Successful treatment of refractory cerebral oedema in ecstasy/cocaine-induced fulminant hepatic failure using a new high-efficacy liver detoxification device (FPSA-Prometheus)

Secondary Dysfunction of the Intestinal Barrier in the Pathogenesis of Complications of Acute Poisoning

The last decade has been marked by an exponential increase in the number of publications on the physiological role of the normal human gut microbiota. The idea of a symbiotic relationship between the human organism and normal microbiota of its gastrointestinal tract has been firmly established as an integral part of the current biomedical paradigm. However, the type of this symbiosis varies from mutualism to parasitism and depends on the functional state of the host organism. Damage caused to the organism by external agents can lead to the emergence of conditionally pathogenic properties in the normal gut microbiota, mediated by humoral factors and affecting the outcome of exogenous exposure. Among the substances produced by symbiotic microbiota, there are an indefinite number of compounds with systemic toxicity. Some occur in the intestinal chyme in potentially lethal amounts in the case they enter the bloodstream quickly. The quick entry of potential toxicants is prevented by the intestinal barrier (IB), a set of structural elements separating the intestinal chyme from the blood. Hypothetically, severe damage to the IB caused by exogenous toxicants can trigger a leakage and subsequent systemic redistribution of toxic substances of bacterial origin. Until recently, the impact of such a redistribution on the outcome of acute exogenous poisoning remained outside the view of toxicology. The present review addresses causal relationships between the secondary dysfunction of the IB and complications of acute poisoning. We characterize acute systemic toxicity of such waste products of the normal gut microflora as ammonia and endotoxins, and demonstrate their involvement in the formation of such complications of acute poisoning as shock, sepsis, cerebral insufficiency and secondary lung injuries. The principles of assessing the functional state of the IB and the approaches to its protection in acute poisoning are briefly considered.

High ambient temperature increases the toxicity and lethality of 3,4-methylenedioxymethamphetamine and methcathinone

RATIONALE

Methylenedioxymethamphetamine (MDMA) and methcathinone (MCAT) are abused psychostimulant drugs that produce adverse effects in human users that include hepatotoxicity and death. Recent work has suggested a connection between hepatotoxicity, elevations in plasma ammonia, and brain glutamate function for methamphetamine (METH)-induced neurotoxicity.

OBJECTIVES

These experiments investigated the effect of ambient temperature on the toxicity and lethality produced by MDMA and MCAT in mice, and whether these effects might involve similar mechanisms to those described for METH neurotoxicity.

RESULTS

Under low (room temperature) ambient temperature conditions, MDMA induced hepatotoxicity, elevated plasma ammonia levels, and induced lethality. Under the same conditions, even a very high dose of MCAT produced limited toxic or lethal effects. High ambient temperature conditions potentiated the toxic and lethal effects of both MDMA and MCAT.

CONCLUSION

These studies suggest that hepatotoxicity, plasma ammonia, and brain glutamate function are involved in MDMA-induced lethality, as has been shown for METH neurotoxicity. The toxicity and lethality of both MDMA and MCAT were potentiated by high ambient temperatures. Although an initial mouse study reported that several cathinones were much less toxic than METH or MDMA, the present results suggest that it will be essential to assess the potential dangers posed by these drugs under high ambient temperatures.

S(n)orting Out the Problem: Fever of Unknown Origin and Unexplained Abnormal Transaminases in a Young Male

Cocaine-induced toxicity is seldom described in humans and interesting interactions with other ‘recreational’ drugs are rarely presented, mostly in animal models. We present an interesting and rare case of a young male with a fever of unknown origin and elevated transaminases in whom the cause was found to be secondary to drug-induced liver injury, confirmed on liver histopathology, related to cocaine abuse.

Extracorporeal Liver Support Systems in Paediatric Liver Failure

Extracorporeal liver support systems (ELSS), encompassing artificial and bioartificial devices, have been used for decades, with the aim of supporting patients with acute liver failure and acute-on chronic liver failure, as a bridge to recovery (acute liver failure only) or liver transplantation, in an era of organ donation shortage. Although biochemical efficacy has been consistently demonstrated by these devices, translation into clinical and survival benefits has been unclear, due to study limitations and lack of reliable prognostic scoring in liver failure. Consequently, extracorporeal devices are not widely accepted as routine therapy in adult liver failure. Recent large multicentre trials using artificial liver systems have not revealed beneficial outcomes associated with albumin dialysis but plasma exchange practices have shown some potential. In paediatric liver failure, data on extracorporeal systems is scarce, comprising few reports on albumin dialysis (namely, Molecular Adsorbent Recirculating System; MARS) and plasma exchange. When extrapolating data from adult studies differences in disease presentation, aetiology, prognosis and the suitability, and safety of such devices in children must be considered. The aim of this review is to critically appraise current practices of extracorporeal liver support systems to help determine efficacy in paediatric liver failure.

