Pathophysiological effects of albumin dialysis in acute-on-chronic liver failure: a randomized controlled study

Use of the molecular adsorbent recirculating system (MARS™) for the management of acute poisoning with or without liver failure

INTRODUCTION

There is an increasing interest in recent developments in bioartificial and non-bioartificial devices, so called extracorporeal liver assist devices, which are now used widely not only to increase drug elimination, but also to enhance the removal of endogenous substances in acute liver failure. Most of the non-bioartificial techniques are based on the principle of albumin dialysis. The objective is to remove albumin-bound substances that could play a role in the pathophysiology of acute liver failure by dialysing blood against an albumin-containing solution across a high flux permeable membrane. The most widely used device is the Molecular Adsorbent Recirculating System (MARS™).

METHODS

The relevant English and French literature was identified through Medline using the terms, 'molecular adsorbent recirculating system', 'MARS', 'acute liver failure', 'acute poisoning', 'intoxication'. This search identified 139 papers of which 48 reported on a toxic cause for the use of MARS™. Of these 48 papers, 39 specified the substance (eighteen different substances were identified); two papers reported on the same group of patients. BIOARTIFICIAL AND NON-BIOARTIFICIAL SYSTEMS: Bioartificial systems based on porcine hepatocytes incorporated in the extracorporeal circuit are no longer in use due to the possibility of porcine retroviral transmission to humans. Historically, experience with such devices was limited to a few cases of paracetamol poisoning. In contrast, an abundant literature exists for the non-bioartificial systems based on albumin dialysis. The MARS™ has been used more widely than other techniques, such as the one using fractionated plasma separation and adsorption (Prometheus™). All the extracorporeal liver assist devices are able to some extent to remove biological substances (ammonia, urea, creatinine, bilirubin, bile acids, amino acids, cytokines, vasoactive agents) but the real impact on the patient's clinical course has still to be determined. Improvement in cardiovascular or neurological dysfunction has been shown both in acute liver failure and acute-on-chronic liver failure but no impact on mortality has been reported. ACUTE POISONING WITH LIVER FAILURE: Randomized controlled trials are very limited in number and patients poisoned by paracetamol or Amanita phalloides are usually included for outcome analysis in larger groups of acute liver failure patients. Initial results look promising but should be confirmed. Beyond its effect in liver failure, MARS™ could also enhance the elimination of the drug or toxin responsible for the failure, as is described with paracetamol. ACUTE POISONING WITHOUT LIVER FAILURE: Extracorporeal liver assist devices have also been used to promote elimination of drugs that are highly protein bound. Data in various case reports confirm a high elimination of phenytoin, theophylline and diltiazem. However, definite conclusions on the toxicokinetic or clinical efficacy cannot be drawn.

CONCLUSIONS

Despite the lack of large multicentre randomized trials on the use of MARS™ in patients with acute liver failure, the literature shows clinical and biological benefit from this technique. In drug or toxin-induced acute liver failure, such as paracetamol or mushroom poisoning, MARS™ has been used extensively, confirming in a non-randomized fashion, the positive effect observed in the larger population of acute liver failure patients. Furthermore, as MARS™ has been shown in experimental studies to remove protein-bound substances, it is potentially a promising treatment for patients with acute poisoning from drugs that have high protein-binding capacity and are metabolized by the liver, especially, if they develop liver failure concomitantly.

Artificial extracorporeal liver support therapy in patients with severe liver failure

Severe liver failure is common and carries a high mortality risk in patients with both acute and acute-on-chronic liver failure. The failing liver constitutes a medical emergency, and in many cases liver transplantation is the only definite treatment. Extracorporeal liver support can be employed as a strategy for bridging to transplantation or recovery. This article focuses on options for artificial (nonbiological) extracorporeal treatment: single-pass albumin dialysis, fractionated plasma separation and adsorption (Prometheus(®)) and the molecular adsorbent recirculatory system. Their different principles, potential advantages and indications are discussed. Despite proven biochemical efficacy, there are little data regarding clinical end points. Thus far, molecular adsorbent recirculatory system therapy in acute and acute-on-chronic liver failure showed no survival benefit compared with standard medical therapy. Prometheus therapy showed reduced mortality in subgroups of higher severity of disease compared with standard medical therapy. Nevertheless, the value of extracorporeal liver support remains to be corroborated by further clinical studies that include the optimal timing, mode, intensity and duration of this treatment.

Effects of intraperitoneal albumin on systemic and cerebral hemodynamics in a swine model of acute liver failure

BACKGROUND

Currently, albumin dialysis is the most widely used nonbiological liver support system. We hypothesized that direct peritoneal albumin exposure in the peritoneal cavity would stabilize blood flow and prevent liver and brain injury, in the same way that had previously been seen with extracorporeal albumin dialysis systems.

MATERIALS AND METHODS

Fourteen Landrace pigs (weight 25-30 kg) underwent 70% right hepatectomy and were randomly assigned into a control (C, n = 7) and an intraperitoneal albumin treated group (A, n = 7). The systemic, cerebral, and pulmonary hemodynamic parameters of the animals were recorded at 0, 6, 9, and 12 hr following reperfusion of the liver remnant.

RESULTS

Mean arterial blood pressure, cardiac output, and stroke volume were significantly higher in group A at the end of the experiment. Significantly higher mean intracranial pressure (ICP) values were observed in group C compared to group A, both at 9 hr (21.3 ± 5.2 versus 14.1 ± 3.5 mmHg, p < .0005) and 12 hr (23 ± 4.3 versus 11 ± 3.5 mmHg, p < .0005). On the contrary, cerebral perfusion pressure (CPP) remained stable in albumin-treated groups after the sixth postreperfusion hour. Mean pulmonary artery pressure and pulmonary vascular resistance (PVR) were significantly lower in group A compared to group C at 12 hr, while pulmonary capillary wedge pressure (PCWP) stabilized in albumin-treated animals.

CONCLUSIONS

This study provides the first evidence that intraperitoneal albumin may be able to attenuate systemic, pulmonary, and cerebral hemodynamic disturbances associated with acute liver failure.

Acute-on-chronic liver failure: current concepts on definition, pathogenesis, clinical manifestations and potential therapeutic interventions

In recent years, acute-on-chronic liver failure has been recognized as a specific clinical form of liver failure associated with cirrhosis. The syndrome refers to an acute deterioration of liver function and subsequently of other end organs over a period of weeks following a precipitating event in a patient with previously well- or reasonably well-compensated cirrhosis. These precipitating events include either an indirect (e.g., variceal hemorrhage, sepsis) or a direct (e.g., drug-induced) hepatotoxic factor. The short-term mortality for this condition is more than 50%. At present, considerable efforts are ongoing to better characterize the syndrome, to gain further insight into its pathophysiology and to optimize therapy. This article aims to highlight the current concepts of these various aspects.

