Hepatic and systemic haemodynamic changes after MARS in patients with acute on chronic liver failure

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.

THIS ARTICLE HAS BEEN RETRACTED: An Australian Experience With the Molecular Adsorbents Recirculating System (MARS)

The molecular adsorbents recirculating system (MARS) is a form of artificial extracorporeal liver support which has the potential to remove substantial quantities of albumin-bound toxins postulated to contribute to the pathogenesis of liver cell damage, hemodynamic instability and multi-organ failure in patients with acute liver failure and acute-on-chronic liver failure (AoCLF). We assessed the efficacy of MARS therapy in a cohort of patients with severe liver damage unresponsive to intensive medical therapy. MARS therapy was instituted late in the clinical course of six patients with severely impaired liver function refractory to intensive medical therapy, including four with AoCLF precipitated by sepsis and two with liver dysfunction due to sepsis in the absence of pre-existing chronic liver disease. Outcome measures included markers of hemodynamic stability, renal function, serum bilirubin and bile acid levels, arterial ammonia levels, the arterial ketone body (acetoacetate/beta-hydroxybutyrate) ratio, hepatic encephalopathy grade and the plasma disappearance rate of indocyanine green. The rates of discharge from the intensive care unit and in-hospital mortality were determined. Our findings suggest that MARS treatment might be associated with some clinical efficacy even in patients with advanced multi-organ dysfunction occurring in the setting of severe liver damage and in whom treatment is instituted late in the clinical course. However, the overall survival rate (1/6; 17%) was poor. More data obtained from larger cohorts of patients enrolled in randomized controlled studies will be required in order to identify categories of liver failure patients who might benefit most from MARS treatment and to ascertain the most appropriate timing of intervention.

[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.

Preconditioning by extracorporeal liver support (MARS) of patients with cirrhosis and severe liver failure evaluated for living donor liver transplantation -- a pilot study

PURPOSE

The aim of this prospective study was to evaluate the effectiveness of preconditioning molecular adsorbent recirculating system (MARS) treatment on patients with acute-on-chronic liver failure (AoCLF), who were awaiting living donor liver transplantation (LDLT).

PATIENTS AND METHODS

Between January and December 2001, 10 consecutive AoCLF patients (with progressive hyperbilirubinemia (>20 mg/dl) and hepatic encephalopathy grade > or =2) were studied. MARS was used in eight of these patients who were evaluated for LDLT during 2001. Three AoCLF patients who received LDLT before clinical use of MARS were used as historical controls.

RESULTS

Because of a shortage of donors, only five out of 10 patients considered for LDLT could receive transplants. Three patients were treated with MARS for 8 h the day before receiving LDLT, and all three survived. The remaining two patients who received transplants, and who were not pretreated with MARS, died from sepsis and multi-organ failure within 2 weeks. Four of the patients who did not receive transplants because of donor shortage died despite 1 or 3 MARS treatments, however bilirubin levels and grade of encephalopathy were significantly reduced in these patients.

CONCLUSIONS

Results of this small pilot study suggest that MARS, by reducing the severity of jaundice and encephalopathy, might be effective as a bridging option in AoCLF patients awaiting LDLT.

[MARS (Molecular Adsorbents Recirculating System). New technique of extracorporeal depuration in liver failure]

MARS (Molecular Adsorbent Recirculating System) is a new technique as a system of liver detoxification in patients with severe acute or acute on chronic hepatic failure. Also, it has shown its usefulness in the control of resistant pruritus in the primary biliary cirrhosis. Due to the fact that this technique is often delivered in Intensive Care Units (ICUs), we have reviewed the literature 1999 until now to describe this technique, its benefits and its mains complications. The technique was developed in Germany, where in 1999 was first used in clinical practice. It was used for the first time in Spain in 2000 and in the Clínica Universitaria of Navarra in July of 2001. Despite the short clinical experience using MARS its obvious beneficial effects such as decrease of hepatic toxins and the improvement of encephalopathy and hemodynamic situation, makes it a very useful technique in these patients. MARS has been shown to be a safe procedure, well tolerated by patients and accessible to the use by specialised nurses. Despite the encouraging clinical results, its used is still limited. Moreover its high cost precludes it widespread use and requires further studies.

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.