Developments in extracorporeal therapy for the poisoned patient

The modern use of extracorporeal therapies to treat poisoning and drug overdoses dates back to the early 20th century and has evolved along with their use as treatment for acute kidney injury or as maintenance therapy in advanced kidney disease. As our understanding of drug pharmacokinetics and membrane materials has increased, the technologies of extracorporeal therapy and their applications have become more sophisticated. Despite that, there is little robust evidence to guide clinicians on the optimal use of extracorporeal therapy in treating poisoning beyond case reports and series. New efforts are underway to remedy that: the Extracorporeal Treatments in Poisoning Workgroup (EXTRIP) is an international effort on the part of nephrologists, pharmacists and toxicologists to review the available data and formulate evidence-based guidelines on how to use extracorporeal techniques to treat poisoning and improve patient outcomes. Meanwhile, new techniques and membranes are under development. This review will summarize those key scientific and technologic developments, the efforts to optimize their use and new directions in research.

Effects of fractionated plasma separation and adsorption on survival in patients with acute-on-chronic liver failure

BACKGROUND & AIMS

Fractionated plasma separation and adsorption (FPSA) is an extracorporeal procedure that supports liver function by removing endogenous toxins that cause complications from acute-on-chronic liver failure (AOCLF). We performed a randomized trial to investigate survival of patients with AOCLF treated with FPSA.

METHODS

Patients with AOCLF were randomly assigned to groups given a combination of FPSA and standard medical therapy (SMT) (FPSA group, n = 77) or only SMT (SMT group, n = 68). The Prometheus liver support system was used to provide 8 to 11 rounds of FPSA (minimum of 4 hours each) for 3 weeks. Primary end points were survival probabilities at days 28 and 90, irrespective of liver transplantation.

RESULTS

Baseline clinical parameters and number of transplant patients were similar between study arms. Serum bilirubin level decreased significantly in the FPSA group but not in the SMT group. In an intention-to-treat analysis, the probabilities of survival on day 28 were 66% in the FPSA group and 63% in the SMT group (P = .70); on day 90, they were 47% and 38%, respectively (P = .35). Baseline factors independently associated with poor prognosis were high SOFA score, bleeding, female sex, spontaneous bacterial peritonitis, intermediate increases in serum creatinine concentration, and combination of alcoholic and viral etiology of liver disease. There were no differences between the 2 groups in the incidence of side effects.

CONCLUSIONS

Among all patients with AOCLF, extracorporeal liver support with FPSA does not increase the probability of survival. Further studies are needed to assess whether therapy might be beneficial in specific subsets of patients.

Use of the molecular adsorbent recirculating system (MARS™) for the management of acute poisoning with or without liver failure

INTRODUCTION

There is an increasing interest in recent developments in bioartificial and non-bioartificial devices, so called extracorporeal liver assist devices, which are now used widely not only to increase drug elimination, but also to enhance the removal of endogenous substances in acute liver failure. Most of the non-bioartificial techniques are based on the principle of albumin dialysis. The objective is to remove albumin-bound substances that could play a role in the pathophysiology of acute liver failure by dialysing blood against an albumin-containing solution across a high flux permeable membrane. The most widely used device is the Molecular Adsorbent Recirculating System (MARS™).

