Is there life in MARS?

[Acute on chronic liver failure]

Acute-on-Chronic Liver Failure (ACLF) is a recently introduced term defined as severe acute deterioration of an established liver disease. This entity usually develops after an acute insult. The main clinical manifestations are hepatorenal syndrome, hepatic encephalopathy and organ failure, with a high risk of death in the short term. The true incidence of ACLF remains difficult to determine due to confusions surrounding the definition of this entity, but seems to be 40% at 5 years in patients with advanced cirrhosis, which translates into 4,000 cases in Europe within this time span. The treatment of choice is liver transplantation. However, due to the shortage of suitable organs and morbidity and mortality in these patients, other options must be used.

Liver support devices

PURPOSE OF REVIEW

Liver support devices are used either as a bridge to liver transplantation or liver recovery in patients with acute or acute-on-chronic liver failure. The review analyzes the recent literature and asks if the current enthusiasm for these devices is justified.

RECENT FINDINGS

Many liver support devices exist and are discussed. Clinical data on artificial devices are rapidly emerging, especially on the molecular adsorbents recirculating system, and fractionated plasma separation and adsorption (Prometheus). While hepatic encephalopathy is improved by the molecular adsorbents recirculating system and probably Prometheus too, neither system has been shown to improve survival. Less clinical data exist for bioartificial support devices. These may use human hepatocytes, such as the extracorporeal liver assist device, although most devices use porcine hepatocytes, such as HepatAssist.

SUMMARY

Enthusiasm in liver support devices is justified as many nonrandomized studies have suggested some biochemical and clinical benefits. The results of several ongoing multicenter randomized controlled trials are anxiously awaited. Meanwhile, because mortality without liver transplantation remains high despite the use of liver support devices, these devices should only be used in the research setting or by experts proficient in their use and as a bridge to liver transplantation rather than liver recovery.

MARS: a futile tool in centres without active liver transplant support

BACKGROUND AND AIM

Studies on Molecular Adsorbent Recycling Systems (MARS) showed inconclusive survival benefits.

PATIENTS AND METHOD

We evaluated the efficacy of MARS for patients with either acute liver failure (ALF) or acute-on-chronic liver failure (AoCLF) at our centre, from February 2002 till April 2006 retrospectively.

RESULTS

Fifty ALF patients underwent median (range) three (1-10) sessions of MARS. Acute exacerbations of chronic hepatitis B (n=26) and drug-induced liver injury (n=12) were the commonest causes. Living donors were available in 6, 2 paediatric patients underwent left lobe and four adults underwent right lobe living donor liver transplant. Among the 44 ALF patients without a suitable living donor, one underwent deceased donor liver transplant and survived, another 19-year-old male with acute exacerbations of chronic hepatitis B recovered without transplant, and the rest died. Twenty-six had AoCLF and underwent four (1-10) MARS sessions. Sepsis (n=16) and upper gastrointestinal bleeding (n=4) were the commonest precipitating factors. None had a suitable living or deceased donor, suitable for transplantation during their hospitalization. Only one of 26 AoCLF patients survived the hospitalization, but the survivor died of sepsis 1 month later.

CONCLUSION

In this non-randomized study, survival after MARS was related to the availability of transplant, and in patients where living or deceased donor transplant was unavailable, MARS was of little benefit. Randomized-controlled trials on MARS((R)) are urgently needed to clarify its clinical utility.

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.

[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.

Intensive Care Complications in Liver and Multivisceral Transplantation

The complications concerning liver and intestinal transplant surgery have relevance for the field of intensive care because they share some characteristics with those following complex long-term surgery. Thus, in this article we shall try to describe complications that are specific to liver and multivisceral transplants. A review of the existing literature on this topic reveals a large number of studies dedicated to early as well as late surgical complications, and immunosuppressive treatment, while there are far fewer contributions describing complications exclusively concerning intensive care. We shall thus attempt to focus on certain aspects where, besides the literature data, we have personal experience. In particular we want to underline the implications of failure in the functional recovery of the graft; alterations in water, electrolyte, and glycemic balance; as well as neurological, respiratory, renal, nutritional, and infective complications.

MARS--does it stand the test of time?

Artificial liver support systems have been tested for decades in the management of liver failure. Generally, after some promising results published as case series, the device either disappears or fails to show significant benefit in controlled trials. Recently, the molecular absorbent recycling systems (MARS) or extracorporeal albumin dialysis (ECAD) technique appears to have broken this trend. Responding to the title one could summarize by saying this technique so far has stood the test of time. Data in support of its use in acute liver failure (ALF) is still scant and difficult to assess. However, in a well known but not very well defined entity of acute on chronic liver failure (AOCLF) the ECAD technique has been shown to improve survival compared to a similar randomized control group receiving standard supportive therapy. This well tolerated liver support system has real potential for widespread application if further well designed multicenter clinical trials continue to support its effectiveness. Its future lies probably in the management of the moribund hospitalized patient on the transplant list awaiting a donor liver.

In vitro comparison of the molecular adsorbent recirculation system (MARS) and single-pass albumin dialysis (SPAD)

The detoxification capacities of single-pass albumin dialysis (SPAD), the molecular adsorbents recirculation system, (MARS) and continuous veno-venous hemodiafiltration (CVVHDF) were compared in vitro. In each experiment 4,100 mL of toxin-loaded human plasma was processed for 6.5 hours. MARS treatment (n = 6) was undertaken in combination with CVVHDF. For SPAD (n = 6) and CVVHDF (n = 6) a high-flux hollow fiber hemodiafilter (identical to the MARS filter) was used. Levels of ammonia, urea, creatinine, bilirubin, and bile acids were determined. Concentrations before and after application of detoxification procedures were expressed as differences and were compared using the Kruskal-Wallis test. Post hoc comparisons for pairs of groups were adjusted according to Bonferroni-Holm. Time, group, and interaction effects were tested using the nonparametric ANOVA model for repeated measurements. SPAD and CVVHDF induced a significantly greater reduction of ammonia levels than MARS. No significant differences were found among SPAD, MARS, and CVVHDF with respect to other water-soluble substances. SPAD induced a significantly greater reduction in bilirubin levels than MARS. Reductions in bile acid levels were similar for SPAD and MARS. When operating MARS in continuous veno-venous hemodialysis mode, as recommended by the manufacturer, no significant differences in the removal of bilirubin, bile acids, urea, and creatinine were found. However, MARS in continuous veno-venous hemodialysis mode was significantly less efficient in removing ammonia than MARS in CVVHDF mode. In conclusion, the detoxification capacity of SPAD is similar to or even greater than that of MARS.

Cholestatic syndromes

Further insights into the cellular and molecular mechanisms underlying hepatobiliary transport function and its regulation now permit a better understanding of the pathogenesis and treatment options of cholestatic liver diseases. Identification of the molecular basis of hereditary cholestatic syndromes will result in an improved diagnosis and management of these conditions. New insights into the pathogenesis of extrahepatic manifestations of cholestasis (eg, pruritus) have facilitated new treatment strategies. Important new studies have been published about the pathogenesis, clinical features, diagnosis, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, drug-induced cholestasis, and viral cholestatic syndromes.