and largely noncurative.

Bioartificial liver systems: why, what, whither?

Acute liver disease is a life-threatening condition for which liver transplantation is the only recognized effective therapy. While etiology varies considerably, the clinical course of acute liver failure is common among the etiologies: encephalopathy progressing toward coma and multiple organ failure. Detoxification processes, such as molecular adsorbent recirculating system (MARS®) and Prometheus, have had limited success in altering blood chemistries positively in clinical evaluations, but have not been shown to be clinically effective with regard to patient survival or other clinical outcomes in any Phase III prospective, randomized trial. Bioartificial liver systems, which use liver cells (hepatocytes) to provide metabolic support as well as detoxification, have shown promising results in early clinical evaluations, but again have not demonstrated clinical significance in any Phase III prospective, randomized trial. Cell transplantation therapy has had limited success but is not practicable for wide use owing to a lack of cells (whole-organ transplantation has priority). New approaches in regenerative medicine for treatment of liver disease need to be directed toward providing a functional cell source, expandable in large quantities, for use in various applications. To this end, a novel bioreactor design is described that closely mimics the native liver cell environment and is easily scaled from microscopic (<1 ml cells) to clinical (∼600 ml cells) size, while maintaining the same local cell environment throughout the bioreactor. The bioreactor is used for study of primary liver cell isolates, liver-derived cell lines and stem/progenitor cells.

Acute liver failure: Summary of a workshop

Acute liver failure (ALF) is a rare but challenging clinical syndrome with multiple causes; a specific etiology cannot be identified in 15% of adult and 50% of pediatric cases. The course of ALF is variable and the mortality rate is high. Liver transplantation is the only therapy of proven benefit, but the rapidity of progression and the variable course of ALF limit its use. Currently in the United States, spontaneous survival occurs in approximately 45%, liver transplantation in 25%, and death without transplantation in 30% of adults with ALF. Higher rates of spontaneous recovery (56%) and transplantation (31%) with lower rates of death (13%) occur in children. The outcome of ALF varies by etiology, favorable prognoses being found with acetaminophen overdose, hepatitis A, and ischemia (approximately 60% spontaneous survival), and poor prognoses with drug-induced ALF, hepatitis B, and indeterminate cases (approximately 25% spontaneous survival). Excellent intensive care is critical in management of patients with ALF. Nonspecific therapies are of unproven benefit. Future possible therapeutic approaches include N-acetylcysteine, hypothermia, liver assist devices, and hepatocyte transplantation. Advances in stem cell research may allow provision of cells for bioartificial liver support. ALF presents many challenging opportunities in both clinical and basic research.

Sorbent-based artificial liver devices: principles of operation, chemical effects and clinical results

Devices for support of patients with liver failure are of two types: bioartificial livers and artificial livers. Bioartificial livers include hepatocytes in bioreactors to provide both excretory and synthetic liver functions. Artificial livers use nonliving components to remove toxins of liver failure, supply nutrients and macromolecules. Current artificial liver devices use columns or suspensions of sorbents (including adsorbents and absorbents) to selectively remove toxins and regenerate dialysate, albumin-containing dialysate, plasma filtrate or plasma. This article reviews three artificial liver devices. Liver Dialysis uses a suspension of charcoal and cation exchangers to regenerate dialysate. MARS uses charcoal and an anion exchanger to regenerate dialysate with albumin. Prometheus uses neutral and anion exchange resins to regenerate a plasma filtrate containing albumin and small globulins. We review the operating principles, chemical effects, clinical effects and complications of use of each type of artificial liver. These devices clearly improve the clinical condition of patients with acute or acute-on-chronic liver failure. Further randomized outcome studies are necessary to prove clinical outcome benefit of the artificial liver support devices, and define what types of patients appear most amenable to therapy.

A surgical model of fulminant hepatic failure in rabbits

AIM

Animal models of fulminant hepatic failure (FHF) have been developed for characterization of disease progression and to evaluate the effectiveness of liver-assist devices, some by treatment with hepatotoxic drugs, viral hepatitis or surgical procedures. We have developed a model in the rabbit by combining resection of the three anterior lobes with ligation of the pedicle of the right lateral lobes, resulting in liver necrosis; the remnant quadrate lobes are left intact.

MATERIALS AND METHODS

Adult male New Zealand white rabbits (n=16) were used. Six animals were killed to measure the weight of the separate liver lobes. The others (n=10) underwent left neck central line placement to monitor continuous blood pressure and collect blood for laboratory analysis, and a burr hole on the right parietal bone to monitor the intracranial pressure (ICP). Blood laboratory analysis, clinical hepatic encephalopathy and ICP levels were measured in FHF animals (n=6). Animals (n=4) undergoing a sham operation served as controls.

RESULTS

All FHF animals died between 12 and 26 h after liver surgery from FHF characterized by a progressive increase in liver enzymes, ammonia, total bilirubin, coagulopathy, hepatic encephalopathy and intracranial hypertension. Histological features of the ischaemic lobes showed coagulative necrosis of hepatocytes with absence of nuclei and collapse of cell plates. Brain histology revealed hypoxic cell damage.

CONCLUSION

We have developed a simple, reproducible model of FHF in rabbits that has a number of features comparable with clinical FHF patients and is well suited for testing experimental bioartificial liver systems and investigating the pathogenesis of FHF.