METHODS

The relevant English and French literature was identified through Medline using the terms, 'molecular adsorbent recirculating system', 'MARS', 'acute liver failure', 'acute poisoning', 'intoxication'. This search identified 139 papers of which 48 reported on a toxic cause for the use of MARS™. Of these 48 papers, 39 specified the substance (eighteen different substances were identified); two papers reported on the same group of patients. BIOARTIFICIAL AND NON-BIOARTIFICIAL SYSTEMS: Bioartificial systems based on porcine hepatocytes incorporated in the extracorporeal circuit are no longer in use due to the possibility of porcine retroviral transmission to humans. Historically, experience with such devices was limited to a few cases of paracetamol poisoning. In contrast, an abundant literature exists for the non-bioartificial systems based on albumin dialysis. The MARS™ has been used more widely than other techniques, such as the one using fractionated plasma separation and adsorption (Prometheus™). All the extracorporeal liver assist devices are able to some extent to remove biological substances (ammonia, urea, creatinine, bilirubin, bile acids, amino acids, cytokines, vasoactive agents) but the real impact on the patient's clinical course has still to be determined. Improvement in cardiovascular or neurological dysfunction has been shown both in acute liver failure and acute-on-chronic liver failure but no impact on mortality has been reported. ACUTE POISONING WITH LIVER FAILURE: Randomized controlled trials are very limited in number and patients poisoned by paracetamol or Amanita phalloides are usually included for outcome analysis in larger groups of acute liver failure patients. Initial results look promising but should be confirmed. Beyond its effect in liver failure, MARS™ could also enhance the elimination of the drug or toxin responsible for the failure, as is described with paracetamol. ACUTE POISONING WITHOUT LIVER FAILURE: Extracorporeal liver assist devices have also been used to promote elimination of drugs that are highly protein bound. Data in various case reports confirm a high elimination of phenytoin, theophylline and diltiazem. However, definite conclusions on the toxicokinetic or clinical efficacy cannot be drawn.

CONCLUSIONS

Despite the lack of large multicentre randomized trials on the use of MARS™ in patients with acute liver failure, the literature shows clinical and biological benefit from this technique. In drug or toxin-induced acute liver failure, such as paracetamol or mushroom poisoning, MARS™ has been used extensively, confirming in a non-randomized fashion, the positive effect observed in the larger population of acute liver failure patients. Furthermore, as MARS™ has been shown in experimental studies to remove protein-bound substances, it is potentially a promising treatment for patients with acute poisoning from drugs that have high protein-binding capacity and are metabolized by the liver, especially, if they develop liver failure concomitantly.

Artificial extracorporeal liver support therapy in patients with severe liver failure

Severe liver failure is common and carries a high mortality risk in patients with both acute and acute-on-chronic liver failure. The failing liver constitutes a medical emergency, and in many cases liver transplantation is the only definite treatment. Extracorporeal liver support can be employed as a strategy for bridging to transplantation or recovery. This article focuses on options for artificial (nonbiological) extracorporeal treatment: single-pass albumin dialysis, fractionated plasma separation and adsorption (Prometheus(®)) and the molecular adsorbent recirculatory system. Their different principles, potential advantages and indications are discussed. Despite proven biochemical efficacy, there are little data regarding clinical end points. Thus far, molecular adsorbent recirculatory system therapy in acute and acute-on-chronic liver failure showed no survival benefit compared with standard medical therapy. Prometheus therapy showed reduced mortality in subgroups of higher severity of disease compared with standard medical therapy. Nevertheless, the value of extracorporeal liver support remains to be corroborated by further clinical studies that include the optimal timing, mode, intensity and duration of this treatment.

Detoxification as a treatment goal in hepatic failure

Acute liver failure (ALF) is a dramatic clinical syndrome with high mortality because of cerebral oedema (type A hepatic encephalopathy) and multi-organ failure. With intensive care medicine and emergent liver transplantation being the mainstay of treatment, alternatives to transplantation are increasingly needed. Ammonia has been recognised as a major toxin in patients with ALF. It can be effectively removed by haemodialysis, haemofiltration and artificial liver support (a combination of extracorporeal toxin absorption and haemodialysis). Previous studies of extracorporeal detoxification, however, have either not specifically targeted ammonia or were hampered by poor biocompatibility and obsolete pathophysiological assumptions, ultimately failing to improve the prognosis. Moreover, most patients were treated only late after the emergence of advanced HE and multi-organ failure, while detoxification should prevent these complications. Acute-on-chronic liver failure (AOCLF) occurs in the setting of chronic liver disease and has an equally poor prognosis. Here, the goals of extracorporeal blood detoxification are renal support and haemodynamic stabilisation in order to support recompensation. Patients with AOCLF, unfortunately, are at a risk for treatment-related complications including bleeding, thrombocytopenia, hypotension and acute renal failure, making biocompatibility a critical issue. Peritoneal dialysis could possibly emerge as a more biocompatible way of treating refractory hepatorenal syndrome. This article will critically analyse the pathophysiological concepts and goals of extracorporeal detoxification in acute and chronic liver diseases.