The ratio of Th-17 to Treg cells is associated with survival of patients with acute-on-chronic hepatitis B liver failure

Both T-helper 17 cells (Th-17) and CD4(+)CD25(+) regulatory T cells (Tregs) play important roles in the pathogenesis of hepatitis B virus (HBV) infection. Recent studies have suggested that Th-17 and Treg cells are increased in patients with chronic hepatitis B (CHB). This study further characterizes Th-17 and Treg cells in the blood of HBV-associated acute-on-chronic liver failure (ACLF) patients, and aids our understanding of how the two subsets of CD4(+) T cells affect each other and contribute to survival. Blood samples were obtained from 30 patients with HBV-associated ACLF, 30 patients with CHB, and 30 normal controls (NC). The frequencies of Th-17 and Treg cells were determined by intracellular cytokine staining analysis. To observe the suppressive function of Tregs, purified CD4(+)CD25(+) Tregs from peripheral blood mononuclear cells (PBMCs) were co-cultured with CD4(+)CD25(-) T cells for 48 h, and then IFN-γ and IL-17A from the supernatants were measured by ELISA. We found that both Th-17 and FoxP3(+) Treg cells were increased in ACLF patients. IL-17A secretion by CD4(+) T cells was not regulated by Treg cells, even though Tregs exhibited significant inhibition of IFN-γ production. Most importantly, the ratio of Th-17 to Treg cells was associated inversely with the survival of ACLF patients. These findings provide new information regarding the pathogenesis of HBV-associated ACLF, and the ratio of Th-17 to Tregs may represent a potential prognostic marker for the disease.

Protective role of α2HS-glycoprotein in HBV-associated liver failure

In this study, levels of plasma α2-Heremans-Schmid glycoprotein, serum tumor necrosis factor-α, serum liver function parameters and short-term mortality were measured in 100 hepatitis B patients. Release of interleukin-6 and tumor necrosis factor-α from the lipopolysaccharide-stimulated peripheral blood mononuclear cells in the presence/absence of spermine and α2-Heremans-Schmid glycoprotein were analyzed by enzyme-linked immunosorbent assay to determine the significance and potential mechanism of α2-Heremans-Schmid glycoprotein in hepatitis B virus-associated liver damage. Results showed that serum α2-Heremans-Schmid glycoprotein levels in acute-on-chronic liver failure patients were significantly lower than that in chronic hepatitis B patients or healthy controls (p < 0.05). A negative dependence between serum human α2-Heremans-Schmid glycoprotein and tumor necrosis factor-α levels was observed. Interleukin-6 and tumor necrosis factor-α levels in the lipopolysaccharide-induced peripheral blood mononuclear cell supernates were significantly reduced by spermine and/or α2-Heremans-Schmid glycoprotein. The latter two proteins jointly inhibited cytokine release. These observations suggest that plasma α2-Heremans-Schmid glycoprotein is an independent marker of liver damage and a prognostic indicator of hepatitis B virus chronicity. It may reduce liver inflammation by partially inhibiting release of inflammatory factors from activated peripheral blood mononuclear cells.

Cryopreservation of encapsulated liver spheroids for a bioartificial liver: reducing latent cryoinjury using an ice nucleating agent

INTRODUCTION

Acute liver failure has high mortality due to donor organ shortages. A bioartificial liver could "bridge the gap" to transplant or spontaneous recovery. Alginate encapsulation of HepG2 cells enables cell spheroid formation, thus providing sufficient functional biomass. Cryopreservation (CryoP) of these spheroids would allow an off-the-shelf capability for unpredictable emergency use. Cell death during CryoP often results from intracellular ice formation, after supercooling. An ice nucleating agent (INA), crystalline cholesterol, was trialled to reduce supercooling and subsequent cryoinjury.

MATERIALS AND METHODS

Spheroids were cooled in a controlled rate freezer in 12% dimethylsulfoxide/Celsior +/- INA, and sample temperatures were recorded throughout. Viability was assessed using fluorescent staining with image analysis, cell number by nuclei count, function using assays to detect liver-specific protein synthesis and secretion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction, and broad-spectrum cytochrome P450 activity.

RESULTS

Spheroids cryopreserved without INA displayed latent cryoinjury in the first 6 h after thawing. INA reduced supercooling during CryoP and also latent cryoinjury. Cell numbers, viability, and function as measured over 72 h post-thaw were all improved when INA was present during CryoP.

Comparison of Molecular Adsorbents Recirculating System (MARS) dialysis with combined plasma exchange and haemodialysis in children with acute liver failure

BACKGROUND

Molecular Adsorbents Recirculating System (MARS) is an extracorporeal liver support system eliminating albumin-bound and water-soluble substances. While it is increasingly applied in patients with acute liver failure (ALF), no comparison with standard dialysis methods has yet been performed.

METHODS

This is an analysis of ten children (0.1-18 years) with ALF, who underwent a total of 22 MARS sessions. Standard adult MARS sets were used in seven (23.5-72 kg) and MARS Mini in three children (2.8-13 kg). In eight children, MARS was alternated with combined plasma exchange (PE) and haemodialysis (HD) treatments. Mean treatment duration was 7.2 (6-10) h for MARS and 5.7 (4.5-6.6) h for PE/HD.

RESULTS

Standard MARS treatment only slightly decreased serum bilirubin (16.3 ± 6.5-13.8 ± 5.9 mg/dL) and ammonia (113 ± 62-99 ± 68 μmol/L) and international normalized ratio (INR) tended to increase (1.5 ± 0.3 and 2 ± 1.1). Mini-MARS did not reduce serum bilirubin (19.7 ± 3-20.5 ± 3.2 mg/dL), ammonia slightly decreased (70 ± 24-56 ± 9 μmol/L) and INR increased (2.5 ± 0.7-2.9 ± 1.1, all P = n.s.). In contrast, PE/HD reduced serum bilirubin (23 ± 8.4-14.7 ± 7 mg/dL), ammonia (120 ± 60-70 ± 40 μmol/L) and INR (2.4 ± 0.8-1.4 ± 0.1, all P < 0.05). Intraindividual comparison showed a slight increase in bilirubin by 2 ± 22% with MARS and a reduction by 37 ± 11% with PE/HD (P < 0.001 versus MARS) and a decrease in ammonia of 18 ± 27 and 39 ± 23% (P < 0.05). INR increased during MARS by 26 ± 41% and decreased with PE/HD by 37 ± 20% (P < 0.01). All treatment sessions were well tolerated. Five children died, including the three children treated with Mini-MARS.

CONCLUSION

Our experience suggests superior efficacy of combined PE/HD as compared to intermittent MARS therapy for treating ALF.