Randomized controlled study of extracorporeal albumin dialysis for hepatic encephalopathy in advanced cirrhosis

Extracorporeal albumin dialysis (ECAD) may improve severe hepatic encephalopathy (HE) in patients with advanced cirrhosis via the removal of protein or non-protein-bound toxins. A prospective, randomized, controlled, multicenter trial of the efficacy, safety, and tolerability of ECAD using molecular adsorbent recirculating system (MARS) was conducted in such patients. Patients were randomized to ECAD and standard medical therapy (SMT) or SMT alone. ECAD was provided daily for 6 hours for 5 days or until the patient had a 2-grade improvement in HE. HE grades (West Haven criteria) were evaluated every 12 hours using a scoring algorithm. The primary endpoint was the difference in improvement proportion of HE between the 2 groups. A total of 70 subjects [median age, 53; 56% male; 56% HE grade 3; 44% HE grade 4; median model for end-stage liver disease (MELD) 32 (11-50) and CPT 13 (10-15)] were enrolled in 8 tertiary centers. Patients were randomized to ECAD + SMT (n = 39) or SMT alone (n = 31). Groups were matched in demographics and clinical variables. The improvement proportion of HE was higher in ECAD (mean, 34%; median, 30%) versus the SMT group (mean, 18.9%; median, 0%) (P = 0.044) and was reached faster and more frequently than in the SMT group (P = 0.045). Subjects receiving ECAD tolerated treatment well with no unexpected adverse events.

CONCLUSION

The use of ECAD may be associated with an earlier and more frequent improvement of HE (grade 3/4). Because this 5-day study was not designed to examine the impact of MARS on survival, a full assessment of the role of albumin dialysis awaits the results of additional controlled trials.

Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases

BACKGROUND

Alcohol and hepatotoxic viruses cause the majority of liver diseases. Randomised clinical trials have assessed whether extracts of milk thistle, Silybum marianum (L) Gaertneri, have any effect in patients with alcoholic and/or hepatitis B or C virus liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of milk thistle or milk thistle constituents versus placebo or no intervention in patients with alcoholic liver disease and/or viral liver diseases (hepatitis B and hepatitis C).

SEARCH STRATEGY

The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and full text searches were combined (July 2007). Manufacturers and researchers in the field were contacted.

SELECTION CRITERIA

Only randomised clinical trials in patients with alcoholic and/or hepatitis B or C virus liver diseases (acute and chronic) were included. Interventions encompassed milk thistle at any dose or duration versus placebo or no intervention. The trials could be double blind, single blind, or unblinded. The trials could be unpublished or published and no language limitations were applied.

DATA COLLECTION AND ANALYSIS

The primary outcome measure was mortality. Binary outcomes are reported as relative risks (RR) with 95% confidence interval (CI). Subgroup analyses were performed with regard to methodological quality.

MAIN RESULTS

Eighteen randomised clinical trials assessed milk thistle in 1088 patients with alcoholic and/or hepatitis B or C virus liver diseases. The methodological quality was low: only 28.6% of the trials reported high methodological quality characteristics. Milk thistle versus placebo or no intervention had no significant effect on mortality (RR 0.78, 95% CI 0.53 to 1.15), complications of liver disease (RR 0.95, 95% CI 0.83 to 1.09), or liver histology. Liver-related mortality was significantly reduced by milk thistle in all trials (RR 0.50, 95% CI 0.29 to 0.88), but not in high-quality trials (RR 0.57, 95% CI 0.28 to 1.19). Milk thistle was not associated with a significantly increased risk of adverse events (RR 0.83, 95% CI 0.46 to 1.50).

AUTHORS' CONCLUSIONS

Our results question the beneficial effects of milk thistle for patients with alcoholic and/or hepatitis B or C virus liver diseases and highlight the lack of high-quality evidence to support this intervention. Adequately conducted and reported randomised clinical trials on milk thistle versus placebo are needed.

Regenerative medicine: an insight

Regenerative Medicine is a rapidly evolving field of therapy integrating different scientific and technological areas, including cell biology, biomedical and computer engineering, and clinical medicine, thus creating an interdisciplinary exchange network of skill, ideas, materials and efforts between basic and clinical research. Even if significant achievements have been obtained particularly in Plastic Surgery, Ophthalmology and Orthopedics, the field is still experimental and so far has failed to meet the expectations. The present article reviews the major hurdles that are still hampering the translational "bench to bedside" process and limiting the availability of these innovative therapeutic tools.

Live donor liver transplantation for acute liver failure

BACKGROUND

Acute liver failure (ALF) carries a high mortality unless urgent orthotopic liver transplantation (OLT) is performed on time. Live donors are utilized to treat this irreversible condition first in pediatric cases and then in adults. Herein, we aimed to report our experience with live donors for ALF in a country of a deceased donor organ donation rate is only 1.5 per million people.

METHODS

Among the 245 live donor liver transplantations (LDLT) performed from June 1999 to December 2005, 14 of them (6%) were performed for ALF in 8 pediatric and 6 adult cases. Right lobes were harvested for the adult cases whereas left lateral segments were harvested for pediatric cases, except one child transplanted with a right lobe graft. The etiology of the disease was; acute hepatitis B in four cases, hepatitis A in three cases, Wilson disease two cases, autoimmune hepatitis in two cases, and was unknown in three cases.

RESULTS

Three-year graft and patient survival is 79% for these series. Five of the six adult patients and six of the eight pediatric cases survived after transplantation. There was not any donor mortality or major morbidity.

CONCLUSIONS

LDLT offers a safe and effective modality of treatment for ALF for both pediatric and adult patients to overcome the problem of organ shortage especially in countries where the chance of receiving an organ from a deceased donor is low.

