Cerebral microdialysis in patients with fulminant hepatic failure

Fulminant hepatic failure (FHF) is often complicated by high intracranial pressure (ICP) and fatal brain damage. In this study, we determined if a rise in [glutamate]ec and [lactate]ec preceded surges of high ICP in patients with FHF (median age, 42; range, 20-55 years; 7 women; 3 men) by inserting a microdialysis catheter into the brain-cortex together with an ICP catheter. The microdialysis catheter was perfused with artificial cerebrospinal-fluid at a rate of 0.3 microL/min. Dialysate was collected approximately every 30 minutes or when ICP increased. A total of 352 microdialysis samples were collected during a median of 3 days and allowed for approximately 1,760 bedside analyses of the collected dialysate. In 5 patients that later developed surges of high ICP, the initial values of [glutamate]ec and [lactate]ec were 2 to 5 times higher compared with patients with normal ICP. [Glutamate]ec then tended to vanish with time in both groups of patients. An increase in [glutamate]ec did not precede high ICP in any of the cases. In contrast, [lactate]ec was high throughout the study in the high ICP group and increased further before surges of high ICP. We conclude that in patients with FHF, cerebral [glutamate]ec and [lactate]ec are elevated. However, the elevated [glutamate]ec is not correlated to high ICP. In contrast, elevations in [lactate]ec preceded surges of high ICP. In conclusion, accelerated glycolysis with lactate accumulation is implicated in vasodilatation and high ICP in patients with FHF. The data suggest that bedside cerebral microdialysis is a valuable tool in monitoring patients with FHF and severe hyperammonemia.

The role of cytokines in liver failure and regeneration: potential new molecular therapies

The liver is a unique organ, and first in line, the hepatocytes encounter the potential to proliferate during cell mass loss. This phenomenon is tightly controlled and resembles in some way the embryonal co-inhabitant cell lineage of the liver, the embryonic hematopoietic system. Interestingly, both the liver and hematopoietic cell proliferation and growth are controlled by various growth factors and cytokines. IL-6 and its signaling cascade inside the cells through STAT3 are both significantly important for liver regeneration as well as for hematopoietic cell proliferation. The process of liver regeneration is very complex and is dependent on the etiology and extent of liver damage and the genetic background. In this review we will initially describe the clinical relevant condition, portraying a number of available animal models with an emphasis on the relevance of each one to the human condition of fulminant hepatic failure (FHF). The discussion will then be focused on the role of cytokines in liver failure and regeneration, and suggest potential new therapeutic modalities for FHF. The recent findings on the role of IL-6 in liver regeneration and the activity of the designer IL-6/sIL-6R fusion protein, hyper-IL-6, in particular, suggest that this molecule could significantly enhance liver regeneration in humans, and as such could be a useful treatment for FHF in patients.

Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expression in fulminant hepatic failure

BACKGROUND/AIMS

Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) have important functions in inflammation and vasoregulation but their role in fulminant hepatic failure (FHF) is not well understood.

METHODS

Intrahepatic in situ staining and semi-quantification of iNOS and eNOS by immunohistochemistry in 25 patients with FHF, in 40 patients with chronic liver diseases (CLD) and in ten normal controls (NC).

RESULTS

Expression patterns of iNOS and eNOS differed. While in NC only faint iNOS expression was found in some Kupffer cells/macrophages and hepatocytes, eNOS was expressed constitutively in sinusoidal and vascular endothelial cells. In CLD, iNOS expression was induced in Kupffer cells/macrophages and hepatocytes, representing the main iNOS expressing cell types. Additionally, bile ducts, vascular endothelial cells and lymphocytes also expressed iNOS (P = 0.001). In contrast, no differences were found between eNOS expression in CLD and NC (P = 0.64). The same cell types expressed eNOS and iNOS in FHF but numbers of both were significantly enhanced, exceeding the levels seen in CLD (P < 0.001, P = 0.017).

CONCLUSIONS

Our data demonstrate that iNOS and eNOS are differently regulated in physiologic conditions and in liver disease. While eNOS seems to be involved in the physiological regulation of hepatic perfusion, strong upregulation of iNOS might contribute to inflammatory processes in FHF.

