Detoxifying capacity and kinetics of prometheus--a new extracorporeal system for the treatment of liver failure

Extracorporeal organ support for critically ill patients: Overcoming the past, achieving the maximum at present, and redefining the future

Extracorporeal organ support (ECOS) has made remarkable progress over the last few years. Renal replacement therapy, introduced a few decades ago, was the first available application of ECOS. The subsequent evolution of ECOS enabled the enhanced support to many other organs, including the heart [veno-arterial extracorporeal membrane oxygenation (ECMO), slow continuous ultrafiltration], the lungs (veno-venous ECMO, extracorporeal carbon dioxide removal), and the liver (blood purification techniques for the detoxification of liver toxins). Moreover, additional indications of these methods, including the suppression of excessive inflammatory response occurring in severe disorders such as sepsis, coronavirus disease 2019, pancreatitis, and trauma (blood purification techniques for the removal of exotoxins, endotoxins, or cytokines), have arisen. Multiple organ support therapy is crucial since a vast majority of critically ill patients present not with a single but with multiple organ failure (MOF), whereas, traditional therapeutic approaches (mechanical ventilation for acute respiratory failure, antibiotics for sepsis, and inotropes for cardiac dysfunction) have reached the maximum efficacy and cannot be improved further. However, several issues remain to be clarified, such as the complexity and cost of ECOS systems, standardization of indications, therapeutic protocols and initiation time, choice of the patients who will benefit most from these interventions, while evidence from randomized controlled trials supporting their use is still limited. Nevertheless, these methods are currently a part of routine clinical practice in intensive care units. This editorial presents the past, present, and future considerations, as well as perspectives regarding these therapies. Our better understanding of these methods, the pathophysiology of MOF, the crosstalk between native organs resulting in MOF, and the crosstalk between native organs and artificial organ support systems when applied sequentially or simultaneously, will lead to the multiplication of their effects and the minimization of complications arising from their use.

Therapeutic plasma-exchange improves short-term, but not long-term, outcomes in patients with acute-on-chronic liver failure: A propensity score-matched analysis

BACKGROUND

Acute-on-chronic liver failure (ACLF) is associated with a high short-term mortality rate in the absence of liver transplantation. The role of therapeutic plasma exchange (TPE) in improving the outcomes of ACLF and acute decompensation (AD) is unclear. In this retrospective analysis, we aimed to determine the impact of TPE on mortality in patients with ACLF.

METHODS

ACLF patients receiving TPE with standard medical treatment (SMT) were propensity score matched (PSM) with those receiving SMT alone (1:1) for sex, grades of ACLF, CLIF C ACLF scores, and the presence of hepatic encephalopathy. The primary outcomes assessed were mortality at 30 and 90 days. Survival analysis was performed using Kaplan Meier survival curves.

RESULTS

A total of 1151 patients (ACLF n = 864 [75%], AD [without organ failure] n = 287 [25%]) were included. Of the patients with ACLF (n = 864), grade 1, 2, and 3 ACLF was present in 167 (19.3%), 325 (37.6%), and 372 (43.0%) patients, respectively. Thirty-nine patients received TPE and SMT, and 1112 patients received only SMT. On PSM analysis, there were 38 patients in each group (SMT plus TPE vs SMT alone). In the matched cohort, the 30-days mortality was lower in the TPE arm compared to SMT (21% vs 50%, P = .008), however, the 90-day mortality was not significantly different between the two groups (36.8% vs 52.6%, P = .166); HR, 0.82 (0.44-1.52), P = .549.

CONCLUSION

TPE improves short-term survival in patients with ACLF, but has no significant impact on long-term outcomes. Randomized control trials are needed to obtain a robust conclusion in this regard.

Progress in hepatitis B virus-related acute-on-chronic liver failure treatment in China: A large, multicenter, retrospective cohort study using a propensity score matching analysis

BACKGROUND

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) has a high short-term mortality. However, the treatment progression for HBV-ACLF in China in the past decade has not been well characterized. The present study aimed to determine whether the HBV-ACLF treatment has significantly improved during the past decade.

METHODS

This study retrospectively compared short-term (28/56 days) survival rates of two different nationwide cohorts (cohort I: 2008-2011 and cohort II: 2012-2015). Eligible HBV-ACLF patients were enrolled retrospectively. Patients in the cohorts I and II were assigned either to the standard medical therapy (SMT) group (cohort I-SMT, cohort II-SMT) or artificial liver support system (ALSS) group (cohort I-ALSS, cohort II-ALSS). Propensity score matching analysis was conducted to eliminate baseline differences, and multivariate logistic regression analysis was used to explore the independent factors for 28-day survival.

RESULTS

Short-term (28/56 days) survival rates were significantly higher in the ALSS group than those in the SMT group (P < 0.05) and were higher in the cohort II than those in the cohort I (P < 0.001). After propensity score matching, short-term (28/56 days) survival rates were higher in the cohort II than those in the cohort I for both SMT (60.7% vs. 53.0%, 50.0% vs. 39.8%, P < 0.05) and ALSS (66.1% vs. 56.5%, 53.0% vs. 44.4%, P < 0.05) treatments. The 28-day survival rate was higher in patients treated with nucleos(t)ide analogs than in patients without such treatments (P = 0.046). Multivariate logistic regression analysis revealed that ALSS (OR = 0.962, 95% CI: 0.951-0.973, P = 0.038), nucleos(t)ide analogs (OR = 0.927, 95% CI: 0.871-0.983, P = 0.046), old age (OR = 1.028, 95% CI: 1.015-1.041, P < 0.001), total bilirubin (OR = 1.002, 95% CI: 1.001-1.003, P = 0.004), INR (OR = 1.569, 95% CI: 1.044-2.358, P < 0.001), COSSH-ACLF grade (OR = 2.683, 95% CI: 1.792-4.017, P < 0.001), and albumin (OR = 0.952, 95% CI: 0.924-0.982, P = 0.002) were independent factors for 28-day mortality.