Extracorporeal liver support with multipass albumin dialysis or plasmapheresis and filtering systems in acute liver failure

Acute liver failure is a very complex type of disease with a mortality of up to 90%, leading to numerous severe disturbances of the whole organism. Bleeding because of absent synthesis of various coagulation factors and disseminated intravascular coagulation, acute kidney failure, circulatory failure with vasopressor dependence, respiratory failure with adult respiratory distress syndrome, neurological failure up to coma because of hepatic encephalopathy, and a very high risk of infection and sepsis frequently result from the initial state of isolated liver failure. High urgency liver transplantation is a highly efficient therapy if performed in time. However, increasing the rate of spontaneous recovery of the patients' own liver, and reducing the need for liver transplantation is preferable and would further improve the outcome of acute liver failure. Extracorporeal liver support by multipass albumin dialysis or plasmapheresis and filtering systems may offer a possibility to fulfill these aims of therapy. A prospective study in 88 patients with acute liver failure has shown a nonsignificant trend in improvement of survival after acute liver failure by multipass albumin dialysis and filtering. Other retrospective studies have shown benefits in improving hepatic encephalopathy and brain oedema. Further, an increase in the rate of spontaneous recovery of liver function has been described. With regional citrate anticoagulation for multipass albumin dialysis and filtering, the need for systemic anticoagulation - a potentially very harmful measure in these patients - can be eliminated and the rate of filter clotting can extremely effectively be reduced.

Management of toxic ingestions with the use of renal replacement therapy

Although rare, renal replacement therapy (RRT) for the treatment of the metabolic, respiratory and hemodynamic complications of intoxications may be required. Understanding the natural clearance of the medications along with their volume of distribution, protein binding and molecular weight will help in understanding the benefit of commencing RRT. This information will aid in choosing the optimal forms of RRT in an urgent setting. Overdose of common pediatric medications are discussed with suggestions on the type of RRT within this educational review.

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

INTRODUCTION

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Neuroprotective strategies in drug abuse-evoked encephalopathy

Encephalopathy is evidenced as an altered mental state with various neurological symptoms, such as memory and cognitive problems. The type of a substance-evoked encephalopathy will depend on the drug, substance, or combination being abused. The categories into which we could place the various abused substances could be tentatively divided into stimulants, amphetamines, hallucinogens, narcotics, inhalants, anesthetics, anabolic steroids, and antipsychotics/antidepressants. Other factors that may underlie encephalopathy, such as infectious agents, environmental, and other factors have also to be taken into account. Drugs of abuse can be highly toxic to the CNS following acute, but more so in chronic exposure, and can produce significant damage to other organs, such as the heart, lungs, liver, and kidneys. The damage to these organs may be at least partially reversible when drug abuse is stopped but CNS damage from repeated or prolonged abuse is often irreversible. The major pathways for the organ and CNS toxicity could be related to ischemic events as well as increased cell damage due to metabolic or mitochondrial dysfunction resulting in increased excitotoxicity, reduced energy production, and lowered antioxidant potential. These susceptibilities could be strengthened by the use of antioxidants to combat free radicals (e.g., vitamin E, lipoic acid); trying to improve energy generation by using mitochondriotropic/metabolic compounds (e.g., thiamine, coenzyme Q10, carnitine, riboflavin); by reducing excitotoxicity (e.g., glutamate antagonists) and other possible strategies, such as robust gene response, need to be investigated further. The drug-abuse-evoked encephalopathy still needs to be studied further to enable better preventative and protective strategies.

Thermodynamic considerations in solid adsorption of bound solutes for patient support in liver failure

New detoxification modes of treatment for liver failure that use solid adsorbents to remove toxins bound to albumin in the patient bloodstream are entering clinical evaluations, frequently in head-to-head competition. While generally effective in reducing toxin concentration beyond that obtainable by conventional dialysis procedures, the solid adsorbent processes are largely the result of heuristic development. Understanding the principles and limitations inherent in competitive toxin binding, albumin versus solid adsorbent, will enhance the design process and, possibly, improve detoxification performance. An equilibrium thermodynamic analysis is presented for both the molecular adsorbent recirculating system (MARS) and fractionated plasma separation, adsorption, and dialysis system (Prometheus), two advanced systems with distinctly different operating modes but with similar equilibrium limitations. The Prometheus analysis also applies to two newer approaches: sorbent suspension reactor and microsphere-based detoxification system. Primary results from the thermodynamic analysis are that: (i) the solute-albumin binding constant is of minor importance to equilibrium once it exceeds about 10(5) L/mol; (ii) the Prometheus approach requires larger solid adsorbent columns than calculated by adsorbent solute capacity alone; and (iii) the albumin-containing recycle stream in the MARS approach is a major reservoir of removed toxin. A survey of published results indicates that MARS is operating under mass transfer control dictated by solute-albumin equilibrium in the recycle stream, and Prometheus is approaching equilibrium limits under current clinical protocols.

