See “Quest for Life on MARS: Mission Incomplete” by Jain and Dhawan on page 140.
Wilson disease (WD) is an autosomal recessive hereditary disease of copper metabolism (1). The most common presentation is either as chronic liver disease or as neurological symptoms (2,3). Rarely, acute liver failure (ALF) is the first manifestation of WD. The patients remain asymptomatic as long as copper can accumulate in the liver; however, when necrotic hepatocytes release high amounts of copper into the circulation, ALF associated with haemolytic anaemia and acute renal failure may occur (4,5). Without liver transplant, the case-fatality rate in such patients is approximately 90% (6). Liver transplantation (LTx) is the only therapeutic option (6). To predict the outcome of all forms of symptomatic patients with WD, Dhawan et al (7) developed a prognostic score to be used at presentation. This score is used in children with severe disease, with or without encephalopathy. All of the children with a score >11 died without transplantation, whereas all those with a score <11 survived, showing that the Wilson index is helpful in identifying children in whom LTx is indicated.
Under normal conditions, the majority of serum copper is incorporated in ceruloplasmin, with approximately 10% of copper reversibly bound to albumin or amino acids. This albumin-bound pool of copper constitutes the “exchangeable fraction” or non–ceruloplasmin-bound serum copper that is significantly increased in WD. In fulminant WD, the non–ceruloplasmin-bound copper represents a significant and potentially toxic portion of the copper load (8). Conventional dialysis does not remove protein-bound substances, such as non–ceruloplasmin-bound copper. Because albumin has specific-binding sites for metals such as copper (9), albumin dialysis may increase the clearance of non–ceruloplasmin-bound copper in fulminant WD. Previous case reports have shown that albumin dialysis either by single-pass albumin dialysis (10,11) or the molecular adsorbents recirculating system (MARS) (12) was able to remove significant amounts of copper.
The MARS is an extracorporeal liver support system using a hollow-fibre dialysis module in which the patient's blood is dialyzed across an albumin-impregnated membrane while maintaining a constant flow of albumin-rich (20%) dialysate in the extracapillary compartment (13). Toxins from the albumin in the patient's blood are adsorbed onto the membrane and then pass to the albumin in the dialysate. This is then perfused over an activated charcoal column and an anion exchange resin column, which take up the toxins from the albumin to regenerate the dialysate. The system includes an additional haemodialysis or haemofiltration module, which removes the water-soluble toxins.
The MARS treatment has repeatedly demonstrated reductions in serum urea and creatinin levels, total bile acid pool, and total and conjugated serum bilirubin levels (14,15). In parallel, MARS demonstrated superiority in the treatment of severe hepatic encephalopathy (HE) when compared with medical treatment (15,16). Several mechanisms have been proposed: removal of ammonia, aromatic amino acids, and benzodiazepine-like substances, increased albumin-binding capacity, and modulated cerebral hemodynamics by changes in endogenous vasoactive substances.
ALF and acute-on-chronic liver failure (AoCLF) represent potential indications for liver support. Limited results have also been obtained for MARS in the treatment of fulminant WD (10,12). One paediatric case and one 18-year-old patient treated by single-pass albumin dialysis have been previously reported, but fewer data exist about neurological improvement, copper removal, tolerance, and outcome in children experiencing fulminant WD and treated by MARS (10,11).
In this study, we report the experience of treatment by MARS in ALF caused by WD in children. The goal of the treatment was to achieve stability in patients with fulminant WD, enabling the recovery of liver function or bridging to LTx.
We reviewed the charts of children admitted in our paediatric intensive care unit for ALF secondary to acute WD and treated by MARS (MARS, Hospal, Lyon, France) since 2004. All of the patients underwent severe ALF associated with haemolysis, acute renal failure, and severe cholestasis.
The following clinical parameters were assessed before and after each MARS session: score of HE, Glasgow coma score, and Fisher index, which is the rate of branched-chain and aromatic amino acids plasma levels. Tolerance of each session was recorded as we monitored haemodynamic parameters (blood pressure, cardiac rate, and use of transfusions) and neurological parameters.