CONCLUSIONS

The treatment for patients with HBV-ACLF has improved in the past decade.

Therapeutic plasma exchange in liver failure

The multi-organ failure syndrome associated with acute and acute-on-chronic liver failure (ACLF) is thought to be mediated by overwhelming systemic inflammation triggered by both microbial and non-microbial factors. Therapeutic plasma exchange (TPE) has been proven to be an efficacious therapy in autoimmune conditions and altered immunity, with more recent data supporting its use in the management of liver failure. Few therapies have been shown to improve survival in critically ill patients with liver failure who are not expected to survive until liver transplantation (LT), who are ineligible for LT or who have no access to LT. TPE has been shown to reduce the levels of inflammatory cytokines, modulate adaptive immunity with the potential to lessen the susceptibility to infections, and reduce the levels of albumin-bound and water-bound toxins in liver failure. In patients with acute liver failure, high volume TPE has been shown to reduce the vasopressor requirement and improve survival, particularly in patients not eligible for LT. Standard volume TPE has also been shown to reduce mortality in certain sub-populations of patients with ACLF. TPE may be most favorably employed as a bridge to LT in patients with ACLF. In this review, we discuss the efficacy and technical considerations of TPE in both acute and acute-on-chronic liver failure.

Artificial liver support systems

Artificial liver systems are used to bridge between transplantation or to allow a patient's liver to recover. They are used in patients with acute liver failure (ALF) and acute-on-chronic liver failure. There are five artificial systems currently in use: molecular adsorbent recirculating system (MARS), single-pass albumin dialysis (SPAD), Prometheus, selective plasma filtration therapy, and hemodiafiltration. The aim is to compare existing data on the efficiency of these devices. A literature search was conducted using online libraries. Inclusion criteria included randomized control trials or comparative human studies published after the year 2000. A systematic review was conducted for the five individual devices with a more detailed comparison of the biochemistry for the SPAD and MARS systems. Eighty-nine patients were involved in the review comparing SPAD and MARS. Results showed that there was an average reduction in bilirubin (-53 μmol/L in MARS and -50 μmol/L in SPAD), creatinine (-19.5 μmol/L in MARS and -7.5 μmol/L in SPAD), urea (-0.9 mmol/L in MARS and -0.75 mmol/L in SPAD), and gamma-glutamyl transferase (-0.215 μmol/L·s in MARS and -0.295 μmol/L·s in SPAD) in both SPAD and MARS. However, there was no significant difference between the changes in the two systems. This review demonstrated that both MARS and SPAD aid recovery of ALF. There is no difference between the efficiency of MARS and SPAD. Because of the limited data, there is a need for more randomized control trials. Evaluating cost and patient preference would aid in differentiating the systems.

Challenges of reducing protein-bound uremic toxin levels in chronic kidney disease and end stage renal disease

The prevalence of chronic kidney disease (CKD) in the worldwide population is currently estimated between 11% and 13%. Adequate renal clearance is compromised in these patients and the accumulation of a large number of uremic retention solutes results in an irreversible worsening of renal function which can lead to end stage renal disease (ESRD). Approximately three million ESRD patients currently receive renal replacement therapies (RRTs), such as hemodialysis, which only partially restore kidney function, as they are only efficient in removing mainly small, unbound solutes from the circulation while leaving larger and protein-bound uremic toxins (PBUTs) untouched. The accumulation of PBUTs in patients highly increases the risk of cardiovascular events and is associated with higher mortality and morbidity in CKD and ESRD. In this review, we address several strategies currently being explored toward reducing PBUT concentrations, including clinical and medical approaches, therapeutic techniques, and recent developments in RRT technology. These include preservation of renal function, limitation of colon derived PBUTs, oral sorbents, adsorbent RRT technology, and use of albumin displacers. Despite the promising results of the different approaches to promote enhanced removal of a small percentage of the more than 30 identified PBUTs, on their own, none of them provide a treatment with the required efficiency, safety and cost-effectiveness to prevent CKD-related complications and decrease mortality and morbidity in ESRD.

Artificial Liver Support System Improves Short-Term Outcomes of Patients with HBV-Associated Acute-on-Chronic Liver Failure: A Propensity Score Analysis

Background

Hepatitis B virus-associated acute-on-chronic liver failure (HBV-ALCF) is a complicated syndrome with extremely high short-term mortality. The artificial liver support system (ALSS) may improve the liver function for patients with HBV-ACLF, but the data on its short-term outcomes are insufficient in China.

Methods

We recruited HBV-ACLF patients in this nationwide, multicenter, retrospective study. Patients with HBV-ACLF were diagnosed by the COSSH-ACLF criteria. Propensity score matching (PSM) analysis was used to generate compared pairs. The short-term (28/90 days) survival rates between the standard medical therapy (SMT) group and ALSS group were calculated using a Kaplan–Meier graph.

