Hemodiabsorption in treatment of hepatic failure

Efficacy and safety of liver support devices in acute and hyperacute liver failure: a systematic review and network meta-analysis

Acute liver failure (ALF) is a potentially life-threatening condition. Liver support therapies can be applied as a bridging-to-transplantation or bridging-to-recovery; however, results of clinical trials are controversial. Our aim was to compare liver support systems in acute and hyperacute liver failure with network meta-analysis. After systematic search, randomized controlled trials (RCT) comparing liver support therapies in adults with acute or hyperacute liver failure were included. In-hospital mortality was the primary outcome, the secondary outcomes were hepatic encephalopathy and mortality-by-aetiology. A Bayesian-method was used to perform network meta-analysis and calculate surface under the cumulative ranking curve (SUCRA) values to rank interventions. Eleven RCTs were included. BioLogic-DT and molecular adsorbent recirculating system (MARS) resulted in the lowest mortality (SUCRAs: 76% and 73%, respectively). In non-paracetamol-poisoned patients, BioLogic-DT, charcoal hemoperfusion and MARS may be equally efficient regarding mortality (SUCRAs: 53%, 52% and 52%, respectively). Considering hepatic encephalopathy, extracorporeal liver assist device (ELAD) may be the most effective option (SUCRA: 78%). However, in pairwise meta-analysis, there were no statistically significant differences between the interventions in the outcomes. In conclusion, MARS therapy seems to be the best available option in reducing mortality. Further research is needed on currently available and new therapeutic modalities. (CRD42020160133).

Uncertainty in the impact of liver support systems in acute-on-chronic liver failure: a systematic review and network meta-analysis

BACKGROUND

The role of artificial and bioartificial liver support systems in acute-on-chronic liver failure (ACLF) is still controversial. We aimed to perform the first network meta-analysis comparing and ranking different liver support systems and standard medical therapy (SMT) in patients with ACLF.

METHODS

The study protocol was registered with PROSPERO (CRD42020155850). A systematic search was conducted in five databases. We conducted a Bayesian network meta-analysis of randomized controlled trials assessing the effect of artificial or bioartificial liver support systems on survival in patients with ACLF. Ranking was performed by calculating the surface under cumulative ranking (SUCRA) curve values. The RoB2 tool and a modified GRADE approach were used for the assessment of the risk of bias and quality of evidence (QE).

RESULTS

In the quantitative synthesis 16 trials were included, using MARS®, Prometheus®, ELAD®, plasma exchange (PE) and BioLogic-DT®. Overall (OS) and transplant-free (TFS) survival were assessed at 1 and 3 months. PE significantly improved 3-month OS compared to SMT (RR 0.74, CrI: 0.6-0.94) and ranked first on the cumulative ranking curves for both OS outcomes (SUCRA: 86% at 3 months; 77% at 1 month) and 3-month TFS (SUCRA: 87%) and second after ELAD for 1-month TFS (SUCRA: 76%). Other comparisons did not reach statistical significance. QE was moderate for PE concerning 1-month OS and both TFS outcomes. Other results were of very low certainty.

CONCLUSION

PE seems to be the best currently available liver support therapy in ACLF regarding 3-month OS. Based on the low QE, randomized trials are needed to confirm our findings for already existing options and to introduce new devices.

Extracorporeal liver support in patients with liver failure: a systematic review and meta-analysis of randomized trials

PURPOSE

Acute liver failure (ALF) and acute on chronic liver failure (ACLF) are associated with significant mortality and morbidity. Extracorporeal liver support (ECLS) devices have been used as a bridge to liver transplant; however, the efficacy and safety of ECLS are unclear. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to examine the efficacy and safety of ECLS in liver failure.

METHODS

We searched MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials from inception through March 13, 2019. RCTs comparing ECLS to usual care in ALF or ACLF were included. We used the Grading of Recommendations Assessment, Development and Evaluation approach to assess the certainty of the evidence.

RESULTS

We identified 25 RCTs (1796 patients). ECLS use was associated with reduction in mortality (RR 0.84; 95% CI 0.74, 0.96, moderate certainty) and improvement in hepatic encephalopathy (HE) (RR 0.71; 95% CI 0.60, 0.84, low certainty) in patients with ALF or ACLF. The effect of ECLS on hypotension (RR 1.46; 95% CI 0.98, 2.2, low certainty), bleeding (RR 1.21; 95% CI 0.88, 1.66, moderate certainty), thrombocytopenia (RR 1.62; 95% CI 1.0, 2.64, very low certainty) and line infection (RR 1.92; 95% CI 0.11, 33.44, low certainty) was uncertain.

CONCLUSIONS

ECLS may reduce mortality and improve HE in patients with ALF and ACLF. The effect on other outcomes is uncertain. However, the evidence is limited by risk of bias and imprecision, and larger trials are needed to better determine the effect of ECLS on patient-important outcomes.

