Early death from paracetamol (acetaminophen) induced fulminant hepatic failure without cerebral oedema

Interstitial ion homeostasis and acid-base balance are maintained in oedematous brain of mice with acute toxic liver failure

Acute toxic liver failure (ATLF) rapidly leads to brain oedema and neurological decline. We evaluated the ability of ATLF-affected brain to control the ionic composition and acid-base balance of the interstitial fluid. ATLF was induced in 10-12 weeks old male C57Bl mice by single intraperitoneal (i.p.) injection of 100 μg/g azoxymethane (AOM). Analyses were carried out in cerebral cortex of precomatous mice 20-24 h after AOM administration. Brain fluid status was evaluated by measuring apparent diffusion coefficient [ADC] using NMR spectroscopy, Evans Blue extravasation, and accumulation of an intracisternally-injected fluorescent tracer. Extracellular pH ([pH]_e) and ([K⁺]_e) were measured in situ with ion-sensitive microelectrodes. Cerebral cortical microdialysates were subjected to photometric analysis of extracellular potassium ([K⁺]_e), sodium ([Na⁺]_e) and luminometric assay of extracellular lactate ([Lac]_e). Potassium transport in cerebral cortical slices was measured ex vivo as ⁸⁶Rb uptake. Cerebral cortex of AOM-treated mice presented decreased ADC supporting the view that ATLF-induced brain oedema is primarily cytotoxic in nature. In addition, increased Evans blue extravasation indicated blood brain barrier leakage, and increased fluorescent tracer accumulation suggested impaired interstitial fluid passage. However, [K⁺]_e, [Na⁺]_e, [Lac]_e, [pH]_e and potassium transport in brain of AOM-treated mice was not different from control mice. We conclude that in spite of cytotoxic oedema and deregulated interstitial fluid passage, brain of mice with ATLF retains the ability to maintain interstitial ion homeostasis and acid-base balance. Tentatively, uncompromised brain ion homeostasis and acid-base balance may contribute to the relatively frequent brain function recovery and spontaneous survival rate in human patients with ATLF.

Forensic pharmacovigilance: Newer dimension of pharmacovigilance

Drug safety for the patients is of paramount importance for a medical professional. Pharmacovigilance attempts to ensure the safety of patients by keeping a close vigil on the pattern of adverse events secondary to drug use. Number of medicolegal cases is at rise since last few years. Forensic sciences and pharmacovigilance need to work hand in hand to unlock the mystery of many criminal and civil proceedings. Pharmacovigilance offers its wide scope in forensic sciences by putting forward its expertise on adverse profile of drugs which may be instrumental in solving the cases and bringing the justice forth. It may range from as simple affairs as defining the adverse drug reaction on one hand to putting expert advice in critical criminal cases on the other one. Pharmacovigilance experts have to abide by the ethics of the practice while executing their duties as expert else it may tarnish the justice and loosen its dependability. As a budding discipline of science, it is confronted with several hurdles and challenges which include reluctance of medical professionals for being involved in court proceedings, extrapolations of facts and data and variations in law across the globe etc. These challenges and hurdles call the medical fraternity come forward to work towards the momentous application of pharmacovigilance in the forensic sciences. Evidence based practice e.g. testing the biological samples for the presence of drugs may prove to be pivotal in the success of this collaboration of sciences.

Liver transplantation in adults: Choosing the appropriate timing

Liver transplantation is indicated in patients with acute liver failure, decompensated cirrhosis, hepatocellular carcinoma and rare liver-based genetic defects that trigger damage of other organs. Early referral to a transplant center is crucial in acute liver failure due to the high mortality with medical therapy and its unpredictable evolution. Referral to a transplant center should be considered when at least one complication of cirrhosis occurs during its natural history. However, because of the shortage of organ donors and the short-term mortality after liver transplantation on one hand and the possibility of managing the complications of cirrhosis with other treatments on the other, patients are carefully selected by the transplant center to ensure that transplantation is indicated and that there are no medical, surgical and psychological contraindications. Patients approved for transplantation are placed on the transplant waiting list and prioritized according to disease severity. Thus, the appropriate timing of transplantation depends on recipient disease severity and, although this is still a matter of debate, also on donor quality. These two variables are known to determine the “transplant benefit” (i.e., when the expected patient survival is better with, than without, transplantation) and should guide donor allocation.