Result

In total, 790 patients with HBV-ACLF were included in this retrospective study; 412 patients received SMT only (SMT group), and 378 patients received SMT and ALSS treatment (ALSS group). PSM generated 310 pairs and eliminated the baseline differences between the two groups (p > 0.05 for all baseline variables). The probabilities of survival on day 28 were 65.2% (205/310) in the ALSS group and 59.0% (185/310) in the SMT group; on day 90, they were 51.0% (163/310) and 42.3% (136/310). The short-term (28/90 days) survival rates of the ALSS group were significantly higher than those of the SMT group (p=0.0452 and p=0.0187, respectively). Compared to receiving SMT alone, treatment with ALSS was associated with a significant reduction in serum bilirubin levels and the model for end-stage liver disease (MELD) scores at day 7 and day 28. Multivariate logistic regression analysis revealed that older age, high total bilirubin (T-Bil), low albumin, high ALT, high MELD scores, and high COSSH-ACLF grade were independent baseline factors associated with poor prognosis.

Conclusions

This retrospective study found that compared to SMT, the ALSS improved the short-term (28/90 days) survival rates and laboratory parameters in HBV-ACLF patients. The ALSS had a better therapeutic effect than SMT for patients with HBV-ACLF in China.

Efficacy of Coupled Plasma Filtration Adsorption in Treating Patients with Severe Intra-Abdominal Infection: A Retrospective Study

Background: Coupled plasma filtration adsorption (CPFA) is an extracorporeal treatment based on plasma filtration associated with an adsorbent cartridge and hemofiltration. CPFA is able to remove inflammatory mediators and it has been used to treat severe sepsis and multiple organ dysfunction. Limited experience exists on the use of CPFA in treating intra-abdominal infection (IAI). Methods: In this study, the efficacy of CPFA in treating patients with severe IAI and liver failure was evaluated in a retrospective analysis of 76 cases. Results: The survival rate of patients treated with CPFA was 82.6%, with effective removal of endotoxin and inflammatory mediators. Conclusion: Our data suggest that CPFA can be safely and effectively used to lower morbidity and mortality rates of patients with severe IAI and liver failure.

An evaluation of the usefulness of extracorporeal liver support techniques in patients with severe liver dysfunction

INTRODUCTION

The mortality rate in patients with severe liver dysfunction with no option of transplantation is unacceptably high. The main aim of this study was to evaluate the usefulness of applying extracorporeal liver support (ECLS) techniques in this group of patients.

MATERIAL AND METHODS

Data from hospital admissions of 101 patients with severe liver dysfunction who were admitted to the department of Anaesthesiology and intensive therapy between 2006 and 2015 were retrospectively analysed. The study group was divided into two subgroups. Standard Medical therapy (SMT) was a subgroup of patients receiving standard Medical therapy, and SMT + ECLS was a subgroup containing patients receiving standard medical therapy complemented by at least one extracorporeal liver support procedure.

RESULTS

Significantly lower intensive care unit (ICU) mortality and 30-day mortality rates were found in the SMT + ECLS subgroup (p = 0.0138 and p = 0.0238 respectively). No difference in 3-month mortality was identified between the two groups. In a multivariate model, independent risk factors for ICU mortality proved to be the SOFA score and prothrombin time. The highest discriminatory power for ICU mortality was demonstrated for the SOFA score, followed by APACHE II, SAPS II, MELD UNOS and GCS scores. For 30-day mortality, however, the best discriminatory power was shown for the SAPS II score, followed by SOFA, APACHE II, MELD UNOS and GCS scores.

CONCLUSIONS

Further studies are needed to assess the contribution of non-biological extracorporeal liver support procedures to a decrease in mortality rates in the population of patients with severe liver dysfunction.

Management of Amanita phalloides poisoning: A literature review and update

Amanita phalloides poisoning with a high mortality is a serious health problem in the world. The typical clinical manifestations are usually characterized by the absence of any symptoms followed by severe gastrointestinal disorders and acute liver failure. Inhibition of RNA polymeraseII (RNAP II) activity, apoptosis, and oxidative stress are considered as the major mechanism of amatoxins intoxication. The current treatment measures mainly include prevention of amatoxins absorption, elimination of absorbed amatoxins, potential antidotes therapy, and liver transplantation. Nevertheless, there are no widely accepted treatment criteria for Amanita phalloides poisoning. This paper will focus on the treatment measures based on the previous studies and provide the currently available information for clinicians.

Prometheus: From Legend to the Real Liver Support Therapy

Background

A large number of patients develop liver disease that may evolve into progressive chronic failure. Artificial liver support systems (e.g., MARS and Prometheus) are considered in the framework of the steady increase in the number of patients who could possibly benefit from these blood purification devices. Albumin dialysis and adsorption are now two integrated concepts. The present know-how enabling us to appropriately modify several intrinsic characteristics of the adsorbents - e.g., their chemical nature, the particle and pore size distribution, as well as a larger surface offered to adsorption - has helped in better fine-tuning liver support systems to improve adsorption kinetics and flow characteristics specifically for the intended clinical application. These properties together with an improved biocompatibility have made possible the development of adsorptive techniques for which clearances and total removal rates of target compound would be unthinkable with conventional hemodialysis or hemofiltration. Several adsorptive techniques are already available commercially for the treatment of sepsis and septic shock and of acute liver failure, but controlled studies with clinical end points are still lacking.

Evaluation of an ADVanced Organ Support (ADVOS) system in a two-hit porcine model of liver failure plus endotoxemia

Background

Novel extracorporeal procedures are constantly being developed and evaluated for use in patients with sepsis. Preclinical evaluation of such procedures usually requires testing in large animal models. In the present work, the safety and efficacy of a recently developed ADVanced Organ Support (ADVOS) system in a newly developed large animal two-hit model of liver failure combined with endotoxemia were tested.

