Binding of bilirubin and bromosulphthalein to albumin: implications for understanding the pathophysiology of liver failure and its management

Bilirubin adsorption versus plasma exchange for hyperbilirubinemia in patients after cardiac surgery: a retrospective study

Objective

Hyperbilirubinemia after cardiac surgery increases in-hospital mortality and is associated with poor prognosis. Our present study aimed to compare the efficacy of bilirubin adsorption (BA) and plasma exchange (PEX) in patients with hyperbilirubinemia after cardiac surgery.

Methods

We retrospectively included patients who underwent BA treatment or PEX treatment due to severe hyperbilirubinemia after cardiac surgery at our center from 2015 to 2020. We collected results from urine and liver function tests before and after treatment and compared the in-hospital mortality and morbidity between the two treatment groups.

Results

A total of 56 patients were enrolled in this study: 14 patients received BA treatment, and 42 patients received PEX treatment. Compared to the PEX group, the BA group exhibited a statistically significant reduction in total bilirubin (p = 0.016) and direct bilirubin (p = 0.036) levels. The in-hospital mortality was 85.7% (48/56) in the whole group, and the BA group had a lower mortality than the PEX group (71.4% vs. 90.5%, p = 0.078). The BA group showed better circulatory support, including lower risks of IABP (21.4% vs. 52.4%, p = 0.044), ECMO (21.4% vs. 50.0%, p = 0.061), reintubation (64.3% vs. 40.5%, p = 0.122) and ventricular arrhythmias (64.3% vs. 45.2%, p = 0.217). The in-hospital mortality was still lower in the BA treatment group than in the PEX treatment group (71.4% vs. 100%, p = 0.049) in the matched cohort.

Conclusions

Compared to PEX treatment, BA treatment had a higher bilirubin removal ability in patients with hyperbilirubinemia and could reduce the mortality and risks of poor clinical outcomes. BA treatment should be considered an effective treatment method for patients with higher total bilirubin or direct bilirubin levels.

Transplant Hepatectomy With Portacaval Shunt and MARS Therapy for Perioperative Catastrophe: A Series of Four Liver Transplant Cases

Increased worldwide focus on maximal donor utilization and transplantation of patients once considered too ill to survive liver transplantation may increase the otherwise rare frequency of catastrophic graft failure. Although the deleterious effects of an acutely failing allograft have been established for decades, the optimal strategy in this patient population in the perioperative period remains ill-defined.

Extracorporeal Mass Exchange Technology Platform for Temporary Liver Support: A Clinical Feasibility Study on a Device and the Cell Source Primary Human Liver Cells

Clinical feasibility phase-I study data are discussed on the use and the safety of a modular mass exchanger for temporary extracorporeal treatment of liver failure; and the use of the cell source primary human liver cells isolated from discarded transplant organs as a metabolic module in this mass exchanger. This technology platform can be compared with the mass exchange functions of a human placenta before giving birth. The "maternal blood side" can be used with various sources/modules of metabolic support including artificial (e.g. absorber) or biological elements (e.g. cells), separated by membrane compartments. These keep the source of metabolic support from contact with the patient, including the immune cells, while allowing exchange of soluble or protein-bound plasma components for therapy. Each of the multiple independent membrane compartments are bundled towards the in/outlets but interwoven to form a decentralized multi-compartment mass exchanger within an effector module compartment. The use of liver cells as a metabolic module in this compartment results in its function as a bioreactor. A combination with further modules outside of the mass exchanger was demonstrated through a continuous SPAD for detoxification. Nine patients (5 m, 4 f) with a median age of 43 years (range 11-55 years) were treated with a total of 11 metabolic modules in 12 sessions, with overall treatment times ranging from 11 to 216 hours. Patients suffered from acute-on-chronic liver failure (AoCLF, n=3), acute liver failure (ALF, n=3) and primary non-function graft after liver transplantation (PNF, n=3). Treatment resulted in a one-year survival of 78%. The results showed a significant decrease in thrombocytes and fibrinogen. No severe adverse effects were found. One patient (AoCLF) recovered without transplantation and remained alive for the one-year follow-up. Six patients (3 ALF, 2 PNF, and 1 AoCLF) were successfully bridged to transplantation, and two (1 AoCLF, 1 PNF) died within ten days after termination of therapy. Total and conjugated bilirubin, ammonia, urea and creatinine were significantly reduced by the end of therapy, compared to baseline. The MELD score decreased significantly, whereas no significant improvements were observed in APACHE-II, APACHE-III, SOFA and Child-Pugh scores. Conclusion: The mass exchanger technology platform, the Core Module used with primary human liver cells as Metabolic Module, proved to be clinically feasible and safe. Further clinical studies are required to prove the efficacy of such therapies. However, the clinical impact of using human liver cells as a Metabolic Module is limited and a reliable, biocompatible and effective metabolic source is in need.

