Acute liver failure

ACUTE LIVER FAILURE

Acute liver failure is defined as the rapid development of hepatocellular dysfunction (WITHIN 8 WEEKS OF DISEASE ONSET), specifically coagulopathy and mental status changes (encephalopathy) in a patient without known prior liver disease.
The commonest causes are viral hepatitis ( A , B,C,E) and drugs and toxins( commonest is acetaminophen)

Hepatic Failure

Most severe clinical consequence of liver disease
May be:
result of sudden and massive hepatic destruction
end-point of progressive chronic liver disease ( the name here is called decompensated liver )
80% - 90% loss of hepatic functional capacity

Hepatic Failure

Morphologic alterations causing liver failure:
Massive hepatic necrosis
Mechanisms:
(i) direct damage to hepatocytes
(ii) immune-mediated hepatocyte destruction
a. drug or toxin-induced
b. infection – viral hepatitis except hep. C
Chronic liver disease – most common cause
Hepatic dysfunction without over necrosis – e.g. Reye’s syndrome, tetracycline toxicity, acute fatty liver of pregnancy


Hepatic Failure
Clinical Features:
Jaundice
Hypoalbuminemia  peripheral edema
Hyperammonemia  cerebral dysfunction
Fetor hepaticus  “musty” or “sweet & sour” body odor due to mercaptan formation by action of GI bacteria on methionine (sulfur-containing)
Impaired estrogen metabolism  hyperestrogenemia
(a) palmar erythema – 2o to local vasodilatation
(b) spider angiomas – central, pulsing, dilated arteriole from which small vessels radiate
(c) hypogonadism & gynecomastia in males

Hepatic Failure

Clinical Features:


Multi-organ system failure
respiratory failure with pneumonia, sepsis + renal failure  cause of death
Coagulopathy
impaired synthesis of factors II, VII, IX and X  (+) bleeding tendency

Hepatic Failure

Complications:

Hepatic encephalopathy

associated with increased blood ammonia levels
reversible if underlying hepatic condition can be corrected
features:
(a) change in consciousness
(b) fluctuating neurologic signs – rigidity, hyperreflexia, asterixis

Hepatic Failure

Complications:

Hepatorenal syndrome

renal failure in patients with chronic liver disease
main renal functional abnormalities:
(a) sodium retention
(b) impaired free water excretion
(c) decreased renal perfusion
(d) decreased GFR


Hepatic Failure
Complications:

Hepatorenal syndrome

decreased urine output with rising BUN & creatinine
ability to concentrate urine retained  hyperosmolar urine without proteins; abnormal sediments; dec. Na+