Methods

After establishing the model in more than 50 animals, a randomized study was performed. An inflammatory cholestatic liver injury was initially provoked in pigs. Three days after surgery, endotoxin was gradually administered during 7½ h. Animals were randomized to receive standard medical treatment either with (ADVOS group, n = 5) or without ADVOS (control group, n = 5). The ADVOS treatment was started 2½ h after endotoxemia and continued for 7 h. Survival, cardiovascular, respiratory, renal, liver, coagulation, and cerebral parameters were analyzed.

Results

Three days after surgery, cholestatic injury resulted in hyperbilirubinemia [5.0 mg/dl (IQR 4.3–5.9 mg/dl)], hyperammonemia [292 μg/dl (IQR 291–296 μg/dl)], leukocytosis [20.2 10³/μl (IQR 17.7–21.8 10³/μl)], and hyperfibrinogenemia [713 mg/dl (IQR 654–803 mg/dl)]. After endotoxemia, the ADVOS procedure stabilized cardiovascular, respiratory, and renal parameters and eliminated surrogate markers as bilirubin [2.3 (IQR 2.3–3.0) vs. 5.5 (IQR 4.6–5.6) mg/dl, p = 0.001] and creatinine [1.4 (IQR 1.1–1.7) vs. 2.3 (IQR 2.1–3.1) mg/dl, p = 0.01]. Mortality: All animals in the ADVOS group survived, while all animals in the control group expired during the 10-h observation period (p = 0.002). No adverse events related to the procedure were observed.

Conclusions

The ADVOS procedure showed a promising safety and efficacy profile and improved survival in a sepsis-like animal model with dysfunction of multiple organs. An amelioration of major organ functions (heart and lung) combined with removal of markers for kidney and liver function was observed.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0144-3) contains supplementary material, which is available to authorized users.

Extracorporeal liver support devices for listed patients

An alternative to liver transplantation for patients with liver failure remains an unmet need. In acute liver failure, the ideal extracorporeal liver support device (ELSD) would replace the functions of the failing liver in order to permit spontaneous recovery, given the incredible regenerative potential of the liver, negating the need for transplantation. In acute-on-chronic liver failure, an ELSD would ideally support hepatic function until a recovery to liver function before acute decompensation or until liver transplantation. In decompensated cirrhosis, an ELSD could again be used to support hepatic function until transplant. In addition, ELSDs may have the potential to treat the multiorgan failure that accompanies liver failure including hepatic encephalopathy, renal failure, and immune dysfunction or indeed potential to promote liver regeneration. Creation of an extracorporeal bioartificial liver able to completely replace liver function remains an unmet need. This review will describe a number of technologies suitable for clinical trials in humans, which have resulted from decades of engineering and biological research to develop a bioreactor able to adequately sustain functional hepatocytes. In addition, this review will describe artificial liver support devices that are primarily designed to replace the detoxifying functions of the liver and will consider the current data available or studies required to support their use in liver failure patients on the transplant waiting list. Liver Transplantation 22 839-848 2016 AASLD.

Efficacy of coupled low-volume plasma exchange with plasma filtration adsorption in treating pigs with acute liver failure: A randomised study

BACKGROUND & AIMS

Extracorporeal blood purification systems for supportive therapy of liver failure are widely used. We developed a novel blood purification system, named Li's artificial liver system (Li-ALS), which couples low-volume plasma exchange (low-volume PE) with plasma filtration adsorption (PFA). This study aims to evaluate the efficacy of our novel system in pigs with acute liver failure (ALF).

METHODS

Thirty-two pigs were infused with D-galactosamine (1.3g/kg) to induce ALF. All animals were equally and randomly divided into four groups: the ALF control group received intensive care, the PFA group underwent five hour plasma recycling filtration and adsorption purification, the low-volume PE group received one hour low-volume PE, and the Li-ALS group underwent one hour low-volume PE, followed by five hour PFA. Intervention was initiated 36hours after drug administration. The efficacy of each treatment was assessed by survival time and improvement in hematological, biochemical, and immunohistological parameters.

RESULTS

Pigs in the Li-ALS group survived longer than those in the other groups (p<0.001, ALF control: 60±2h; PFA group: 74±2h; low-volume PE group: 75±2h; and Li-ALS group: 90±3h). Liver enzyme, bilirubin, bile acid and blood ammonia levels were decreased significantly after Li-ALS treatment, and increases in inflammatory cytokines were ameliorated. A higher hepatocyte regeneration index was also observed in the Li-ALS group.

CONCLUSION

Our novel Li-ALS could expedite liver regeneration and improve survival time; hence, it could be promising for treating ALF.

Treatment of pruritus with Prometheus dialysis and absorption system in a patient with benign recurrent intrahepatic cholestasis

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive liver disorder characterized by recurrent episodes of jaundice and itching. Episodes of cholestasis last variously from 1 week to several months, may start at any age and usually resolve spontaneously. No effective treatment has been found as yet. We report a case of genetically proven BRIC in a male patient who developed three episodes of pruritus and jaundice at the age of 14, 16 and 19 years. During the third episode, he did not respond to pharmacological medical therapy, and fractionated plasma separation and absorption (FPSA, Prometheus) was performed to manage intractable pruritus. The treatment immediately alleviated pruritus, lowered serum bilirubin concentration and induced sustained remission in the 5-year follow up. FPSA seems to be a safe and effective way of treatment for BRIC in patients with severe pruritus and prolonged jaundice.

Entecavir vs lamivudine therapy for naïve patients with spontaneous reactivation of hepatitis B presenting as acute-on-chronic liver failure

AIM: To investigate the short-term and long-term efficacy of entecavir versus lamivudine in patients with spontaneous reactivation of hepatitis B presenting as acute-on-chronic liver failure (ACLF).