Development of liposome as a novel adsorbent for artificial liver support system in liver failure

Artificial liver support systems (ALSS), represented by albumin dialysis, are designed to replace the liver detoxification function and to serve as supportive therapy until liver transplantation or liver regeneration. We introduce liposome, which is majorly formed by soybean lecithin as the adsorbent nanomaterial in dialysate for the removal of protein-bound and liver failure-related solutes. The binding rate was detected by ultrafiltration column. In vitro and in vivo dialysis was performed in a recirculation system. Unconjugated bilirubin (52.83-99.87%) and bile salts (50.54-94.75%) were bound by liposomes (5-80 g/L) in a dose-response relationship. The in vitro haemodialysis model showed that the concentration of unconjugated bilirubin (45.64 ± 0.90 μmol/L vs. 54.47 ± 3.48 μmol/L, p < 0.05) and bile salts (153.75 ± 7.72 μmol/L vs. 180.72 ± 7.95 μmol/L, p < 0.05) were significantly decreased in the liposome dialysis group than in the phosphate buffer saline group. The in vivo haemodialysis model showed that 40 g/L liposome-containing dialysate led to a significant higher reduction ratio in total bilirubin (6.56 ± 5.72% vs. -1.86 ± 5.99%, p < 0.05) and more total bile acids (7.63 ± 5.27 μmol vs. 2.13 ± 2.32 μmol, p < 0.05) extracted in the dialysate in comparison with the conventional dialysate. In conclusion, the liposome-added dialysate proved to impose good extraction effects on the unconjugated bilirubin and bile salts. These findings indicate that conventional dialysate supported by this nanomaterial can markedly improve the removal of protein-bound and liver failure-related solutes, thus suggesting a novel and promising liver dialysis system.

Safety and effectiveness of midazolam for cirrhotic patients undergoing endoscopic variceal ligation

BACKGROUND/AIMS

Endoscopic variceal ligation (EVL) is an established treatment for esophageal variceal bleeding. Midazolam (MDZ) is most commonly used for sedation during endoscopic procedures. However, adverse events (AEs) may occur more frequently in patients with cirrhosis due to altered MDZ metabolism.

MATERIALS AND METHODS

We retrospectively reviewed the records of 325 patients with cirrhosis who received EVL.

RESULTS

No significant differences were found in treatment outcome and procedure time among 151 patients in the MDZ group and 169 patients in the non-MDZ group. Desaturation (23.2% vs. 7.7%, p<0.01), bradycardia (22.5% vs. 17.2%, p=0.03), and hepatic encephalopathy (HE) (6.6% vs. 0.6%, p<0.01) were more common in the MDZ group than in the non-MDZ group. Logistic regression analyses revealed that an Eastern Cooperative Oncology Group (ECOG) score of ≥2 (p<0.01) and the use of MDZ (p<0.01) were associated with the development of overall AEs. An ECOG score of ≥2 (p=0.01), high serum creatinine level (p=0.02), and the use of MDZ (p<0.01) were significant risk factors for HE.

CONCLUSION

Extreme caution should be taken when sedating patients with cirrhosis receiving EVL due to the AEs associated with the use of MDZ.

Significant Decrease in Dialysate Albumin Concentration during Molecular Adsorbent Recirculating System (M.A.R.S.) Therapy

Aim

The molecular adsorbent recirculating system (M.A.R.S.) is widely used as liver support therapy in patients with hepatic dysfunction. The goal of this study was to measure changes in dialysate albumin and bilirubin concentrations during clinical MARS treatments.

