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

[Safety and efficacy of the MARS therapy applied by continuous renal replacement therapy (CRRT) monitors]

OBJECTIVE

Analyze the utility and safety of MARS therapy applied with the CRRT monitor.

DESIGN

Prospective study of cohorts.

SCOPE

Polyvalent ICU in tertiary university hospital with hepatic transplantation program.

PATIENTS

Thirty one patients: 9 (22.6%) with acute liver failure (ALF) (1 hepatic surgery, 1 primary graft failure, 7 other causes) and 22 (71%) with acute-on-chronic failure (AoCLF).

INTERVENTIONS

For the treatment, the patients with ALF are maintained in the ICU but those with AoCLF are admitted for the performance of the different sessions, that are programmed for a duration of at least 15 hours in AoCLF and in ALF are maintained continuously, changing the circuit every 24 hours.

VARIABLES OF INTEREST

Metabolic control and complications registered in 75 sessions on 31 patients.

RESULTS

Urea decrease was 33.5 (29-38%), creatinine 36 (31-41%), total bilirubin 29 (25-33%) and direct bilirubin 34 (30-38%). Clearance was slower, but sustained, after the first 4 hours of each session both for urea (p<0.001) as well as for bilirubin (p<0.05). The hemodynamic parameters improved and the hematological ones were not altered. We detected decrease in platelets (131 to 120x109/L, p<0.01). In 95 of the sessions in which heparin was used and in 6% where epoprostenol was used, we observed mild bleeding. We cultured albumin of the circuit at the end of the session in 50 occasions and only obtained growth in 3 cases (6%) (2 Staphylococcus epidermidis, 1 S. haemolyticus) without signs of contamination in the patients.

CONCLUSIONS

The MARS system applied by CRRT monitors provide adequate bilirubin clearance percentages and is safe, even in serious patients. Prolongation of the duration of the sessions was not accompanied by an increase in the risk of infection secondary to the albumin contamination.

Characterization of pro-apoptotic effect of liver failure plasma on primary human hepatocytes and its modulation by molecular adsorbent recirculation system therapy

Plasma from patients with liver failure may contain toxic molecules that cause hepatocyte apoptosis and worsen liver disease, suggesting that removal of pro-apoptotic factors is an appropriate therapeutic strategy. We investigated the apoptosis of human hepatocytes induced by plasma from patients with both acute and acute-on-chronic liver disease, and the effect of molecular adsorbent dialysis (molecular adsorbent recirculation system [MARS] dialysis) on this. Apoptotic effects of acute and acute-on-chronic liver failure plasmas from 46 patients were assessed on cultured primary human hepatocytes using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) labeling and caspase 3 activation. In 11 patients undergoing MARS dialysis, the pro-apoptotic effect of their plasma was analyzed before and after therapy. Acute liver failure plasma induced more apoptosis than normal plasma (within 4-6 h of culture, a 2.5-fold increase by TUNEL labeling, 1.8-fold by caspase 3 activation), via a pathway involving caspase 8, suggesting involvement of the death-receptor pathway. However, not all acute liver failure plasmas were significantly more pro-apoptotic than normal plasma. Plasma from patients with acutely decompensated chronic liver disease induced apoptosis at the same rate as normal plasma. MARS dialysis improved biochemical parameters indicating effective removal of albumin-bound molecules, but the apoptotic effects of the plasma were unchanged. Thus, plasma of patients with acute liver failure, compared to normal plasma, induced increased apoptosis of primary human hepatocytes by a caspase-8- and caspase-3-dependent pathway. The apoptosis induced in the presence of liver failure plasma was not reduced by MARS dialysis.

The patient with refractory ascites

Refractory ascites indicates advanced chronic liver disease and represents a therapeutic challenge. It may be triggered by spontaneous bacterial peritonitis and denotes poor prognosis. While liver transplantation is the ultimate treatment, for the relief of ascites therapeutic paracentesis with iv-administration of albumin and/or transjugular intrahepatic portosystemic shunt (TIPS) are well established. With rapid deterioration of renal function patients can develop hepatorenal syndrome. There is increasing evidence that these patients can be bridged to transplantation with vasopressin analogs (terlipressin) and albumin.

Urinary acidification assessed by simultaneous furosemide and fludrocortisone treatment: an alternative to ammonium chloride

Distal renal tubular acidosis (RTA) can lead to rickets in children or osteomalacia in adults if undetected. This disorder is normally diagnosed by means of an oral ammonium chloride-loading test; however, the procedure often leads to vomiting and abandonment of the test. In this study, we assess an alternative, more palatable approach to test urinary acidification. This was achieved by the simultaneous oral administration of the diuretic furosemide and the mineralocorticoid fludrocortisone to increase distal tubular sodium delivery, principal cell sodium reabsorption, and alpha-intercalated cell proton secretion. We evaluated 11 control subjects and 10 patients with known distal RTA by giving oral ammonium chloride or furosemide/fludrocortisone in random order on separate days. One control and two patients were unable to complete the study owing to vomiting after NH4Cl; however, there were no adverse effects with the furosemide/fludrocortisone treatment. The urine pH decreased to less than 5.3 in the controls with both tests, whereas none of the patients was able to lower the urine pH below 5.3 with either test. We conclude that the simultaneous administration of furosemide and fludrocortisone provides an easy, effective, and well-tolerated alternative to the standard ammonium chloride urinary acidification test for the diagnosis of distal RTA.

