Acute Liver Failure

Acute liver failure is a disease of related to the impairment of liver functioning. It is an acute liver dysfunction that results in hepatic coma and coagulopathy (INR >2.0). This condition results within six weeks after the onset. It is an onset of hepatic encephalopathy within eight weeks of first symptoms of illness.

Classification of Acute Liver Failure

1. Hyperacute- Jaundice to encephalopathy results within 7 days after the onset. Cerebral oedema is a common clinical presentation. The common causes include paracetamol, hepatitis A, Ischemia.
2. Acute- Jaundice to encephalopathy results within 8-28 days after the onset. The common clinical presentation is cerebral oedema. The common causes are hepatitis B and drugs.
3. Subacute- Jaundice to encephalopathy results within 29 days to 12 weeks after the onset. The clinical presentations include rare cerebral oedema, ascites, peripheral oedema and renal failure is more common. The major cause is drugs.

What are the Causes of Acute Liver Failure?

The main cause of acute liver failure is viral hepatitis. The self-poisoning of paracetamol causes acute liver failure for 40-60 % and also caused due to idiosyncratic drug reactions.

• Infections – Infections caused by Hepatitis A, B, C, D, E, Herpes simplex, Epstein-Barr virus, Cytomelaovirus, TTV (Transfusion-transmitted virus) and Dengue fever.
• Drugs and Toxins­- Paracetamol, Carbon tetrachloride, idosynchratic drug reactions, Mushroom poisoning, and Sea anemone sting.
• Ischaemic- Cardiogenic shock, Hypotension, Heat stroke, Cocaine, ephedrine, methamphetamines.
• Vascular- Acute Budd-Chiari syndrome, Sinusoidal obstruction syndrome
• Miscellaneous- Wilson’s disease, Acute fatty liver of pregnancy, HELLP syndrome (Eclampsia), Non-functuioning of primary graft after liver transplantation.
• Drugs- They cause idiosyncratic acute liver failure. These drugs includes Isoniazid, Sulfonamides, Phenytoin, Nitrofurantoin , Allopurinol, Diclofenac, Ofloxacin, Dapsone, Valproic acid, Propylthiouracil, Halothane, Disulfiram, Amiodarone, Didanosine, Metformin, Ciproflixacin, Ketoconazole, Nicotinic acid, Gemtuzumab etc.
• Other combination agents with enhanced toxicity- These drugs are Trimethoprim-sulfamethoxazole, Rifampin-isoniazid, Amoxicillin-clavulanate.

Aetiology of Acute Liver Failure

1. In Western countries and some developing nations, about 12% of acute liver failure is caused by

 

idioidiosyncratic drug reactions. Antituberculosis medications, non-steroidal anti-inflammatory drugs, anaesthetic agents and antiseizure medications and recreated drug ecstasy (3, 4-methlene dioxymetamphetamine) can also cause ALF. Herbal remedies containing green tea extract can also be the cause of ALF.

2. Amanita phalloides is a poisonous mushroom that causes acute liver failure. Mushroom poisoning shows muscarinic effects such as, profuse sweating, vomiting and diarrhea.
3. The pregnant woman shows hepatic necrosis in the last trimester due to fatty liver and eclampsia.
4. Low cardiac output, Hypotension and some other ischemic syndromes can cause ALF.
5. Autoimmune hepatitis can cause acute liver failure.

Clinical Findings & Symptoms of Acute Liver Failure

• Patients of acute liver failure reported with deepening jaundice, coagulopathy, ascites, hyperammonia, progressing coma, rapid shrinking of liver.
• Common symptoms may include fever, anorexia, abdominal pain and vomiting due to liver impairment.
• AST and ALT are greatly elevated (200-10,000 U/L ).
• Liver undergoes massive necrosis and collapse.
• The disease starts with benign hepatitis but becomes severe during second week of the disease.
• Hyperreflexia can be seen.
• A positive extensor plantar response can be seen.
• Fector hepaticus is present.
• Impairment of renal function.

Laboratory findings include

• Elevated levels of serum bilirubin (>15-20 mg/dL).
• Increased levels of AST and ALT (> 3000 U/L)-they may decrease due to massive necrosis and collape.
• Decrease in serum albumin level.
• Prolonged Prothrombin time and INR.
• Elevation of blood ammonia levels.
• Hypoglycemia
• Low blood urea nitrogen
• Frequent hyperpnea
• Metabolic acidosis.
• Mixed respiratory alkalosis

Investigations for the diagnosis of Acute Liver Failure

1. Haematology Findings- Complete blood count (white blood cells, hematocrit, haemoglobi, anti-hepatitis B core), Coagulation Panel (Prothrombin time/INR, Factor V), Blood group.
2. Biochemical Findings- Serum chemistries (sodium, potassium, bicarbonate, chloride, urea, creatinine, calcium, magnesium, phosphate, glucose). Hepatic Panel (Aspartate aminotrasferase, Alanine aminotrasferase, alkaline phosphatase,level of albumin, total protein level,and the total bilirubin level).
3. Arterial Blood Gas- It includes pH, PaCo2, PaO2, ammonia and lactate.
4. Virology Findings- Hepatitis B surface antigen, Hepatitis A antibody, Hepatitis antibody, HCV RNA, IgM Hepatitis E antibody, Hepatitis D antibody, HSV, CMV, EBV, PCR, HIV.
5. Toxicology Findings- Level of Paracetamol, Blood alcohol and urine drug screen.
6. Miscellaneous Findings- pregnancy test and urine copper.

Complications of Acute Liver Failure

• Renal failure
• Hepatic coma
• Cerebral edema
• Extreme prolongation of prothrombin time
• INR greater than 4
• Sepsis
• Hemorrhage
• Cardiorespiratory arrest
• Hepatic fibrosis and cirrhosis

What is the treatment Acute Liver Failure?

The most effective therapy is excellent care. Orthotopic liver transplantation is successful.

N-acetylcysteine is used that help in acetaminophen toxicity. Close monitoring of fluids and electrolytes is important. Normal blood glucose level is maintained by the infusion of 10% dextrose solution (6-8 mg/kg/min). Diuretics, tranquelizers and sedatives are prescribed to the ALF patients.

Tags: causes of liver failure, liver diseases, liver failure