Hot topics in liver intensive care

Liver dysfunction is an independent predictor of mortality among intensive care patients. Avoidance or early restoration of normal liver function should therefore be targeted in all critically ill patients. The present work seeks to provide an overview of the "hottest topics" among liver-related problems in intensive care. The management of increased intracranial pressure in severe hepatic encephalopathy is still not sufficiently documented. The promising results with regard to intracranial pressure control by the molecular adsorbent recycling system (MARS) in animal studies are only partially reproducible in patients. Intracranial pressure monitoring is inconsistently applied in various centers, mainly because of the lack of information about the risk benefit ratio. Further, we still do not know which coagulation management protocol reduces the risk of intracranial bleeding. Type I hepatorenal syndrome is a complication of liver failure that is strongly associated with bad outcomes. Only about the half of the patients will recover from dialysis-dependent hepatorenal syndrome after liver transplantation. The usefulness of combined liver and kidney transplantation has not been sufficiently clarified. Terlipressin together with fluid and albumin substitution appear to be the most promising therapeutic interventions. Extracorporeal liver support systems, such as single-pass albumin dialysis, MARS, and the dialysis- and plasmapheresis-based Prometheus, are still under investigation with regard to effectiveness of toxin elimination, appropriate indications, and number duration of treatments.

Bioartificial liver systems: why, what, whither?

Acute liver disease is a life-threatening condition for which liver transplantation is the only recognized effective therapy. While etiology varies considerably, the clinical course of acute liver failure is common among the etiologies: encephalopathy progressing toward coma and multiple organ failure. Detoxification processes, such as molecular adsorbent recirculating system (MARS®) and Prometheus, have had limited success in altering blood chemistries positively in clinical evaluations, but have not been shown to be clinically effective with regard to patient survival or other clinical outcomes in any Phase III prospective, randomized trial. Bioartificial liver systems, which use liver cells (hepatocytes) to provide metabolic support as well as detoxification, have shown promising results in early clinical evaluations, but again have not demonstrated clinical significance in any Phase III prospective, randomized trial. Cell transplantation therapy has had limited success but is not practicable for wide use owing to a lack of cells (whole-organ transplantation has priority). New approaches in regenerative medicine for treatment of liver disease need to be directed toward providing a functional cell source, expandable in large quantities, for use in various applications. To this end, a novel bioreactor design is described that closely mimics the native liver cell environment and is easily scaled from microscopic (<1 ml cells) to clinical (∼600 ml cells) size, while maintaining the same local cell environment throughout the bioreactor. The bioreactor is used for study of primary liver cell isolates, liver-derived cell lines and stem/progenitor cells.

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.

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

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

Radiology of Recreational Drug Abuse

Recreational drug abuse is increasing throughout the world. Use of these drugs may result in a diverse array of acute and chronic complications involving almost any body organ, and imaging frequently plays a vital role in detection and characterization of such complications. The nature of the complications depends to a large extent on the drug used, the method of administration, and the impurities associated with the drug. Radiologically demonstrable sequelae may be seen after use of opiates, cocaine, amphetamines and their derivatives such as 3,4-methylenedioxymethamphetamine ("ecstasy"), marijuana, and inhaled volatile agents including amyl nitrite ("poppers") and industrial solvents such as toluene. Cardiovascular complications include myocardial infarction, cardiomyopathy, arterial dissection, false and mycotic aneurysms, venous thromboembolic disease, and septic thrombophlebitis. Respiratory complications may involve the upper airways, lung parenchyma, pulmonary vasculature, and pleural space. Neurologic complications are most commonly due to the cerebrovascular effects of illicit drugs. Musculoskeletal complications are dominated by soft-tissue, bone, and joint infections caused by intravenous drug use. Awareness of the imaging features of recreational drug abuse is important for the radiologist because the underlying cause may not be known at presentation and because complications affecting different body systems may coexist. Intravenous drug abuse in particular should be regarded as a multisystem disease with vascular and infective complications affecting many parts of the body, often synchronously. Discovery of one complication should prompt the radiologist to search for coexisting pathologic conditions, which may alter management.

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.

