| Hepatic Encephalopathy |
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| CATEGORIES ABOUT HEPATIC ENCEPHALOPATHY | |
| gastroenterology | |
| hepatology | |
| neurology | |
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PATHOGENESIS Cirrhosis will obstruct the passage of blood through the Liver causing Portal Hypertension . This means it is difficult for blood from the Intestine s to go through the liver to get back to the Heart . Portal-systemic Anastamoses ("shunts") develop, and portal blood (from the intestinal veins) will bypass the liver and return to the heart via another route without undergoing first-pass detoxification by the liver. Furthermore, the liver (damaged from the cirrhosis) will not be functioning as well as it should be, so blood that does travel through the liver may not be as detoxified as it otherwise would be. The toxic substances involved are not well understood, but have been thought to include Ammonia (NH3) and Mercaptan s. Ammonia is normally converted to Urea by the liver and, as with Mercaptan s, is produced by the Bacteria l breakdown of protein in the intestines. Ammonia can cross the Blood-brain Barrier , where it causes the support cells of the brain ( Astrocyte s) to swell. The swelling of the brain tissue increases Intracranial Pressure , and can lead to Coma or Death via Herniation of the brainstem. GRADING OF SYMPTOMS Grading of the symptoms of hepatic encephalopathy is as follows:
TREATMENT It is important to remove excess protein from the lumen of the gut. If there is a gastrointestinal bleed (for instance, ruptured Oesophageal Varices ) this should be stopped, as it serves as a protein supply for bacteria. Dietary intake of protein should be minimised. Special enteral feeding formulations with a high concentration of branched-chain amino acids are sometimes used in therapy, as is parenteral nutrition. Lactulose is a compound that will cause osmotic diarrhoea, lessening the time bacteria have to metabolise proteins and produce toxic substances. As well as this, it acidifies the bowel, causing ammonia (NH3) to be converted to ammonium (NH4+) which is less readily absorbed. Recent evidence suggests there is little evidence for its use, although it continues to be used in clinical practise. (Als-Nielsen ''et al'' 2004). Antibiotics (such as Metronidazole ) may be given to kill bacteria present in the gut. Neomycin , a non-absorbable aminoglycoside, is becoming less popular as it has been found that part of it was indeed absorbed due to increased gut permeability, increasing the risk of renal failure and hearing loss. REFERENCE
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