Endotoxemia produces coma and brain swelling in bile duct ligated rats

This study explores the hypothesis that the inflammatory response induced by administration of lipopolysaccharide (LPS) exacerbates brain edema in cirrhotic rats; and if so whether this is associated with altered brain metabolism of ammonia or anatomical disturbance of the blood-brain barrier. Adult Sprague-Dawley rats 4 weeks after bile duct ligation (BDL)/Sham-operation, or naïve rats fed a hyperammonemic diet (HD), were injected with LPS (0.5 mg/kg, intraperitoneally) or saline, and killed 3 hours later. LPS administration increased brain water in HD, BDL, and sham-operated groups significantly (P < 0.05), but this was associated with progression to pre-coma stages only in BDL rats. LPS induced cytotoxic brain swelling and maintained anatomical integrity of the blood-brain barrier. Plasma/brain ammonia levels were higher in HD and BDL rats than in sham-operated controls and did not change with LPS administration. Brain glutamine/myoinositol ratio was increased in the HD group but reduced in the BDL animals. There was a background pro-inflammatory cytokine response in the brains of cirrhotic rats, and plasma/brain tumor necrosis factor alpha (TNF-alpha) and IL-6 significantly increased in LPS-treated animals. Plasma nitrite/nitrate levels increased significantly in LPS groups compared with non-LPS controls; however, frontal cortex nitrotyrosine levels only increased in the BDL + LPS rats (P < 0.005 versus BDL controls).

CONCLUSION

Injection of LPS into cirrhotic rats induces pre-coma and exacerbates cytotoxic edema because of the synergistic effect of hyperammonemia and the induced inflammatory response. Although the exact mechanism of how hyperammonemia and LPS facilitate cytotoxic edema and pre-coma in cirrhosis is not clear, our data support an important role for the nitrosation of brain proteins.

Extracorporeal liver support: a continuing challenge

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

Albumin dialysis has no clear effect on cytokine levels in patients with life-threatening liver insufficiency

Cytokines play a important role in life-threatening liver insufficiency. They are released within the liver in response to hepatic injury and inflammation. To study cytokine clearance during albumin dialysis treatment (Molecular Adsorbent Recirculating System [MARS]), we monitored proinflammatory (tumor necrosis factor alpha [TNF-alpha] and interleukin-8 [IL-8]) and anti-inflammatory (IL-10 and IL-6) cytokines and the lymphocyte activation marker IL-2sRalpha in 81 consecutive ICU patients displaying serious hepatic decompensation. Cytokine levels were measured before treatment and after the last MARS treatment in 49 acute liver failure (ALF) and 32 acute decompensation of chronic liver disease (AcOChr) patients who were mainly considered for liver transplantation. No significant change in cytokines was observed before versus after the last MARS treatment in the AcOChr group, and only IL-10 decreased significantly in the ALF group. Baseline levels of IL-8 and IL-6 were significantly lower and IL-10 was higher in the ALF group compared with those in the AcOChr group. TNF-alpha and IL-2sRalpha levels did not differ between the groups. After treatment, IL-8 was also significantly lower in ALF patients compared with the levels in AcOChr patients. In this study, MARS therapy did not show a clearly identifiable efficacy at removing circulating cytokines. However, the results revealed that ALF and AcOChr patients displayed different profiles of circulating cytokines.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Construction and transplantation of an engineered hepatic tissue using a polyaminourethane-coated nonwoven polytetrafluoroethylene fabric

BACKGROUND

Acute liver failure (ALF) is a serious condition that has a high mortality rate. Construction of an efficient culture and transplantation engineering system of hepatic tissue is an important approach to treat patients suffering from ALF to provide short-term hepatic support until the damaged liver spontaneously recovers or a donor liver becomes available for transplantation. Here, we evaluate the construction and transplantation of an engineered hepatic tissue (EHT) using primary isolated hepatocytes cultured onto polyaminourethane (PAU)-coated, nonwoven polytetrafluoroethylene (PTFE) fabric.

METHODS

The isolated hepatocytes cultured onto PAU-coated PTFE fabric were able to adhere and spread over the individual fibers of the net and formed hepatic clusters after 3 days, such clusters revealed Gap junctions and well-developed bile canaliculi.

RESULTS

When PAU-coated PTFE was utilized, ammonia-, and diazepam- metabolizing capacities and albumin production ability were significantly increased compared with collagen control. To test the function of this hepatic tissue in vivo, we transplanted a nonwoven PAU-coated PTFE fabric inoculated with one million hepatocytes on the surface of the spleen of Balb/c mice suffering from ALF induced by 90% hepatectomy, and found that this EHT prolonged the survival of liver failure-induced mice without adverse effects. Ultrastructure analyses showed good attachment of the cells on the surface of PTFE fabric and strong albumin expression seven days after the newly formed hepatic tissue was transplanted.

CONCLUSION

We have here demonstrated the efficient construction and transplantation of hepatic tissue using primary hepatocytes and PAU-coated PTFE fabric.