How can liver toxins be removed? Filtration and adsorption with the Prometheus system

The application of extracorporeal blood circuits in liver failure therapy has its roots in the two functions of the liver, first as a detoxifying and second as a synthetizing organ. In contrast to hydrophilic uremic toxins, most liver toxins are hydrophobic and bind preferentially to blood proteins. Consequently, the majority of these compounds cannot be removed by hemodialysis or similar dialytic procedures. Current systems use albumin as a transport vehicle for hydrophobic compounds across high flux membranes (e.g. albumin-dialysis, molecular adsorbent recirculating system (MARS)). In contrast to these devices, the Prometheus system (Fresenius Medical Care, Bad Homburg, Germany) applies filtration across highly permeable membranes with a molecular weight cut-off of >300.000. These membranes facilitate a direct filtration of most of the toxin-bearing proteins. In a secondary circuit these toxins are then removed by adsorber beads assembled in specially designed cartridges. The protein-containing toxin-free solution returns to the primary circuit. Clinical testing of the Prometheus system's safety and efficacy parameters showed that cell counts and coagulation factors were not significantly affected. Total bilirubin-, bile acid- and plasma ammonia-levels were reduced in vivo by -21%, -43% and -40%, respectively. First successful therapeutic results have been obtained for patients treated for drug abuse and for patients waiting for transplantation. Thus, a combination of plasma fractionation with highly permeable membranes followed by a secondary circuit with adsorber cartridges proves to be the most effective method of removing toxic waste in liver failure. Further investigations will follow in order to extend the application of the Prometheus system to larger cohorts of patients.

Review article: clinical experience with Prometheus

Prometheus is a new extracorporeal liver support device which facilitates the combined removal of both albumin-bound and water-soluble toxins based upon the method of fractionated plasma separation and adsorption (FPSA). The pilot trial included 11 patients with acute-on-chronic liver failure and concomitant renal failure. Prometheus therapy was found to be safe except for a reversible decrease of blood pressure. In three patients, clotting of the secondary system occurred. Prometheus treatment significantly improved blood levels of protein-bound (conjugated bilirubin, bile acids, ammonia) and water-soluble (creatinine, urea) substances. Thus, Prometheus might be a new therapeutic option in patients with severe hepatorenal syndrome. Furthermore, there is some preliminary experience with Prometheus in the treatment of refractory cholestatic pruritus and in successful bridging to liver transplantation. In order to compare extraction capacities of Prometheus and the molecular adsorbent recirculating system (MARS), five patients were crossover-treated with both systems. Prometheus resulted in significantly higher reduction ratios of bilirubin, ammonia and urea. Another study closely monitored whether the device causes an unselective removal. Neither important cytokines nor coagulation factors were found to be removed. In conclusion, Prometheus seems to be a new therapeutic option in artificial liver support. A significant improvement of the biochemical milieu was already observed after two treatments. The potential to remove protein-bound and water-soluble substances has been shown without signs of a significant unselective removal.

The use Prometheus FPSA system in the treatment of acute liver failure: preliminary results

The preliminary outcomes of patients with acute liver failure treated with the Prometheus Fractionated Plasma Separation and Absorption (FPSA) system are presented herein.

PATIENTS AND METHODS

The procedures were performed in 13 patients (4, intoxication by Amanita phalloides; 4, unknown reason; 3, acetaminophen intoxication; 1, Wilson disease, and 1, liver insufficiency after hemihepatectomy owing to metastases of colon adenocarcinoma). The patients were qualified for the procedure according to the King's College Hospital criteria. The patients' general status was assessed on basic of GCS, UNOS, and the 4-grade encephalopathy classifications. The procedures were performed with the Prometheus 4008H Fresenius Medical Care unit.

RESULTS

The 29 procedures were of mean duration 6.5 hours. There were statistically significant reductions in total bilirubin, ammonia, and aminotransferase levels. In addition, the procedures corrected water, mineral, and carbohydrate disorders. One patient did not require liver transplantation. Seven patients received liver transplants: three patients with positive outcomes; two died due to septicemia within 30 days perioperatively, one died at 6 months after OLT owing to respiratory failure; and one, owing to hemorrhagic diathesis. Four patients did not receive a liver transplant because of lack of a organ, no consent for the surgery, or neoplastic disease with metastases.

CONCLUSIONS

The Prometheus FPSA-System was an effective detoxication method for patients with acute liver failure. The system was useful as a symptomatic treatment before liver transplantation allowing a longer wait for a graft.