Fulminant hepatic failure: outcome after listing for highly urgent liver transplantation-12 years experience in the nordic countries

Fulminant hepatic failure is a common indication for liver transplantation. Outcomes of patients listed for a highly urgent liver transplantation have been studied, with special emphasis on etiology of the liver disease, clinical condition, and ABO blood type. Data have been collected from the Nordic Liver Transplantation Registry. All Nordic patients listed for a highly urgent primary liver transplantation during a 12-year period have been included. Of the 315 patients listed for a highly urgent liver transplantation, 229 (73%) received a first liver allograft, 50 patients (16%) died without transplantation, and 36 patients (11%) were permanently withdrawn and survived. In 43% of the patients, no definite etiology of the liver failure could be established. Paracetamol intoxication was the most frequent specific indication for listing. Patients with blood type A had no significant shorter waiting time (3.8 v 6.6 days; P =.1) but a higher rate of transplantation (82% v 66%, P =.006) as compared with blood type O patients. In a multivariate analysis, paracetamol intoxication remained the single independent predictor of an outcome without transplantation. In conclusion, a high transplantation rate was observed among patients listed for a highly urgent liver transplantation because of fulminant hepatic failure. Blood type O patients had a lower chance of receiving a liver allograft. Patients with paracetamol intoxication had both a higher mortality without transplantation and a higher withdrawal rate attributable to improved condition.

Role of echocardiography in detecting portopulmonary hypertension in liver transplant candidates

Portopulmonary hypertension (PPHTN) is a recognized complication of end-stage liver disease that adversely affects the outcome of orthotopic liver transplantation (OLT). There are limited data on the role of Doppler echocardiography in assessing pulmonary artery systolic pressure (PASP) in this population. The purpose of our study was to examine the accuracy of Doppler echocardiography in evaluating pulmonary artery pressures in liver transplant candidates. Clinical and demographic data were gathered retrospectively for 78 liver transplant candidates (48 men and 30 women, mean age 51 +/- 9.6 yr) who had PASP determined both by right heart catheterization (RHC) and echocardiography. Paired sample t-test was used to compare mean PASP by echocardiography and RHC. Correlation of PASP between echocardiography and RHC was determined using Pearson's linear correlation. Positive and negative predictive values for echocardiography for PASP > 50 mmHg are reported as compared with RHC. The mean PASP by echocardiography (43.2 +/- 12.3 mm Hg) was significantly higher than mean PASP by RHC (33.7 +/- 15.5 mm Hg; P <.001). Regarding PASP, there was a significant but weak correlation between echocardiography and RHC (r = 0.46, P =.01). The positive and negative predictive values of echocardiography for identifying clinically significant pulmonary hypertension (PASP > 50 mm Hg) were 37.5% and 91.9%, respectively. Echocardiography is a useful tool in estimating PASP in liver transplant candidates. Patients with apparently elevated PASP by echocardiography should undergo invasive assessment by RHC before being excluded from liver transplant.

Losing balance: cytokine signaling and cell death in the context of hepatocyte injury and hepatic failure

Fulminant hepatic failure (FHF) represents a clinical scenario that is associated with high morbidity and mortality, and very limited treatment options. Therefore, great efforts have been made recently on defining its biological mechanisms. This article gives an overview of the cellular processes that are linked to the loss of hepatocytes as a reaction to various agents that cause hepatic failure, and summarizes recent results from clinical and experimental studies of the role of pro- and antiapoptotic cytokines and their intracellular signaling in this context.

Hepatic stimulator substance activity in animal model of fulminant hepatic failure and encephalopathy

Hepatic stimulator substance (HSS) is a known liver-specific but species-nonspecific growth factor. In the present study we examined the activity of the endogenously produced HSS in an established experimental model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA). FHF was induced by three consecutive intraperitoneal injections of TAA (400 mg/kg body weight) in rats, at time intervals of 24 hr. The animals were killed at 0, 6, 12, or 18 hr following the last injection of TAA. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of liver thymidine kinase (EC 2.7.1.21), and the assessment of mitotic index in hepatocytes were used to estimate liver regeneration. HSS extract obtained from the livers of TAA-treated rats, sacrificed at the above-mentioned time points was tested for its activity. Increased HSS activity was noted in all TAA-treated animals, presenting a peak at 12 hr following the third TAA dose, suggesting active participation of this growth factor in hepatocyte replication in this animal model of FHF and encephalopathy. It may also be suggested that up-regulation of HSS activity could be used in future as a therapeutic approach in FHF.

