Reversal of hepatic coma with flumazenil with improvement in visual evoked potentials

Reversal of sedation with flumazenil in a child after traumatic brain injury

The authors report on a case of successful reversal of sedation with flumazenil, a benzodiazepine antagonist, in a child following a moderate traumatic brain injury and demonstrate the utility of flumazenil to reverse benzodiazepine effects in traumatically injured children.

Benzodiazepine receptor antagonists for hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.

OBJECTIVES

To evaluate the beneficial and harmful effects of benzodiazepine receptor antagonists for patients with hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register on The Cochrane Library, MEDLINE and EMBASE (last search: January 2004), reference lists of relevant articles, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently included trials and extracted data. Binary outcomes are reported as risk difference (RD) with 95% confidence intervals (CI) based on a random effects model. Statistical heterogeneity was explored by a chi-squared test with significance set at P < 0.1. The inconsistency across trials was assessed by I(2). Potential sources of heterogeneity were explored through subgroup analyses.

MAIN RESULTS

Thirteen randomised trials with 805 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (361/390 [93%] survived in the flumazenil group versus 345/376 [92%] in the placebo group). Flumazenil had a significant beneficial effect on improvement of hepatic encephalopathy at the end of treatment (RD 0.28; 95% CI 0.20 to 0.37, eight trials). Flumazenil had no significant effect on recovery (RD 0.13; 95% CI -0.09 to 0.36, two trials) or mortality RD 0.01; 95% CI -0.05 to 0.07, 10 trials). Flumazenil may be associated with adverse events, but trial results were heterogeneous.

REVIEWERS' CONCLUSIONS

Flumazenil had a significant beneficial effect on short-term improvement of hepatic encephalopathy in patients with cirrhosis and a highly favourable prognosis. Flumazenil had no significant effect on recovery or survival. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Factor structure and ammonia-related modulation of the human retinal oscillatory potentials

OBJECTIVE

To investigate in man the factor structure of retinal oscillatory potentials (OPs) to full-field luminance stimulation (0.9-9.5 cd.s.m(-2)) and the correlation with the spontaneous fluctuations of plasma ammonia.

METHODS

Six male healthy volunteers were studied. Five OP recordings and ammonia determinations (GLDH method) were obtained for each subject at 2 h interval during an 8 h experimental session. A standard factor analysis was applied on the OP latency (time from stimulus to peak) and amplitudes values.

RESULTS

Two consecutive factors on latencies and two factors on amplitudes were identified, consistent with reported differences between the earlier and later OP waves. The model explained a large portion of the OP variance. Both factors on latencies and factor 1 on amplitudes were directly correlated to the stimulus intensity and the ammonia plasma concentration in the 15.8-39.5 micromol/l range. Factors 1 and 2 on latencies decreased and factor 1 on amplitude increased at increasing stimulus intensities. The latency factors decreased and the amplitude factor increased with increasing ammonia concentration. Factor 2 on amplitudes did not correlate with the stimulus intensity or ammonia concentration.

CONCLUSIONS

The factor structure further supports the evidence of functional differences between early and late OP waves. The observed correlation conceivably reflects a role of ammonia in the modulation of retinal electrophysiology in physiological conditions and potentially accounts for spontaneous variability in otherwise controlled electrophysiological studies.

Benzodiazepine receptor antagonists for acute and chronic hepatic encephalopathy

BACKGROUND

The pathogenesis of hepatic encephalopathy is unknown. It has been suggested that liver failure leads to the accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition which may progress to coma. Several trials have assessed benzodiazepine receptor antagonists for hepatic encephalopathy, but the results are conflicting.

OBJECTIVES

To evaluate the efficacy and safety of benzodiazepine receptor antagonists for patients with acute or chronic hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register, MEDLINE, EMBASE, reference lists of relevant articles, authors of trials, and the pharmaceutical company known to produce benzodiazepine receptor antagonists.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy were included, regardless of language or publication status.

DATA COLLECTION AND ANALYSIS

Trial inclusion and data extraction were made independently by two contributors. Depending on the presence or absence of significant heterogeneity (P<0.1) a random or fixed effect model was used. Potential causes for heterogeneity were explored by sensitivity analyses.