Thromboelastography to monitor clotting/bleeding complications in patients treated with the molecular adsorbent recirculating system

Background. The Molecular Adsorbent Recirculating System (MARS) has been shown to clear albumin-bound toxins from patients with liver failure but might cause bleeding complications potentially obscuring survival benefits. We hypothesized that monitoring clotting parameters and bed-side thromboelastography allows to reduce bleeding complications. Methods. Retrospective analysis of 25 MARS sessions during which clotting parameters were monitored by a standardized protocol. Results. During MARS therapy median INR increased significantly from 1.7 to 1.9 platelet count and fibrinogen content decreased significantly from 57 fL(-1) to 42 fL(-1) and 2.1 g/L to 1.5 g/L. Nine relevant complications occurred: the MARS system clotted 6 times 3 times we observed hemorrhages. Absent thrombocytopenia and elevated plasma fibrinogen predicted clotting of the MARS system (ROC 0.94 and 0.82). Fibrinolysis, detected by thromboelastography, uniquely predicted bleeding events. Conclusion. Bed-side thromboelastography and close monitoring of coagulation parameters can predict and, therefore, help prevent bleeding complications during MARS therapy.

Regional citrate anticoagulation in patients with liver failure supported by a molecular adsorbent recirculating system

OBJECTIVE

Regional citrate anticoagulation has emerged as a promising method in critically ill patients at high risk of bleeding. However, in patients with liver failure, citrate accumulation may lead to acid-base and electrolyte imbalances, notably of calcium. The aim of this study was to evaluate the feasibility and safety of regional citrate anticoagulation during liver support using a molecular adsorbent recirculating system as well as its effects on electrolyte and acid-base balance in patients with liver failure.

DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENTS

Twenty critically ill patients supported by molecular adsorbent recirculating system resulting from liver failure between January 2007 and May 2009.

MEASUREMENTS AND MAIN RESULTS

The median duration of molecular adsorbent recirculating system treatment was 20 hrs (interquartile range, 18-22 hrs). Two of 77 molecular adsorbent recirculating system treatments (2%) were prematurely discontinued as a result of filter clotting and bleeding, respectively. The median citrate infusion rate, necessary to maintain the postfilter ionized calcium between 0.2 and 0.4 mmol/L, was 3.1 mmol/L (interquartile range, 2.3-4 mmol/L) blood flow. The median calcium chloride substitution rate was 0.9 mmol/L (0.3-1.7 mmol/L) dialysate. Total serum calcium remained stable during molecular adsorbent recirculating system treatments. There was a statistically significant increase of the ratio of total calcium to systemic ionized calcium (2.04 ± 0.32 mmol/L to 2.17 ± 0.35; p = .01), which reflected citrate accumulation resulting from liver failure. Under close monitoring, no clinically relevant electrolytes or acid-base disorders were observed.

CONCLUSIONS

Our results suggest that regional citrate anticoagulation is a safe and feasible method to maintain adequate circuit lifespan without increasing the risk of hemorrhagic complications while maintaining a normal acid-base as well as electrolyte balance in patients with liver failure supported by molecular adsorbent recirculating system.

Systematic review and meta-analysis of survival following extracorporeal liver support

Background

Extracorporeal liver support (ELS) systems offer the potential to prolong survival in acute and acute-on-chronic liver failure. However, the literature has been unclear on their specific role and influence on mortality. This meta-analysis aimed to test the hypothesis that ELS improves survival in acute and acute-on-chronic liver failure.

Methods

Clinical trials citing MeSH terms ‘liver failure’ and ‘liver, artificial’ were identified by searching MEDLINE, Embase and the Cochrane registry of randomized controlled trials (RCTs) between January 1995 and January 2010. Only RCTs comparing ELS with standard medical therapy in acute or acute-on-chronic liver failure were included. A predefined data collection pro forma was used and study quality assessed according to Consolidated Standards of Reporting Trials (CONSORT) criteria. Risk ratio was used as the effect size measure according to a random-effects model.

Results

The search strategy revealed 74 clinical studies including 17 RCTs, five case–control studies and 52 cohort studies. Eight RCTs were suitable for inclusion, three addressing acute liver failure (198 participants) and five acute-on-chronic liver failure (157 participants). The mean CONSORT score was 14 (range 11–20). Overall ELS therapy significantly improved survival in acute liver failure (risk ratio 0·70; P = 0·05). The number needed to treat to prevent one death in acute liver failure was eight. No significant survival benefit was demonstrated in acute-on-chronic liver failure (risk ratio 0·87; P = 0·37).

Conclusion

ELS systems appear to improve survival in acute liver failure. There is, however, no evidence that they improve survival in acute-on-chronic liver failure.

Non-hepatic insults are common acute precipitants in patients with acute on chronic liver failure (ACLF)

INTRODUCTION

Acute-on-chronic liver failure (ACLF) is a newly coined term to describe simultaneous coexistence of two liver conditions, one of them being chronic or long-standing and the other acute or recent. There is limited data on the entity of ACLF. This study was performed to review our experience in ACLF patients from a tertiary care centre.

PATIENTS AND METHODS

ACLF was defined as per the Asian Pacific Association for the Study of the Liver (APASL) criteria, except for including the non-hepatic insults as precipitating events. Based on the type of acute insult, patients were divided into type I (non hepatic injury) and type II (hepatic injury-further divided in to IIA-acute viral hepatitis (AVH) on underlying chronic liver disease (CLD), IIB-other acute hepatitic insults like drugs/toxins and IIC-same disease responsible for worsening). Patients were also analyzed for the mode of presentation, severity of liver illness, presence of acute kidney injury and other organ failure, hospital stay and final outcome.

RESULTS

One hundred two patients with ACLF (85 males, mean age 44 ± 12.5 years) were included in the study; they accounted for 49% of all liver failures and 27% of all admissions during the study period. Sixty patients (59%) had known cirrhosis whereas 42 (41%) patients presented for the first time as ACLF, unaware of the underlying CLD. Sixty-two (60%) patients had type I ACLF while 40 (40%) patients had type II ACLF. Infections (47%) were the most common non-hepatic causes of acute deterioration in type I ACLF. Amongst type II, acute viral hepatitis (IIA) accounted for six patients (4 hepatitis E virus, 2 hepatitis A virus) and type II C was the most common with alcoholic hepatitis accounting for 30 (29%) patients. Acute kidney injury was present in 47 (46%) and hypotension in 36 (35%) patients. Hypoxemia with ventilatory support was required in 22 (21%) patients. Mean hospital stay of patients was 9.7 ± 6 days (2-27 days). Forty-seven (46%) patients either died or left hospital in a very sick state.

CONCLUSION

ACLF is a common problem in our clinical practice. Non-hepatic insults like non-hepatotropic infections/sepsis are common acute precipitating events.

[Evaluation of extracorporeal liver support systems in the treatment of liver failure. A systematic review]

OBJECTIVE

To evaluate the safety and efficacy of the MARS and Prometheus extracorporeal liver support systems in the treatment of liver failure.