Extracorporeal treatment in fulminant hepatic failure: pathophysiologic considerations

Fulminant hepatic failure is a life-threatening clinical syndrome following severe hepatic injury leading to cerebral edema and brainstem herniation. Excessive mortality can be currently reduced only by timely orthotopic liver transplantation. Due to the shortage of donor organs, a considerable proportion of patients develop irreversible neurological damage, multiorgan failure or death while waiting for transplantation. Consequently, alternatives to orthotopic liver transplantation and methods of stabilizing patients on the waiting list including extracorporeal detoxification treatment are currently investigated. Recent advances in the pathophysiology of cerebral edema have challenged some of the traditional assumptions on which many blood detoxification systems are based. This article aims to integrate pathophysiology of hepatic encephalopathy and cerebral edema into a proposed future concept of liver support.

Application of a continuous disease severity score to the OPTN liver waiting list

In a move to establish measurable, objective criteria for cadaveric liver allocation, the United Network for Organ Sharing OPTN will implement the Model for End Stage Liver Disease (MELD) system in early 2002 as a replacement for the current Child-Turcotte-Pugh (CTP)-based Status 2A, 2B, and 3 categories for patients waiting for a cadaver donor liver transplant. The MELD is a continuous mortality risk score based on serum creatinine, bilirubin, and INR. Although originally developed in patients undergoing the transjugular intrahepatic portosystemic shunt (TIPS) procedure, analysis of OPTN data shows that the components of MELD (in particular, bilirubin) have a very strong correlation with mortality in liver transplant candidates. Univariate analyses showed that pretransplant mortality significantly increased when the MELD score was > 1.8. In the study cohort, 25% of the patients had a MELD score > 1.8. Multivariate analysis showed that the MELD score was an independent predictor of mortality, with a 2-unit increase multiplying the risk of mortality by a factor of 5.6. The MELD and CTP scores were correlated, but MELD scores varied widely for any given CTP score, indicating that some patients could be disadvantaged with the status-based system. The MELD score was validated in an independent dataset; concordance with 3-month mortality was 0.88. We conclude that the MELD score is a good indicator of disease severity and that implementation of this system should direct more livers to those patients in greatest need of transplantation.

Increased hepatosplanchnic inflammation precedes the development of organ dysfunction after elective high-risk surgery

This study investigated the relationship of the hepatosplanchnic production and uptake of inflammatory mediators, hepatosplanchnic perfusion, and outcome during major abdominal surgery to evaluate the hypothesis that regional production of inflammatory mediators precedes the development of hepatic dysfunction. This retrospective analysis of data and blood samples collected during a randomized controlled clinical trial included high-risk surgical patients undergoing major abdominal surgery in a 24-bed university-afilliated intensive care unit. Patients were divided into a subgroup that developed hepatic dysfunction (HD+) postoperatively and a subgroup without hepatic dysfunction (HD-). Hepatic vein and arterial plasma levels of IL-6, IL-8, s-E-selectin, s-ICAM-1, and the TNF-receptors 55 and 75 were measured, and the flux was calculated by multiplying the difference in hepatic vein minus arterial levels of the mediators by the hepatosplanchnic flow. Systemic (thermodilution) and total hepatosplanchnic blood flow (using indocyanine green [ICG]-dilution method) and gastric intramucosal pH (pHi) were assessed preoperatively, 4, 24, and 36 h postoperatively. Of a total of 26 patients, 6 patients developed hepatic dysfunction after their abdominal surgery (mean 6 days postoperatively). The number of sepsis-related deaths and postoperative days on the ventilator were significantly higher in this group. A higher production of IL-8, TNF-receptor-75 and 55 in the hepatosplanchnic area in the HD+ subgroups was found, which preceded the development of organ dysfunction (P = 0.04, P = 0.02, and P = 0.02, respectively). Moreover, the uptake of s-ICAM-1 was significantly increased in this subgroup. Furthermore, total hepatosplanchnic blood flow was significantly higher and pHi was significantly lower in the HD+ group, whereas global hemodynamic data were similar in the two subgroups. In conclusion, the development of postoperative organ dysfunction is preceded by an increased regional inflammatory response, indicated by an increased soluble TNF-receptor shedding and IL-8 production from the hepatosplanchnic area together with an increased uptake of s-ICAM-1. Moreover, an increased total hepatosplanchnic blood flow with intramucosal acidosis was associated with this regional inflammatory response.