New type of artificial liver support system (ALSS) using the photocatalytic effect of titanium oxide

Although various types of artificial liver support systems (ALSSs) including a hybrid type have been made, few are practical ALSSs for treatment of acute and/or chronic hepatic failure. Titanium oxide (TiO(2)), a stable material, dismantles various materials using a photocatalytic action under ultraviolet irradiation. The aim of this study was to assess the effect of a new ALSS using TiO(2). Hepatic failure plasma obtained from patients undergoing plasma exchange therapy due to acute liver failure was used in these experiments. The plasma was perfused using a closed circuit model with a column filled with TiO(2). The plasma concentrations of total bilirubin, albumin, fibrinogen, interleukin (IL)-6, IL-8, and IL-10 were serially measured. We evaluated the photocatalytic effect of TiO(2) irradiated with ultraviolet light. The effect of initial perfusion with fresh-frozen plasma (FFP) was also investigated, focusing on the decrease in fibrinogen during perfusion. Levels of total bilirubin decreased after perfusion using the column filled with TiO(2), compared with no UV irradiation. The levels of IL-6, IL-8, and IL-10 decreased after perfusion using the TiO(2) device. The albumin level was maintained at the initial level, however, the fibrinogen level decreased within 4 hr. Initial perfusion of the circuit with FFP improved the decrease in fibrinogen for up to 8 hr. Our new perfusion device using the photocatalytic action of TiO(2) may be a promising ALSS.

Extracorporeal liver support: a continuing challenge

Given that liver failure continues to pose an enormous clinical challenge, the concept of hepatic dialysis has enjoyed significant interest. In particular, many investigations have examined the therapeutic mechanisms and efficacy of artificial albumin dialysis based systems in acute on chronic liver failure, the results of which have been conflicting. Albumin dialysis systems do not appear to significantly decrease serum concentrations of inflammatory cytokines in severe acute on chronic liver failure. Thus, if these treatments do result in clinical improvement, then other therapeutic mechanisms must be involved.

Modern management of acute liver failure

Liver transplantation has revolutionized the management of acute or fulminant liver failure. Overall success rates of liver transplantation are satisfactory, although not as high as for elective transplantation. Although the bulk of liver transplants use standard whole grafts, interesting data are emerging on auxiliary liver grafts and donations from living donors. Liver transplantation is an integral part of management protocols complementing the sophisticated critical care protocols that have contributed significantly to the overall improved outcomes seen in acute liver failure. The potential for liver support devices to have an impact on the need for liver transplantation and outcomes after transplantation remains exciting.

Self-assembling peptide nanofiber as a novel culture system for isolated porcine hepatocytes

Freshly isolated porcine hepatocytes are a very attractive cell source in the cell-based therapies to treat liver failure because of unlimited availability. However, due to the loss of hepatocyte functions in vitro, there is a need to develop a functional culture system to keep the cells metabolically active. Here we compared the effect of a self-assembling peptide nanofiber (SAPNF) as an extracellular matrix (ECM) with collagen type I on hepatocyte metabolic and secretion activities following hepatocyte isolation. Isolated porcine hepatocytes were cultured in SAPNF and collagen type I. Morphological assessment at different time points was performed by using SEM and phase contrast microscope. Metabolic and secretion activities were comparatively performed in the groups, by means of ammonia, lidocaine, and diazepam as well as albumin. Hepatocytes cultured on SAPNF revealed a three-dimensional spheroidal formation, thus maintaining cell differentiation status during 2 weeks of culture. On the other hand, hepatocytes in collagen revealed a spread shape, and by day 14 no hepatocyte-like cells were observed, but cells with long shape were present, thus revealing a degree of dedifferentiation in collagen culture. Hepatocytes in SAPNF were capable of drug-metabolizing activities and albumin secretion in higher ratio than those cultured on collagen. The present work clearly demonstrates the usefulness of SAPNF for maintaining differentiated functions of porcine hepatocytes in culture.

Effect of extracorporeal liver support by MARS and Prometheus on serum cytokines in acute-on-chronic liver failure

Introduction

Cytokines are believed to play an important role in acute-on-chronic liver failure (ACLF). Extracorporeal liver support systems may exert beneficial effects in ACLF via removal of cytokines. At present, two systems are commercially available, the Molecular Adsorbent Recirculating System (MARS™) and Fractionated Plasma Separation, Adsorption and Dialysis (Prometheus™). The aim of this study was to compare the effects of MARS and Prometheus treatments on serum cytokine levels and their clearances.

Methods

Eight patients with ACLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Thirty-four treatments (17 MARS, 17 Prometheus) were available for analysis. Serum cytokines were measured before and after each treatment, and cytokine clearance was calculated from paired arterial and venous samples and effective plasma flow one hour after the start of treatment.

Results

Baseline serum levels of interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-α), and soluble TNF-α receptor 1 were significantly elevated in patients with ACLF. Measurable plasma clearances were detected for all cytokines tested, but no significant changes in serum levels of any cytokine were found after treatments with MARS or Prometheus. In MARS treatments, IL-10 was cleared from plasma more efficiently than IL-6. Clearance of IL-10 was higher in Prometheus than in MARS treatments.

Conclusion

Cytokines are cleared from plasma by both MARS and Prometheus, but neither system is able to change serum cytokine levels. This discrepancy is probably due to a high rate of cytokine production in patients with ACLF.

Use of molecular adsorbent recirculating system in acute liver failure attributable to dengue hemorrhagic fever

Fulminant liver failure is an uncommon but life-threatening complication of severe dengue infection. Molecular adsorbent recirculating system (MARS), which reverses hepatic encephalopathy, is an emerging important element in the armamentarium of organ support in the intensive care unit in patients suffering from acute liver failure. We report an intensive care unit case of fulminant liver failure secondary to dengue hemorrhagic fever, which was supported with MARS. MARS led to rapid reversal of biochemical profile and encephalopathy, resulting in early extubation and intensive care unit discharge.