METHODS: This was a single center, prospective cohort study. Eligible, consecutive hospitalized patients received either entecavir 0.5 mg/d or lamivudine 100 mg/d. All patients were given standard comprehensive internal medicine. The primary endpoint was survival rate at day 60, and secondary endpoints were reduction in hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) levels, and improvement in Child-Turcotte-Pugh (CTP) and model for end-stage liver disease (MELD) scores at day 60 and survival rate at week 52.

RESULTS: One hundred and nineteen eligible subjects were recruited from 176 patients with severe acute exacerbation of chronic hepatitis B: 65 were included in the entecavir group and 54 in the lamivudine group (full analysis set). No significant differences were found in patient baseline clinical parameters. At day 60, entecavir did not improve the probability of survival (P = 0.066), despite resulting in faster virological suppression (P < 0.001), higher rates of virological response (P < 0.05) and greater reductions in the CTP and MELD scores (all P < 0.05) than lamivudine. Intriguingly, at week 52, the probability of survival was higher in the entecavir group than in the lamivudine group [42/65 (64.6%) vs 26/54 (48.1%), respectively; P = 0.038]. The pretreatment MELD score (B, 1.357; 95%Cl: 2.138-7.062; P = 0.000) and virological response at day 30 (B, 1.556; 95%Cl: 1.811-12.411; P =0.002), were found to be good predictors for 52-wk survival.

CONCLUSION: Entecavir significantly reduced HBV DNA levels, decreased the CTP and MELD scores, and thereby improved the long-term survival rate in patients with spontaneous reactivation of hepatitis B presenting as ACLF.

MARS therapy, the bridging to liver retransplantation - Three cases from the Hungarian liver transplant program

Besides orthotopic liver transplantation (OLT) there is no long-term and effective replacement therapy for severe liver failure. Artificial extracorporeal liver supply devices are able to reduce blood toxin levels, but do not replace any synthetic function of the liver. Molecular adsorbent recirculating system (MARS) is one of the methods that can be used to treat fulminant acute liver failure (ALF) or acute on chronic liver failure (AoCLF). The primary non-function (PNF) of the newly transplanted liver manifests in the clinical settings exactly like acute liver failure. MARS treatment can reduce the severity of complications by eliminating blood toxins, so that it can help hepatic encephalopathy (HE), hepatorenal syndrome (HRS), and the high rate mortality of cerebral herniation. This might serve as a bridging therapy before orthotopic liver retransplantation (reOLT). Three patients after a first liver transplantation became candidate for urgent MARS treatment as a bridging solution prior to reOLT in our center. Authors report these three cases, fo-cusing on indications, MARS sessions, clinical courses, and final outcomes.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Liver support systems: will they ever reach prime time?

Liver support systems aim to provide temporary support of liver function while maintaining extra-hepatic function in patients with liver failure. Important advances have been achieved in the design of artificial and bio-artificial devices, but the current systems are far from meeting the ideal. Artificial devices provide detoxification through different dialysis procedures, whereas bio-artificial devices add synthetic functions by incorporating a cellular component into the system. Overall, liver support systems have consistently shown beneficial effects on the pathophysiology of liver failure, especially in acute-on-chronic liver failure. However, these beneficial effects have not been translated into an improvement of survival. Our review discusses the current evidence, paying special attention to the clinical aspects of (bio)-artificial liver support devices.

Evaluation of the Hepa Wash® treatment in pigs with acute liver failure

Background

Mortality of patients with acute liver failure (ALF) is still unacceptably high. Available liver support systems are still of limited success at improving survival. A new type of albumin dialysis, the Hepa Wash^® system, was newly introduced. We evaluated the new liver support system as well as the Molecular Adsorbent Recycling System (MARS) in an ischemic porcine model of ALF.

Methods

In the first study animals were randomly allocated to control (n=5) and Hepa Wash (n=6) groups. In a further pilot study, two animals were treated with the MARS-system. All animals received the same medical and surgical procedures. An intraparenchymal intracranial pressure was inserted. Hemodynamic monitoring and goal-directed fluid therapy using the PiCCO system was done. Animals underwent functional end-to-side portacaval shunt and ligation of hepatic arteries. Treatment with albumin dialysis was started after fall of cerebral perfusion pressure to 45 mmHg and continued for 8 h.

Results

All animals in the Hepa Wash group survived the 13-hour observation period, except for one that died after stopping treatment. Four of the control animals died within this period (p=0.03). Hepa Wash significantly reduced impairment of cerebral perfusion pressure (23±2 vs. 10±3 mmHg, p=0.006) and mean arterial pressure (37±1 vs. 24±2 mmHg, p=0.006) but had no effect on intracranial pressure (14±1 vs. 15±1 mmHg, p=0.72). Hepa Wash also enhanced cardiac index (4.94±0.32 vs. 3.36±0.25 l/min/m2, p=0.006) and renal function (urine production, 1850 ± 570 vs. 420 ± 180 ml, p=0.045) and eliminated water soluble (creatinine, 1.3±0.2 vs. 3.2±0.3 mg/dl, p=0.01; ammonia 562±124 vs. 1382±92 μg/dl, p=0.006) and protein-bound toxins (nitrate/nitrite 5.54±1.57 vs. 49.82±13.27 μmol/l, p=0.01). No adverse events that could be attributed to the Hepa Wash treatment were observed.

Conclusions

Hepa Wash was a safe procedure and improved multiorgan system failure in pigs with ALF. The survival benefit could be the result of ameliorating different organ functions in association with the detoxification capacity of water soluble and protein-bound toxins.