The albumin dialysate was sampled for copper concentration from the 4 ports on the MARS circuit, which are between MARS filter and haemofiltration or haemodialysis filter, between filter and charcoal column, between charcoal and anion exchange columns, and between anion exchange column and MARS filter. These concentrations were measured every 2 hours in the serum and in the different parts of the circuit by inductively coupled plasma optical emission spectrometry.
Other biological assessments (standard liver function tests, platelets, ammonia levels, creatinin, and amino acids chromatography) before and after each MARS session were also reported when these data were available. We then calculated mean values obtained before and after MARS each session in each patient and deducted mean variation.
In the present study, each dialysis session was performed using a double-lumen catheter for blood access, and the albumin-enriched dialysate contained 500 mL of 20% human serum albumin. We used a MARS circuit connected to an haemofiltration machine (PRISMARS connected to Prisma, Hospal, Lyon, France) or to a dialysis machine (MARS connected to Integra, Hospal France). The median blood flow rate and albumin dialysate flow rate were set up at 4.3 mL · kg−1 · hour−1 (range 2–5). The median dialysate flow rate was at 47.5 mL · kg−1 · hour−1 (range 37.5–420). The dialysate was maintained at body temperature to avoid cooling of the patient.
In our centre, MARS treatment was only indicated in ALF as a bridge to LTx. Consequently, improvement with MARS treatment was not taken into account in the decision to have or not have the patient undergo LTx.
In accordance with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1975, as revised in 2000, fully informed consent was obtained from the patient if he or she was still legally capable or otherwise from his or her parents. All of the patients received full information about this clinical research and they all knew that the information obtained would only be used for medical research.
Four children (1 boy, 3 girls), with a median age of 12.3 years (range 7.4–15), were treated from 2004 to 2009 for a severe ALF (international normalised ratio >2) associated with acute renal failure, haemolysis, and severe cholestasis (median maximal total bilirubin level at 1154 μmol/L). All of the children had a new Wilson index >11 (12–18). Three patients were receiving both parenteral and enteral nutrition. Case 4 was receiving exclusive enteral nutrition. There were neither supplementations nor restrictions of any amino acids. All were haemodynamically stable, did not require additional circulatory support, and had no evidence of severe infection or multiorgan failure. All of the patients were listed for LTx before the onset of MARS sessions. Biological and clinical characteristics of these cases before MARS sessions are summarised in Table 1.
At presentation, only 1 patient (case 4) had a known history of WD (diagnosis was made 1 month before admission). The other 3 were admitted for ALF and were transferred to our unit to consider LTx. Clinical diagnosis was taken because they all had low ceruloplasmin serum level (median 132 mg/L, range 110–155 mg/L), and high 24-hour urine copper excretion. A Kayser-Fleischer ring was checked in all of the cases and detected on the slit lamp examination in 2 patients. The liver biopsies in explants showed both macrovacuolar cirrhosis and statuses. There also was marked hepatocellular degeneration and parenchymal collapse. All hepatic copper dosages in explants were >290 μg/g of liver tissue. Diagnosis was then confirmed by mutation analysis in all cases.
Treatment by D-penicillamine was started at diagnosis (9–15 mg · kg−1 · day−1) and continued until LTx. A total of 14 MARS sessions were performed, for a median duration of 7.5 hours (range 5–9 hours). MARS sessions started from 17 to 51 hours after admission (median 37 hours).
Global tolerance of MARS sessions was good except for case 4, who experienced haemorrhage resulting from vascular injury following insertion of the dialysis catheter. For this patient, total bilirubin rates were high and did not decrease with MARS because of participation of haemolysis. No other serious adverse event was reported because none developed disseminated intravascular coagulation with bleeding.
Haemodynamically, patients tolerated the treatment without significant changes in blood pressure or heart rate. The median decrease of platelet counts was 42% (range 20%–69%). Platelets transfusions were required in all of the patients.