[Albumin dialysis in patients with acute exacerbation of chronic liver failure in an intensive care unit]

BACKGROUND AND OBJECTIVE

To describe our experience with albumin dialysis (Molecular Adsorbent Recirculating System [MARS]) in patients who are in an intensive care unit due to an acute exacerbation of chronic liver failure.

PATIENTS AND METHOD

From January 2004 to October 2005 10 patients, aged 40 to 65 years (mean age 58.8), were admitted due to acute exacerbation of chronic liver failure. All of them suffered from an encephalopathy and were candidates for a liver transplantation. One to six MARS sessions were applied. Clinical parameters were registered before and after each session.

RESULTS

Of the 10 patients treated, 9 survived and 1 died. Five out of the 9 survivors were successfully transplanted. In 2 patients (one of them was the deceased one) the grade of encephalopathy was > I (II and III respectively), and in both improved to grade I. In the other ones, the encephalopathy did not worsen. The serum bilirubin diminished from 39.2 to 28.2 mg/dl (p < 0.01). In the 3 patients with serum creatinin > 1.5 mg/dl, this parameter diminished from 2.6 to 1.5 mg/dl (p < 0.01). Two patients had thrombocytopaenia and haemorrhage, and in one of them the MARS treatment had to be interrupted. No hypotension was observed.

CONCLUSIONS

The reduction in the serum bilirrubin and creatinin, as well as the clinical improvement of the two patients with encephalopathy grade > I, make us to think that the MARS can be useful to patients with acute exacerbation of a chronic liver failure as a bridge to a liver transplantation.

Review article: clinical experience with Prometheus

Prometheus is a new extracorporeal liver support device which facilitates the combined removal of both albumin-bound and water-soluble toxins based upon the method of fractionated plasma separation and adsorption (FPSA). The pilot trial included 11 patients with acute-on-chronic liver failure and concomitant renal failure. Prometheus therapy was found to be safe except for a reversible decrease of blood pressure. In three patients, clotting of the secondary system occurred. Prometheus treatment significantly improved blood levels of protein-bound (conjugated bilirubin, bile acids, ammonia) and water-soluble (creatinine, urea) substances. Thus, Prometheus might be a new therapeutic option in patients with severe hepatorenal syndrome. Furthermore, there is some preliminary experience with Prometheus in the treatment of refractory cholestatic pruritus and in successful bridging to liver transplantation. In order to compare extraction capacities of Prometheus and the molecular adsorbent recirculating system (MARS), five patients were crossover-treated with both systems. Prometheus resulted in significantly higher reduction ratios of bilirubin, ammonia and urea. Another study closely monitored whether the device causes an unselective removal. Neither important cytokines nor coagulation factors were found to be removed. In conclusion, Prometheus seems to be a new therapeutic option in artificial liver support. A significant improvement of the biochemical milieu was already observed after two treatments. The potential to remove protein-bound and water-soluble substances has been shown without signs of a significant unselective removal.

Prometheus versus molecular adsorbents recirculating system: comparison of efficiency in two different liver detoxification devices

Albumin dialysis by the molecular adsorbents recirculating system (MARS) and by fractionated plasma separation, adsorption, and dialysis (Prometheus[PROM]) represent novel nonbiological liver support systems specifically designed to remove albumin-bound substances. Preliminary evidence suggests a favorable impact of MARS on the course and outcome of liver failure. This study aimed at comparing the detoxification capacity of both devices. For this purpose, we performed a retrospective analysis on data prospectively collected in patients with acute-on-chronic liver failure treated with either the MARS (n = 9) or the PROM (n = 9) device on 2-5 consecutive days. Each treatment was performed for at least 5 h at identical blood and dialysate flows. Blood clearances were calculated during the first treatment session for urea nitrogen, creatinine, total bilirubin, and bile acids from paired arterial and venous line samples after 1, 4, and 6 h of treatment. Reduction ratios for all single-treatment sessions, and the overall treatment phase, were calculated from pretreatment and post-treatment values. For all markers but bile acids, the single-treatment as well as the overall treatment phase reduction ratios obtained with PROM were significantly higher compared with those obtained with MARS. PROM led at all time points to higher clearances for all evaluated solutes. Blood clearances of protein-bound substances declined over time with MARS, but not with PROM. In conclusion, a significant decline in the serum level of water-soluble and protein-bound toxins was achieved with both devices. PROM produces higher blood clearances for most toxins, which results in higher delivered treatment doses compared with a matching treatment with MARS.

Acute liver failure

Acute liver failure in children is a rare but potentially fatal disease. Causes of ALF in neonatal period are different from those in early or late childhood. Despite the improvement in the paediatric intensive care, liver transplantation remains the only effective treatment. Use of newer treatment modalities (liver assist devices and hepatocyte transplantation) is still in experimental phase. Management requires early recognition, prompt diagnosis of treatable condition, supportive therapy and prevention of complications hence these children should ideally be treated in a specialist unit.

Treatment of severe refractory pruritus with fractionated plasma separation and adsorption (Prometheus)

OBJECTIVE

Severe pruritus is a serious complication of cholestatic liver disease. Prometheus is a recently introduced extracorporeal liver support system with direct toxin adsorption of the patient's albumin fraction (FPSA; fractionated plasma separation and adsorption). Here we report on the effect of Prometheus therapy in patients with intractable cholestatic pruritus.