Methods

Eight patients with acute liver dysfunction and hyperbilirubinemia were enrolled in this study. Five of them received a total of 10 treatments with MARS, in which 600 mL of 20% human albumin was used as dialysate, continuously regenerated by two adsorbent columns in the circuit. Three patients received 4 treatments of a modified MARS, in which the two adsorbent columns were bypassed in the first course for 4 h, and then connected to the circuit in the second course for another 4 h. The total, conjugated and unconjugated bilirubin (TB, CB, UCB) and albumin concentrations in serum and albumin dialysate were dynamically measured, and the adsorbent column inlet pressures were recorded during each session. In one session, dialysate albumin levels were measured during the priming process, at the time points prior to the priming process, immediately after priming, and at the end of the treatment.

Results

During MARS therapies, the reduction ratio of serum TB, CB and UCB was 26.6±9.0%, 29.5±9.6% and 14.8±12.3%, respectively. The molar ratio of TB/albumin in serum was approximately 20-fold higher than dialysate at all time points. A significant albumin concentration decrease from baseline in the dialysate was found (mean±SD, 34.6±16.6%). For the first four hours of modified treatments, in which only albumin dialysis without albumin regeneration by adsorbent columns was performed, the dialysate albumin decrease was substantially smaller (mean, 8.3±1.5%). After switching to standard MARS, there was a further decrease in the dialysate albumin concentration of 35.1±14.5%. In one session, dialysate albumin concentrations were measured during the priming process, and levels decreased from 196.9 g/L to 144.4 g/L. Adsorber inlet pressure increased from 40±10mmHg at the start of priming to 150±50mmHg at the end of priming, and further increased to 340±100mmHg at the end of treatment.

Conclusion

There is a significant reduction in dialysate albumin concentration during MARS therapy. Binding of albumin to the adsorbent columns used for albumin regeneration is largely responsible for this decrease.

A comparison among three different apheretic techniques for treatment of hyperbilirubinemia

Liver failure is associated to high mortality due to the accumulation of protein-bound metabolites, such as bilirubin, not removed by conventional hemodialysis. Different methods can efficiently remove them, such as the molecular adsorbent recirculating system (MARS), plasma exchange (PEX), and bilirubin or plasma adsorption perfusion (PAP). No direct comparison exists between MARS, PEX and PAP, and current guidelines do not specify which method (and when) to use. We have retrospectively evaluated MARS, PEX and PAP in their effectiveness in lowering plasma bilirubin concentration, and their effects on liver and kidney function. A total of 98 patients have been recruited, which comprised 68 patients treated with PAP (177 sessions), 16 patients with PEX (41 sessions) and 11 patients with MARS (21 sessions). Bilirubin, creatinine, liver enzymes were analyzed before and after the first treatment with each technique. The three methods did not differ for bilirubin lowering efficiency, with MARS showing only slightly less effective reductions. Finally, the three techniques did not differ in the amount of change of cholinesterase, but a lower reduction in AST was found using PAP. Our retrospective observation is one of the largest case series of hepatic failure treated with bilirubin absorption. The choice of the technique cannot be based on the desired reduction in bilirubin concentration. Based on costs and duration of treatment, we suggest that PAP could be considered as a first-line approach. In case of kidney involvement, MARS remains a valuable option.

Albumin infusion improves renal blood flow autoregulation in patients with acute decompensation of cirrhosis and acute kidney injury

BACKGROUND & AIMS

In cirrhotic patients with renal failure, renal blood flow autoregulation curve is shifted to the right, which is consequent upon sympathetic nervous system activation and endothelial dysfunction. Albumin infusion improves renal function in cirrhosis by mechanisms that are incompletely understood. We aimed to determine the effect of albumin infusion on systemic haemodynamics, renal blood flow, renal function and endothelial function in patients with acute decompensation of cirrhosis and acute kidney injury.

METHODS

Twelve patients with refractory ascites and 10 patients with acute decompensation of cirrhosis and acute kidney injury were studied. Both groups were treated with intravenous albumin infusion, 40-60 g/days over 3-4 days. Cardiac and renal haemodynamics were measured. Endothelial activation/dysfunction was assessed using von Willebrand factor and serum nitrite levels. F2α Isoprostanes, resting neutrophil burst and noradrenaline levels were quantified as markers of oxidative stress, endotoxemia and sympathetic activation respectively.