Effectiveness and Safety Assessment of Citrate Anticoagulation During Albumin Dialysis in Comparison to Other Methods of Anticoagulation

Liver failure is a serious and often deadly disease often requiring MARS (Molecular Adsorbent Recirculating System) therapy. Choosing the safe and effective method of anticoagulation during artificial liver support systems seems to be very difficult and extremely important. The aim of this study was to assess effectiveness and safety of regional anticoagulation with citrate in liver failure patients during MARS. We used a single center observational study. We analyzed 158 MARS sessions performed in 65 patients: 105 (66.5%) sessions in 41 patients with heparin anticoagulation, 40 (25.3%) sessions in 19 patients with citrate, and 13 (8%) sessions in only five patients without anticoagulation, that were excluded from part of the analysis. To determine the effectiveness of regional anticoagulation with citrate, probability of filter survival and changes in laboratory parameters were analyzed according to the applied method of anticoagulation. The safety of citrate was determined by Ca/Ca²⁺ ratio, acid-base balance, bleeding complications, and the need for blood product transfusions. The probability of filter survival in the citrate group was 94% and in the heparin group 82% (P = 0.204). There was no relationship between the method of anticoagulation and effectiveness of MARS therapy in lowering the levels of the analyzed parameters. Only one patient had a Ca/Ca²⁺ ratio higher than he safety margin. There were no statistically significant changes in pH and lactate level irrespective of anticoagulation; bicarbonate dropped significantly only in the heparin group (P = 0.03). The frequency of bleeding complications and the need for transfusions did not differ significantly between groups. Regional anticoagulation with citrate can be an effective and safe method of anticoagulation during MARS therapy, but requires attentive monitoring and further studies in liver failure patients.

Survival Benefits With Artificial Liver Support System for Acute-on-Chronic Liver Failure: A Time Series-Based Meta-Analysis

The artificial liver support system (ALSS) offers the potential to improve the prognosis of patients with acute-on-chronic liver failure (ACLF). However, the literature has been inconsistent on its survival benefits. We aimed to conduct a time series-based meta-analysis of randomized clinical trials (RCTs) and observational studies which examined differences in mortality in ACLF patients treated with ALSS or not.MEDLINE, EMBASE, OVID, and COCHRANE library database were systemically searched up to December 2014. Quality of included studies was evaluated using the Jadad score. The outcome measure was mortality at different follow-up endpoints. Odds ratios (ORs) and survival curve data were pooled for analysis.Ten studies, 7 RCTs, and 3 controlled cohorts were enrolled, involving a total of 1682 ACLF patients, among whom 842 were treated with ALSS. ALSS was found to reduce the risk of short-term (1-month and 3-month) mortality for patients with ACLF by nearly 30%. Randomized trials and observational studies provided good internal and external validity respectively. The combined Kaplan-Meier curves showed a consistent pattern of findings. Meta-analysis also suggested that ALSS might reduce medium-term (6-month and 1-year) mortality risk by 30% and long-term (3-year) mortality risk by 50% in ACLF patients.ALSS therapy could reduce short-term mortality in patients with ACLF. Meanwhile, its impacts on medium- and long-term survival seem to be promising but remained inconclusive. Clinical utility of this system for survival benefit may be implied.

Artificial and bioartificial liver support systems for acute and acute-on-chronic hepatic failure: A meta-analysis and meta-regression

Artificial and bioartificial liver support systems (LSSs) appear to be safe and effective in the treatment of acute and acute-on-chronic hepatic failure (AHF and AOCHF); however, individually published studies and previous meta-analyses have revealed inconclusive results. The aim of the present meta-analysis was to derive a more precise estimation of the benefits and disadvantages of artificial and bioartificial LSSs for patients with AHF and AOCHF. A literature search was conducted in the PubMed, Embase, Web of Science and Chinese Biomedical (CBM) databases for publications prior to March 1, 2013. Crude relative risks (RRs) or standardized mean differences (SMDs) with 95% confidence intervals (95% CI) were calculated using either the fixed effects or random effects models. Nineteen randomized controlled trials (RCTs) were included, which comprised a total of 566 patients with AHF and 371 patients with AOCHF. The meta-analysis showed that artificial LSS therapy significantly reduced mortality in patients with AOCHF; however, it had no apparent effect on total mortality in patients with AHF. The results also indicated that the use of bioartificial LSSs was correlated with decreased mortality in patients with AHF. A significant reduction in the bridging to liver transplantation was observed in patients with AOCHF following artificial LSS therapy; however, similar results were not observed in patients with AHF. Patients with AHF and those with AOCHF showed significant reductions in total bilirubin levels following artificial LSS therapy. There were no significantly increased risks of hepatic encephalopathy or bleeding in either the patients with AHF or AOCHF following artificial or bioartificial LSS therapies. Univariate and multivariate meta-regression analyses confirmed that none of the factors explained the heterogeneity. The present meta-analysis indicated that artificial LSSs reduce mortality in patients with AOCHF, while the use of bioartificial LSSs was correlated with reduced mortality in patients with AHF.