Liver support systems--a review

Liver failure is associated with a high morbidity and mortality rate and is the seventh leading cause of death worldwide. Orthotopic liver transplantation remains the definitive treatment; however, because of the limited number of available organs many patients expire while on the transplant list. Currently, there are no established means for providing liver support as a means of bridging patients to transplantation or allowing for recovery from liver injury. Analogous to the clinical situation of renal failure, there is great interest in developing liver support systems that replace the metabolic and waste removal functions of the liver. These support systems are of two general types: artificial and bioartificial livers. In this review, based on a presentation from the 57th American Society of Artificial Internal Organs Annual Meeting (Washington, D.C., June 2011), we review the current status of liver support systems.

Artificial and bioartificial liver support

The fact that liver failure constitutes a life-threatening condition and can, in most cases, only be overcome by orthotopic liver transplantation, lead to the development of various artificial and bioartificial liver support devices. While artificial systems are based on the principles of adsorption and filtration, the more complex concept of bioartificial devices includes the provision of liver cells. Instead of solely focussing on detoxification, these concepts also support the failing organ concerning synthetic and regulative functions.The systems were evaluated in a variety of clinical studies, demonstrating their safety and investigating the impact on the patient's clinical condition. This review gives an overview over the most common artificial and bioartificial liver support devices and summarizes the results of the clinical studies.

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.

Fractionated plasma separation and adsorption: current practice and future options

Fractionated plasma separation and adsorption (FPSA) is a method of albumin dialysis that is integrated into an extracorporeal liver support device (Prometheus(®)). This concept allows the effective removal of both protein-bound and water-soluble substances without the need for external albumin. Several studies comparing the in vivo extraction capacities of FPSA and molecular adsorbent recirculating system (MARS) concluded that detoxification by FPSA seems to be more effective than by MARS. Overall, FPSA therapy has been shown to be safe. Over the last few years, the anticoagulation protocol for FPSA therapy was optimised by using regional anticoagulation with citrate to avoid clotting of system components. Recently, the results of a large randomised-controlled multicentre trial (HELIOS) have been presented. Survival after 1 and 3 months was evaluated in 145 patients with acute-on-chronic liver failure comparing FPSA therapy with standard medical treatment versus standard medical treatment alone. There was no statistically significant survival benefit for patients undergoing FPSA therapy. However, patients with hepatorenal syndrome type I or MELD score >30 showed a significant survival benefit under FPSA in a predefined subgroup analysis. Furthermore, there have been promising results with FPSA in the treatment of refractory cholestatic pruritus. Regarding acute liver failure, only few data are currently available.

Acute-on-chronic liver failure: extracorporeal liver assist devices

PURPOSE OF REVIEW

Acute-on-chronic liver failure (ACLF), a syndrome precipitated by acute liver injury in patients with advanced cirrhosis, is associated with multiorgan dysfunction and high rates of mortality. Liver support systems have been developed in an attempt to improve survival of patients with ACLF by providing a bridge until recovery of the native liver function.

RECENT FINDINGS

Nonbiological devices such as molecular adsorbent recirculating system (MARS) and fractionated plasma separation and adsorption (Prometheus) are effective in improving severe hepatic encephalopathy and cholestasis, have good safety and tolerability profiles and are frequently employed in patients with ACLD; however, randomized controlled trials (RCTs) failed to show improvement in survival. Biologic devices that incorporate hepatic cells in bioreactors are also under development. Recent data from pilot studies suggested improvement in survival rates in some groups of patients with ACLF; however, their effect on patient survival in RCT is still unknown.

SUMMARY

Liver support systems are safe and well tolerated when used in management of patients with ACLF. Their use should continue in controlled clinical trials to explore their role in bridging patients to liver transplantation or recovery in well defined patient groups.

The treatment of acute liver failure with fractionated plasma separation and adsorption system: Experience in 85 applications

INTRODUCTION

Artificial liver support systems represent a potential useful option for the treatment of liver failure. The outcomes of patients treated with the fractionated plasma separation and adsorption (FPSA) system are presented.

PATIENTS AND METHODS

FPSA was performed 85 times for 27 patients (median 3 treatments/patient) with liver failure [85.2% acute liver failure (ALF) and 14.8% acute-on-chronic liver failure] using the Prometheus 4008H (Fresenius Medical Care) unit. Citrate was used for anticoagulation. A variety of clinical and biochemical parameters were assessed. Comparisons between pretreatment and post-treatment data were performed using paired t-test.

RESULTS

The 85 sessions had a mean duration of 6 h. There were significant decreases in total bilirubin (13.18 +/- 9.46 mg/dL vs. 9.76 +/- 7.05 mg/dL; P < 0.0001), ammonia (167.6 +/- 75 mg/dL vs. 120 +/- 43.8 mg/dL; P < 0.0001), blood urea nitrogen (BUN; 12.55 +/- 13.03 mg/dL vs. 8.18 +/- 8.15 mg/dL; P < 0.0001), creatinine (0.54 +/- 0.47 mg/dL vs. 0.46 +/- 0.37 mg/dL; P = 0.0022) levels, and in pH (7.48 +/- 0.05 vs. 7.44 +/- 0.08; P = 0.0045). Four patients (14.8%) received liver transplantation after the treatments; in nine patients, transplantation was not necessary anymore (33%); the remaining 14 patients did not receive a transplantation because they were either not appropriate candidates or no organ was available. Overall survival was 48.1% (4 transplanted and 9 treated patients). No hematological complications related to FPSA were observed.

CONCLUSIONS

FPSA system is a safe and effective detoxification method for patients with liver dysfunction, including ALF. The system is useful as a symptomatic treatment before liver transplantation; in up to 1/3 of the cases, it can even be used as a sole method of treatment.