Extracorporeal membrane oxygenation and extracorporeal albumin dialysis in pediatric patients with sepsis and multi-organ dysfunction syndrome

Extracorporeal membrane oxygenation (ECMO) is used in managing patients with potentially reversible cardio-respiratory failure refractory to conventional methods. Multiorgan dysfunction syndrome (MODS), usually due to sepsis, remains the main cause of mortality in such patients. We report a series of six pediatric patients with sepsis-induced MODS where extracorporeal albumin dialysis (EAD) was used while the patients were on ECMO. The age of the patients ranged between 1 month and 17 years. The mean pediatric index of mortality (PIM) score at admission was 67.5%. All these patients further deteriorated with MODS and EAD was used as rescue therapy. At institution of EAD, 4 patients had dysfunction of 4 organs and 2 patients had dysfunction of 5 organs. The number of EAD cycles ranged between 1 and 3. Three out of the 6 patients (50%) survived to discharge from the intensive care unit and two of the six patients (33%) survived to hospital discharge. According to our previous experience and published results, all these patients would have been expected to die. The present results suggest that EAD may prove to have a role in the treatment of pediatric patients with sepsis-induced MODS. Further research is required to identify the group of patients who would benefit most by EAD as well as understand the clearance of inflammatory mediators and other mechanisms involved with the use of EAD.

Drug insight: the role of albumin in the management of chronic liver disease

Albumin is the most abundant protein in the circulation. Its main physiologic function is to maintain colloid osmotic pressure. Better understanding of albumin's other physiologic functions has expanded its application beyond maintenance of intravascular volume. In patients with cirrhosis, albumin has been used as an adjunct to diuretics to improve the diuretic response. It has also been used to prevent circulatory dysfunction developing after large-volume paracentesis. Newer indications in cirrhotic patients include preventing hepatorenal syndrome in those with spontaneous bacterial peritonitis, and treating established hepatorenal syndrome in conjunction with vasoconstrictor therapies. The use of albumin for many of these indications is controversial, mostly because of the paucity of well-designed, randomized, controlled trials. The cost of albumin infusions, lack of clear-cut benefits for survival, and fear of transmitting unknown viruses add to the controversy. The latest indication for albumin use in cirrhotic patients is extracorporeal albumin dialysis, which has shown promise for the treatment of hepatic encephalopathy; its role in hepatorenal syndrome or acute on chronic liver failure has not been established. Efforts should be made to define the indications for albumin use, dose of albumin required and predictors of response, so that patients gain the maximum benefit from its administration.

MARS in the treatment of liver failure: controversies and evidence

Molecular Adsorbent Recirculation System (MARS) is a form of extracorporeal detoxification system used as an artificial liver support system. Numerous studies have been published on the topic, with the majority of them describing the capability of MARS in removing albumin-bound toxins and improving systemic hemodynamics. Whether such improvement could be translated into survival benefit is still uncertain, given the paucity of randomized controlled trials available. The outcome of patients receiving MARS treatment is difficult to analyze because liver failure patients constitute a heterogeneous population and different subgroups carry different prognoses. An evidence-based recommendation on the timing of MARS initiation is not available and currently MARS is usually commenced for hyperbilirubinemia or presence of complications of liver failure. MARS is in general a safe procedure, but there are still potential complications that need to be cautioned, along with various operative issues that are worth attention. The future prospects of MARS would rely on the completion of adequately powered randomized controlled trials.

Molecular Adsorbent Recirculating System in Liver Transplantation: Safety and Efficacy

We assessed the safety and clinical efficacy of the Molecular Adsorbent Recirculating System (MARS) in liver failure patients admitted to our intensive care unit (ICU) from May 2000 to February 2006. Of 28 adult patients with bilirubin >15 mg/dL and hepatic encephalopathy (HE) grade > or =2 or hepato-renal syndrome, 22 patients were included in the study, because 6 patients were older than 65 years of age or showed recent alcohol abuse or extrahepatic malignancy. Patients were assigned to 2 groups according to whether MARS therapy was associated with a transplantation procedure: 11 patients received MARS therapy and liver transplantation (OLT group) and 11 patients received MARS therapy alone (non-OLT group). Five of 11 patients in the OLT group were listed for transplantation and 6 patients with graft failure for retransplantation. The patients in the OLT and non-OLT groups were similar in MELD, SOFA, and SAPS scores. All patients were stable and free from complications. MARS significantly reduced bilirubin, bile acids, and blood urea nitrogen (BUN) levels in both groups (P < .05), whereas a significant decrease in ammonia level was observed in the OLT group. Patient survival rates at 3 and 6 months in the OLT group were 91% and 73%, respectively, and in the non-OLT group, 9% and 9%, respectively (P < .001). MARS was safe and well tolerated, improving biochemical parameters, neurological function, and pruritus. In terms of survival, the use of MARS alone was not effective due to the high rate of multiple organ failure. Nevertheless, the association of MARS with a transplant/retransplantation procedure was highly effective.

Molecular adsorbent recirculating system and hemostasis in patients at high risk of bleeding: an observational study

Introduction

Liver failure is associated with reduced synthesis of clotting factors, consumptive coagulopathy, and platelet dysfunction. The aim of the study was to evaluate the effects of liver support using a molecular adsorbent recirculating system (MARS) on the coagulation system in patients at high risk of bleeding.

Methods

We studied 61 MARS treatments in 33 patients with acute liver failure (n = 15), acute-on-chronic liver failure (n = 8), sepsis (n = 5), liver graft dysfunction (n = 3), and cholestasis (n = 2). Standard coagulation tests, standard thromboelastography (TEG), and heparinase-modified and abciximab-fab-modified TEG were performed immediately before and 30 minutes after commencement of MARS, and after the end of MARS treatment. Prostaglandin I₂ was administered extracorporeally to all patients; 17 patients additionally received unfractioned heparin.