Continuous venovenous hemodialysis with regional citrate anticoagulation in patients with liver failure: a prospective observational study

Introduction

Liver failure patients might be at risk for citrate accumulation during continuous venovenous hemodialysis (CVVHD) with regional citrate anticoagulation. The aim of this study was to investigate the predictive capability of baseline liver function parameters regarding citrate accumulation, expressed as an increase in the calcium total/calcium ionized (Ca_tot/Ca_ion) ratio ≥2.5, and to describe the feasibility of citrate CVVHD in liver failure patients.

Methods

We conducted a prospective observational study in medical ICU patients treated in a German university hospital. We performed 43 CVVHD runs using citrate for regional anticoagulation in 28 critically ill patients with decompensated liver cirrhosis or acute liver failure (maximum of two CVVHD runs per patient). Liver function was characterized before CVVHD using laboratory parameters, calculation of Child-Pugh and Model of End-stage Liver Disease scores, and determination of the plasma disappearance rate of indocyanine green. In addition to blood gas analysis, we measured total calcium and citrate in serum at baseline and after definitive time points for each CVVHD run.

Results

Accumulation of citrate in serum correlated with an increase in the Ca_tot/Ca_ion ratio. Although the critical upper threshold of Ca_tot/Ca_ion ratio ≥2.5 was exceeded 10 times in seven different CVVHD runs, equalization of initial metabolic acidosis was possible without major disturbances of acid-base and electrolyte status. Standard laboratory liver function parameters showed poor predictive capabilities regarding citrate accumulation in terms of an elevated Ca_tot/Ca_ion ratio ≥2.5. In contrast, serum lactate ≥3.4 mmol/l and prothrombin time ≤26% predicted an increase in the Ca_tot/Ca_ion ratio ≥2.5 with high sensitivity (86% for both lactate and prothrombin time) and specificity (86% for lactate, 92% for prothrombin time).

Conclusions

Despite substantial accumulation of citrate in serum, CVVHD with regional citrate anticoagulation seems feasible in patients with severely impaired liver function. Citrate accumulation in serum is reflected by an increase in the Ca_tot/Ca_ion ratio. To identify patients at risk for citrate accumulation in terms of a Ca_tot/Ca_ion ratio ≥2.5, baseline serum lactate (threshold ≥3.4 mmol/l) and prothrombin time (threshold ≤26%) may be useful for risk prediction in daily clinical practice. Careful monitoring of electrolytes and acid-base status is mandatory to ensure patient safety.

Hepatorenal syndrome: the 8th International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group

Introduction

Renal dysfunction is a common complication in patients with end-stage cirrhosis. Since the original publication of the definition and diagnostic criteria for the hepatorenal syndrome (HRS), there have been major advances in our understanding of its pathogenesis. The prognosis of patients with cirrhosis who develop HRS remains poor, with a median survival without liver transplantation of less than six months. However, a number of pharmacological and other therapeutic strategies have now become available which offer the ability to prevent or treat renal dysfunction more effectively in this setting. Accordingly, we sought to review the available evidence, make recommendations and delineate key questions for future studies.

Methods

We undertook a systematic review of the literature using Medline, PubMed and Web of Science, data provided by the Scientific Registry of Transplant Recipients and the bibliographies of key reviews. We determined a list of key questions and convened a two-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated recommendations and/or directions for future research.

Results

Of the 30 questions considered, we found inadequate evidence for the majority of questions and our recommendations were mainly based on expert opinion. There was insufficient evidence to grade three questions, but we were able to develop a consensus definition for acute kidney injury in patients with cirrhosis and provide consensus recommendations for future investigations to address key areas of uncertainty.

Conclusions

Despite a paucity of sufficiently powered prospectively randomized trials, we were able to establish an evidence-based appraisal of this field and develop a set of consensus recommendations to standardize care and direct further research for patients with cirrhosis and renal dysfunction.

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.

Treatment of hepatic encephalopathy by on-line hemodiafiltration: a case series study

Background

It is thought that a good survival rate of patients with acute liver failure can be achieved by establishing an artificial liver support system that reliably compensates liver function until the liver regenerates or a patient undergoes transplantation. We introduced a new artificial liver support system, on-line hemodiafiltration, in patients with acute liver failure.

Methods

This case series study was conducted from May 2001 to October 2008 at the medical intensive care unit of a tertiary care academic medical center. Seventeen consecutive patients who admitted to our hospital presenting with acute liver failure were treated with artificial liver support including daily on-line hemodiafiltration and plasma exchange.

Results

After 4.9 ± 0.7 (mean ± SD) on-line hemodiafiltration sessions, 16 of 17 (94.1%) patients completely recovered from hepatic encephalopathy and maintained consciousness for 16.4 ± 3.4 (7-55) days until discontinuation of artificial liver support (a total of 14.4 ± 2.6 [6-47] on-line hemodiafiltration sessions). Significant correlation was observed between the degree of encephalopathy and number of sessions of on-line HDF required for recovery of consciousness. Of the 16 patients who recovered consciousness, 7 fully recovered and returned to society with no cognitive sequelae, 3 died of complications of acute liver failure except brain edema, and the remaining 6 were candidates for liver transplantation; 2 of them received living-related liver transplantation but 4 died without transplantation after discontinuation of therapy.