MAIN RESULTS

Twelve randomised trials with 765 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (341/370 (92%) survived in the flumazenil group versus 325/356 (91%) in the placebo group). Flumazenil had no significant effect on full recovery (two trials), survival (nine trials), or on the occurrence of adverse events (five trials). However, flumazenil was associated with a significant effect on improvement of hepatic encephalopathy compared to placebo at the end of treatment (103/346 (30%) versus 23/332 (7 %), risk difference 0.23, 95% confidence interval 0.18 to 0.28, five trials).

REVIEWER'S CONCLUSIONS

Flumazenil had no significant effect on recovery or survival from hepatic encephalopathy. However, flumazenil had a significant effect on short-term improvement of hepatic encephalopathy in some patients with chronic liver disease and a highly favourable prognosis. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Flumazenil for hepatic encephalopathy grade III and IVa in patients with cirrhosis: an Italian multicenter double-blind, placebo-controlled, cross-over study

The rationale for use of benzodiazepine receptor antagonists is based on the so-called benzodiazepine pathogenetic hypothesis of hepatic encephalopathy (HE). To assess the efficacy of flumazenil, a specific benzodiazepine receptor antagonist, in a large and selected population of cirrhotic patients with severe HE, we conducted a double-blind, placebo-controlled, cross-over trial on 527 cirrhotic patients with HE grade III and IVa admitted to Intensive Care Units over a 5-year period; among them, 265 (132 of grade III and 133 of grade IVa) received flumazenil, whereas 262 (130 of grade III and 132 of grade IVa) received placebo. Treatment was begun within 15 minutes of randomization; the response to treatment was assessed by neurological score and by continuous electroencephalographic (EEG) recordings. Improvement of the neurological score was documented in 17.5% of grade III patients treated with flumazenil and in 14.7% of grade IVa patients, compared, respectively, with 3.8% and 2.7% of the patients of both groups treated with placebo. Improvements in EEG tracings were observed in 27.8% of grade III patients and in 21.5% of grade IVa patients, compared, respectively, with 5% and 3.3% of the patients of both groups treated with placebo. Benzodiazepines were detected in the serum of 10 patients (4 in grade III group and 6 in grade IVa group). Flumazenil is beneficial only in a selected subset of cirrhotic patients with severe HE; the applicability of this treatment to unselected patients with severe HE still remains to be determined.

Functional integrity of benzodiazepine receptors of the geniculo-striate visual pathways in Creutzfeldt-Jakob disease. A pharmacological evoked potential study

We evaluated the effects of flumazenil (FMZ), a high-affinity benzodiazepine receptor antagonist, on flash-evoked visual potentials (FEPs) in a patient with Creutzfeldt-Jacob disease (CJD). FEPs were recorded in three different consecutive sessions: (1) basal condition, without any pharmacological treatment; (2) 3.5 min after i.v. administration of 5 mg FMZ; (3) 1 min after i.v. administration of 10 mg diazepam (DZP). FMZ provoked a marked increase in the amplitude as well as evident shortening of the latency of early FEP components. DZP reversed these effects. These results are in agreement with our previous findings of anatomical and functional integrity of the geniculo-striate pathways in human CJD and demonstrate functional integrity of benzodiazepine receptors in this visual system in CJD.

Flumazenil. A reappraisal of its pharmacological properties and therapeutic efficacy as a benzodiazepine antagonist

Flumazenil is a specific benzodiazepine antagonist which is indicated when the central effects of a benzodiazepine need to be attenuated or terminated. Following intravenous administration of up to 1 mg, flumazenil effectively reverses sedation and improves psychomotor performance following administration of short and longer acting benzodiazepines used for sedation, or general anaesthesia supplemented with benzodiazepines. The duration of action is short at generally 30 to 60 minutes and supplemental doses of flumazenil may be needed to maintain the desired level of consciousness in some patients. After poisoning with high dosages of benzodiazepines alone or combined with other drugs, the initial single dose of flumazenil will require supplementing with repeated low intravenous doses or an infusion to maintain wakefulness. In such patients, flumazenil also facilitates differential diagnosis and reduces the necessity for interventions. Flumazenil thus enhances recovery and allows more rapid discharge of patients sedated with benzodiazepines for diagnostic procedures and facilitates management of patients during the initial recovery period following general anaesthesia supplemented with benzodiazepines, but does not preclude normal monitoring during the recovery period. Flumazenil is clearly very useful in treating drug poisoning when benzodiazepines are a major component. By virtue of its specific benzodiazepine antagonist effects, flumazenil provides an innovative and well tolerated approach in clinical situations requiring rapid reversal of benzodiazepine-induced central nervous system depressant effects.