MATERIAL AND METHODS

Seven patients with different liver diseases and severe pruritus refractory to all medical treatment efforts for more than 4 weeks were treated with Prometheus (3-5 times, 18+/-3 h total). Pruritus intensity was assessed using the visual analogue scale (VAS; from 0 = no pruritus to 10 = unbearable pruritus), and VAS, serum bile acids and total bilirubin were evaluated directly before and after Prometheus treatment, as well as 4 weeks later.

RESULTS

After Prometheus therapy, VAS values had dropped significantly from 9+/-1 to 3+/-3 (p<0.001). Likewise, serum bile acids decreased (from 248+/-192 to 101+/-85 micromol/l; p<0.03). All patients, with the exception of one with no initial bile acid elevation, reported a pronounced improvement in pruritus with Prometheus therapy, although in two anicteric patients the amelioration lasted only a few days. In the other four patients a distinct benefit was still observed 4 weeks after the treatment.

CONCLUSIONS

Prometheus therapy significantly improved refractory pruritus in all patients with elevated bile acid levels, but in some patients the clinical benefit was of short duration. The clinical findings suggest that we have to better characterize those patients who might derive a long-lasting benefit from this invasive and expensive treatment.

New management options for end-stage chronic liver disease and acute liver failure: potential for pediatric patients

The management of children with end-stage chronic liver disease and acute liver failure mandates a multidisciplinary approach and intense monitoring. In recent years, considerable progress has been made in developing specific and supportive medical measures, but studies and publications have mainly concerned adult patients. Therapeutic approaches to complications of end-stage chronic liver disease and acute liver failure (e.g. refractory ascites, hepatorenal syndrome, encephalopathy, and cerebral edema) that may be applied to children are reviewed in this article.Mild-to-moderate ascites should be managed by modest salt restriction and oral diuretic therapy in the first instance. Large volume paracentesis associated with colloid volume expansion and diuretic therapy may be effective for acute relief. Treatment of hepatorenal syndrome type 1 with vasopressin analogs (terlipressin) is recommended prior to liver transplantation in order to improve renal function. Prevention and treatment of chronic hepatic encephalopathy are directed primarily at controlling the events that may precipitate hepatic encephalopathy and at reducing ammonia generation and increasing its detoxification or removal. In addition to reduction of gut ammonia production using non-absorbable disaccharides such as lactulose and/or antibacterials such as neomycin, sodium benzoate may be used on a long-term basis to prevent, stabilize, or improve hepatic encephalopathy. The management of hepatic encephalopathy in acute liver failure is considerably more unsatisfactory; treatment is aimed at preventing brain edema and intracranial hypertension. Extracorporeal liver support devices are now used commonly in critically ill children with acute renal failure, advanced hepatic encephalopathy, cerebral edema, intracranial hypertension, and severe coagulopathy. Continuous renal replacement therapy could potentially help support patients until liver transplantation is performed or liver regeneration occurs. The Molecular Adsorbent Recirculating System (MARS or albumin dialysis) is the liver support system most frequently used worldwide in adults and appears to offer distinct advantages over hepatocyte-based systems. There are no specific medical therapies or devices that can correct all of the functions of the liver. Apart from a few metabolic diseases presenting with severe liver dysfunction for which specific medical therapies may preclude the need for liver transplantation, liver transplantation still remains the only definitive therapy in most instances of end-stage chronic liver disease and acute liver failure. Future research should focus on gaining a better understanding of the mechanisms responsible for liver cell death and liver regeneration, as well as developments in hepatocyte transplantation and liver-directed gene therapy.

Advances in critical care management of hepatic failure and insufficiency

BACKGROUND

Chronic liver disease is becoming an increasingly frequent diagnosis for patients in the intensive care setting with such diagnoses as symptomatic ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, or fulminant hepatic failure.

OBJECTIVE

To review frequent diagnoses for patients with chronic liver disease admitted to the intensive care unit and discuss current concepts in management and investigational modalities.

RESULTS

Patients with new-onset ascites in the intensive care setting should undergo immediate ultrasound to rule out acute thrombosis. A transjugular intrahepatic portosystemic shunt is indicated when control of the refractory ascites or hepatic hydrothorax is required. In patients with hepatorenal syndrome, hemodialysis can be used as a bridge to liver transplantation. Otherwise, hepatorenal syndrome carries a high mortality. When hepatic encephalopathy is present, a precipitating cause should be sought and treated, if identified. Although bioartificial support systems are under active investigation, standard treatment for hepatic encephalopathy is lactulose and alteration of gut flora. Patients with fulminant hepatic failure should be stabilized and transferred to the intensive care unit of a liver transplant center and supported with appropriate airway management, close neurologic evaluation, glucose monitoring, and correction of coagulopathy when there is overt bleeding or an invasive procedure is planned. Intracranial pressure monitoring is recommended to maintain an adequate cerebral perfusion pressure of >60 mm Hg.

CONCLUSION

Review of the literature demonstrates that certain critically ill patients with chronic liver disease may benefit from invasive modalities such as transjugular intrahepatic portosystemic shunting, hemodialysis, and in some cases, liver transplantation, which may be offered only at tertiary care centers.

Molecular adsorbent recirculating system (MARS) application in liver failure: clinical and hemodepurative results in 22 patients

PURPOSE

Acute liver failure (ALF) and acute on chronic liver failure (ACLF) still show a poor prognosis. MARS was used in 22 patients with ALF or ACLF to prolong patient survival for liver function recovery or as a bridge to transplantation.

DESIGN

Evaluation of depurative efficiency, biocompatibility, hemodynamics, encephalopathy (HE) and clinical outcome.