A neurological improvement or stabilisation was noted in all of the children because HE decreased from grade 2 to grade 1 in case 2 and remained stable for the other 3 patients. HE was assessed using the clinical criteria of West Haven and was validated by electroencephalography criteria. All Glasgow Coma Scales were improved, with a median gain of 2 points after each MARS session. This clinical improvement was associated with a decrease in ammonia level of 19%, as well as an improvement of the Fisher index. This ratio was calculated before and after MARS session in cases 2 and 3, with a mean increase of 20%.
The modifications of other biological assessments are shown in Table 2. We found a reduction in serum creatinin and total bilirubin levels >25%.
Figure 1 illustrates the reduction of total serum copper during MARS and the rebound upon discontinuation of the treatment. The copper level decreased after each MARS session in all of the patients and was in the normal range (0.88–1.2 mg/L) before LTx in case 2 after session number 4. This decrease was 28% in mean.
The albumin dialysate was sampled for copper concentration from the 4 ports on the MARS circuit. This did reveal a significant difference in the gradient of copper concentration at different times of treatment; there is an increase in copper concentration that is the same in different parts of MARS in time. This is the result of the functioning of MARS by extracting liver toxins from albumin and it was not evident for copper. The level of copper increased within the albumin circuit during the sessions, and at the same time, albumin was not detoxified in copper because we found the same levels of copper in different parts of the circuit (Fig. 2).
All of the children subsequently underwent LTx. The delay for transplantation was a median of 5.5 days (range 4–6 days after admission). The postoperative period was complicated by a graft dysfunction in case 3 and she had to undergo another LTx 4 days later. She received 2 MARS sessions to bridge her to retransplantation. The long-term outcome of these 4 patients was good without disabilities.
ALF is one of the potentially fatal modes of presentation of WD and an indication of urgent LTx. All of the patients described in this article had a new Wilson index >11. Therefore, without a transplant, all would have been expected to have a poor outcome (7). In such cases, a liver-support system, which can prevent organ dysfunctions for a few days, is potentially lifesaving. Our data, like those of others (12,14), suggest that MARS can be used effectively to bridge such patients to LTx. Moreover, the clinical improvement observed after MARS treatments means that patients are in a better condition to undergo LTx.
HE is a feature clearly associated with poor prognosis in patients with liver failure. The pathophysiology is not completely understood, and different hypotheses have emerged (16,17). There are some data suggesting that HE results from the accumulation of neurotoxic or neuroactive substances in the brain, including ammonia, manganese, aromatic amino acids, mercaptans, phenols, and short-chain fatty acids (17). The results of the present study indicate that albumin dialysis is able to prevent these accumulations in patients with fulminant WD. The degree of HE was improved or stabilised after albumin dialysis. That could be explained by the removal of both water-soluble and protein-bound putative toxins, reductions in ammonia concentration of approximately 19%, bile acid levels, change in the ratio of branched/aromatic chain amino acids (as the Fisher index increased significantly), or the improvement in systemic hemodynamics. Similar data on the effects of albumin dialysis on the amino acid profile have been reported in patients with ALF and AoCLF (16–18), but have never been reported in paediatric fulminant WD. To better understand the mechanism of neurological improvement linked to MARS, it would be extremely interesting to assess the evolution of transcranial Doppler data with treatment. The effect of MARS on cerebral oedema and level of intracranial pressure would be of interest, but intracranial pressure monitoring in the context of ALF is controversial because of the high risk of intracranial haemorrhage (19).
MARS treatments have repeatedly demonstrated reductions in serum urea and creatinin levels in several trials (14,15). Mitzner et al (14) found a reduction in serum creatinin (from 3.8 ± 1.6 to 2.3 ± 1.5 mg/dL, P = 0.01) in 13 patients with cirrhosis and type 1 hepatorenal syndrome. Heeman et al (15) found similar results in a prospective randomised controlled trial including 23 patients with AoCLF without hepatorenal syndrome. These results are confirmed in our study that found a 36% decrease in serum creatinin level. Moreover, we confirmed the efficacy of albumin dialysis in decreasing total bile acid as well as total and conjugated serum bilirubin levels (14,15).
