Hepatic Pathophysiology Flashcards
Acute Hepatitis
Liver inflammation d/t viral infection, drug reaction, exposure to hepatotoxin (i.e. alcohol or carbon tetrachloride)
Acute Fulminant Hepatic Failure
Presents as rapid, massive necrosis of liver parenchyma & ↓liver size
Acute Viral Hepatitis
A oral-fecal route
B & C transmitted primarily percutaneously & via bodily fluid contact
Other viruses D, E, Epstein-Barr, Herpes Simplex, Cytomegalovirus, & Coxsackievirsus
Prodromal illness 1-2wks w/ fatigue, malaise, low-grade fever, N/V
Period may or may not be follow by jaundice - typically lasts 2-12wks
Complete recovery aeb normal serum transaminases usually takes 4mos
Clinical courses complicated & prolonged w/ Hepatitis B/C viruses
Hepatitis A
Least severe
Most patients recover in week to months
Transmission via fecal contamination
Common in 3rd world countries d/t improper sanitation
Hepatitis B
HBsAg (surface antigen)
Often anicteric - does not present w/ jaundice
→ fulminant hepatic necrosis or chronic hepatitis
HBsAg disappears w/ recovery but disease able to be diagnosed through Hepatitis B antibody presence
Transmission via sexual contact or blood
Hepatitis C
Antibodies not present for long period
Difficult to diagnosis - exclusion primarily
Subclinical non-icteric infection common
Rarely produces fulminant hepatic failure
Significant number those who are chronically infected will develop cirrhosis or liver cancer
20% percent develop cirrhosis (major cause hepatocellular carcinoma)
Produces asymptomatic carriers
No effective vaccine currently available
Transmission via blood
Hepatitis E
Similar to Hepatitis A
3rd world countries
Transmission via fecal contamination
Chronic Viral Hepatitis
Chronic active viral hepatitis = acute hepatitis byproduct
3-10% after B virus infection
At least 50% after C virus infection
Chronic Viral Hepatitis
Chronic active viral hepatitis = acute hepatitis byproduct
3-10% after B virus infection
At least 50% after C virus infection
Asymptomatic infectious carriers
- 3-30% patients w/ Hepatitis B (persistent HBsAg present in blood)
- 5-1% patient w/ Hepatitis C remain infectious (correlates w/ amount Hepatitis C viral RNA in blood)
Avoid contact w/ blood & secretions
Immunization highly effective against Hepatitis B infection
No Hepatitis C vaccine available & prior infection does not = immunity upon re-exposure
Post-exposure prophylaxis w/ hyperimmune globulin effect for Hepatitis B not C
Drug-Induced Acute Hepatitis
Clinical course resembles viral hepatitis
Difficult diagnosis
Most common cause = alcohol-induced
Other causes: Tylenol, salicylates, carbon tetrachloride, volatile anesthetics, Phenytoin, sulfonamides, Rifampin, Indomethacin, Isoniazid, Amiodarone, etc.
Acute Hepatitis
Preop Considerations
Postpone elective surgery
↑periop morbidity & mortality
Further hepatic dysfunction & failure risk
- Encephalopathy
- Coagulopathy
- Hepatorenal syndrome
Labs: BUN, creatinine, bilirubin, electrolytes, glucose, transaminase, alk phos, albumin, PT/INR, plt count
- Hep B HBsAg
- ETOH blood alcohol level
Hypokalemia & metabolic acidosis d/t vomiting
Hypomagnesemia in chronic alcoholics → predisposes to dysrhythmias
Correct dehydration & electrolyte abnormalities
Hypoalbuminemia usually not present except in protracted cases w/ severe malnutrition or chronic hepatitis
N/V → RSI
ALT > AST
ACUTE hepatitis
AST > ALT
Alcoholic hepatitis
Synthetic Liver Function
PT = best indicator
Prolongation >3-4sec (INR <1.5) following vitamin K (correct coagulopathy onset 24hr) admin indicates severe liver dysfunction
Acute Hepatitis
Intraop Considerations
GOAL = preserve existing hepatic function
Individualized drug selection & dosages
Acute viral hepatitis → CNS sensitivity to aesthetics
Alcoholic patients (unless acute intoxication) display cross-tolerance to IV & volatile anesthetic agents, require CV monitoring d/t additive depressant effects & possible alcoholic cardiomyopathy
↓anesthetic agents
Inhalational agents are generally preferable to IV agents d/t dependence on liver metabolism & elimination
Standard induction doses IV agents generally used d/t action terminated by redistribution vs. metabolism or excretion
Volatile Agent
Isoflurane - least effect on hepatic blood flow
Avoid ↓hepatic blood flow
- Hypotension, excessive SNS stimulation, ↑mean airway pressure during controlled ventilation
Chronic Hepatitis
Persistent hepatic inflammation >6mos aeb ↑serum aminotransferases
Classification based on 3 distinct syndromes (determined by liver biopsy)
- Chronic persistent hepatitis
- Chronic lobular hepatitis
- Chronic active hepatitis
Chronic Persistent Hepatitis
Present w/ acute Hepatitis (B or C) that has protracted course but eventually resolves
Characterized by chronic portal tract inflammation w/ normal cellular architecture preservation (minimal cell death)
Usually does not progress to cirrhosis (typically resolves)
Chronic Lobular Hepatitis
Present w/ acute hepatitis that resolves but followed by recurrent exacerbations
Characterized by inflammation foci & cellular necrosis in the lobules
Usually does not progress to cirrhosis
Chronic Active Hepatitis
Occurs most commonly after acute Hepatitis B or C episode
Characterized by chronic hepatic inflammation w/ cellular architecture destruction → global
Evidence of cirrhosis present initially or eventually develops