DESIGN

We performed a systematic review of the literature from January 1999 to June 2009 in the Medline, Embase, HTA, DARE, NHSEED, Cochrane Library Plus, Clinical Trials Registry and HSRPROJ databases. Study selection was based on a series of previously established inclusion criteria related to the study design, population, type of intervention, language, and outcome measures.

PATIENTS AND INTERVENTIONS

Patients with acute liver failure or acute exacerbations of chronic liver failure treated with the MARS or Prometheus systems.

OUTCOME MEASURES

Data on safety, long-term survival, clinical effects and biochemical and hemodynamic variables.

RESULTS

We selected 22 studies evaluating the safety and efficacy of the MARS and Prometheus systems. Adequate evaluation of these techniques was hampered by the heterogeneity of the studies and their methodological limitations.

CONCLUSIONS

Extracorporeal liver support systems are able to purify both hydrosoluble and protein-bound substances. However, current data show that only the MARS system reduces mortality in acute liver failure and in acute exacerbations of chronic liver failure, although this reduction is non-significant. These techniques can be considered safe, with adverse effects similar to those of the control group. Their main indication is severe liver failure, for short periods while the liver recovers or a liver transplant becomes available.

Innate immune dysfunction in acute and chronic liver disease

Liver cirrhosis is a common disease causing great public-health concern because of the frequent complications requiring hospital care. Acute liver failure is also prone to several complications but is rare. One of the main complications for both acute and chronic liver diseases is infection, which regularly causes decompensation of cirrhosis, possibly leading to organ failure and death. This review focuses on innate immune function in cirrhosis, acute-on-chronic liver failure and acute liver failure. The known defects of Kupffer cells, neutrophils and monocytes are discussed, together with the pathophysiological importance of gut permeability, portal hypertension and intrinsic cellular defects, and the role of endotoxin, albumin, lipoproteins and toll-like receptors. Based on these different pathomechanisms, the available information on therapeutic strategies is presented. Antibiotic and probiotic treatment, nutritional support, artificial liver support, and experimental strategies such as inhibition of toll-like receptors and use of albumin and colony-stimulating factors are highlighted.

Liver transplantation avoided in patients with fulminant hepatic failure who received albumin dialysis with the molecular adsorbent recirculating system while on the waiting list: impact of the duration of therapy

Eighteen patients with fulminant hepatic failure due to various medical causes were listed for emergency liver transplantation and treated with extracorporeal albumin dialysis sessions using the molecular adsorbent recirculating system (MARS) at our center over a 74-month period. Due to improvement of liver function, transplantation could be avoided in 9 patients (50%, 95% confidence interval 29% to 71%) who fully recovered afterwards. This improvement rate was higher than the rate of improvement in the French cohort of fulminant hepatic failure patients with similar etiologies (19.3%, 95% confidence interval 14.9% to 24.6%, P = 0.002). In our 18 patients, there were no statistically significant differences in any baseline characteristics or in the time with liver failure meeting transplant criteria between the patients who improved while waiting and those who did not. However, the patients who improved received a greater number of sessions and a longer total duration of MARS therapy (all P < 0.001). In the whole study population, a MARS therapy duration > or =15 h was significantly associated with improvement of liver function without transplantation (adjusted adds ratio [OR] 65.76, 2.48-1743.11, P = 0.01). Tolerance of therapy was acceptable. These results suggest that MARS therapy could contribute to native liver recovery and is safe in patients on the waiting list for fulminant hepatic failure. A minimum duration of therapy (> or =15 h) could be necessary to expect significant liver function improvement.

Cost-effectiveness of the artificial liver support system MARS in patients with acute-on-chronic liver failure

BACKGROUND

For patients with an acute exacerbation of chronic liver failure (ACLF), the molecular adsorbent recirculating system (MARS) can result in a prolongation of life, but data on costs and cost-effectiveness are lacking.

METHODS

A health economic evaluation of a prospective controlled cohort trial in patients with ACLF not eligible for liver transplantation with 3 years follow-up and consecutive modelling of long-term costs, outcomes and cost-effectiveness was conducted. Costs were calculated from the perspective of the German health-care system.

RESULTS

One hundred and forty-nine patients with ACLF were included of which 67 (44.9%) were treated with MARS and 82 (55.1%) assigned to the control group. Mean survival was 692 days in MARS-treated patients (33% survival after 3 years) and 453 days in control patients (15% after 3 years, logrank P = 0.022). MARS patients gained 0.66 [95% confidence interval (CI): -0.12 to 1.46] life years (LYs), determined by the bootstrap method. The mean cost difference was 19.835 euro (95% CI: 13.308-25.429) with 35639 euro for MARS-treated patients and 15804 euro for controls. Incremental costs per LY gained were 29.985 euro (95% CI: 9.441-321.761) and 43.040 euro (95% CI: 13.551-461.856) per quality-adjusted LY gained.

CONCLUSION

There is an acceptable cost-effectiveness of MARS, compared with other medical technologies presently reimbursed. Randomized controlled trials with sufficient sample size are necessary before a final recommendation for MARS can be given.

Albumin dialysis in liver failure: comparison of molecular adsorbent recirculating system and single pass albumin dialysis--a retrospective analysis

Despite improvement in critical care, liver failure is still associated with high mortality. Therapeutic concepts are aimed at restoring endogenous liver function or to bridge the time to liver transplantation. In addition to standard medical treatment, extracorporeal liver support with albumin dialysis is used for this purpose. The aim of this study was to analyze the efficacy of single pass albumin dialysis (SPAD) in comparison to the molecular adsorbent recirculating system (MARS) in patients treated at our university hospital intensive care unit between July 2004 and August 2008. In this retrospective analysis we studied patients presenting with liver failure who were treated with albumin dialysis. Laboratory parameters, daily health scoring, the number of transfusions, and mortality were recorded. The (paired) t-test, Mann-Whitney U-test, and Wilcoxon test were used for statistical analysis. In all, 163 albumin dialysis treatments, 126 with MARS and 37 with SPAD, in 57 patients were performed. MARS resulted in a significant decrease in bilirubin (-38 +/- 66.5 micromol/L from a baseline of 301 +/- 154.6 micromol/L), gamma-glutamyltransferase (gamma-GT), alanine aminotransferase, creatinine, and urea. SPAD resulted in a significant decrease in bilirubin (-41 +/- 111.2 micromol/L from a baseline of 354 +/- 189.4 micromol/L) and gamma-GT, while lactate levels increased. No differences in the need for blood transfusion, health scoring, or mortality between the two treatment modalities were detected. This retrospective analysis suggests equal efficacy of MARS and SPAD; however, prospective assessment to further define the role of SPAD in the treatment of acute or acute-on-chronic liver failure is needed.