Conclusions

On-line hemodiafiltration was effective in patients with acute liver failure, and consciousness was maintained for the duration of artificial liver support, even in those in whom it was considered that hepatic function was completely abolished.

Thermodynamic considerations in solid adsorption of bound solutes for patient support in liver failure

New detoxification modes of treatment for liver failure that use solid adsorbents to remove toxins bound to albumin in the patient bloodstream are entering clinical evaluations, frequently in head-to-head competition. While generally effective in reducing toxin concentration beyond that obtainable by conventional dialysis procedures, the solid adsorbent processes are largely the result of heuristic development. Understanding the principles and limitations inherent in competitive toxin binding, albumin versus solid adsorbent, will enhance the design process and, possibly, improve detoxification performance. An equilibrium thermodynamic analysis is presented for both the molecular adsorbent recirculating system (MARS) and fractionated plasma separation, adsorption, and dialysis system (Prometheus), two advanced systems with distinctly different operating modes but with similar equilibrium limitations. The Prometheus analysis also applies to two newer approaches: sorbent suspension reactor and microsphere-based detoxification system. Primary results from the thermodynamic analysis are that: (i) the solute-albumin binding constant is of minor importance to equilibrium once it exceeds about 10(5) L/mol; (ii) the Prometheus approach requires larger solid adsorbent columns than calculated by adsorbent solute capacity alone; and (iii) the albumin-containing recycle stream in the MARS approach is a major reservoir of removed toxin. A survey of published results indicates that MARS is operating under mass transfer control dictated by solute-albumin equilibrium in the recycle stream, and Prometheus is approaching equilibrium limits under current clinical protocols.

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.

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.

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.

Cell-Free Artificial Liver Support: Design of Appropriate Clinical Studies

The clinical use of cell-free liver support devices is dependent upon proof of safety and efficacy in clinical trials. The current published data to support their use is limited in both quantity and quality. In most studies, the methodology is such that the effects of these devices are difficult to establish with certainty. Bias might be introduced by the use of uncontrolled studies, and in randomized controlled trials limited size, poorly matched control groups or medical therapy or the use of clinically inappropriate endpoints might be important. Guidelines are now available to provide a framework for the design and execution of such trials, specifically to minimize the systematic errors that are frequently present and that might result in biased estimates of treatment effects. In the present review, the limitations of current studies are discussed and suggestions made as to the design and conduct of future clinical trials.

The Molecular Adsorbent Recirculating System (MARS) in the intensive care unit: a rescue therapy for patients with hepatic failure

Treatment in the intensive care unit of patients with end-stage liver disease has been limited. Liver transplantation has been a major improvement in this and has become standard in the management of these patients. However, many patients die awaiting liver transplantation, mainly due to the scarcity of organ donors. Conventional hemodialysis techniques have little or no effect on liver detoxification and do not improve the prognosis of these patients. In patients with acute hepatic failure, the majority of endogenous toxins leading to organ failure and accumulating in the blood are bound to albumin; therefore, the concept of albumin dialysis is of major interest. To date, the most widely developed system has been the Molecular Adsorbent Recirculating System (MARS), which is based on the selective removal of albumin-bound toxins from the blood. MARS enables simultaneous liver and kidney detoxification, improving the patient's clinical condition. It is a major improvement in the management of patients with hepatic failure that could permit, when appropriately indicated, recovery from an acute episode and enhance the chances of survival while waiting for an available organ donor.

Reviews: The Current State of Nonuremic Applications for Extracorporeal Blood Purification

Despite the commonly accepted indications for hemodialysis and extracorporeal depuritive techniques, some clinicians have come to rely on blood purification for clinical states where the targeted substance for removal differs from uremic waste products. Over the last decade, a number of studies have emerged to help define the application of extracorporeal blood purification (ECBP) to these "nonuremic" indications. This review describes the application of extracorporeal blood purification in clinical states including sepsis, rhabdomyolysis, congestive heart failure, hepatic failure, tumor lysis syndrome, adult respiratory distress syndrome, intravenous contrast exposure, and lactic acidosis. Additional comments are provided to review existing literature on thermoregulation and osmoregulation, including acute brain injury.

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.

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.

Bridges to transplantation

The definitive treatment of patients with acute liver failure is liver transplantation. Organ Procurement and Transplantation Network status 1 patients receive priority, but the median waiting time in 2002 was 11 days. Patients who are small or have an unusual blood type are expected to wait even longer. Because cerebral edema and death may occur before a liver is available, numerous methods of bridging patients to transplantation by artificial means have been proposed. To date, no system of hepatic support has been proven effective at delaying the onset of cerebral edema in controlled trials.

Artificial and bioartificial support systems for liver failure

BACKGROUND

Artificial and bioartificial liver support systems may 'bridge' patients with acute or acute-on-chronic liver failure to liver transplantation or recovery.

OBJECTIVES

To evaluate beneficial and harmful effects of artificial and bioartificial support systems for acute and acute-on-chronic liver failure.