Removal of asymmetric dimethylarginine during artificial liver support using fractionated plasma separation and adsorption

OBJECTIVE

Asymmetric dimethylarginine (ADMA) is the most potent endogenous nitric oxide synthase inhibitor. Elevated ADMA levels have been linked to increased mortality in different patient populations. Key regulation of ADMA levels mainly takes place in the liver. Hence, ADMA is elevated in liver disease. There is no specific pharmacological treatment to lower the elevated ADMA levels. Hemodialysis is of limited efficiency in removing ADMA as it is highly protein bound. Prometheus is an extracorporeal liver support system which allows the removal of protein-bound toxins. We assessed the efficiency of the Prometheus system in reducing high ADMA levels in patients with liver failure.

MATERIAL AND METHODS

We studied nine patients with acute-on-chronic liver failure and concomitant renal failure already necessitating hemodialysis. Seven patients needed intensive care treatment. Two consecutive sessions of Prometheus therapy of each 4 h were performed in all patients. ADMA and its structural isomer symmetrical dimethylarginine (SDMA) were determined using liquid chromatography-mass spectrometry.

RESULTS

ADMA levels correlated to model for end stage liver disease (MELD) score (r(s) = 0.62; p < 0.0001). Before Prometheus was started, levels of ADMA and SDMA were elevated (1.36 +/- 0.5 micromol/l and 1.90 +/- 0.4 micromol/l, respectively). During Prometheus treatments, plasma levels of ADMA dropped by a mean 25% (p < 0.0001) and SDMA levels by 22% (p < 0.0001). However, there was a significant rebound of ADMA levels between the two therapy sessions (p < 0.01).

CONCLUSIONS

This study shows for the first time that plasma levels of ADMA can be effectively lowered by an artificial liver support system (Prometheus). Effective elimination of ADMA might explain some of the beneficial clinical effects of these systems in patients with liver failure.

[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.

Extracorporeal liver support therapy with Prometheus in patients with liver failure in the intensive care unit

Acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF) are associated with a high mortality. In these patients an accumulation of both water-soluble and water-insoluble, protein-bound, metabolic waste products occurs. Conventional extracorporeal blood purification techniques based on diffusion and/or convection such as hemodialysis or hemofiltration may only eliminate small molecular weight, water-soluble compounds. In recent years, fractionated plasma separation and adsorption (FPSA) with the Prometheus system has been introduced for extracorporeal liver support therapy. To date, however, only limited data is available regarding the effect of this treatment on mortality and outcome of patients with advanced liver disease. Here we report on our experience with 23 patients with severe liver failure who were treated with Prometheus in our medical intensive care unit. Fourteen patients had AoCLF, and nine patients experienced ALF. The median bilirubin level at the start of Prometheus therapy was 30.5 mg/dL and the median Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 26. During 40 individual treatment sessions lasting 5-6 h, Prometheus therapy reduced serum bilirubin levels from 23.7 mg/dL to 15.0 mg/dL (median values) (P < 0.001), and the overall survival was 26%. ALF patients had a better survival compared to AoCLF patients (44% vs. 22%; P = 0.022). Apart from one patient who developed hemodynamic instability during a treatment session, Prometheus therapy was well tolerated without relevant side-effects. In conclusion, extracorporeal liver support therapy with Prometheus is a novel and safe treatment option in patients with severe liver failure. In this series, patients with ALF showed a significantly better outcome with Prometheus therapy compared to AoCLF patients.

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.

Proteomic analysis of proteins bound to adsorption units of extracorporeal liver support system under clinical conditions

Fractionated Plasma Separation, Adsorption and Dialysis (Prometheus) has a well-documented capacity to remove protein-bound organic toxins in patients with liver failure. However, the compositions of adsorbed proteins remain unknown. Elution of both adsorbers constituting Prometheus system was performed following a 6-h session in a patient with acute on chronic liver failure. Sodium dodecylsulphate was employed to elute proteins from the neutral adsorber (P1), while acetic acid was applied to the cationic one (P2). Eluted proteins were resolved by two-dimensional gel electrophoresis (2-DE) and identified by mass spectrometry (MS). Totally, 4113 and 8280 mg of proteins were obtained from P1 and P2 eluates, 2-DE yielded 148 and 163 protein fractions in P1 and P2, respectively. MS identified 18 unique proteins in P1, and 30 unique proteins in P2 sample. Proteins with the highest selective adsorption (as determined by eluate to plasma ratio) included transthyretin (37), trypsin-2 (29), prothrombin (23), hyaluronan-binding protein 2 (13) and plasma retinol-binding protein (8.7), all of which adsorbed to P2. We identified a large number of proteins removed by extracorporeal liver support system. A selective adsorption was demonstrated in a subset of proteins depending on the type of adsorber and proteins' characteristics.

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.

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.

A bench to bedside view of uremic toxins

Reviewing the current picture of uremic toxicity reveals its complexity. Focusing on cardiovascular damage as a model of uremic effects resulting in substantial morbidity and mortality, most molecules with potential to affect the function of a variety of cell types within the vascular system are difficult to remove by dialysis. Examples are the larger middle molecular weight molecules and protein-bound molecules. Recent clinical studies suggest that enhancing the removal of these compounds is beneficial for survival. Future therapeutic options are discussed, including improved removal of toxins and the search for pharmacologic strategies blocking responsible pathophysiologic pathways.