Results

Three moderate bleeding complications in three patients, requiring three to four units of packed red blood cells, were observed. All were sufficiently managed without interrupting MARS treatment. Although there was a significant decrease in platelet counts (median, 9 G/l; range, -40 to 145 G/l) and fibrinogen concentration (median, 15 mg/dl; range, -119 to 185 mg/dl) with a consecutive increase in thrombin time, the platelet function, as assessed by abciximab-fab-modified TEG, remained stable. MARS did not enhance fibrinolysis.

Conclusion

MARS treatment appears to be well tolerated during marked coagulopathy due to liver failure. Although MARS leads to a further decrease in platelet count and fibrinogen concentration, platelet function, measured as the contribution of the platelets to the clot firmness in TEG, remains stable. According to TEG-based results, MARS does not enhance fibrinolysis.

Effect of the molecular adsorbent recirculating system and Prometheus devices on systemic haemodynamics and vasoactive agents in patients with acute-on-chronic alcoholic liver failure

Introduction

Patients with acute-on-chronic liver failure show an aggravated hyperdynamic circulation. We evaluated, in a controlled manner, potential changes in systemic haemodynamics induced by the molecular adsorbent recirculating system (MARS) and the Prometheus system liver detoxification devices in a group of patients with acute-on-chronic liver failure.

Methods

Eighteen patients (51.2 ± 2.3 years old; Child–Pugh score, 12.5 ± 0.2; Maddrey score, 63.1 ± 5.0; hepatic venous pressure gradient, 17.6 ± 0.9 mmHg) with biopsy-proven alcoholic cirrhosis and superimposed alcoholic hepatitis were either treated with standard medical therapy (SMT) combined with MARS (n = 6) or Prometheus (n = 6) or were treated with SMT alone (n = 6) on three consecutive days (6 hours/session). Liver tests, systemic haemodynamics and vasoactive substances were determined before and after each session.

Results

Groups were comparable for baseline haemodynamics and levels of vasoactive substances. Both MARS and Prometheus decreased serum bilirubin levels (P < 0.005 versus SMT), the Prometheus device being more effective than MARS (P = 0.002). Only MARS showed significant improvement in the mean arterial pressure (Δchange, +9 ± 2.4 mmHg versus -0.3 ± 2.4 mmHg with Prometheus and -5.2 ± 2.1 mmHg with SMT, P < 0.05) and in the systemic vascular resistance index (Δchange, +131.5 ± 46.2 dyne.s/cm⁵/m² versus -92.8 ± 85.2 dyne.s/cm⁵/m²with Prometheus and -30.7 ± 32.5 dyne.s/cm⁵/m² with SMT; P < 0.05), while the cardiac index and central filling remained constant. This circulatory improvement in the MARS group was paralleled by a decrease in plasma renin activity (P < 0.05), aldosterone (P < 0.03), norepinephrine (P < 0.05), vasopressin (P = 0.005) and nitrate/nitrite levels (P < 0.02).

Conclusion

The MARS device, and not the Prometheus device, significantly attenuates the hyperdynamic circulation in acute-on-chronic liver failure, presumably by a difference in removal rate of certain vasoactive substances. These findings suggest conspicuous conceptual differences among the albumin dialysis devices.

Systemic and regional hemodynamics in pigs with acute liver failure and the effect of albumin dialysis

OBJECTIVE

Acute liver failure (ALF) is haemodynamically characterized by a hyperdynamic circulation. The aims of this study were to investigate the systemic and regional haemodynamics in ALF, to measure changes in nitric oxide metabolites (NOx) and to evaluate whether these haemodynamic disturbances could be attenuated with albumin dialysis.

MATERIAL AND METHODS

Norwegian Landrace pigs (23-30 kg) were randomly allocated to groups as controls (sham-operation, n = 8), ALF (hepatic devascularization, n = 8) and ALF + albumin dialysis (n = 8). Albumin dialysis was started 2 h after ALF induction and continued for 4 h. Systemic and regional haemodynamics were monitored. Creatinine clearance, nitrite/nitrate and catecholamines were measured. A repeated measures ANOVA was used to analyse the data.

RESULTS

In the ALF group, the cardiac index increased (PGT < 0.0001), while mean arterial pressure (PG = 0.02) and systemic vascular resistance decreased (PGT < 0.0001). Renal resistance (PG = 0.04) and hind-leg resistance (PGT = 0.003) decreased in ALF. There was no difference in jejunal blood flow between the groups. ALF pigs developed renal dysfunction with increased serum creatinine (PGT = 0.002) and decreased creatinine clearance (P = 0.02). Catecholamines were significantly higher in ALF, but NOx levels were not different. Albumin dialysis did not attenuate these haemodynamic or renal disturbances.

CONCLUSIONS

The haemodynamic disturbances during the early phase of ALF are characterized by progressive systemic vasodilatation with no associated changes in metabolites of NO. Renal vascular resistance decreased and renal dysfunction developed independently of changes in renal blood flow. After 4 h of albumin dialysis there was no attenuation of the haemodynamic or renal disturbances.

Reversal of mouse hepatic failure using an implanted liver-assist device containing ES cell-derived hepatocytes

Severe acute liver failure, even when transient, must be treated by transplantation and lifelong immune suppression. Treatment could be improved by bioartificial liver (BAL) support, but this approach is hindered by a shortage of human hepatocytes. To generate an alternative source of cells for BAL support, we differentiated mouse embryonic stem (ES) cells into hepatocytes by coculture with a combination of human liver nonparenchymal cell lines and fibroblast growth factor-2, human activin-A and hepatocyte growth factor. Functional hepatocytes were isolated using albumin promoter-based cell sorting. ES cell-derived hepatocytes expressed liver-specific genes, secreted albumin and metabolized ammonia, lidocaine and diazepam. Treatment of 90% hepatectomized mice with a subcutaneously implanted BAL seeded with ES cell-derived hepatocytes or primary hepatocytes improved liver function and prolonged survival, whereas treatment with a BAL seeded with control cells did not. After functioning in the BAL, ES cell-derived hepatocytes developed characteristics nearly identical to those of primary hepatocytes.