Pathophysiology and clinical basis of prevention and treatment of complications of chronic liver disease

Chronic liver failure is characterized by the appearance of jaundice, ascites, encephalopathy and/or gastrointestinal bleeding. Acute episodes of hepatic decompensation are frequently precipitated by additional events, e.g. septicaemia, diuretic therapy or excessive protein intake. Identification, correction and treatment of these precipitating factors are first steps in the management of chronic liver failure. Nutritional support is important in the treatment of cirrhotic patients, because malnutrition is one of the major determinants of patient outcome. Management of encephalopathy reduces the appearance of gut-derived nitrogenous toxins and corrects imbalances in amino acid metabolism. Treatment of ascites is salt restriction supported by gentle and incremental administration of diuretics. Ursodesoxycholic acid has become a new and promising modality in the management of cholestatic liver diseases. If conservative therapy fails to recompensate liver function, liver transplantation may be indicated.

Flumazenil in the treatment of portal systemic encephalopathy--an overview

Hepatic encephalopathy is a complex neuropsychiatric syndrome associated with acute, subacute and chronic liver failure, involving increased neural inhibition by activation of the GABA/benzodiazepine inhibitory neurotransmitter system. Improvement by GABA and benzodiazepine receptor antagonists as well as by chloride ionophore blockers has been shown in animal experiments. Recent reports indicate that flumazenil may improve hepatic encephalopathy in man. To date 46 episodes of HE in 41 patients have been treated with flumazenil with a short term success rate of 72%. Most of the patients were screened for exogenous benzodiazepines and found negative. These interesting observations should now be investigated in a randomised double-blind controlled study in patients with HE to evaluate the efficiency of this therapy.

Flumazenil does not improve hepatic encephalopathy associated with acute ischemic liver failure in the rabbit

The effect of flumazenil, a benzodiazepine antagonist, on hepatic encephalopathy was studied in rabbits with acute hepatic failure induced by a two-stage liver devascularization procedure. The rabbits were randomized for treatment with 5 mg/kg of flumazenil or the placebo. The drug was administered at two easily recognizable time points in the course of the encephalopathy: first, when the righting reflex was disturbed, and second, when the animal could no longer achieve to the sitting position. The response after flumazenil did not differ from that after the placebo, as measured by clinical evaluation and automated EEG analysis. Furthermore, the progression of the encephalopathy, as measured by the survival time after the first injection, was not affected by flumazenil.

Reversal of the behavioral and electrophysiological abnormalities of an animal model of hepatic encephalopathy by benzodiazepine receptor ligands

Behavioral and electrophysiological evidence implicating the GABA-benzodiazepine receptor complex in the pathogenesis of hepatic encephalopathy was obtained using an improved rat model of hepatic encephalopathy caused by thioacetamide-induced fulminant hepatic failure. After the administration of thioacetamide together with supportive therapy, acute hepatocellular failure developed in rats as a result of massive hepatocellular necrosis without evidence of renal failure or hypoglycemia. The evolution of hepatic encephalopathy in this model was sufficiently slow to readily permit the staging of the syndrome. Prominent features of the encephalopathy include a marked reduction in open field activity and an abnormal visual evoked response. Both the deficits in spontaneous motor function and visual evoked response abnormalities of rats in stages III to IV hepatic encephalopathy were significantly improved after the administration of the benzodiazepine receptor ligands flumazenil or Ro 15-4513. Doses of flumazenil or Ro 15-4513 that produced these effects in rats with hepatic encephalopathy had no detectable action on either the behavior or the visual evoked responses of normal rats. The ability of benzodiazepine receptor ligands to ameliorate both the behavioral depression and the visual evoked response abnormalities associated with hepatic encephalopathy in the thioacetamide-induced rat model suggest an involvement of the GABA/benzodiazepine receptor complex in the pathogenesis of hepatic encephalopathy. In addition, the similarity of these observations to those in rabbits with hepatic encephalopathy caused by galactosamine-induced fulminant hepatic failure is compatible with the hypothesis that the mechanisms of hepatic encephalopathy in these two distinct models share a common final pathway, the allosteric enhancement of GABAergic tone through the benzodiazepine receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzodiazepine antagonist in the treatment of human hepatic encephalopathy