Hemodynamic effects of albumin dialysis in patients with liver failure: for better or for worse?

Liver failure, irrespective of is cause, is frequently associated with multi-organ dysfunction, including hemodynamic instability, and renal and cerebral insufficiency. As a result of the combined impact of these complications, liver failure carries an exceptionally high risk of mortality. A central role in the etiopathogenesis of different end-organ manifestations, as well as in the aggravation of the underlying liver failure, has been attributed to the hyperdynamic (hypotensive) state, which is characterized by a reduced systemic vascular resistance and mean arterial pressure, as well as an increased cardiac index, heart rate, and total plasma volume. Since the accumulation of toxins due to the decreased detoxification capacity by the failing liver is considered vital herein, the emergence of extracorporeal liver support has provided a rational basis for the potential reversal of these phenomena. The present article critically reviews data with regard to the hemodynamic effects of artificial liver support in the context of liver failure. Although these are scarce for acute liver failure, several uncontrolled series and small randomized trials have clearly documented that artificial liver support is able to improve both portal hypertension and the associated systemic circulatory dysfunction in patients with acute-on-chronic liver failure. The molecular basis for these effects have been related to temporary changes and/or elimination in endogenous vasoactive substances, improved albumin binding capacity, or restoration of oxidative stress-mediated damage to albumin.

[Acute on chronic liver failure]

Acute-on-Chronic Liver Failure (ACLF) is a recently introduced term defined as severe acute deterioration of an established liver disease. This entity usually develops after an acute insult. The main clinical manifestations are hepatorenal syndrome, hepatic encephalopathy and organ failure, with a high risk of death in the short term. The true incidence of ACLF remains difficult to determine due to confusions surrounding the definition of this entity, but seems to be 40% at 5 years in patients with advanced cirrhosis, which translates into 4,000 cases in Europe within this time span. The treatment of choice is liver transplantation. However, due to the shortage of suitable organs and morbidity and mortality in these patients, other options must be used.

MCP-1 and MIP3-alpha serum levels in acute liver failure and molecular adsorbent recirculating system (MARS) treatment: a pilot study

OBJECTIVE

The CC chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-3 alpha (MIP3-alpha) may be involved in the pathogenesis of acute liver failure (ALF) and acute-on-chronic liver failure (ACLF). In ALF and ACLF, the molecular adsorbent recirculating system (MARS) has been used to support liver function. Enhancement of MCP-1, as seen in other extracorporeal support systems such as haemodialysis, might thus have mitigated the beneficial effects of the MARS system in acute hepatic failure.

MATERIAL AND METHODS

Serum concentrations of MCP-1 and MIP3-alpha were measured in 10 patients with ALF or ACLF treated with MARS. Thirteen patients suffering from chronic hepatic failure (CHF) and 15 healthy individuals served as controls.

RESULTS

Baseline MCP-1 serum concentrations were significantly increased in ALF and ACLF patients as compared to patients with CHF (p=0.0027 and p=0.0046, respectively) and controls (p=0.0006 and p=0.0012, respectively). MIP3-alpha serum concentrations were also significantly enhanced in the ALF and ACLF groups as compared with those in CHF patients (p=0.0002 and p=0.0003, respectively) and controls (p<0.0001 and p<0.0001, respectively). Moreover, MIP3-alpha levels were significantly increased in CHF patients as compared to controls (p=0.0002). MCP-1 and MIP3-alpha concentrations did not change significantly during MARS treatment in ALF and ACLF patients.

CONCLUSIONS

The CC chemokines MCP-1 and MIP3-alpha are increased in ALF and ACLF patients. MARS had no effect on MCP-1 and MIP3-alpha serum concentrations in patients with ALF and ACLF, and yielded no evidence of any harmful effects of the increase of these potentially hepatocidal chemokines.

Alterations in the functional capacity of albumin in patients with decompensated cirrhosis is associated with increased mortality

Albumin concentration is diminished in patients with liver failure. Albumin infusion improves survival of cirrhotic patients with spontaneous bacterial peritonitis, and it is hypothesized that this may be due in part to its detoxifying capabilities. The aim of this study was to perform detailed quantitative and qualitative assessment of albumin function in patients with cirrhosis. Healthy controls and patients with acute deterioration of cirrhosis requiring hospital admission (n = 34) were included. Albumin function was assessed using affinity of the fatty acid binding sites using a spin label (16 doxyl-stearate) titration and electron paramagnetic resonance spectroscopy and ischemia-modified albumin (IMA) was measured. Twenty-two patients developed acute-on-chronic liver failure. Twelve were treated with the Molecular Adsorbents Recirculating System (MARS) and 10 with standard medical therapy. For each parameter measured, the patients' albumin had reduced functional ability, which worsened with disease severity. Fifteen patients died, and IMA, expressed as an albumin ratio (IMAR), was significantly higher in nonsurvivors compared with survivors (P < 0.001; area under the receiver operating curve = 0.8). No change in the patients' albumin function was observed following MARS therapy. A significant negative correlation between IMAR and the fatty acid binding coefficients for sites 1 and 2 (P < 0.001 for both) was observed, indicating possible sites of association on the protein.

CONCLUSION

The results of this study suggests marked dysfunction of albumin function in advanced cirrhosis and provide further evidence for damage to the circulating albumin, which is not reversed by MARS therapy. IMAR correlates with disease severity and may have prognostic use in acute-on-chronic liver failure.

Hepatic encephalopathy: pathophysiology and emerging therapies

Hepatic encephalopathy is characterized by neuropsychiatric abnormalities in patients with liver failure. Severe hepatic encephalopathy is an indication for liver transplantation as it portends poor outcome. Treatment of hepatic encephalopathy involves correction of precipitating factors such as sepsis, gastrointestinal bleeding, medications, and electrolyte imbalance. Effective therapies include lactulose and antibiotics such as neomycin, metronidazole, and rifaximin.

Survival predictors in patients treated with a molecular adsorbent recirculating system

AIM: To identify prognostic factors for survival in patients with liver failure treated with a molecular adsorbent recirculating system (MARS).

METHODS: MARS is a liver-assisting device that has been used in the treatment of liver failure to enable native liver recovery, and as a bridge to liver transplantation (LTX). We analyzed the 1-year outcomes of 188 patients treated with MARS, from 2001 to 2007, in an intensive care unit specializing in liver disease. Demographic, clinical and laboratory parameters were recorded before and after each treatment. One-year survival and the number of LTXs were recorded. Logistic regression analysis was performed to determine factors predicting survival.