The management of severe alcoholic liver disease and variceal bleeding in the intensive care unit

PURPOSE OF REVIEW

To address recent advances in the understanding and management of alcohol-related chronic liver disease and its acute complications.

RECENT FINDINGS

Refinements have been made in the prognosis and treatment of alcoholic hepatitis, and new insights have been gained into the pathophysiology of the hepatorenal syndrome. Further trial evidence has emerged concerning therapy in the hepatorenal syndrome, and there has been some clarification of the benefits and risks relating to albumin dialysis/extracorporeal liver support, and consensus in the early management of variceal haemorrhage.

SUMMARY

Recent developments have led to modifications in the standard of care of patients with severe alcoholic liver disease, many of which are highly applicable to the general critical care setting. These changes apply specifically to alcoholic hepatitis, the hepatorenal syndrome and variceal bleeding, common conditions with a high mortality rate, upon which changes in practice can have a significant impact.

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

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

Differentiation of human embryonic stem cells to hepatocytes using deleted variant of HGF and poly-amino-urethane-coated nonwoven polytetrafluoroethylene fabric

Human embryonic stem (hES) cells have recently been studied as an attractive source for the development of a bioartificial liver (BAL). Here we evaluate the differentiation capacity of hES cells into hepatocytes. hES cells were subjected to suspension culture for 5 days, and then cultured onto poly-amino-urethane (PAU)-coated, nonwoven polytetrafluoroethylene (PTFE) fabric in the presence of fibroblast growth factor-2 (bFGF) (100 ng/ml) for 3 days, then with deleted variant of hepatocyte growth factor (dHGF) (100 ng/ml) and 1% dimethyl sulfoxide (DMSO) for 8 days, and finally with dexamethasone (10(-7) M) for 3 days. The hES cells showed gene expression of albumin in a time-dependent manner of the hepatic differentiation process. The resultant hES-derived hepatocytes metabolized the loaded ammonia and lidocaine at 7.8% and 23.6%, respectively. A million of such hepatocytes produced albumin and urea at 351.2 ng and urea at 7.0 microg. Scanning electron microscopy showed good attachment of the cells on the surface of the PTFE fabric and well-developed glycogen rosettes and Gap junction. In the present work we have demonstrated the efficient differentiation of hES cells to functional hepatocytes. The findings are useful to develop a BAL.

Molecular adsorbent recirculating system in patients with early allograft dysfunction after liver transplantation: a pilot study

Early allograft dysfunction (EAD) after orthotopic liver transplantation (OLT) causes marked morbidity and mortality. We conducted a prospective pilot study to assess the safety and efficacy of molecular adsorbent recirculating system (MARS) in treatment of EAD after OLT. Twelve consecutive adult liver allograft recipients with a median age of 48 years, 9 of whom were male, were prospectively included and supported with MARS. EAD was defined as the presence of at least 2 of the following: serum bilirubin >10 mg/dL, prothrombin time <40%, aspartate aminotransferase or alanine transferase >1,000 U/L, and plasma disappearance rate of indocyanine green (PDR(ICG)) <10% per minute within 72 hours after reperfusion. One-year patient and graft survival was 66%. There was a significant decrease in serum bilirubin (P = 0.002), serum creatinine (P = 0.006), and aspartate aminotransferase (P = 0.005) and a significant increase in PDR(ICG) (P = 0.007) after MARS treatment. Prothrombin time, albumin level, and platelet count remained stable. Sustained improvement of renal and neurological function and of mean arterial pressure were observed. No MARS-related adverse effects occurred. MARS treatment provides a safe approach to the treatment of EAD after OLT. On the basis of this pilot study, a multicenter randomized clinical trial that uses MARS treatment in EAD after OLT has been initiated.

Molecular adsorbent recirculating system dialysis in patients with acute liver failure who are assessed for liver transplantation

OBJECTIVE

To assess the usefulness of dialysis with the molecular adsorbent recirculating system (MARS) in patients with acute liver failure who fulfil criteria for liver transplantation.

DESIGN

Observational cohort study.

SETTING

ICU at a liver transplantation centre.

PATIENTS

Twenty-two patients (23 episodes) received MARS dialysis. They were either listed for LT (n=14), delayed (n=1), or not listed (contra-indication, n=7).

INTERVENTIONS

A total of 56 MARS treatments (median per patient 2; mean duration 7.6+/-2.6h) were performed on haemodialysis.

MEASUREMENTS AND RESULTS

Clinical and biological variables were assessed before and 24[Symbol: see text]h after MARS therapy. The rate of recovery of liver function without transplantation was compared with an expected rate and survival was analysed. Following MARS dialysis, we observed an improvement in the grade of hepatic encephalopathy (P=0.02) and the Glasgow coma score (P=0.02), a decrease in conjugated bilirubin (P=0.05) and INR (P=0.006), and an increase in prothrombin index (P=0.005). Overall, liver function improved in seven patients (32%): four listed patients in whom transplantation could be avoided and three patients among those not listed due to contra-indications. The transplant-free recovery rate in listed patients was 29% (vs. expected 9%, P=0.036). Listed patients (n=14) had a higher 30-day survival rate [86% (12/14) vs 38% (3/8), P=0.05] and a higher long-term survival rate (P=0.02).