RESULTS

Albumin infusion leads to a shift in the renal blood flow autoregulation curve towards normalization, which resulted in a significant increase in renal blood flow. Accordingly, improvement of renal function was observed. In parallel, a significant decrease in sympathetic activation, inflammation/oxidative stress and endothelial activation/dysfunction was documented. Improvement of renal blood flow correlated with improvement in endothelial activation (r = 0.741, P < 0.001).

CONCLUSIONS

The data suggest that albumin infusion improves renal function in acutely decompensated cirrhotic patients with acute kidney injury by impacting on renal blood flow autoregulation. This is possibly achieved through endothelial stabilization and a reduction in the sympathetic tone, endotoxemia and oxidative stress.

Safety of propofol in cirrhotic patients undergoing colonoscopy and endoscopic retrograde cholangiography: results of a prospective controlled study

BACKGROUND AND AIMS

Safety of propofol sedation in patients with liver cirrhosis undergoing colonoscopy or endoscopic retrograde cholangiopancreatography (ERCP) remains to be studied. The aim of this study was to investigate whether the use of propofol is safe for endoscopic procedures more complex than gastroscopy in patients with liver cirrhosis in a prospective controlled study.

METHODS

Two hundred and fourteen consecutive patients, with or without cirrhosis, who underwent colonoscopy or ERCP with propofol sedation were recruited between January and June 2009. Administration of sedation was performed by anesthesiologists and outcome measures were recorded. Main outcomes were complication rates and recovery times.

RESULTS

Sixty-one (28.5%) cirrhotic patients and 153 (71.5%) noncirrhotic patients were included. The incidence of sedation-related complications did not significantly differ between the two populations (11.5 vs. 17.0%, respectively, P=0.31). The mean (±SD) dose of propofol administered (213±86 vs. 239±100 mg, P=0.07), the mean time to achieve adequate sedation (3.3±1.1 vs. 3.0±1.2 min, P=0.21), the mean total duration of the endoscopic procedure (24.5±10.6 vs. 27.4±11.8 min, P=0.08), the mean time to reach Observer's Assessment of Alertness and Sedation Scale 5 (17.2±4.4 vs. 18.4±5.6 min, P=0.15), the mean time from completion of the procedure to release (9.0±2.5 vs. 9.1±3.2 min, P=0.86), and the mean time to full recovery (42.2±7.3 vs. 42.3±7.8 min, P=0.88) were very similar between the two groups. The limitation of this study was lack of randomization, and a control group of cirrhotic patients using standard sedation with benzodiazepines and opioids.

CONCLUSION

Propofol deep sedation administered by an anesthesiologist with appropriate monitorings seems to be a safe procedure during colonoscopy or ERCP in cirrhotic patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

OBJECTIVE

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

DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENTS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Sub-clinical hepatic encephalopathy in cirrhotic patients is not aggravated by sedation with propofol compared to midazolam: a randomized controlled study

BACKGROUND & AIMS

The risk of exacerbating sub-clinical hepatic encephalopathy (HE) by propofol has not been established. The aim of this study is to determine whether the use of propofol, for upper endoscopy in patients with cirrhosis, precipitates sub-clinical HE.

METHODS

Sixty-one patients with compensated HCV and HBV cirrhosis (CP score 5-6) were randomly selected and divided into two groups (intent-to-treat population) matched for age, gender, and BMI. The first group received a single propofol sedation (N = 31, age 57 ± 12, dose range 70-100 mg/procedure) and the second group (N = 30, age 56 ± 12, dose 3-6 mg/procedure) received a single midazolam sedation, all done by an anesthesiologist. All patients completed number connection test (NCT), cognitive function score, time to recovery, time to discharge sheets, and hemodynamic parameters before sedation, and at discharge from the endoscopy unit, 1h post-procedure. Thirty control subjects without cirrhosis were matched to the cirrhotic patients who received sedation with regard to age, gender, BMI, and education level.