PROCEDURES

During 71 five-hour sessions we evaluated (0', 60', 120', 180', 240', 300'): bilirubin, ammonia, cholic acid (CCA), chenodeoxycholic acid (CCDCA), leukocytes, platelets, hemoglobin and mean arterial pressure (MAP). Serum creatinine, electrolytes, cardiac output, cardiac index (bioimpedence) and HE (West Haven Criteria score) were evaluated at 0' and 300'. STATISTICAL METHODS AND OUTCOME MEASURES: Student's t-test for pre- vs. end-session values was used. For bilirubin and ammonia the correlation test was made between pre- and end-session values and between pre-session values and removal rates (RRS).

MAIN FINDINGS

Survival was 90.9% at 7 days, 40.9% at 30 days. Pre- vs. end-session: bilirubin from 37.2 +/- 12.5 mg/dL to 24.9 +/- 8.9 mg/dL (p < 0.01), ammonia from 88.0 +/- 60.4 micromol/L to 43.6 +/- 32.9 micromol/L (p < 0.01), CCA from 42.8 +/- 21.0 micromol/L 18.2 +/- 9.8 micromol/L (p < 0.01), CCDCA from 26.3 +/- 6.3 micromol/L to 15.7+/-7.6 micromol/L (p<0.01). The correlation test between pre-session values of bilirubin and ammonia vs. RR S was respectively 0.32 (p = 0.01) and 0.30 (p = 0.04). Leukocytes, platelets and hemoglobin remained stable. MAP increased from 82.0 +/- 12.0 mmHg to 87.0 +/- 13.0 mmHg (p < 0.05), West Haven Criteria score decreased from 2.7 +/- 0.7 to 0.7 +/- 0.7 (p < 0.001).

CONCLUSION

MARS treatment led in all patients to an improvement of clinical, hemodynamic and neurological conditions, with significant reduction in the hepatic toxins blood level. Treatment biocompatibility and tolerance were satisfactory.

Personal view: current role of artificial liver support devices

Enthusiasm for liver support devices, particularly cell-based biological systems and albumin dialysis, increased over the last decade and there has been considerable clinical activity both within and without the construct of clinical trials. Most data have been generated on patients with acute liver failure or in patients with decompensation of chronic liver disease, often referred to as acute-on-chronic liver failure. In acute liver failure liver, liver support devices are more realistically being used as a 'bridge' to liver transplantation rather than to transplant-free survival. In acute-on-chronic liver failure the clinical objective of attaining clinical stability with treatment appears more achievable. The so-called bioartificial liver device, based on porcine hepatocytes, is the most extensively evaluated biological device. A sizeable clinical trial failed to demonstrate efficacy, but secondary analyses suggest it would be unwise to assume futility had been established with this device. Molecular adsorbent recirculating system leads the way in the non-biological category in terms of the number of patients treated, but data from large clinical trials are not yet available. One of the strongest conclusions of this review is that the amount of high-quality data available on liver support devices dramatically understates the effort and money that have been expended in their assessment. It is very clear that randomized controlled trials are mandatory to establish clinical efficacy, but it is less clear how the ideal trial should be constructed.

Portal vein oxygen supply through a liver extracorporeal device to treat acute liver failure in Swine induced by subtotal hepatectomy: preliminary data

AIM

To determine whether the increase of oxygen supply in the portal system by a liver extracorporeal (L.E.O.NARDO) device is effective in treating swine with subtotal hepatectomy leading to acute liver failure (ALF).

METHODS

Eight swine with ALF induced by 85% to 90% liver resection and 5 minutes of ischemia-reperfusion injury were randomly divided into two groups: four animals received L.E.O.NARDO treatment and four swine were not treated (control group). Blood was withdrawn from the iliac artery and reversed in the portal venous system. An extracorporeal device was interposed between the outflow and the inflow in order to monitor the hemodynamic parameters. Each treatment lasted 6 hours. Serum and liver samples were collected in both groups. The survival was assessed at 1 week.

RESULTS

L.E.O.NARDO treatment yielded beneficial effects for subtotal hepatectomy-induced ALF in swine with decreased serum transaminases as compared with the untreated group. International normalized ratio recovered rapidly in the L.E.O.NARDO group, remaining significantly lower than in untreated animals. The 7-day survival of L.E.O.NARDO group swine was significantly higher than that of untreated animals, with a significant difference. Three swine in the L.E.O.NARDO group survived 1 week while none of the swine in the control group were alive at that time.

CONCLUSIONS

Oxygen supply in the portal vein through the L.E.O.NARDO device is easily applicable, efficacious, and safe and may represent a novel approach for ALF in swine induced by subtotal liver resection.

A Modeling Study of Bilirubin Kinetics During Molecular Adsorbent Recirculating System Sessions

This work presents a quantitative description, by means of a mathematical model, of bilirubin removal during Molecular Adsorbent Recirculating System sessions. The model includes four compartments: two for the patient, and two for the albumin circuit. Equations in each compartment express mass preservation, mass exchange between compartments, and bilirubin-albumin binding kinetics. Model development and validation are based on in vivo data of bilirubin concentration acquired in eight sessions at different times during the session. The accuracy of the model in reproducing real data is high (error in blood = -0.3 +/- 0.93 mg/dL), if three parameters, representing the depurative efficacy of the system (the dialysance of the blood filter and the initial and final clearance of the depurative elements in the albumin circuit), are estimated on each single session. However, model accuracy is only slightly deteriorated (error in blood = -0.4 +/- 0.99 mg/dL) if a single set of parameters (fixing the three parameters at their mean values) is adopted. These results suggest that the model may be used a priori (i.e., using a single set of parameters) to achieve a satisfactory prediction of the overall bilirubin removal, as well as a posteriori for the estimation of device parameters. The latter use may allow the investigation of the dependence of these parameters on the operative and clinical conditions, in the effort to arrive at a rationalization and optimization of the treatment.