CONCLUSIONS

A statistically significant improvement of liver function was observed after MARS therapy. Transplant-free recovery was more frequent than expected. The apparent benefit of MARS dialysis to treat acute liver failure needs to be confirmed by a controlled study.

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

PURPOSE

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

DESIGN

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

PROCEDURES

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

MAIN FINDINGS

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

CONCLUSION

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

Molecular adsorbent recirculating system treatment for patients with liver failure: the Hong Kong experience

BACKGROUND

The molecular adsorbent recirculating system (MARS) is an extracorporeal liver dialysis system that allows selective removal of bilirubin and other albumin-bound toxins. We reported here our experience with the use of this technique for management of liver failure at Queen Mary Hospital, Hong Kong.

METHODS

From December 2002 to 2004, a total of 74 MARS sessions were performed on 22 patients. The cause of liver failure included acute liver failure (n = 2), acute on chronic liver failure (n = 12), posthepatectomy liver failure (n = 4), and posttransplantation allograft failure (n = 4).

RESULTS

MARS treatment showed significant reduction in total bilirubin level, serum ammonia level and blood urea, and nitrogen (P < 0.001 for all three parameters). Five patients (22.7%) were able to bridge to transplantation and one patient (4.5%) made a spontaneous recovery. The 30-day mortality rate was 72.7%.

CONCLUSIONS

Our results indicated that MARS can effectively improve serum biochemistry and is suitable for temporarily supporting patients with liver failure where transplantation is not immediately available. There is, however, no clear evidence showing that MARS can increase survival, improve the chance of transplantation or assist liver regeneration. Future studies in the form of randomized-controlled trials are crucial to characterize the true potential of this treatment.

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.

Progress in treatment of massive ascites and hepatorenal syndrome

Massive ascites and hepatorenal syndrome (HRS) are frequent complications of liver cirrhosis. Thus, effective therapy is of great clinical importance. This concise review provides an update of recent advances and new developments. Therapeutic paracentesis can be safely performed even in patients with severe coagulopathy. Selected patients with a refractory or recurrent ascites are good candidates for non-surgical portosystemic shunts (TIPS) and may have a survival benefit and improvement of quality of life. Novel pharmaceutical agents mobilizing free water (aquaretics) are currently under test for the therapeutic potential in patients with ascites.

Prophylaxis of hepatorenal syndrome in patients with spontaneous bacterial peritonitis is recommended and should be considered in patients with alcoholic hepatitis. Liver transplantation is the best therapeutic option with long-term survival benefit for patients with HRS. To bridge the time until transplantation, TIPS or Terlipressin and albumin are good options. Albumin dialysis can not be recommended outside prospective trials.

Catholic university experience with molecular adsorbent recycling system in patients with severe liver failure

BACKGROUND AND AIM

Molecular adsorbent recycling system (MARS) treatment is able to remove both hydrosoluble and small- and medium-sized lipophilic toxins. MARS plays an important role in modifying liver failure complications, such as hepatorenal syndrome and hepatic encephalopathy. We sought to evaluate the clinical efficacy and safety of a MARS device in a consecutive series of hepatic failure patients.

MATERIALS

Twenty patients with acute liver failure, transplantation failure, or acute on chronic liver failure fulfilled the inclusion criteria of total bilirubin > or =10 mg/dL and at least one of the following: hepatic encephalopathy (HE) > or =II grade, hepatorenal syndrome (HRS) for chronic patients or total bilirubin > or =5 mg/dL and HE > or =I grade for acute patients.

RESULTS

MARS was able to reduce cholestatic parameters and improve neurologic status and renal function parameters in all treated patients. We also observed an improvement in the 3-month survival rate compared to the expected outcome in patients with MELD scores between 20 and 29, as well as 30 and 39.

CONCLUSIONS

Based on these results, we confirm the safety and clinical efficacy of MARS treatment, with the best results in patients with MELD score of 20 to 29. Further studies are necessary to confirm whether this treatment is able to modify patient outcomes and prognosis.

Effect of albumin dialysis on intracranial pressure increase in pigs with acute liver failure: a randomized study

BACKGROUND

Increased intracranial pressure (ICP) worsens the outcome of acute liver failure (ALF). This study investigates the underlying pathophysiological mechanisms and evaluates the therapeutic effect of albumin dialysis in ALF with use of the Molecular Adsorbents Recirculating System without hemofiltration/dialysis (modified, M-MARS).

METHODS

Pigs were randomized into three groups: sham, ALF, and ALF + M-MARS. ALF was induced by hepatic devascularization (time = 0). M-MARS began at time = 2 and ended with the experiment at time = 6. ICP, arterial ammonia, brain water, cerebral blood flow (CBF), and plasma inflammatory markers were measured.

RESULTS

ICP and arterial ammonia increased significantly over 6 hrs in the ALF group, in comparison with the sham group. M-MARS attenuated (did not normalize) the increased ICP in the ALF group, whereas arterial ammonia was unaltered by M-MARS. Brain water in the frontal cortex (grey matter) and in the subcortical white matter at 6 hrs was significantly higher in the ALF group than in the sham group. M-MARS prevented a rise in water content, but only in white matter. CBF and inflammatory mediators remained unchanged in all groups.