SEARCH STRATEGY

Trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register (September 2002), The Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1985 - September 2002), and The Chinese Biomedical Database (September 2002), manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised clinical trials on artificial or bioartificial support systems for acute or acute on-chronic liver failure were included irrespective of blinding, publication status, or language. Non-randomised studies were included in explorative analyses.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by three reviewers. Results were presented as relative risks (RR) with 95% confidence intervals (CI). Sources of heterogeneity were explored through sensitivity analyses and meta-regression. The primary outcome was mortality.

MAIN RESULTS

Twelve trials on artificial or bioartificial support systems versus standard medical therapy (483 patients) and two trials comparing different artificial support systems (105 patients) were included. Most trials had unclear methodological quality. Compared to standard medical therapy, support systems had no significant effect on mortality (RR 0.86; 95% CI 0.65-1.12) or bridging to liver transplantation (RR 0.87; 95% CI 0.73-1.05), but a significant beneficial effect on hepatic encephalopathy (RR 0.67; 95% CI 0.52-0.86). Meta-regression indicated that the effect of support systems depended on the type of liver failure (P = 0.03). In subgroup analyses, artificial support systems appeared to reduce mortality by 33% in acute-on-chronic liver failure (RR 0.67; 95% CI 0.51-0.90), but not in acute liver failure (RR 0.95; 95% CI 0.71-1.29). Two trials comparing artificial support systems showed significant mortality reductions with intermittent versus continuous haemofiltration (RR 0.58; 95% CI 0.36-0.94) and no significant difference between five versus ten hours of charcoal haemoperfusion (RR 1.03; 95% CI 0.65-1.62). The incidence of adverse events was inconsistently reported.

REVIEWER'S CONCLUSIONS

This Review indicates that artificial support systems may reduce mortality in acute-on-chronic liver failure. Artificial and bioartificial support systems did not appear to affect mortality in acute liver failure. However, considering the strength of the evidence additional randomised clinical trials are needed before any support system can be recommended for routine use.

Artificial and bioartificial support systems for liver failure

BACKGROUND

Artificial and bioartificial liver support systems may 'bridge' patients with acute or acute-on-chronic liver failure to liver transplantation or recovery.

OBJECTIVES

To evaluate beneficial and harmful effects of artificial and bioartificial support systems for acute and acute-on-chronic liver failure.

SEARCH STRATEGY

Trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register (September 2002), The Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1985 - September 2002), and The Chinese Biomedical Database (September 2002), manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised clinical trials on artificial or bioartificial support systems for acute or acute on-chronic liver failure were included irrespective of blinding, publication status, or language. Non-randomised studies were included in explorative analyses.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by three reviewers. Results were presented as relative risks (RR) with 95% confidence intervals (CI). Sources of heterogeneity were explored through sensitivity analyses and meta-regression. The primary outcome was mortality.

MAIN RESULTS

Twelve trials on artificial or bioartificial support systems versus standard medical therapy (483 patients) and two trials comparing different artificial support systems (105 patients) were included. Most trials had unclear methodological quality. Compared to standard medical therapy, support systems had no significant effect on mortality (RR 0.86; 95% CI 0.65-1.12) or bridging to liver transplantation (RR 0.87; 95% CI 0.73-1.05), but a significant beneficial effect on hepatic encephalopathy (RR 0.67; 95% CI 0.52-0.86). Meta-regression indicated that the effect of support systems depended on the type of liver failure (P = 0.03). In subgroup analyses, artificial support systems appeared to reduce mortality by 33% in acute-on-chronic liver failure (RR 0.67; 95% CI 0.51-0.90), but not in acute liver failure (RR 0.95; 95% CI 0.71-1.29). Two trials comparing artificial support systems showed significant mortality reductions with intermittent versus continuous haemofiltration (RR 0.58; 95% CI 0.36-0.94) and no significant difference between five versus ten hours of charcoal haemoperfusion (RR 1.03; 95% CI 0.65-1.62). The incidence of adverse events was inconsistently reported.

REVIEWER'S CONCLUSIONS

This Review indicates that artificial support systems may reduce mortality in acute-on-chronic liver failure. Artificial and bioartificial support systems did not appear to affect mortality in acute liver failure. However, considering the strength of the evidence additional randomised clinical trials are needed before any support system can be recommended for routine use.

Citrate pharmacokinetics and metabolism in cirrhotic and noncirrhotic critically ill patients

OBJECTIVES

To investigate pharmacokinetics and metabolism of sodium citrate in critically ill patients. To determine the risk of citrate accumulation in the setting of liver dysfunction (cirrhosis, hepatorenal syndrome).

DESIGN

Prospective cohort study.

SETTING

Intensive Care Unit, Department of Medicine IV, University Hospital Vienna.

PATIENTS

Consecutive critically ill cirrhotic (n = 16) and noncirrhotic patients (n = 16).

INTERVENTIONS

Infusion of sodium citrate (0.5 mmol.kg-1.hr-1) and calcium chloride (0.17 mmol.kg-1.hr-1) for 2 hrs. Analysis of serial arterial blood samples.