RESULTS: The study included 113 patients with acute liver failure (ALF), 62 with acute-on-chronic liver failure (AOCLF), 11 with graft failure (GF), and six with miscellaneous liver failure. LTX was performed for 29% of patients with ALF, 18% with AOCLF and 55% with GF. The overall 1-year survival rate was 74% for ALF, 27% for AOCLF, and 73% for GF. The poorest survival rate, 6%, was noted in non-transplanted patients with alcohol-related AOCLF and cirrhosis, whereas, patients with enlarged and steatotic liver had 55% survival. The etiology of liver failure was the most important predictor of survival (P < 0.0001). Other prognostic factors were encephalopathy (P = 0.001) in paracetamol-related ALF, coagulation factors (P = 0.049) and encephalopathy (P = 0.064) in non-paracetamol-related toxic ALF, and alanine aminotransferase (P = 0.013) and factor V levels (P = 0.022) in ALF of unknown etiology.

CONCLUSION: The etiology of liver disease was the most important prognostic factor. MARS treatment appears to be ineffective in AOCLF with end-stage cirrhosis without an LTX option.

Pro-inflammatory interleukin-18 and Caspase-1 serum levels in liver failure are unaffected by MARS treatment

BACKGROUND

The pro-inflammatory cytokine IL-18 and its activator Caspase-1 are involved in acute liver failure and acute-on-chronic-liver-failure. In acute liver failure and acute-on-chronic-liver-failure, the MARS system has been used to support liver function. Enhancement of IL-18, as seen in other extracorporeal-support systems like hemodialysis might thus have mitigated beneficial effects of the MARS system in acute hepatic failure.

PATIENTS AND METHODS

We measured serum concentrations of IL-18 and Caspase-1 in 10 patients with acute liver failure and 10 patients suffering from acute-on-chronic-liver-failure, who were all treated with MARS. Thirteen patients suffering from chronic hepatic failure and 15 healthy individuals served as controls. Data are given as mean with 95% CI.

RESULTS

Baseline IL-18 serum concentrations were significantly increased in acute liver failure and acute-on-chronic-liver-failure patients as compared to chronic hepatic failure (P=0.0039 and P=0.0011, respectively) and controls (P=0.0028 and P=0.0014, respectively). Caspase-1 serum concentrations were as well significantly elevated in the acute liver failure and acute-on-chronic-liver-failure groups as compared to chronic hepatic failure patients (P=0.0039 and P=0.0232, respectively) and controls P<0.0001 and P<0.0007, respectively). IL-18 and Caspase-1 did not change significantly during MARS treatment in acute liver failure and acute-on-chronic-liver-failure patients.

CONCLUSIONS

MARS had no effect on IL-18 and Caspase-1 serum concentrations in acute liver failure and acute-on-chronic-liver-failure, providing no evidence of harmful effects by the increase of these potentially hepatocidal cytokines.

What clinical alternatives to whole liver transplantation? Current status of artificial devices and hepatocyte transplantation

Shortage of organ donors limits the number of possible liver transplantations. Alternative therapies for treatment of liver failure are currently being developed: (i) extracorporeal artificial liver devices; (ii) bioartificial liver devices using hepatocytes; and (iii) hepatocyte transplantation. The objective of these strategies is to bridge patients with liver failure until a suitable liver allograft is obtained for transplantation or the patient's own liver regenerates sufficiently to resume normal function. In this review, we discuss these strategies and summarize the current status of clinical experience.

Long-lasting extracorporeal albumin dialysis in a child with end-stage renal disease and severe cholestasis

We report a case of long-lasting MARS therapy as a bridge to liver-kidney transplantation. A 26-month-old girl with congenital tubulointerstitial nephritis and severe liver fibrosis was placed on MARS for an acute-on-chronic liver failure due to sepsis. She underwent two sessions with good tolerance and recovered her previous neurological status. On the basis of pruritus, sleep, and vomiting improvement, repeated MARS sessions were performed to bridge her to combined liver-kidney transplantation. During eight months, 40 sessions were performed with the MARSmini kit and the MARS monitor (Gambro, Lyon, France). The treatment significantly decreased mean pruritus score from 2.2 +/- 0.9 to 0.8 +/- 0.6 night-time awakening and vomiting episodes. Body weight, height, and HC were -3.2, -3.5 and -2.2 SDS before and -1.7, -4.2, -2.0 SDS after eight months on MARS therapy, respectively. The arm circumference/HC ratio increased from 0.28 to 0.31. Mean total bilirubin serum levels were 303 +/- 72 micromol/L before and 214 +/- 42 micromol/L after MARS cycles. Long-lasting MARS dialysis is feasible in children, decreases adverse effects of severe chronic cholestasis, and may help to preserve nutritional status prior to combined liver-kidney transplantation.

Acute-on-chronic liver failure: consensus recommendations of the Asian Pacific Association for the study of the liver (APASL)

The Asian Pacific Association for the Study of the Liver (APASL) set up a working party on acute-on-chronic liver failure (ACLF) in 2004, with a mandate to develop consensus guidelines on various aspects of ACLF relevant to disease patterns and clinical practice in the Asia-Pacific region. Experts predominantly from the Asia-Pacific region constituted this working party and were requested to identify different issues of ACLF and develop the consensus guidelines. A 2-day meeting of the working party was held on January 22-23, 2008, at New Delhi, India, to discuss and finalize the consensus statements. Only those statements that were unanimously approved by the experts were accepted. These statements were circulated to all the experts and subsequently presented at the Annual Conference of the APASL at Seoul, Korea, in March 2008. The consensus statements along with relevant background information are presented in this review.

Role of artificial liver support in hepatic encephalopathy

Hepatic encephalopathy (HE) refers to the reversible neuropsychiatric disorders observed in acute liver failure and as a complication of cirrhosis and/or portal hypertension. This review aims to describe the pathophysiology of HE, the rationale for the use of artificial liver support in the treatment of HE, the different concepts of artificial liver support and the results obtained. Ammonia has been considered central to its pathogenesis but recently an important role for its interaction with inflammatory responses and auto-regulation of cerebral hemodynamics has been suggested. Artificial liver support might be able to decrease ammonia and modulate inflammatory mediators and cerebral hemodynamics. Bioartificial liver support systems use hepatocytes in an extracorporeal device connected to the patient's circulation. Artificial liver support is intended to remove protein-bound toxins and water-soluble toxins without providing synthetic function. Both systems improve clinical and biochemical parameters and can be applied safely to patients. Clinical studies have shown that artificial liver support, especially albumin dialysis, is able to improve HE in acute and acute-on-chronic liver failure. Further studies are required to better understand the mechanism, however, artificial liver support can be added to the therapeutic bundle in treating HE.

Imbalanced intrahepatic cytokine expression of interferon-gamma, tumor necrosis factor-alpha, and interleukin-10 in patients with acute-on-chronic liver failure associated with hepatitis B virus infection

GOALS

This study attempts to determine expressions of intrahepatic proinflammatory and anti-inflammatory cytokines and their secreting immunocytes to evaluate their roles in the pathogenesis of acute-on-chronic liver failure (ACLF) in chronically hepatitis B virus (HBV)-infected patients.