CONCLUSION

The initial development of cerebral edema and increased ICP occurs independently of CBF changes in this noninflammatory model of ALF. Factor(s) other than or in addition to hyperammonemia are important, however, and may be more amenable to alteration by albumin dialysis.

[Artificial liver support systems: update on albumin dialysis (MARS)]

Mortality among patients with liver insufficiency continues to be unacceptably high. The prognosis of patients with acute episodes of chronic liver insufficiency is almost as poor as that of patients with acute liver failure. Therefore, systems that support liver function, either until liver transplantation can be performed or until resolution of the situation before acute injury occurs, are essential. Albumin dialysis is a system of artificial liver support that allows detoxification of albumin-related and hydrosoluble substances, thus maintaining the patient's homeostasis. Current clinical experience of this therapy is still limited, although beneficial effects on clinical, laboratory and hemodynamic parameters have been demonstrated. Multicenter, controlled trials to evaluate the effect of this therapy on survival in distinct diseases are needed.

Liver support systems: promise and reality

Effective liver support is needed for a variety of indications. A large number of both biological (containing hepatocytes) and non-biological extracorporeal liver support systems have been described in the literature over the last 50 years. Despite this, there is a paucity of good quality randomized control data examining the effectiveness of these therapies in human liver failure. In this review article, we examine the available data, with particular emphasis on the current front runners, the MARS and HepatAssist systems. Other problems associated with the development of these liver support systems are also discussed. Although promising in animal studies, we conclude that the use of these technologies is not supported currently by a sufficient evidence base to recommend them for routine clinical use and that a lack of understanding about the critical functions required of a liver support system is retarding a more rational approach to the design of these systems.

Impact of pretransplant renal failure: when is listing for kidney-liver indicated?

Renal and hepatic function are often intertwined both through the existence of associated primary organ diseases and hemodynamic interrelationships. This connection occasionally results in the chronic failure of both organs, necessitating the need for combined kidney-liver transplantation. Since 1990, over 1,790 patients in the United States have received such transplants with a patient survival somewhat less than that for patients receiving either organ alone. Patients with renal failure due to acute injury or to the hepatorenal syndrome have classically not been included as candidates for combined transplantation due to the reversibility of the renal dysfunction following liver transplantation. However, the rate and duration of renal failure prior to liver transplantation continues to be prolonged even with the new allocation scheme prioritizing liver transplants to those with renal failure. Thus the issue of when kidney transplantation should be offered and what evaluation is necessary prior to the decision continues to confront the transplant community.

Extracorporal liver support with molecular adsorbents recirculating system in patients with hepatitis B-associated fulminant hepatic failure

Hepatitis B virus (HBV) infection is the most prevalent cause of fulminant hepatic failure (FHF) in the Far East. HBV-associated FHF is characterised by rapidly progressive end organ dysfunction/failure and a very poor prognosis. To investigate how molecular adsorbent recirculating system (MARS) treatment impacts multiple organ system function in HBV-associated FHF. Ten consecutive patients were treated with MARS in a period of 12 months. Clinical, biochemical and haemodynamic parameters were assessed before and after MARS. Various disease severity scoring systems including model for end-stage liver disease, APACHE II, APACHE III, sequential organ failure assessment and organ system failure scores were also assessed. There were significant improvements in hepatic encephalopathy grading (p < 0.001), mean arterial pressure (p < 0.001), plasma renin activity (p = 0.027), bilirubin (p < 0.001), ammonia (p = 0.001) and creatinine levels (p < 0.001). There were also significant improvements in all the scoring systems evaluated. Meanwhile, platelet count was significantly decreased (p < 0.001). One patient was successfully bridged to liver transplantation. Three patients were alive at 3 months of follow-up. MARS can improve multiple organ functions in HBV-associated FHF. On the basis of these findings, randomised controlled studies are indicated and justified.

The effect of molecular adsorbent recirculating system on pathophysiological parameters in patients with acute liver failure

OBJECTIVE

To investigate the effect of the molecular adsorbent recirculating system (MARS) on physiological variables in patients with acute liver failure.

DESIGN

A prospective, observational study of MARS in addition to standard medical therapy in the management of patients presenting with acute liver failure.

SETTING

A regional liver transplant centre.

PATIENTS

Ten consecutive patients admitted with acute liver failure with a grade III or IV hepatic encephalopathy.

INTERVENTIONS

MARS therapy for 8 h on 2 consecutive days. Standard monitoring included the use of a pulmonary artery catheter and an intracranial pressure monitor.

MEASUREMENTS AND RESULTS

During the first MARS treatment there was a significant increase in systemic vascular resistance index (SVRI) from 1114+/-196 to 1432+/-245 dyne s(-1) cm(-5) m(-2) with a reduction in cardiac index from 5.5+/-0.6 to 4.2+/-0.4 l min(-1) m(-2). The changes were maintained between the start of the first and second sessions but not to the end of second. Significant clearance of urea and creatinine was observed. Intracranial pressure did not change during the treatments. Overall mortality was 70%.

CONCLUSIONS

MARS therapy was well tolerated, with significant increases in vascular tone during the first session. This increase was not sustained over the duration of the study with a return to baseline values by the end of the second session. Based on our experience we cannot recommend the routine use of MARS therapy in acute liver failure outside of a clinical trial.