MEASUREMENTS AND MAIN RESULTS

Total body clearance of citrate was normal in noncirrhotic critically ill patients but significantly reduced in cirrhotic patients (710 vs. 340 mL/min, p =.008). Citrate peak concentrations and concentration over time were increased by 65% and 114% in cirrhotic patients (p <.001), respectively; volumes of distribution were similar. Net metabolic changes were quantitatively similar, with pH and plasma bicarbonate concentrations increasing more slowly in cirrhotic patients. No citrate-related side effects were noted. Citrate clearance could not be predicted by standard liver function tests and was not appreciably influenced by renal function and Acute Physiology and Chronic Health Evaluation II scores.

CONCLUSIONS

This first systematic study on citrate pharmacokinetics and metabolism in critically ill patients confirms a major role of hepatic citrate metabolism by demonstrating reduced citrate clearance in cirrhotic patients. Pharmacokinetic data could provide a basis for the clinical use of citrate anticoagulation in critically ill patients. Provided dose adaptation and monitoring of ionized calcium, citrate anticoagulation seems feasible even in patients with decompensated cirrhosis. Metabolic consequences of citrate infusion were not different between groups in this study but may be more pronounced in prolonged infusion.

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

CONTEXT

Artificial and bioartificial support systems may provide a "bridge" for patients with severe liver disease to recovery or transplantation.

OBJECTIVE

To evaluate the effect of artificial and bioartificial support systems for acute and acute-on-chronic liver failure.

DATA SOURCES

Randomized trials on any support system vs standard medical therapy were included irrespective of publication status or language. Nonrandomized studies were included in explorative analyses. Trials were identified through electronic searches (Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Library, MEDLINE, EMBASE, and the Chinese Medical Database), bibliographies, and contact with experts. Searches were conducted of the entire databases through September 2002.

STUDY SELECTION

Of 528 references identified, 12 randomized trials with 483 patients were included. Eight nonrandomized studies were included in explorative analyses.

DATA EXTRACTION

Data were extracted and trial quality was assessed independently by 3 reviewers (L.L.K., J.L., B.A-N.). The primary outcome measure was all-cause mortality. Results were combined on the risk ratio (RR) scale. Random-effects models were used. Sources of heterogeneity were explored through meta-regression and stratified meta-analyses.

DATA SYNTHESIS

Of the 12 trials included, 10 assessed artificial systems for acute or acute-on-chronic liver failure and 2 assessed bioartificial systems for acute liver failure. Overall, support systems had no significant effect on mortality compared with standard medical therapy (RR, 0.86; 95% confidence interval [CI], 0.65-1.12). Meta-regression indicated that the effect of support systems depended on the type of liver failure (P =.03). In stratified meta-analyses, support systems appeared to reduce mortality by 33% in acute-on-chronic liver failure (RR, 0.67; 95% CI, 0.51-0.90), but not in acute liver failure (RR, 0.95; 95% CI, 0.71-1.29). Compared with randomized trials, nonrandomized studies produced significantly larger estimates of intervention effects (P =.01).

CONCLUSION

This review suggests that artificial support systems reduce mortality in acute-on-chronic liver failure compared with standard medical therapy. Artificial and bioartificial support systems did not appear to affect mortality in acute liver failure.

Temporary support for acute liver failure

GOAL

To review treatment approaches for temporary liver support of patients with acute liver failure (ALF). STUDY A MEDLINE: search of English language reports published between 1960 and 1999 and a manual search of bibliographies of relevant papers were performed. Studies of humans in whom non-orthotopic liver transplant (OLT)-based approaches were used were reviewed, including case reports, case series, review articles describing unpublished cases, and controlled trials. Relevant clinical information was extracted with emphasis on improvement in liver function, successful bridging to OLT, recovery without OLT, and death. There was a lack of more than one controlled trial for each therapy, and most case reports were anecdotal in nature; therefore, no statistical analysis was attempted. Predefined outcomes from individual patients were synthesized collectively into tables.

RESULTS

Both cell-based and non-cell-based therapies for ALF appear promising. Preliminary experience has established the safety of these approaches, but current data are inadequate to evaluate efficacy.

CONCLUSIONS

Routine use of artificial liver support systems cannot be recommended at this time. However, the established safety of cell- and non-cell-based liver support devices warrants additional prospective (Phase III) controlled trials among patients with ALF. We suggest an algorithm for management of patients with ALF that incorporates recent data.

Extracorporeal support of the failing liver

Successes in machine-based extracorporeal support for different organ functions stimulated research in the field of liver support approximately 50 years ago. Initial failure to improve outcome using detoxification methods like dialysis, blood and plasma exchange, or plasmapheresis over sorbents fueled interest in biologic liver support concepts using bioreactors or combined methods. New device configurations, technical improvement of existing detoxification methods, and the refinement in cell culture techniques led to a boost in research on biologic and nonbiologic approaches. Currently, many systems are in the preclinical phase or have entered clinical studies. A number of completed clinical trials have reported a favorable therapeutic impact of the most advanced solutions on the course and outcome of liver failure. Often, findings must be reconfirmed. However, current knowledge suggests that extracorporeal liver support can successfully stabilize liver function, improve the clinical condition of patients, and considerably improve survival in certain subgroups of patients with fulminant hepatic failure and acute decompensation of chronic hepatic failure. Although the initial focus of liver support methods was bridging to liver transplantation, bridging to recovery of organ function and treatment of intractable pruritus are now valuable indications.