BACKGROUND

ACLF generally affects patients with established, compensated chronic liver diseases who develop an acute deterioration in liver function. In China, HBV-associated ACLF patients account for more than 80% of ACLF patients owing to a high prevalence of chronic HBV infection. Clinical observation showed that the deterioration of this disease may correlate with host immune responses, but related underlying mechanism remains largely unknown.

STUDY

In situ expressions of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), and their secreting CD4, CD8 T cells, and Kupffer cells (KCs) were analyzed in the livers of patients with ACLF, chronic hepatitis B (CHB), and normal controls (NC) using immunohistochemistry.

RESULTS

Intrahepatic proinflammatory IFN-gamma and TNF-alpha expressions were markedly up-regulated in ACLF compared with CHB and NC. However, similar anti-inflammatory IL-10 expressions were observed in ACLF and CHB. IFN-gamma overexpression correlated significantly with increased CD4 and CD8 T-cell accumulation. TNF-alpha up-regulation also correlated significantly with increased KCs.

CONCLUSIONS

The imbalanced expression of proinflammatory and anti-inflammatory cytokines and increased accumulation of CD4, CD8 T cells, and KCs may contribute to immunopathogenesis in HBV-infected ACLF.

Serum and ascitic fluid bacterial DNA: a new independent prognostic factor in noninfected patients with cirrhosis

We tested the hypothesis that the presence of bacterial DNA (bactDNA) in ascitic fluid and serum is associated with decreased survival in patients with cirrhosis. In a prospective, multicenter study, we analyzed the clinical evolution of 156 patients with cirrhosis and ascites (first or recurrence) with lower than 250 polymorphonuclear cells (PMN)/muL, negative ascites bacteriological culture, and absence of other bacterial infections being admitted for evaluation of large-volume paracentesis, according to the presence of bactDNA at admission. Survival, causes of death, and successive hospital admissions were determined during a 12-month follow-up period. BactDNA was detected in 48 patients. The most prevalent identified bactDNA corresponded to Escherichia coli (n = 32/48 patients, 66.6%). Patients were followed for 12 months after inclusion and in this period 34 patients died: 16 of 108 (15%) bactDNA negative versus 18 of 48 (38%) bactDNA positive (P = 0.003). The most frequent cause of death was acute-on-chronic liver failure in both groups (7/16 and 9/18 in patients without or with bactDNA, respectively), although more prevalent in the first month of follow-up in patients with presence of bactDNA (0 versus 4/7). When considering patients with model for end-stage liver disease (MELD) score less than 15, mortality was significantly higher in those with presence of bactDNA. Spontaneous bacterial peritonitis developed similarly in patients with or without bactDNA at admission.

CONCLUSION

The presence of bactDNA in a patient with cirrhosis during an ascitic episode is an indicator of poor prognosis. This fact may be related to the development of acute-on-chronic liver failure at short term and does not predict the development of spontaneous bacterial peritonitis.

Extracorporeal albumin dialysis

Patients with liver failure still present a high mortality. It can only be significantly improved by the rare resource of liver transplantation. Extracorporeal liver support devices have been developed to temporarily support liver detoxification. Artificial devices without hepatocytes ("liver dialysis" or "albumin dialysis") are already widely used in Europe. The two best-known systems, MARS and Prometheus, use a different technical approach to remove water-soluble as well as albumin-bound toxins from the blood. In MARS, toxins diffuse along a concentration gradient through an albumin-impermeable membrane into a secondary circuit that is pre-filled with an albumin solution. The albumin is continuously "recycled" inside the secondary circuit by different adsorber and low flux dialysis. In contrast, Prometheus includes an albumin-permeable filter allowing separation of the albumin fraction into the secondary circuit where the albumin-bound toxins are directly removed by two adsorbers. Thereafter, high flux dialysis is performed inside the primary circuit. For both extracorporeal systems, an improvement of hepatic encephalopathy and biochemical markers such as bilirubin is consistently reported. In-vivo comparisons of both systems showed significantly higher extraction capacities for protein-bound and water-soluble substances under Prometheus than under MARS treatment. Possible pathophysiological mechanisms could be a reduction of portal pressure or a removal of vasoactive cytokines. However, only few randomised controlled trials with low patient numbers and conflictive results regarding patient survival exist. Nevertheless, a Cochrane meta-analysis revealed a significant survival benefit for extracorporeal liver support devices in patients with acute-on-chronic liver failure. Other promising indications are severe refractory cholestatic pruritus, intoxication with protein-bound substances and graft dysfunction after liver transplantation. As large randomised controlled multi-center trials are currently underway, better evidence will be available soon to define the clinical role of extracorporeal liver support devices.

Hepatorenal syndrome: current management

Hepatorenal syndrome (HRS) is a dreaded complication of advanced cirrhosis, with dismal prognosis if left untreated. Recent understanding of the pathophysiology underlying HRS development has led to many new treatments. Vasoconstrictors (eg, midodrine, terlipressin, or norepinephrine) together with albumin can improve the effective arterial blood volume with increased renal perfusion pressure. This combination has been proven successful in reversing HRS in approximately two thirds of patients. Transjugular intrahepatic portosystemic shunt (TIPS), which reduces portal pressure and decreases the sympathetic drive associated with portal hypertension, is effective in improving renal function. The combination of a TIPS and vasoconstrictor therapy has been shown to normalize renal function in a small number of patients. Liver transplantation corrects many of the pathophysiological abnormalities associated with HRS, and is the best treatment option. Patient outcome is improved further if the renal function is normalized prior to liver transplantation.

Multiple organ system extracorporeal support in critically ill children

Multiple organ system extracorporeal support effectively supports brain, heart, lung, liver, kidney, coagulation, red blood cell, and immune cell function in the sickest infants and children who have multiple organ system failure. These therapies have optimum benefit if: (1) the underlying disease is reversible; (2) the therapies are performed expertly and are monitored to prevent and minimize systemic hemolysis; and (3) the therapies are provided in a goal-directed manner. These therapies represent a significant advance in pediatric critical care medicine. This article provides a framework for this multidisciplinary team approach for implementing these therapies.

Effect of probiotic treatment on deranged neutrophil function and cytokine responses in patients with compensated alcoholic cirrhosis

BACKGROUND/AIM

Endotoxaemia contributes to neutrophil dysfunction, infection risk and mortality in patients with alcoholic cirrhosis. As probiotics may decrease Gram-negative gut organisms, we hypothesised that probiotic treatment would restore neutrophil function.

METHODS

In an open-label study, patients with alcoholic cirrhosis (n=12) received Lactobacillus casei Shirota (6.5 x 10(9)) 3 times daily for 4 weeks. Data were compared to healthy controls (n=13) and cirrhotic patients (n=8) who did not receive probiotics. Neutrophil oxidative burst, phagocytosis, toll-like-receptor (TLR) expression, plasma cytokines and ex vivo endotoxin-stimulated cytokine production were measured.