Long-term survivors with artificial liver support in fulminant hepatic failure

Clinical ability of artificial liver support (ALS) has been improved greatly in recent years which has allowed us to encounter long-term survivors with fulminant hepatic failure (FHF) whose liver function has been almost completely lost. This suggests that application of ALS in patients with FHF gains time while awaiting transplantation as well as time for functional recovery and regeneration of the liver graft following receipt of the graft with marginal function and/or size. Thus, ALS will contribute greatly to extending the indications for liver transplantation and increase the number of patients receiving and benefiting from this treatment. On the other hand, introduction of ALS prolongs the duration of intensive treatment which increases the risk of infection and increases medical costs. In addition, when to discontinue intensive treatment of patients whose level of consciousness is maintained only by ALS is controversial. Thus, further investigation will be needed to establish a consensus on indications for long-term ALS in FHF.

[Fulminant hepatic failure]

Fulminant hepatic failure (FHF) is an acute and eventually fatal illness, caused by a severe hepatocyte damage with massive necrosis. Its hallmarks are hepatic encephalopathy and a prolonged prothrombin time (< 40%). FHF is currently defined as hyperacute (encephalopathy appearing within 7 days of the onset of jaundice), acute (encephalopathy appearing between 8 and 28 days) or subacute (encephalopathy appearing between 5 and 12 weeks). FHF can be caused by viruses, drugs, toxins, and miscellaneous conditions such as Wilson's disease, Budd-Chiari syndrome, ischemia and others. However, a single most common etiology is still not defined. Factors that are valuable in assessing the likelihood of spontaneous recovery are age, etiology, degree of encephalopathy, prothrombin time and serum bilirubin. The management is based in the early treatment of infections, hemodynamic abnormalities, cerebral edema, and other associated conditions. Liver transplant has emerged as the most important advance in the therapy of FHF, with a survival rate that ranges between 60 and 80%. The use of hepatic support systems, extracorporeal liver support and auxiliary liver transplantation are innovative therapies.

Evaluation of the splanchnic circulation with indocyanine green pharmacokinetics in liver transplant patients

Although indocyanine green (ICG) can be used to estimate cardiac output (CO) and blood volume independently, a recirculatory multicompartmental ICG model enables description of these and additional intravascular factors. This model was used to describe the effect of end-stage liver disease (ESLD) on systemic and splanchnic hemodynamics in patients undergoing orthotopic liver transplantation. ICG disposition was determined during the dissection phase in six patients with ESLD undergoing orthotopic liver transplantation and six healthy adult living liver donors. After injecting ICG, plasma concentrations were obtained for approximately 10 to 12 minutes by noninvasive pulse dye densitometry. The recirculatory model characterizes three distinct intravascular circuits: lumped parallel fast (presumably nonsplanchnic circulation) and slow peripheral (splanchnic) circuits and a central circuit (central blood volume). Mean transit time (MTT) in the fast peripheral circuit was not different in patients with ESLD and controls. However, ESLD resulted in a significant decrease in MTT in the central (0.11 +/- 0.028 [SD] v 0.24 +/- 0.094 minutes in controls; P <.001) and slow peripheral circuit (0.67 +/- 0.41 v 1.37 +/- 0.37 minutes in controls; P <.001) because of increased flows to the central and slow peripheral circuits. These findings are consistent with the described hyperdynamic systemic and splanchnic circulations in patients with ESLD. In conclusion, the ICG model is able to derive estimates of not only blood volume and CO, but also splanchnic hemodynamics under different physiological conditions. This model can be a useful tool to evaluate the effect of pharmacological manipulation of splanchnic hemodynamics.