Critical care management of patients before liver transplantation

The critical care management of patients before liver transplantation is aimed at optimizing hepatic and extrahepatic organ function before the transplant operation, with a goal to favorably influence perioperative and postoperative graft and patient outcomes. Critical illness in liver disease can present in the context of acute liver failure or acute on chronic liver failure. The differing pathophysiologic processes underlying these 2 types of liver failure necessitate specific approaches to their intensive care management. In their extreme presentations, both types of liver failure present as multiorgan system failure; and therefore, the critical care management of these entities requires a systematic multiorgan system approach to address hepatic and extrahepatic organ dysfunction. This review provides a multiorgan system-based description of critical care management of acute liver failure and acute on chronic liver failure before liver transplantation.

Arterial ammonia and clinical risk factors for encephalopathy and intracranial hypertension in acute liver failure

High circulating ammonia concentrations are common in patients with acute liver failure (ALF) and are associated with hepatic encephalopathy (HE) and intracranial hypertension (ICH). Other risk factors are poorly characterized. We evaluated the relation of the admission arterial ammonia concentration and other clinical variables with the development of HE and ICH. Arterial ammonia was measured on admission to the intensive care unit in 257 patients; 165 had ALF and severe HE, and there were 3 control groups: acute hepatic dysfunction without severe HE (n = 50), chronic liver disease (n = 33), and elective surgery (n = 9). Variables associated with ICH and HE were investigated with regression analysis. Ammonia was higher in ALF patients than controls. An independent risk factor for the development of severe HE and ICH, a level greater than 100 mumol/L predicted the onset of severe HE with 70% accuracy. The model for end-stage liver disease (MELD) score was also independently predictive of HE, and its combination with ammonia increased specificity and accuracy. ICH developed in 55% of ALF patients with a level greater than 200 mumol/L, although this threshold failed to identify most cases. After admission, ammonia levels remained high in those developing ICH and fell in those who did not. Youth, a requirement for vasopressors, and renal replacement therapy were additional independent risk factors.

CONCLUSION

Ammonia is an independent risk factor for the development of both HE and ICH. Additional MELD scoring improved the prediction of HE. Factors other than ammonia also appear important in the pathogenesis of ICH. Ammonia measurements could form part of risk stratification for HE and ICH, identifying patients for ammonia-lowering therapies and invasive monitoring.

Amanita phalloides poisoning: reassessment of prognostic factors and indications for emergency liver transplantation

BACKGROUND/AIMS

Amanita phalloides poisoning is an uncommon cause of acute liver failure with an especially rapid course. The aim of this study was to re-assess transplantation criteria in patients with mushroom poisoning.

METHODS

Twenty-seven patients admitted for Amanita phalloides poisoning were studied. Previously reported transplantation criteria, including the recent Ganzert's criteria, were tested retrospectively.

RESULTS

The rate of fatal intoxication (death and/or transplantation) was 8/27 (30%). An interval between ingestion and diarrhea <8h was a very early predictor of a fatal outcome (accuracy of 78%). Later on, non-paracetamol and paracetamol King's College criteria were superior to Clichy's and Ganzert's criteria (accuracy of 100% compared to 85% and 85%, respectively). Encephalopathy and renal insufficiency were not constant in the fatal intoxication group. Prothrombin index below 10% 4 days or more after ingestion had a 100% accuracy for predicting a fatal outcome.

CONCLUSIONS

Liver transplantation should be strongly considered in patients with an interval between ingestion and diarrhea <8h. Encephalopathy should not be an absolute prerequisite for deciding transplantation. From day 4 after ingestion, prothrombin index lower than 10% ( approximately INR of 6) alone is a reliable tool for deciding emergency transplantation.