Bridging to transplantation in acute liver failure in a 7-month-old infant

BACKGROUND

Acute liver failure (ALF) in children is a rare but often fatal event. At present, liver transplantation is the only successful therapy in most cases. In the face of deteriorating hepatic encephalopathy in these children, some bridging therapy using artificial detoxification can be necessary to enable successful transplantation. In adults, albumin dialysis using the molecular absorbent recycling system (MARS) has been described as effective for bridging to liver transplantation.

CASE REPORT

A previously healthy 7-month-old infant was admitted with ALF due to autoimmune hepatitis. King's College criteria for children with ALF indicated the need for transplantation (bilirubin 13.7 mg/dl, leukocytes 18,980/mm3, INR 5.83, age<2 years). Despite moderate hyperammonemia (75 microm/l) along with the development of pneumonia, the child deteriorated hemodynamically and neurologically, showing grade III encephalopathy proven by EEG. Albumin dialysis using MARS was used to bridge 36 hours to successful living-donor split-liver transplantation, and resulted in improvements in EEG, plasma levels of amino acids and hemodynamics. Twenty-four months after transplantation the child shows normal liver function and normal neuropsychological development. The explanted liver showed 80 % tissue destruction from autoimmune hepatitis.

CONCLUSION

Albumin dialysis as described can be used successfully in infants < 1 year old for bridging to liver transplantation in cases of acute hepatic failure with deteriorating encephalopathy.

Sorbent Suspensions vs. Sorbent Columns for Extracorporeal Detoxification in Hepatic Failure

Hepatic failure is a significant medical problem which has been unsuccessfully treated by hemodialysis. However, similar therapies using recirculated dialysate regenerated by sorbents in place of single-pass dialysate have been beneficial in treating acute-on-chronic liver failure. The advantages of sorbent-based treatments include some selectivity of toxin removal and improved removal of protein-bound toxins. Activated carbon has been extensively used in detoxification systems, but has often had insufficient toxin capacity. Powdered activated carbon, because of its large surface area, can provide greater binding capacity for bilirubin and other toxins than granular carbon commonly used in detoxifying columns. Methods of using powdered carbon in extracorporeal blood treatment devices are reviewed in the present paper, including liver dialysis and a new sorbent suspension reactor (SSR); and the abilities and limitations of the SSR and columns to process protein solutions are discussed.

Review article: non-biological liver support in liver failure

Liver failure, whether acute or acute-on-chronic, remains an important cause of morbidity and mortality. The lack of liver detoxification, metabolic and regulatory functions of the liver leads to life-threatening complications, such as renal failure, altered immune response, hepatic coma and systemic haemodynamic dysfunction, eventually culminating in multiorgan failure. Current medical therapy involves the management of the precipitating event and treatment of complications until the liver eventually recovers, leaving us with no other treatment options than transplantation if these attempts fail. However, the shortage in cadaveric organs and other transplant-related problems, have prompted the need for alternative methods to provide liver support. As liver failure is often potentially reversible, considerable effort has been invested in the development of liver support systems. Currently, most of the experience is available for non-biological support systems. They represent the focus of this review, which aims to define the goals of liver support, to describe the design of the different existing devices and to analyse the available data to determine their current status in the management of patients with liver failure.

In vivo quantification of liver dialysis: comparison of albumin dialysis and fractionated plasma separation

BACKGROUND/AIMS

Artificial liver support represents a potentially useful option for the treatment of severe liver failure. A sufficient 'dose' might be crucial for such treatments to provide a survival benefit. The aim of this study was to compare in vivo efficiency and resulting delivered treatment dose of two commercially available devices that use different therapeutic principles: albumin dialysis (AD, MARS) and fractionated plasma separation (FPS, Prometheus).

METHODS

Eight patients with acute-on-chronic liver failure were treated alternately with AD and FPS. Thirty-two treatments at identical blood and dialysate flow rates were evaluated. Clearance and reduction ratio (a measure of delivered treatment dose) were compared for bilirubin subfractions, ammonia and urea.

RESULTS

FPS achieved significantly higher clearance for all measured protein-bound and water-soluble markers. This resulted in significantly higher reduction ratios for FPS compared to AD. Unconjugated bilirubin, a marker for strongly albumin-bound toxins, was influenced only by FPS.

CONCLUSIONS

FPS provided a higher delivered treatment dose than a matching treatment with AD. Reduction ratios of bilirubin and urea should be reported in clinical studies on liver dialysis, since delivered dose is likely to be linked to the clinical effectiveness of extracorporeal liver support therapies.