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

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

The therapeutical efficiency of the newest extracorporal elimination procedure (Prometheus® treatment) in acute liver failure caused by intoxication

Az akut májelégtelenség mortalitása az intenzív terápia ellenére májtranszplantáció nélkül 60–90%. Az átültethető szervek korlátozott száma miatt azonban a betegek jelentős része a várólistán exitál. A mortalitás csökkentése érdekében számos próbálkozás történt a májelégtelenségben felhalmozódó albuminhoz kötött és vízoldékony méreganyagok eltávolítására, elősegítve ezzel a máj spontán regenerációját, illetve a beteg életben tartását a májtranszplantációig. A Prometheus®-kezelés egy viszonylag új technika, a frakcionált plazmaszeparáció és -adszorpció (FPSA) és egy high-flux dialízis kombinációja. Az eljárás során a beteg saját, szeparált, albuminban gazdag plazmája speciális adszorbereken halad keresztül, lehetővé téve az albuminhoz kötött toxinok eliminációját, miközben a vízoldékony toxinok eltávolítása hemodialízissel történik. Célkitűzés: A szerzők szándéka az volt, hogy a Prometheus®-kezelés hatékonyságát igazolják mérgezés okozta akut májelégtelenségben. Betegek és módszer: A Prometheus®-kezelést három, konzervatív kezeléssel nem uralható akut májelégtelenségben szenvedő, súlyos, paracetamol-, káliumpermanganát- és Amanita phalloides-mérgezett beteg esetében alkalmazták. Eredmények: A három nőbetegnél 10 kezelés történt. Súlyos szövődményt nem észleltek. A kezelések során az albuminhoz kötött (indirekt bilirubin p = 0,048; epesav p = 0,001) és a vízoldékony (direkt bilirubin p = 0,002; kreatinin p = 0,007) toxinok szignifikáns csökkenését tapasztalták. Az ammónia, a karbamid, a fibrinogén és az antitrombin III szint szignifikánsan nem változott. Mindhárom beteg májtranszplantáció nélkül meggyógyult. Következtetés: A Prometheus®-kezelés hatékonyan távolítja el az akut májelégtelenségben akkumulálódó toxinokat. Biztonságos eljárás. Konzervatív terápiával nem uralható esetekben lehetővé teszi a beteg életben tartását a máj spontán regenerációjáig vagy a májtranszplantációig.

Major coagulation disturbances during fractionated plasma separation and adsorption

Fractionated Plasma Separation and Adsorption (FPSA) is a novel nonbiologic detoxification system for the removal of protein-bound solutes. FPSA is used to bridge patients during fulminant liver failure, either to functional recovery or to liver transplantation. Besides liver failure associated protein bound solutes, several important uremic retention solutes share important protein binding. We observed repeated occlusive thrombosis of the arterio-venous conduit during FPSA in hemodialysis (HD) patients, resulting in acute loss of function. A major reduction of several coagulation factors was demonstrated, exceeding 50% for factor II, factor X and protein C. Broad disturbances of the coagulation system were confirmed in FPSA treated liver failure patients. An ex vivo recirculation model demonstrated nonspecific adsorption of coagulation factors protein S and protein C on the anion exchange cartridge. Direct contact between fractionated plasma and the Prometh02 anion exchanger causes significant adsorption of procoagulant and anti-coagulant factors, associated with clinically relevant adverse events.

Removal of bile acids by two different extracorporeal liver support systems in acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is accompanied by marked intrahepatic cholestasis leading to accumulation of cytotoxic bile acids. Extracorporeal liver support systems efficiently remove bile acids, but their effect on bile acid composition in ACLF is unknown. The aim of the present study was to compare elimination of individual plasma bile acids by albumin dialysis (Molecular Adsorbents Recirculating System, MARS) and fractionated plasma separation (Prometheus). Eight consecutive patients with ACLF underwent alternating 6-hour sessions with MARS or Prometheus in a randomized, cross-over design. Serum samples were obtained before, during, and after each treatment, and individual bile acids including cholic acid and chenodeoxycholic acid (CDCA) were measured by gas chromatography. MARS and Prometheus removed total bile acids to a similar extent (reduction ratio, 45% and 46%, respectively). Both devices cleared cholic acid more efficiently than did CDCA. The molar fraction of CDCA (fCDCA) was elevated at baseline and correlated with the degree of liver dysfunction. Prometheus but not MARS treatments further increased fCDCA. Although both devices eliminate total bile acids to a similar extent, clearance of individual bile acids is different, leading to a slight change of the bile acid profile toward hydrophobic bile acids during Prometheus treatments.

Technology Insight: artificial extracorporeal liver support—how does Prometheus® compare with MARS®?

Artificial extracorporeal liver support or 'liver dialysis' has been used in patients with severe liver failure with increasing frequency since the Molecular Adsorbents Recirculating System (MARS), a variant of albumin dialysis, was introduced in 1999. Nevertheless, liver dialysis must still be thought of as experimental because its contribution to improved patient survival has not been proven in large randomized trials. Prometheus is a novel device for fractionated plasma separation via an albumin-permeable filter that was developed to improve removal of albumin-bound toxins. Initial studies have proven clinical use of Prometheus to be feasible and safe. Head-to-head comparisons of Prometheus and MARS have shown treatment with the former to be more efficient with respect to removal of most albumin-bound and water-solved markers. As controlled studies with clinical end points are lacking, it is not known whether the observed greater detoxification capacity of Prometheus will translate into clinical benefit; two small studies indicate that there might be a beneficial effect in hepatic encephalopathy and pruritus. In a recent randomized comparison of MARS and Prometheus, however, hemodynamic improvement was observed in response to MARS, but not Prometheus, treatment. A large randomized controlled trial investigating the effect of Prometheus on survival--the HELIOS study--has been initiated. First results are expected in 2008 and will be crucial to establishing a role for Prometheus in the field of extracorporeal liver support.