RESULTS

A total of 58/61 cirrhotic patients (95%) had sub-clinical encephalopathy before the endoscopy (mean NCT 84.7 ± 77 s, normal < 30 s). No patient developed overt HE after sedation. There were no differences between groups in the incidence of adverse effects, cognitive function, MELD score, CP score, oxygen saturation, or respiratory and heart rates before and after sedation. Propofol did not exacerbate minimal HE when compared to midazolam (NCT changed from 87.5 ± 62 s prior to sedation to 74.2 ± 58 s after sedation in the propofol group versus 72.8 ± 62 s before to 85.6 ± 72 s after sedation in the midazolam group; p < 0.01). Time to recovery (4.1 ± 1.9 min vs. 11.5 ± 5.0 min, p < 0.001), and time to discharge (38.0 ± 9 min vs. 110 ± 42 min, p < 0.001) were significantly shorter with propofol than midazolam. Pre- and post-procedure NCT (from 25 ± 20 s to 24 ± 20 s), cognitive function score (from 25 to 26), time to recovery (3.5 ± 1.0 min), and time to discharge (35 ± 10 min) did not change in the healthy controls.

CONCLUSIONS

Sedation with propofol has a shorter time recovery and a shorter time to discharge than midazolam and does not exacerbate sub-clinical hepatic encephalopathy in patients with compensated liver cirrhosis.

Nucleosome serum levels in acute hepatic failure and MARS treatment

Serum nucleosomes have been suggested to be markers for cell death and apoptosis. Increased hepatocyte apoptosis can be demonstrated in acute liver failure (ALF) as well as acute-on-chronic liver failure (ACLF). We investigated the relevance of nucleosomes in the setting of acute hepatic failure. Further, we studied the effects of the molecular adsorbent recirculating system (MARS) on this marker of cell death. We measured serum nucleosome concentrations with ELISA in 12 patients with ACLF and 7 patients suffering from ALF, with 14 patients experiencing stable chronic hepatic failure (CHF) as controls. In a subset of 8 ACLF and ALF patients treated with MARS, nucleosomes were determined immediately before and after the first MARS session. Baseline nucleosome serum concentrations were significantly increased in ACLF and ALF patients as compared with CHF patients (P = .0161 and P = .0037, respectively). There was no significant difference between the ALF and ACLF groups. Moreover, serum nucleosome levels did not change significantly during MARS treatment in ALF and ACLF patients. Serum nucleosome levels therefore may be useful to discern acute from chronic hepatic failure or to monitor the course and the severity of the disease. Our results, however, warrant further larger clinical studies regarding the clearance of nucleosome in artificial liver-assist devices and to assess their role in acute hepatic failure.

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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.

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.

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.

Slow continuous ultrafiltration with bound solute dialysis

Bound solute dialysis (BSD), often referred to as "albumin dialysis" (practiced clinically as the molecular adsorbents recirculating system, MARS, or single-pass albumin dialysis, SPAD) or "sorbent dialysis" (practiced clinically as the charcoal-based Biologic-DT), is based upon the thermodynamic principle that the driving force for solute mass transfer across a dialysis membrane is the difference in free solute concentration across the membrane. The clinically relevant practice of slow continuous ultrafiltration (SCUF) for maintenance of patients with liver failure is analyzed in conjunction with BSD. The primary dimensionless operating parameters that describe SCUF-BSD include (1) beta, the dialysate/blood binder concentration ratio; (2) kappa, the dialyzer mass transfer/blood flow rate ratio; (3) alpha, the dialysate/blood flow rate ratio; and, (4) gamma, the ultrafiltration/blood flow rate ratio. Results from mathematical modeling of solute removal during a single pass through a dialyzer and solute removal from a one-compartment model indicate that solute removal is remarkably insensitive to gamma. Solute removal approaches an asymptote (improvement in theoretical clearance over that obtainable with no binder in the dialysate) with increasing beta that is dependent on kappa and independent of alpha. The amount of binder required to approach the asymptote decreases with increasing solute-binder equilibrium constant, i.e., more strongly bound solutes require less binder in the dialysate. The results of experimental observations over a range of blood flow rates, 100 to 180 mL/min, dialysate flow rates, 600 to 2150 mL/h, ultrafiltration rates, 0 to 220 mL/h, and dialysate/blood albumin concentration ratios, beta = 0.01 to 0.04, were independently predicted remarkably well by the one-compartment model (with no adjustable parameters) based on BSD principles.