In vivo estimation of bioartificial liver with recombinant HepG2 cells using pigs with ischemic liver failure

Biological efficacy of a recombinant human hepatic cell line, glutamine synthetase transfected HepG2 (GS-HepG2), was examined with large-scale culture in a circulatory flow bioreactor and in pigs with ischemic liver failure. GS-HepG2 cells were cultured in a circulatory flow bioreactor from 5 x 10(7) to 4 x 10(9) cells for 109 days. The cells showed ammonia removal activity even under substrate (glutamic acid)-free medium, suggesting that the GS catalyzed the activity using intracellular glutamic acid that had been pooled during conventional culture. When GS-HepG2 bioartificial liver (BAL) was applied to pigs with ischemic liver failure, survival time was prolonged to 18.8 +/- 6.1 h (mean +/- SD, n = 4) from 13.8 +/- 5.4 h (n = 6) and 10.7 +/- 4.1 h (n = 6) (groups treated with cell-free BAL and treated with plasma exchange and continuous hemodiafiltration, respectively). Laboratory data indicated the tendency for improvement in increase of blood ammonia level and decline of blood coagulation indices in the GS-HepG2 BAL-treated group. The advantages and potential for the cell line as a bioreactor in BAL is also discussed, comparing to those of isolated porcine hepatocytes.

Hepatic dysfunction after left ventricular mechanical assist in patients with end-stage heart failure: role of inflammatory response and hepatic microcirculation

BACKGROUND

In the condition of preexisting vital organ failure induced by heart failure, hepatic failure often progresses despite establishment of adequate hemodynamic support through a left ventricular assist device (LVAD) and results in a high mortality rate. We hypothesized that inflammatory responses, including those induced by infection and their influence on organ perfusion, may contribute to the pathogenesis of this progressive hepatic failure and subsequent multiple organ failure as reported in the current investigation on multiple organ failure after major surgery or trauma.

METHODS

Hepatic function and its relation to inflammatory response and hepatic microcirculation were evaluated in 16 consecutive patients who received an implantation of LVAD for end-stage cardiomyopathy, between 1992 and 2000. Patients were divided into two groups: 5 patients who died from multiple organ failure after severe hepatic failure (group 1) and 11 patients who did not develop severe hepatic failure (group 2). Serum levels of CRP, interleukin (IL)-6, IL-8, and serum hyaluronan, a known indicator of hepatic sinusoidal function, were measured pre- and postoperatively in both groups.

RESULTS

Serum ALT and AST levels during LVAD support were similar in the two groups. Serum total bilirubin (T-Bil), CRP, IL-6, and IL-8 levels before and during the first 20 days of LVAD support were significantly higher in group 1 than those in group 2 (p < 0.01 to 0.05). Serum hyaluronan levels in both groups were significantly correlated with T-Bil levels (r = 0.60, p < 0.05 in group 1; r = 0.68, p < 0.0001 in group 2). Histopathological examination by transvenous liver biopsy in a group 1 patient showed hepatic sinusoidal damage as well as cholestasis and fibrosis.

CONCLUSIONS

Patients with hyperbilirubinemia and inflammatory reactions before LVAD support showed increased hyperbilirubinemia and inflammatory cytokine and hyarulonan levels despite adequate hemodynamics achieved under LVAD support. These results suggest that inflammatory response contributes to subsequent aggravation of hepatic dysfunction, probably with underlying and continuing derangement in hepatic sinusoidal microcirculation even under systemic circulatory support.

Plasma and urine levels of urinary trypsin inhibitor in patients with acute and fulminant hepatitis

BACKGROUND AND AIM

Urinary trypsin inhibitor (UTI) is synthesized by hepatocytes and excreted into urine. Plasma and urine UTI levels have been measured to evaluate whether these levels may be useful markers in various pathological conditions. However, there has been no study on plasma and urine UTI levels in patients with acute liver diseases. The aim of the present study was to evaluate plasma and urine UTI levels and their relationship with the severity of hepatic damage in patients with acute liver diseases.