Sorbent Suspensions vs. Sorbent Columns for Extracorporeal Detoxification in Hepatic Failure

Hepatic failure is a significant medical problem which has been unsuccessfully treated by hemodialysis. However, similar therapies using recirculated dialysate regenerated by sorbents in place of single-pass dialysate have been beneficial in treating acute-on-chronic liver failure. The advantages of sorbent-based treatments include some selectivity of toxin removal and improved removal of protein-bound toxins. Activated carbon has been extensively used in detoxification systems, but has often had insufficient toxin capacity. Powdered activated carbon, because of its large surface area, can provide greater binding capacity for bilirubin and other toxins than granular carbon commonly used in detoxifying columns. Methods of using powdered carbon in extracorporeal blood treatment devices are reviewed in the present paper, including liver dialysis and a new sorbent suspension reactor (SSR); and the abilities and limitations of the SSR and columns to process protein solutions are discussed.

Present and Future Developments in Hepatic Tissue Engineering for Liver Support Systems : State of the art and future developments of hepatic cell culture techniques for the use in liver support systems

The liver is the most important organ for the biotransformation of xenobiotics, and the failure to treat acute or acute-on-chronic liver failure causes high mortality rates in affected patients. Due to the lack of donor livers and the limited possibility of the clinical management there has been growing interest in the development of extracorporeal liver support systems as a bridge to liver transplantation or to support recovery during hepatic failure. Earlier attempts to provide liver support comprised non-biological therapies based on the use of conventional detoxification procedures, such as filtration and dialysis. These techniques, however, failed to meet the expected efficacy in terms of the overall survival rate due to the inadequate support of several essential liver-specific functions. For this reason, several bioartificial liver support systems using isolated viable hepatocytes have been constructed to improve the outcome of treatment for patients with fulminant liver failure by delivering essential hepatic functions. However, controlled trials (phase I/II) with these systems have shown no significant survival benefits despite the systems' contribution to improvements in clinical and biochemical parameters. For the development of improved liver support systems, critical issues, such as the cell source and culture conditions for the long-term maintenance of liver-specific functions in vitro, are reviewed in this article. We also discuss aspects concerning the performance, biotolerance and logistics of the selected bioartificial liver support systems that have been or are currently being preclinically and clinically evaluated.

Review article: non-biological liver support in liver failure

Liver failure, whether acute or acute-on-chronic, remains an important cause of morbidity and mortality. The lack of liver detoxification, metabolic and regulatory functions of the liver leads to life-threatening complications, such as renal failure, altered immune response, hepatic coma and systemic haemodynamic dysfunction, eventually culminating in multiorgan failure. Current medical therapy involves the management of the precipitating event and treatment of complications until the liver eventually recovers, leaving us with no other treatment options than transplantation if these attempts fail. However, the shortage in cadaveric organs and other transplant-related problems, have prompted the need for alternative methods to provide liver support. As liver failure is often potentially reversible, considerable effort has been invested in the development of liver support systems. Currently, most of the experience is available for non-biological support systems. They represent the focus of this review, which aims to define the goals of liver support, to describe the design of the different existing devices and to analyse the available data to determine their current status in the management of patients with liver failure.

Technology insight: liver support systems

Emergency orthotopic liver transplantation (OLT) is currently the only standard treatment for fulminant hepatic failure (FHF). The waiting time for transplantation can exceed a week-using a liver assist device to bridge patients with FHF to OLT might therefore decrease the mortality rate. Several liver support systems have been described, but no system has gained FDA approval or widespread clinical acceptance. Although the results of many experimental and clinical trials are encouraging, the field is still in its initial stages. Using nonbiologic liver support is based on the assumption that several toxins that cause hepatic coma can be removed from the circulation by blood or plasma sorption methods. As these toxins could be involved in many FHF complications recovery without the need for transplantation is the ultimate aim. Biologic liver support uses xenogeneic livers or hepatocytes to support the failed human liver, exploiting biological cell functions, namely detoxification, metabolism, and biosynthesis. The classical nonbiologic dialysis methods could decrease mortality in patients with acute-on-chronic liver failure, but definitive conclusions are impossible to draw because of the small number of patients studied and inadequate follow-up. Larger studies performed in specialty centers should provide conclusive data about the role of the bioartificial liver support system as a possible universal bridge to OLT. This article presents an overview of published experience with liver support systems since the 1960s.

Coup de chaleur d'exercice avec hépatite fulminante : intérêt du système MARS® ?

Exertional heat stroke (EHS) is a life-threatening condition caused by an extreme elevation in core body temperature. Acute liver failure has been reported during EHS justifying liver transplantation in some cases. The Molecular Adsorbent Recirculating System (MARS) could be indicated in such situations. We report a case of a 58-year old patient who suffered acute liver failure occurring after EHS. The patient was referred for liver transplantation and benefited of MARS therapy. After three sessions of MARS, liver function improved progressively and the transplantation was not necessary. The patient completely recovered.

Adenovirus-mediated hepatocyte nuclear factor-4α overexpression maintains liver phenotype in cultured rat hepatocytes

Hepatocyte nuclear factor 4alpha (HNF-4alpha) is a transcription factor that controls embryonal liver development and that maintains and regulates gene expression in adult liver cells. We have previously demonstrated that transient overexpression of HNF-4alpha up-regulates a number of liver-specific genes in hepatoma cell lines. In this study, we extend these studies by assessing the functional role of HNF-4alpha in regulating cellular viability and liver-specific functions of primary rat hepatocytes. In cells transfected with an adenovirus vector carrying rat HNF-4alpha cDNA, induction and maintenance of liver-specific genes and functions were observed over a long-term culture, which might be associated with the prevention of a rapid loss of the mitochondrial membrane potential. In addition, we demonstrated that transthyretin mRNA was up-regulated by HNF-4alpha in primary hepatocytes, but not in hepatoma cells. These results indicate that HNF-4alpha plays a role in the maintenance of morphologically and biochemically functional hepatocytes and that the difference in expression of liver-specific genes induced by HNF-4alpha may depend on a differentiation state of cells.