Improvement of mitochondrial function evaluated by ketoisocaproic acid breath test in patients with HCV infection undergoing albumin dialysis

BACKGROUND AND AIM

Oxidative injury occurs as a direct result of hepatitis C virus (HCV) core protein expression both in vitro and in vivo, and may be due to a direct effect on mitochondria. The ketoisocaproic acid (KICA) breath test is a simple, reliable, and noninvasive test to evaluate hepatic mitochondrial function. Albumin dialysis (MARS) is an effective bridge treatment for patients with acute failure superimposed on chronic liver disease. The aim of our study was to evaluate the improvement of mitochondrial function measured by KICA in patients undergoing MARS for acute-on-chronic HCV liver failure.

MATERIALS AND METHODS

Five patients with HCV chronic infection undergoing MARS treatment for acute decompensation were enrolled. Before and after each MARS treatment, patients underwent blood testing for the main hematochemical parameters as well as for mitochondrial function by the KICA breath test and the arterial ketone bodies ratio (AKBR).

RESULTS

MARS treatment effectively decreased the serum level of total bilirubin, bile acids, urea, and ammonium. Moreover, MARS treatment produced an increase in AKBR and in the cumulative percentage of (13)CO(2) recovered in exhaled air 2 hours after KICA ingestion.

CONCLUSION

Liver mitochondrial function appears to be beneficially affected by MARS treatment.

The decrease in cytokine concentration during albumin dialysis correlates with the prognosis of patients with acute on chronic liver failure

BACKGROUND AND AIM

The clearance of plasma cytokines by means of albumin dialysis (MARS) has been demonstrated in various studies involving patients affected by either acute liver failure (ALF) or acute on chronic liver failure. The aim of the study was to measure the plasma levels of TNF-alpha, IL-6, and IL-1beta in patients with ALF after each MARS treatment to evaluate the relationship between variations in cytokines levels and patient prognosis.

MATERIALS AND METHODS

Ten patients with ALF undergoing several MARS treatments were enrolled (group 1). Blood samples were collected before and after each MARS treatment to measure TNF-alpha, IL-6, and IL-1beta, and other hematochemical parameters. We also enrolled 10 patients with ALF who underwent standard therapy (group 2) as well as a control group of 10 healthy subjects matched for sex and age (group 3).

RESULTS

MARS reduced total bilirubin levels, biliary acids, BUN, ammonia, TNF-alpha, IL-6, and IL-1beta (P < .05). Moreover, the reduction in inflammatory cytokines levels and improved prognosis were related.

CONCLUSIONS

We confirmed the therapeutic efficacy of MARS treatment for ALF, which appeared to be related to removal of toxins and inflammatory cytokines determine that which patients prognosis.

Albumin dialysis reduces portal pressure acutely in patients with severe alcoholic hepatitis

BACKGROUND/AIMS

In patients with alcoholic hepatitis (AH), inflammation contributes to the severity of portal hypertension. This study evaluates the acute effects of albumin dialysis, using the Molecular Adsorbents Recirculating System (MARS), on portal pressure in AH.

METHODS

Eleven patients with AH and portal hypertension were treated with MARS (n=8) or haemofiltration (n=3). All patients had associated organ failure manifested by hepatic encephalopathy (Grade 2 or more) or renal failure. Hepatic venous pressure gradient (HVPG) was measured before, during and after the treatment session.

RESULTS

A rapid significant reduction of HVPG was observed by 6 h (falling by > or =20% in 7/8 patients, reaching 12 mmHg in 6/8), which was sustained up to 18 h after stopping dialysis. Similar rapid sustained improvements of systemic haemodynamics were also observed. No changes occurred in three patients receiving haemofiltration alone.

CONCLUSIONS

Albumin dialysis produces clinically significant, acute reduction in portal pressure but the mechanism by which this effect is achieved is not clear. Our results suggest that MARS may be a useful adjunct in management of portal hypertension, particularly in patients with severe AH with associated organ failure.

Preoperative optimization of patients with liver disease

PURPOSE OF REVIEW

Recent papers relevant to the preoperative evaluation and optimization of patients with severe liver disease will be discussed. The emphasis will be placed on cardiovascular, pulmonary, and renal complications. Other aspects such as preoperative management of hepatitis B and C, other infectious issues, and liver cancer will not be discussed because this rarely involves the anesthesiologist.

RECENT FINDINGS

Dobutamine stress echocardiography has been the cornerstone of cardiac evaluation of liver transplant candidates. Combining liver transplantation with cardiac procedures has been shown to be feasible. While mild hepatopulmonary syndrome is well-tolerated, severe hepatopulmonary syndrome carries a fairly high mortality rate. New treatment modalities of severe portopulmonary hypertension have been introduced, and may have advantages over epoprostenol administration. Hepatic hydrothorax requires similar therapy to ascites [repeated thoracentesis or paracentesis, and transjugular intrahepatic portosystemic shunt (TIPS)], but refractory hydrothorax may require other interventions. Hepatorenal syndrome may improve by increasing renal blood flow through the use of vasoconstrictors (vasopressin, norepinephrine) in combination with albumin administration. Interventional radiologists can now change the flow through an established TIPS. Hepatic encephalopathy may result in some irreversible changes in the brain. It remains difficult to predict whether a patient with acute fulminant failure will recover spontaneously. Support devices that include hepatocytes show early promising results. The coagulation changes in living donors are incompletely understood. Finally, autonomic neuropathy as a complication of severe liver disease results in more hemodynamic instability.

SUMMARY

Recent advances in preoperative evaluation and optimization are presented and discussed.