METHODS

Plasma and urine UTI levels were measured by newly developed enzyme-linked immunosorbent assay in 15 patients with acute hepatitis (AH), 12 patients with acute severe hepatitis (ASH) and 10 patients with fulminant hepatitis (FH), as assessed on admission. The serial changes in plasma and urine UTI were also observed in some patients with AH and ASH.

RESULTS

Plasma UTI levels (U/mL, median [25-75th percentile]) were: 11.0, (9.5-16.1) in patients with AH; 7.8 (5.6-11.5) in those with ASH; 6.5 (4.0-9.5) in patients with FH; and 9.7 (7.3-11.0) in normal controls. Plasma UTI levels in patients with FH were significantly lower than in those with AH. Plasma UTI levels showed significant positive correlations with the levels of prothrombin time (PT), hepaplastin test, antithrombin III, alpha2-plasmin inhibitor, plasminogen (Plg) and fibrinogen. After the recovery of liver dysfunction, increased plasma UTI levels in patients with AH were decreased, whereas previously decreased plasma UTI levels in patients with ASH were increased. Urine UTI levels were significantly increased in patients with AH compared with those of normal controls. In patients with ASH and FH, urine UTI levels were increased but not significantly. Urine UTI levels significantly positively correlated with PT and Plg. After the recovery of liver dysfunction, previously increased urine UTI levels in patients with AH were decreased. The correlation between plasma UTI and urine UTI levels was not significant.

CONCLUSIONS

The findings of the present study suggested that the levels of plasma and urine UTI changed in patients with AH and were closely related to the abnormalities of coagulo-fibrinolysis, including PT. Further studies are needed to clarify whether these levels may be useful markers to predict the prognosis of acute hepatitis.

[Study on the natural history of chronic hepatitis B]

OBJECTIVE

By clarifying the natural history of chronic hepatitis B, to evaluate its long-term therapeutic outcome, antiviral drugs efficacy and economic significance.

METHODS

A cohort of 183 (mean age of 31.75?.03 years, male/female ratio: 152:31) chronic hepatitis B patients with biopsy-proven and 247 cases of general population as control were followed up by retrospective cohort study. The follow-up time was 11.81?.08 years. This study was focused on long-term clinical outcome including the rate of liver cirrhosis, hepatocellular carcinoma and death, the long-term effect of antiviral drugs and prognostic factors.

RESULTS

In chronic hepatitis B patients, 22 (12.02%) developed liver cirrhosis, 12 (6.56%) hepatocellular carcinoma, and 20 (10.93%) died. The cumulative survival probabilities were 97.27%, 91.62%, and 84.47% in 5, 10, and 15 years, respectively. The cumulative probabilities of HCC were 0.00%, 3.19%, and 11.56% in 5, 10, and 15 years, respectively. In 247 control subjects, 6 (2.43%) died, none of them developed cirrhosis or HCC. The rates of death, liver cirrhosis, and HCC in hepatitis B patients were markedly different (P<0.005) compared with controls. The overall mortality of hepatitis B patients was 4.50 folds of the general population. Cox multiple regression analysis showed that old age, severe histological injury, and the positive HBeAg were closely related to liver cirrhosis, while old age, severe histological injury, and male were major factors leading to death. The independent variable of predicted HCC was not found.

CONCLUSIONS

The long-term outcome of hepatitis B is poor.

Extracorporeal tissue engineered liver-assist devices

The treatment of acute liver failure has evolved to the current concept of hybrid bioartificial liver (BAL) support, because wholly artificial systems have not proved efficacious. BAL devices are still in their infancy. The properties that these devices must possess are unclear because of our lack of understanding of the pathophysiology of liver failure. The considerations that attend the development of BAL devices are herein reviewed. These considerations include choice of cellular component, choice of membrane component, and choice of BAL system configuration. Mass transfer efficiency plays a role in the design of BAL devices, but the complexity of the systems renders detailed mass transfer analysis difficult. BAL devices based on hollow-fiber bioreactors currently show the most promise, and available results are reviewed herein. BAL treatment is designed to support patients with acute liver failure until an organ becomes available for transplantation. The results obtained to date, in this relatively young field, point to a bright future. The risks of using xenogeneic treatments have yet to be defined. Finally, the experience gained from the past and current BAL systems can be used as a basis for improvement of future BAL technology.