Despite the high severity of our study population, patients tolerated well MARS therapy because only 1 adverse event was reported. Case 4 experienced haemorrhage because of vascular injury following insertion of the dialysis catheter, but no haemodynamic instability during MARS sessions was noted. MARS is associated with the same risks as any extracorporeal technique requiring intravascular access in the context of ALF. Mild thrombocytopaenia and disseminated intravascular coagulation with bleeding have sometimes been reported (9,10,20). In our study, platelets decreased by 42% (range 20%–69%), and platelet transfusions were required in all of the patients.
The fatality rate of acute decompensated WD approaches 100% if transplantation cannot be performed in time (6). Acute decompensated WD is indistinguishable from other causes of fulminant hepatic failure, except that a large amount of copper is released from the necrotic hepatocytes. This acute increase in the copper load induces severe Coombs negative haemolytic anaemia and renal failure (4,5). We hypothesised that the reduction of copper load by MARS may confer benefit in the management of acute decompensated WD. This hypothesis was supported by other investigators who have used extracorporeal treatments to remove excessive copper in acute decompensated WD (10–12,21). Manz et al (21) reported an 18-year-old patient with fulminant WD who was successfully treated with MARS. In this case, renal function stabilised with MARS, which allowed the removal of the majority of copper in the urine through chelation with penicillamine. Sen et al (12) reported 2 patients with WD who were successfully bridged to LTx with MARS. Analysis of the albumin dialysate circuit in 1 patient revealed that copper removal through the MARS system occurred primarily in the first few hours, through adsorption by albumin and by the MARS flux membrane, with no substantial removal by the albumin regeneration process. Kreymann et al (11) reported the use of single-pass albumin dialysis in the management of a patient with WD, from whom a significant amount of copper was removed, and the patient was stabilised and eventually received LTx. Clinical reports on this method have also indicated favourable results (10).
Consistent with the study by Sen et al, the copper assay performed at different sites within the albumin dialysate circuit did not show a concentration gradient across different components (12). At the same time, albumin was not detoxified in copper because the copper concentration did not differ significantly whether it was proximal or distal to the hemodialyzer, distal to the charcoal column, or distal to the resin column. Although the transcolumn copper assay difference was small, a significant amount of copper can be removed by these columns when using higher flow rates along with a longer treatment time. This is confirmed by the fact that serum copper level decreased after each MARS session. Therefore, our results suggested that MARS was able to remove copper. Compared with haemofiltration, MARS allowed the removal of copper, bile acids, and bilirubin and improved the Fisher index.
The following limitations of the study are noted. HE stabilised or improved during the patients’ stay in the paediatric intensive care unit, but all of the patients have undergone haemodiafiltration between or before the MARS session so that we could not evaluate the part only because of MARS therapy; however, no study has previously reported the improvement of HE in children with ALF by using haemodiafiltration. Because this study has no control group, the effect of MARS treatment cannot be proven. Another limitation of the study is the fact that circuit copper levels were not obtained at the same time as the MARS session in the 4 patients. Nonetheless, the increase in copper level with time was found in all of the patients.
In summary, we found that MARS was able to remove copper without detoxifying albumin dialysate from copper. It would be useful to test a cationic resin to allow the regeneration of the albumin dialysate. MARS was able to improve the renal function and the HE. This clinical improvement was associated with a decrease in ammonia level, as well as an improvement in the Fisher index. Moreover, MARS was able to remove significant amounts of bilirubin from the blood and to stabilise patients until a liver transplant was available. A study comparing MARS with continuous haemofiltration on HE and clinical stabilisation is warranted. It would be interesting to investigate the effect of MARS treatment in patients with the neurological form of WD to know whether it would be able to prevent neurological deterioration.
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