Hepatic tissue engineering for adjunct and temporary liver support: critical technologies

The severe donor liver shortage, high cost, and complexity of orthotopic liver transplantation have prompted the search for alternative treatment strategies for end-stage liver disease, which would require less donor material, be cheaper, and less invasive. Hepatic tissue engineering encompasses several approaches to develop adjunct internal liver support methods, such as hepatocyte transplantation and implantable hepatocyte-based devices, as well as temporary extracorporeal liver support techniques, such as bioartificial liver assist devices. Many tissue engineered liver support systems have passed the "proof of principle" test in preclinical and clinical studies; however, they have not yet been found sufficiently reliably effective for routine clinical use. In this review we describe, from an engineering perspective, the progress and remaining challenges that must be resolved in order to develop the next generation of implantable and extracorporeal devices for adjunct or temporary liver assist.

Acute liver failure

Acute liver failure is a rare and life-threatening clinical syndrome following severe hepatic injury. Depending on the rapidity of its development, two distinct complications contribute to a high mortality: in hyperacute liver failure, rapid development of massive hepatic necrosis and apoptosis gives rise to severe hyperammonemia, hepatic encephalopathy and life-threatening cerebral edema. The high risk of cerebral herniation requires early listing for emergency liver transplantation. Patients with hyperacute liver failure surviving the initial episode of cerebral edema have a substantial potential for hepatic recovery. If progressive hepatic failure develops more slowly, astrocytic osmoregulation prevents cerebral herniation in most instances. Unfortunately, these patients have a small potential of hepatic regeneration and transplantation should be performed before renal failure, sepsis or multiorgan failure emerge. Experimental treatment methods including detoxification by artificial or bioartificial liver support or by stimulating hepatic regeneration are currently evaluated. Recognition of ammonia toxicity has stimulated the search for early ammonia-lowering strategies and strongly renewed the interest in dialytic therapies. Anti-apoptotic interventions are among the most promising pharmacological options for the near future.

Living-related liver transplantation: implication for the anaesthetist

PURPOSE OF REVIEW

Living donor liver transplantation, originally introduced about a decade ago to overcome paediatric cadaveric organ shortage, has rapidly gained acceptance within the transplant community and is nowadays almost routinely applied to the growing number of adult and paediatric patients awaiting a live-saving liver transplantation. In fact its introduction has contributed to a continuing decrease of waiting list deaths.

RECENT FINDINGS

The risk of potential complications and even death for the donor increases with the extent of liver tissue resected. Better preoperative evaluation of suitability, refinement of surgical technique and smarter anaesthetic management, based on extended knowledge of underlying pathophysiology, have made the procedure safer for donors, with low morbidity and even lower mortality rates, tending towards zero in experienced centres. Despite these improvements, a certain risk is inherent. Yet from an ethical point of view it has to remain unacceptable especially because donors are otherwise healthy people and their only motives are altruistic. The procedure of living donor liver transplantation like conventional liver transplantation involves various disciplines, each of which contributes in a specific manner. There is a broad scope of issues that anaesthetists are responsible for and these largely depend on the department and hospital requirements. These issues may range from perioperative anaesthetic management and pain relief, to--and there are definite continental differences--the coordination of donor evaluation, intensive care management, postoperative complication management, as well as psychological support for donors, recipients and their relatives.

SUMMARY

In this paper we review and summarize the potential impact of findings and advances made in this particular field as described by the most important articles published during the past year.

Drug-induced liver disease in 2003

Drug-induced liver disease remains an important topic of concern for all prescribers as well as drug manufacturers. The withdrawal of troglitazone (Rezulin) and bromfenac (Duract) a few years ago remains fresh in the minds of regulatory authorities as well as clinicians and researchers who are focusing renewed attention on ways to better understand mechanisms of injury to predict and avert serious drug-induced liver disease in the future from drugs under development as well as existing agents known to cause liver injury. As in past years, this review describes new and first-time reports of various aspects of drug-induced liver disease for several classes of compounds, including herbal products (such as kava kava), reviews the risk factors seen with antiretroviral and antituberculosis agents among others. It provides a sampling of experimental hepatoprotection studies that may hold the key to treatment and prevention of drug-induced liver disease in the future and discusses the ongoing approaches to be taken to restrict the availability of acetaminophen that have proved successful in reducing the number of overdoses, deaths, and liver transplantations from this drug in the United Kingdom. Given the fact that acetaminophen is the single most important cause of acute liver failure here and abroad, such efforts to limit its use seem appropriate for other nations as well.