Therapie des Organversagens bei prim�r extrakardialen Erkrankungen

There are a number of primary extracardiac circulatory disorders leading to organ dysfunction, multi-organ dysfunction syndrome and finally to multi-organ-failure. The origin of this hemodynamic disturbances are potentially different forms of circulatory shock (septic, hypovolemic, anaphylactic or neurogenic shock) and the systemic inflammatory reaction syndrome (SIRS). The primary aim of therapy is the removal of the underlying causes and the restoration of adequate tissue perfusion by using fluids, vasopressors and inotropics. The supportive treatment of the individual organ dysfunction is - at present - unequally efficient.

Value of albumin dialysis therapy in severe liver insufficiency

A blood purification system, molecular adsorbents re-circulating system (MARS), is based on the removal of both protein-bound and water-soluble substances and toxins in the liver. We treated a total of 88 patients within 2 years. Of these patients, 45 had acute liver failure (ALF), 31 had acute decompensation of chronic liver disease, eight had graft failure and four had miscellaneous conditions. Of the patients with ALF, 80% survived; in 23 patients their own liver recovered and 13 patients underwent successful transplantation. Only 23% of patients with acute-on-chronic liver failure survived. Most of them were not considered for transplantation due to their having liver failure from alcoholism and from not abstaining from drinking. MARS is a promising therapy for ALF, allowing the patient's own liver to recover or allowing enough time to find a liver graft. Best results were achieved in patients who had been intoxicated with a lethal dose of toxin. On the other hand, we did not observe much benefit in patients with severe acute-on-chronic liver failure (AcoChr) who did not undergo liver transplantation.

Extracorporeal albumin dialysis

Previous studies reported that dialysis with albumin dialysate (AD) was effective in removing albumin-binding toxins (ABT), and the Molecular Adsorption Recycling System (MARS) and Continuous Albumin Purification System (CAPS) have been developed. These blood purification therapies were categorized into the concept of extracorporeal albumin dialysis (ECAD). ECAD is defined as extracorporeal therapies using AD for the removal of not only water-soluble but also ABT. It was reported that symmetric as well as asymmetric membrane dialyzers had the effect of the removal of bilirubin by AD. The larger pore size membrane can remove more bilirubin. In the greater albumin concentration in AD, the removal capacity for bilirubin by AD increased. Bilirubin in AD could be removed by a charcoal and a bilirubin adsorption column, and its concentration in AD remained approximately constant. In clinical performance of CAPS, cellulose triacetate membrane, 5% AD, bilirubin adsorber columns, and charcoal adsorber columns were used. This system was applied continuously for 24 h for treatment. CAPS could control not only renal but also liver function during the 24 h, without any adverse effect. MARS removes many toxic substances including ABT, and has beneficial effect on brain, liver, renal, and cardiovascular functions, and improvement of 30-day survival were reported. ECAD may become a possible therapeutic tool in patients with the disease state of ABT accumulation as an artificial kidney and liver. However, several attempts such as the application of recombinant human albumin and acetate free dialysate, should be required.

Equipment review: the molecular adsorbents recirculating system (MARS)

The molecular adsorbents recirculating system (MARS^®) is a form of artificial liver support that has the potential to remove substantial quantities of albumin-bound toxins that have been postulated to contribute to the pathogenesis of liver cell damage, haemodynamic instability and multi-organ failure in patients with acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF). These toxins include fatty acids, bile acids, tryptophan, bilirubin, aromatic amino acids and nitric oxide. Data from controlled clinical trials are limited so far. One of two studies performed on small numbers of patients with AoCLF suggest a survival benefit, but no controlled data are available in the ALF setting. Our preliminary experience with MARS therapy, instituted late in the clinical course of five patients with severely impaired liver function, including three with AoCLF precipitated by sepsis and two with liver dysfunction due to sepsis in the absence of pre-existing chronic liver disease, indicates some clinical efficacy. However, the overall survival rate (1 of 5; 20%) remained poor. More data obtained from larger cohorts of patients enrolled in randomised controlled studies will be required in both the AoCLF and ALF settings to identify categories of liver failure patients who might benefit most from MARS treatment, to ascertain the most appropriate timing of intervention and to determine the overall impact on outcome, including cost-effectiveness.