Treatment of severe tricyclic antidepressant overdose with extracorporeal sorbent detoxification

Tricyclic overdose can be a medical emergency, and therapy with intravenous bicarbonate is not always successful in preventing cardiac toxicity or coma. Mortality in patients developing these complications is from 1% to 15%. Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition. Ten patients with serious drug overdose caused by tricyclics failed to respond quickly to standard therapy and were in stage 3-4 encephalopathy. Nine of these patients were on respirator support, 5 had hypotension, and 6 had QRS widening. Average level was 1,423 microg/L at presentation. Enteral activated charcoal and intravenous (IV) bicarbonate were initiated in the emergency room. The patients were treated for 3 to 4 hours with the Liver Dialysis Unit, a hemodiabsorption device using a cellulosic plate dialyzer and sorbent suspension as dialysate. Inflow and outflow blood levels indicated that the hemodetoxifier removed modest amounts of the tricyclics, metabolites, and other consumed drugs. The clinical improvement of the patients was dramatic, with patients reaching stage 0 or 1 encephalopathy during the treatment. Ventilator support was removed at the end of treatment for 3 patients who had not already developed pneumonia, and for others was prolonged up to 48 hours because of pneumonia, rather than mental status. Average length of stay in the intensive care unit (ICU) was 4.8 days (range 1 to 7 days). None of the patients died despite their high risk for ventricular arrhythmias, seizures, and death. Clinical improvement may have been attributable to removal of free drug from the blood or to removal of drug metabolites.

Extracorporeal blood detoxification by sorbents in treatment of hepatic encephalopathy

Extracorporeal blood detoxification by sorbent therapy long has been applied in treatment of hepatic failure and encephalopathy, starting with hemoperfusion columns and more recently with the currently marketed Liver Dialysis Unit. Liver Dialysis employs hemodiabsorption (dialysis of blood against powdered sorbents including charcoal and cation exchanger) to remove selectively numerous small-molecular-weight toxins of hepatic failure. Liver Dialysis is used in treatment of acute hepatic encephalopathy (AHE) because of decompensation of chronic liver disease (A-on-C) or fulminant hepatic failure (FHF). Controlled, prospective and randomized studies of daily 6-hour Liver Dialysis have shown physiologic and neurologic improvement of patients with AHE, regardless of etiology. Liver dialysis significantly improved the incidence of positive outcomes (recovery of hepatic function or improvement for transplant) of A-on-C patients versus controls (71.5% treated, and 35.7% control, P =.036), but had an insignificant improvement in outcome of patients with FHF as compared with the control group. Other extracorporeal sorbent devices are now in clinical testing phase. The molecular adsorbent regenerating system (MARS) device employs a polysulfone high-permeability dialyzer with albumin on the dialysate side to aid transfer of protein-bound toxins such as bilirubin and bile acids across the membranes. Sorbent columns of charcoal and an anion exchanger remove hepatic toxins from the albumin dialysate, and a second dialyzer removes water-soluble toxins, such as ammonium. Clinical results of daily MARS treatments of patients with hepatic failure are similar to that of Liver Dialysis, with neurologic and physical improvement occurs in most patients with AHE, and improved outcome for patients with A-on-C. The system extends the life of patients with hepatorenal syndrome. PF-Liver Dialysis is an experimental device combining hemodiabsorption with push-pull sorbent-based pheresis with powdered sorbent surrounding plasmafilters. PF-Liver Dialysis (Hemocleanse, Inc, W. Lafayette, IN) has been tested in a few patients with hepatic failure, grade 3-4 encephalopathy, and respiratory and kidney insufficiency. Treatments appeared to be safe and resulted in marked decreases in plasma levels of bilirubin, aromatic amino acids, ammonium, creatinine, and interleukin-1beta (IL-1beta). The PF add-on module adds the capability to Liver Dialysis to remove bilirubin, bile acids, and other strongly protein-bound toxins from treated patients and may be of clinical benefit in management of patients with the most severe hepatic failure and encephalopathy, including patients with FHF or concomitant sepsis.

