Atlas of pathophysiology, 2 Edition

Part II - Disorders

Gastrointestinal Disorders

Liver Failure

Any liver disease can end in organ failure. The liver performs more than100 separate functions in the body. When it fails, a complex syndrome involving the impairment of many different organs and body functions ensues. The only cure for liver failure is liver transplantation.

Causes

·   Viral or nonviral hepatitis

·   Cirrhosis

·   Liver cancer

Pathophysiology

Manifestations of liver failure include hepatic encephalopathy and hepatorenal syndrome.

Hepatic encephalopathy, a set of central nervous system disorders, results when the liver can no longer detoxify the blood. Liver dysfunction and collateral vessels that shunt blood around the liver to the systemic circulation permit toxins absorbed from the GI tract to circulate freely to the brain. Ammonia, a by-product of protein metabolism, is one of the main toxins causing hepatic encephalopathy. The normal liver transforms ammonia to urea, which the kidneys excrete. When the liver fails, ammonia is delivered to the brain. Short-chain fatty acids, serotonin, tryptophan, and false neurotransmitters may also accumulate in the blood and contribute to hepatic encephalopathy.

Hepatorenal syndrome is renal failure concurrent with liver disease. The kidneys appear to be normal but abruptly cease functioning. Blood volume expands, hydrogen ions accumulate, and electrolyte disturbances ensue. It's most common in patients with alcoholic cirrhosis or fulminating hepatitis. The cause may be the accumulation of vasoactive substances that cause inappropriate constriction of renal arterioles, leading to decreased glomerular filtration and oliguria. The vasoconstriction may also be a compensatory response to portal hypertension and the pooling of blood in the splenic circulation.

Signs and symptoms

·   Jaundice

·   Abdominal pain or tenderness

·   Nausea, anorexia, weight loss

·   Fetor hepaticus

·   Fatigue

·   Pruritus

·   Oliguria

·   Splenomegaly

·   Ascites, peripheral edema

·   Varices of esophagus, rectum, abdominal wall

·   Bleeding tendencies from thrombocytopenia (secondary to blood accumulation in the spleen), prolonged prothrombin time (from the impaired production of coagulation factors), petechiae

·   Amenorrhea, gynecomastia

Complications of liver failure include variceal bleeding, GI hemorrhage, coma, and death.

Diagnostic test results

·   Liver function tests reveal elevated levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and bilirubin.

·   Blood studies reveal anemia, impaired red blood cell production, elevated bleeding and clotting times, low blood glucose levels, and increased serum ammonia levels.

·   Urine analysis reveals increased urine osmolarity.

Treatment

·   Liver transplantation

·   Low-protein, high-carbohydrate diet

·   Lactulose

For ascites

·   Salt restriction, potassium-sparing diuretics, potassium supplements

·   Eliminating alcohol intake

·   Paracentesis, shunt placement

For portal hypertension

·   Shunt placement between the portal vein and another systemic vein

For variceal bleeding

·   Vasoconstrictor drugs

·   Balloon tamponade

·   Surgery

·   Vitamin K

P.199

SIGNS OF LIVER FAILURE

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