RESULTS

Baseline neutrophil phagocytic capacity in patients was significantly lower compared to healthy controls (73% versus 98%, p<0.05), but normalised at the end of the study (n=10, 100%, p<0.05). No improvement was seen in disease controls. Soluble TNF-receptor (sTNFR)-1 and-2 and interleukin (IL)10 were significantly elevated in patients' plasma but did not change during the study. Ex vivo endotoxin-stimulated levels of sTNFR1, sTNFR2 and IL10 were significantly lower at the end of the study (p<0.05). TLR2, 4 and 9 were overexpressed in patients. TLR4 expression normalised by the end of the study.

CONCLUSIONS

Our data provide a proof-of-concept that probiotics restore neutrophil phagocytic capacity in cirrhosis, possibly by changing IL10 secretion and TLR4 expression, warranting larger randomised controlled and mechanistic studies.

The future of extracorporeal support

Extracorporeal therapy has expanded significantly over the past few decades from solely artificial renal replacement therapy. In patients with multiple organ dysfunction syndrome, it becomes necessary to provide multiple organ support therapy. Technological advances have opened the door to a multifaceted intervention directed at supporting the function of multiple organs through the treatment of blood. Indications for "old" therapies such as hemofiltration and adsorption have been expanded, and using these therapies in combination further enhances blood detoxification capabilities. Furthermore, new devices are constantly in development. Nanotechnology allows us to refine membrane characteristics and design innovative monitoring/biofeedback devices. Miniaturization is leading down the path of wearable/implantable devices. With the incorporation of viable cells within medical devices, these instruments become capable not only of detoxification but synthetic functions as well, bringing us closer to the holy grail of complete replacement of organ function. This article provides a brief overview of current and future direction in extracorporeal support in the critical care setting.

Effect of Prometheus liver assist system on systemic hemodynamics in patients with cirrhosis: A randomized controlled study

AIM: To evaluate treatment safety and hemodynamic changes during a single 6-h treatment with the Prometheus™ liver assist system in a randomized, controlled study.

METHODS: Twenty-four patients were randomized to either the study group or to one of two control groups: Fractionated Plasma Separation Adsorption and Dialysis, Prometheus™ system (Study group; n = 8); Molecular Adsorbent Recirculation System (MARS)™ (Control group 1, n = 8); or hemodialysis (Control group 2; n = 8). All patients included in the study had decompensated cirrhosis at the time of the inclusion into the study. Circulatory changes were monitored with a Swan-Ganz catheter and bilirubin and creatinine were monitored as measures of protein-bound and water-soluble toxins.

RESULTS: Systemic hemodynamics did not differ between treatment and control groups apart from an increase in arterial pressure in the MARS group (P = 0.008). No adverse effects were observed in any of the groups. Creatinine levels significantly decreased in the MARS group (P = 0.03) and hemodialysis group (P = 0.04). Platelet count deceased in the Prometheus group (P = 0.04).

CONCLUSION: Extra-corporal liver support with Prometheus is proven to be safe in patients with end-stage liver disease but does not exert the beneficial effects on arterial pressure as seen in the MARS group.

Liver support devices

PURPOSE OF REVIEW

Liver support devices are used either as a bridge to liver transplantation or liver recovery in patients with acute or acute-on-chronic liver failure. The review analyzes the recent literature and asks if the current enthusiasm for these devices is justified.

RECENT FINDINGS

Many liver support devices exist and are discussed. Clinical data on artificial devices are rapidly emerging, especially on the molecular adsorbents recirculating system, and fractionated plasma separation and adsorption (Prometheus). While hepatic encephalopathy is improved by the molecular adsorbents recirculating system and probably Prometheus too, neither system has been shown to improve survival. Less clinical data exist for bioartificial support devices. These may use human hepatocytes, such as the extracorporeal liver assist device, although most devices use porcine hepatocytes, such as HepatAssist.

SUMMARY

Enthusiasm in liver support devices is justified as many nonrandomized studies have suggested some biochemical and clinical benefits. The results of several ongoing multicenter randomized controlled trials are anxiously awaited. Meanwhile, because mortality without liver transplantation remains high despite the use of liver support devices, these devices should only be used in the research setting or by experts proficient in their use and as a bridge to liver transplantation rather than liver recovery.

Bench-to-bedside review: current evidence for extracorporeal albumin dialysis systems in liver failure

Acute liver failure (ALF) and acute on chronic liver failure (AoCLF) carry a high mortality. The rationale for extracorporeal systems is to provide an environment facilitating recovery or a window of opportunity for liver transplantation. Recent technologies have used albumin as a scavenging molecule. Two different albumin dialysis systems have been developed using this principle: MARS (Molecular Adsorbent Recirculation System) and SPAD (Single-Pass Albumin Dialysis). A third system, Prometheus (Fractionated Plasma Separation and Adsorption), differs from the others in that the patient's albumin is separated across a membrane and then is run over adsorptive columns. Although several trials have been published (particularly with MARS), currently there is a lack of controlled studies with homogenous patient populations. Many studies have combined patients with ALF and AoCLF. Others have included patients with different etiologies. Although MARS and Prometheus have shown biochemical improvements in AoCLF and ALF, additional studies are required to show conclusive benefit in short- and long-term survival. The appropriate comparator is standard medical therapy rather than head-to-head comparisons of different forms of albumin dialysis.

Cytokine profiles in acute liver failure treated with albumin dialysis

Cytokines are released within the liver in response to hepatic injury, and acute liver failure (ALF) triggers systemic inflammation. Pro-inflammatory (tumor necrosis factor-alpha [TNF-alpha] and interleukin-8 [IL-8]) and anti-inflammatory (interleukin-10 [IL-10] and interleukin-6 [IL-6]) cytokines and the lymphocyte activation marker (interleukin-2-soluble receptor alpha chain [IL-2sRalpha]) were monitored in 49 ALF patients considered for liver transplantation and treated with albumin dialysis (molecular adsorbent recirculating system [MARS]). Twenty-six patients were categorized by clinical outcome as "good" (native liver recovered) and 23 as "poor" (patient bridged to liver transplantation or deceased). MARS did not clearly affect cytokine profiles during treatment; only IL-10 levels decreased in the whole patient population and mostly in patients with the worst prognosis. In the good outcome group, IL-8 and IL-6 levels decreased during treatment; on the contrary, in poor outcome patients IL-6 levels even increased. Initial IL-2sRalpha levels were higher in poor outcome patients relative to the good outcome subset. Cytokine profiles seem to differ in ALF according to patient outcome. A deeper understanding of cytokine patterns during pathogenesis could reveal prognostic markers and aid the development of immunomodulating ALF therapies.