Powdered sorbent liver dialysis and pheresis in treatment of hepatic failure

The Liver Dialysis Unit (the Unit) is a liver-assist device that employs hemodiabsorption (dialysis of blood against powdered sorbents) to selectively remove numerous small molecular weight toxins of hepatic failure. The Unit has been cleared by the Food and Drug Administration and is indicated and marketed for treatment of acute hepatic encephalopathy (AHE) due to decompensation of chronic liver disease (A-on-C) or fulminant hepatic failure (FHF). Controlled, prospective, and randomized studies of liver dialysis were conducted at several centers, enrolling 56 patients with AHE, grades II-IV with or without renal and respiratory insufficiency or failure. Liver dialysis treatments were for 6 h daily, 1-5 days with similar observation periods for control patients. Physiologic status, neurologic status, and outcome (recovery of hepatic function, improvement for transplant, or death) were measured, and results were compared for treated patients versus controls for patients with A-on-C and patients with FHF. Liver dialysis resulted in physiologic and neurologic improvement of patients with AHE, regardless of etiology. Liver dialysis significantly improved the incidence of positive outcomes (recovery of hepatic function or improvement for transplant) of A-on-C patients versus controls (71.5% treated, 35.7% control, p = 0.036), but had an insignificant improvement in the outcome of patients with FHF as compared with the control group. Among the overall 31 treated patients, 51.6% survived. Outcome was not negatively affected by the presence of kidney failure or respiratory failure. The plasmafilter unit (PF-Unit) combines hemodiabsorption with push-pull sorbent-based pheresis (the PF add-on module, with powdered sorbent surrounding plasmafilters). At blood flow rates of 200 ml/min, the system clears creatinine and aromatic amino acids at 120-160 ml/min, unconjugated bilirubin at 20-40 ml/min, and cytokines at 15-25 ml/min. The PF-Unit has been tested in a few patients with hepatic failure with Grades III and IV encephalopathy, and respiratory, and kidney insufficiency. Treatment appeared to be safe, and there were no significant hematologic changes. Physiologic changes included improved blood pressure, and encephalopathy, and stable urine output. Chemical changes included a decrease in the plasma levels of bilirubin, aromatic amino acids, ammonium, creatinine, and IL-1beta. The PF add-on module adds the capability to the Unit to remove bilirubin and other strongly protein-bound toxins from treated patients and may be of clinical benefit in the management of patients with the most severe hepatic failure and encephalopathy, including patients with FHF or concomitant sepsis.

Management of drug-induced liver disease

The treatment and prevention of drug-induced liver injury starts with the recognition of hepatotoxicity at the earliest possible time so that the suspected drug can be discontinued expeditiously. Both liver enzyme monitoring and vigilance for signs of hypersensitivity involving the liver are useful strategies for many agents known to cause hepatocellular necrosis leading to liver failure. Specific antidotes to prevent or limit hepatic damage exist for only a few drugs, the most important being N-acetylcysteine for the treatment of acetaminophen hepatotoxicity. Corticosteroids are of unproven benefit in the setting of fulminant failure. Ursodiol may be helpful in instances of cholestatic injury. For other agents, supportive measures and the increasing use of liver-assist devices as well as emergency liver transplantation are available when drug injury evolves into irreversible liver failure. It is hoped that a better understanding of hepatotoxicity mechanisms will lead to the development of more specific and effective forms of therapy in the near future.

Push-pull sorbent-based pheresis and hemodiabsorption in the treatment of hepatic failure: preliminary results of a clinical trial with the BioLogic-DTPF System

The BioLogic-DTPF System combines hemodiabsorption (the BioLogic-DT System with dialysis against powdered sorbent) with push-pull sorbent-based pheresis (the BioLogic-PF System with powdered sorbent surrounding plasma filters). At blood flow rates of 200 ml/min, the system clears creatinine and aromatic amino acids at 120-160 ml/min, unconjugated bilirubin at 20-40 ml/min, and cytokines at 15-25 ml/min. This article outlines a study of the DTPF System in treatment of patients with hepatic failure with Grade 3 or 4 encephalopathy and respiratory and kidney insufficiency. Treatment appeared to be safe, and there are no significant hematologic changes. Physiologic changes include improved blood pressure and encephalopathy and stable urine output. Chemical changes include decrease in plasma levels of bilirubin, aromatic amino acids, ammonium, creatinine, and interleukin-3 (IL-1beta). The BioLogic-DT System is now marketed for treatment of acute hepatic failure with encephalopathy. The BioLogic-DTPF System adds the capability of removing bilirubin and other strongly protein-bound toxins from treated patients and may be of clinical benefit in management of patients with the most severe hepatic failure and encephalopathy.

Temporary Extracorporeal Liver Support for Severe Acute Alcoholic Hepatitis Using the Biologic-Dt

Patients with severe acute alcoholic hepatitis develop multiple organ failure which is associated with production of inflammatory cytokines and a poor prognosis. The aim of the present pilot study was to evaluate the effects of the BioLogic-DT sorption-suspension dialyser in patients with severe acute alcoholic hepatitis. Ten patients with encephalopathy (grade II-IV) were entered into the study, 5 received treatment with the BioLogic-DT for 6 hours daily for 3 days and 5 received conventional treatment as controls. The system was biocompatible with no adverse effects on blood pressure or platelet counts, factor V, fibrinogen or antithrombin III. No bleeding episodes were observed even with the use of small doses of heparin. After 3 days, blood ammonia was lower in the BioLogic-DT treated patients than in the controls, although blood lactate was higher. There were slight increases in plasma TNF and IL-8 during treatment over and above the higher levels present initially, possibly as a result of activation of white cells in the extracorporeal circuit. The further development of the BioLogic-DT dialyser with the addition of a plasma treatment module capable of removing cytokines would be worth evaluating in acute alcoholic hepatitis.