A Risk Quantification Instrument for Acute Acetaminophen Overdose Patients Treated With N-Acetylcysteine

STUDY OBJECTIVE

The risk of hepatotoxicity after acute acetaminophen overdose varies with timed serum acetaminophen concentration and delay to treatment. The ability to accurately predict hepatotoxicity is needed to reduce confusion about the optimal treatment regimen for individual patients and the effects of risk modifiers such as ethanol. We quantitatively estimate the risk of hepatotoxicity based on the degree and duration of pretreatment exposure to supratherapeutic concentrations of acetaminophen.

METHODS

We examined all hospitalizations for acute acetaminophen overdose within a retrospective multicenter Canadian registry. We used a previously developed composite measure incorporating timed serum acetaminophen concentration and time to N-acetylcysteine treatment into a single parameter. We then modeled hepatotoxicity on this parameter, as well as age, sex, and ethanol use. Hepatotoxicity was defined as peak aminotransferase level of 1,000 IU/L or greater at 24 hours or longer.

RESULTS

Of 1,270 admitted patients treated mostly with intravenous N-acetylcysteine for less than 24 hours, our model accurately identified the 94 patients who developed hepatotoxicity (discriminatory index 0.93). Hepatotoxicity occurred in none of the 313 patients (95% confidence interval [CI] 0% to 1.0%) above the traditional 150 mug/mL treatment line who were classified as low risk (<1%) using our instrument. After adjustment for severity of exposure, the risk of hepatotoxicity was considerably higher in the absence of coingested ethanol (median hepatotoxic dose 16.5 mmol/L x hour [95% CI 8.74 to 31.0 mmol/L x hour] versus 27.1 mmol/L x hour [95% CI 11.1 to 66.3 mmol/L x hour]), particularly among alcoholics (4.79 mmol/L x hour [95% CI 2.13 to 10.8 mmol/L x hour]).

CONCLUSION

Our risk prediction instrument identifies a large group of low-risk patients for whom 20-hour intravenous N-acetylcysteine therapy is sufficient. Our results suggest that acute and chronic ethanol use dramatically influences acetaminophen toxicity. This work may facilitate the evaluation of individualized treatment strategies for higher-risk patients.

Liver support for fulminant hepatic failure: is it time to use the molecular adsorbents recycling system in children?

OBJECTIVE

To describe the main liver support devices used for fulminant hepatic failure (FHF) and to review data on the Molecular Adsorbents Recycling System (MARS) and assess its efficiency in children.

DATA SOURCE

Studies were identified through selected readings and a MEDLINE search from 1975 and 2004 using fulminant hepatic failure, acute liver failure, primary graft dysfunction, liver support, MARS, and extracorporeal liver assist device as key words.

STUDY SELECTION

All original studies, including case reports, relating to the use of the MARS or albumin dialysis system were included. Additional attention was put on prognosis criteria of FHF severity in children.

DATA EXTRACTION

Study design, numbers and diagnoses of patients, definite or bridging treatment, outcome measures, and complications were extracted and compiled. Results of individual trials were combined on the risk ratio scale.

DATA SYNTHESIS

Nine randomized trials including 354 patients were identified. However, liver support failed to significantly affect mortality when compared with standard medical therapy. Albumin dialysis, and particularly MARS, emerges as an easily applicable technique for temporary liver support. Some well-designed studies have characterized its efficiency in a few indications, such as in intractable pruritus in chronic liver disease, in acute or chronic liver diseases, and in decompensated cirrhosis with hepatorenal syndrome. In adults and children with FHF, anecdotal reports suggest that MARS may stabilize the patient. However, no randomized controlled study has validated its use in this indication. A randomized controlled study is ongoing in adults with FHF. Such a trial seems to be unfeasible in children for several methodologic reasons.

CONCLUSIONS

Although promising preliminary results suggest that MARS may have a significant position in the therapeutic arsenal for FHF, no sufficient data exist to justify its use in children. For as long as the results of the ongoing adult trial are not available, the indications of this expensive technique in children with FHF are limited.

The Prometheus device for extracorporeal support of combined liver and renal failure

BACKGROUND/AIMS

Prometheus is a newly developed extracorporeal liver support system that combines removal of albumin-bound substances (adsorption on resin adsorbers) and water-soluble substances (diffusion during high-flux hemodialysis). Therefore, it is a promising treatment option for patients with hepatorenal syndrome (HRS).

METHODS

We studied 10 patients with HRS in a prospective clinical study. All patients underwent 2 consecutive Prometheus treatments. A variety of clinical and biochemical parameters were assessed.

RESULTS

Prometheus treatment was uncomplicated and safe. A statistically significant improvement of serum creatinine and urea concentrations as well as blood pH was observed after Prometheus treatment. Furthermore, liver detoxification was supported by a significant decrease of serum levels of conjugated bilirubin, bile acids and ammonia.

CONCLUSIONS

Prometheus is a safe treatment for patients with HRS. Both, albumin-bound and water-soluble substances were effectively removed. Controlled studies will evaluate the effect of this new treatment option on survival in patients with HRS.