Recently it was suggested that hepatic encephalopathy (HE) is mediated by an increased GABA-ergic tone. The logical consequence of such a hypothesis is the use of antagonists of the GABA -benzodiazepine receptor for treatment of HE. The experience with these drugs in human HE is limited. In order to get an estimate of the efficacy of this type of drug in humans 20 consecutive episodes of HE in 17 patients with acute or chronic liver failure were treated with flumazenil. All patients entered into the study were encephalopathic for up to 120 hours and failed to respond to conventional therapy. After an observation period of 8 hours, 15 mg of flumazenil were infused intravenously over 3 hours. Before and after treatment patients were examined neurologically and the Glasgow coma scale was calculated. In addition, somatosensory evoked potentials were recorded. In 5 out of 11 episodes in 10 patients with fulminant hepatic failure and in 7 out of 9 episodes in 7 patients with cirrhosis an unequivocal amelioration of HE was observed. The response to treatment occurred very rapidly. After stopping treatment in 8 out of these 12 episodes HE worsened again after 2 to 4 hours. The favourable clinical response was also documented by improvement of somatosensory evoked potentials. In 5 of the 8 episodes not reacting to flumazenil patients had signs of increased intracranial pressure. These findings indicate that flumazenil may be valuable in treatment of acute HE occurring in fulminant hepatic failure or in decompensated cirrhosis.

[Treatment of acute hepatic encephalopathy with flumazenil]

In animal studies as well as in a few cases in humans, the benzodiazepine antagonist flumazenil has been shown to reverse hepatic encephalopathy. The authors treated 3 patients with acute hepatic encephalopathy stage III or IV complicating cirrhosis. Two patients had an immediate recovery, maintained with a continuous infusion of flumazenil. In the third patient the clinical status dit not improve but the hepatic encephalopathy coexisted with major abnormalities in blood gases and electrolytes abnormalities, which could participate to the neurologic failure.

Evidence for the presence of a benzodiazepine receptor binding substance in cerebrospinal fluid of a rabbit model of hepatic encephalopathy

Based on the reversal of hepatic encephalopathy in animal models with administration of specific benzodiazepine receptor antagonists, it has been postulated that this syndrome may be mediated by an endogenous benzodiazepine-like compound. In this study using a radio-receptor assay, evidence for the existence of this substance has been demonstrated in cerebrospinal fluid but not sera of rabbits with hepatic encephalopathy due to galactosamine-induced hepature failure. Cerebrospinal fluid from rabbits with hepatic encephalopathy caused 36.1 +/- 5.03% displacement of 3H-Ro 15-1788 specific binding to cortical benzodiazepine receptors, compared to 11.7 +/- 0.76% in control animals (P less than 0.01). The benzodiazepine receptor binding activity has been shown to behave as a competitive inhibitor of radiolabeled benzodiazepine receptor binding. The finding of endogenous benzodiazepine binding activity affords a potential explanation for the amelioration of hepatic encephalopathy in this model with the administration of benzodiazepine receptor antagonists.

Improvement of hepatic encephalopathy treated with flumazenil

The effects of the benzodiazepine antagonist flumazenil were studied in 20 episodes of hepatic encephalopathy (HE) in 17 patients with acute (n = 9) or chronic (n = 8) liver failure who had not responded to conventional therapy. Patients with a history of benzodiazepine intake were excluded. Changes in HE stage, in Glasgow coma scale, and in somatosensory evoked potentials were measured. In 12 of 20 episodes HE stage improved. The response to treatment occurred rapidly (within 3-60 min). In 8 of these 12 episodes HE worsened 0.5-4 h after treatment. In 5 of the 8 episodes that did not respond to flumazenil patients had clinical evidence of brain oedema. Flumazenil may be valuable in the treatment of HE in acute and chronic liver failure.