Acute Liver Failure
PGMEE High Yielding Facts
1. The clinical evidence of severe acute hepatitis associated with the altered sensorium and elevated prothrombin time indicates that the patient is suffering from Acute Liver Failure (ALF).
2. The most widely accepted definition of ALF includes evidence of coagulation abnormality - usually an INR >= 1.5 and any degree of mental alteration in a patient without preexisting cirrhosis and with an illness of < 26 weeks duration.
3. The term fulminant hepatic failure (FHF) has also been used for patients in whom encephalopathy develops within 2 weeks of the onset of jaundice. However, the American Association for the Study of Liver Diseases (AASLD) mentions that terms signifying the length of illness are not particularly helpful since they do not have prognostic significance distinct from the cause of the illness.
4. Causes of ALF include acetaminophen (paracetamol) toxicity, drug induced hepatotoxicity, viral hepatitis, autoimmune disease, Wilson disease, Budd-Chiari syndrome and malignant infiltration. In up to 17% of cases the etiology is indeterminate.
5. Any history of frequent travel and stays away from home suggestive of either food borne hepatitis A or hepatitis B following sexual contact. However, it should be kept in mind that the patient may be in the window period, during which serology may yield false negative results.
6. In addition, although acetaminophen (paracetamol) levels are not elevated, overdose cannot be ruled out as levels may have normalized by the time of presentation.
7. Transaminase levels are rarely elevated beyond 500 U/l in alcoholic hepatitis. ALT/AST levels >500 U/l make alcoholic hepatitis unlikely and should prompt consideration of another etiology. In addition, AST levels are usually higher than ALT levels in alcoholic hepatitis.
8. While right heart failure may precipitate ALF, this is highly unlikely when the JVP is not elevated.
9. Key elements of management include prevention of constipation and lactulose administration, IV antibiotics and a dose of Vitamin K.
10. While N-acetylcysteine is primarily used for management of acetaminophen (paracetamol) over-dosage and associated ALF, there is evidence showing it to be of benefit in acute liver failure due to other causes as well and thus should be considered.
11. Since the condition may progress rapidly, early transfer to the intensive care unit (ICU) is preferred once the diagnosis of ALF is made. In addition, these patients should ideally be managed at a transplant center as liver transplantation may be considered in select cases.
12. The King's College Hospital (KCH) criteria and the Model for End-Stage Liver Disease (MELD) score may be used as prognostic models to decide on which of these patients would benefit from liver transplantation.
13. The administration of nephrotoxic antibiotics such as neomycin should be avoided in patients with ALF because of the risk of nephrotoxicity.
14. Sedation is to be avoided if possible. Unmanageable agitation may be treated with short-acting benzodiazepines in small doses - not a long acting one like chlordiazepoxide.
15. Note that if a definite etiology for the ALF is found (for example, Wilson Disease), specific therapy should be instituted where possible (i.e. copper chelation in Wilson Disease).
