Liver Failure Flashcards
When does hepatic failure occur?
- when 80-90% of the functional capacity of the liver is lost
- 80% mortality w/o transplant
What is acute hepatic failure defined as?
- occurring w/in 26 weeks (6 months) of some initial injury
- occurs in absence of preexisting liver dz
- is associated with encephalopathy and coagulopathy
What are the main causes of acute liver failure? (mnemonic)
ABCDEF
- Acetominophen, Hepatitis A, Autoimmune hepatitis
- Hepatitis B
- Hepatitis C, Cryptogenic
- Drugs/toxins/ hepatitis D
- Hepatitis E, esoteric causes (Wilson’s dz, Budd-chiari)
- Fatty change of the microvesicular type (fatty liver of pregnancy, valproate, tetracycline, Reye syndrome)
What are the morphological changes of acute hepatic failure?
- massive hepatic necrosis leading to broad regions of parenchymal loss surrounding areas of regenerating hepatocytes
- small shrunken liver
- diffuse microvesicular steatosis (diffuse poisoning of liver cells w/o obvious cell death and parenchymal collapse)
What are the clinical signs of acute hepatic failure?
- N/V, jaundice that progresses to life-threatening encephalopathy and coagulation defects
- moderate increase in liver transaminases
- hepatomegaly (and eventual shrunken liver)
In acute hepatic failure, what is a decline in serum transaminases indicative of?
Fewer viable hepatocytes, NOT recovery!
What is indicative of a poor prognosis in acute hepatic failure?
- decrease in liver enzymes (indicates few remaining hepatocytes)
- worsening jaundice
- coagulopathy
- encephalopathy
What are the possible consequences of acute hepatic failure? (7)
- jaundice and icterus
- cholestasis
- hepatic encephalopathy (due to increased serum ammonia) leading to:
- – rigidity and hyperreflexia
- – asterixis (CHARACTERISTIC)
- coagulopathy
- DIC
- portal HTN
- hepatorenal syndrome (a form of renal failure in ppl w/liver failure whose kidneys are otherwise normal)
How is chronic liver failure defined?
- it is associated with cirrhosis, though not mutually exclusive
- is associated with hepatitis B and C, NAFLD, alcoholic fatty liver dz
What are the ultimate causes of death in chronic liver failure?
- hepatic encephalopathy
- bleeding from esophageal varices
- bacterial infections
How is cirrhosis defined?
- diffuse transformation of the entire liver into regenerative parenchymal nodules surrounded by fibrous bands and variable degrees of vascular (portosystemic) shunting)
What are the Child-Pugh classifications of cirrhosis and what is it for?
- the classifications help monitor the decline of the patients on the path to chronic liver failure
- Class A: well compensated
- Class B: partially decompensated
- Class c: decompensated
What are clinical symptoms of cirrhosis? Do you always see them?
- don’t always see symptoms, ~40% of patients
Symptoms:
- jaundice + pruritis
- hypoalbuminemia –> systemic edema
- hyperammonemia
- fetor hepaticus: mercaptan formation
- hyperestrogenemia due to impaired metabolism can lead to palmar erythema, spider angiomata, hypogonadism, gynecomastia (males)
- increased risk of developing hepatocellular carcinoma
What are prehepatic causes of portal HTN?
- obstructive thrombosis
- narrowing of portal v. before entering the liver
- massive splenomegaly w/increased splenic blood flow
What are posthepatic causes of portal HTN?
- severe right heart failure
- constrictive pericarditis
- hepatic v. outflow obstruction
What are intrahepatic causes of portal HTN?
- usually CIRRHOSIS
- shistosomiasis
- massive fatty change
- diffuse fibrosing granulomatous dz (like sarcoidosis)
- increased resistance to portal flow (at lvl of sinusoids)
- increased portal venous flow due to hyperdynamic circulation
What are clinical consequences of portal HTN?
- ascites
- portosystemic shunt formation
- congestive splenomegaly
- hepatic encephalopathy
What is ascites?
- excess fluid in the peritoneal cavity
What is the composition of ascites fluid?
- serous fluid (< 3gm/dl albumin)
- neutrophils (suggests infection)
- blood (suggests disseminated intraabdominal cxr
What are the mechanisms that lead to ascites?
- sinusoidal HTN: drives fluid into Space of Disse which is drained by lymphatics (space beneath endothelial cells)
- percolation of hepatic lymph in peritoneal cavity: thoracic duct can’t keep up, fluid leaks out
- splanchnic vasodilation: causes systemic hypotension -> vasoconstriction –> RAAS activation –> Na+ retention –> increased perfusion pressure –> transudation into abd. cavity
What are portosystemic shunts? Examples of some?
- flow that’s reversed from the portal into systemic circulation where there are shared capillary beds
- esophageal varices
- caput medusa (dilated subq veins from umbilicus to rib margins)
- hemorrhoids (rectum)
What is hepatopulmonary syndrome? Symptoms of?
- hypoxia + dyspnea due to ventilation/perfusion (V/Q) mismatch from rapid blood flow through dilated vessels w/decreased time for diffusion
- exacerbated in upright position due to gravity
- improves in recumbent position
What is portopulmonary HTN? Symptoms of?
- excessive pulmonary vasoconstriction and vascular remodeling w/concomitant portal HTN
- it’s when you have pulmonary arterial HTN in liver dz and portal HTN
- dsypnea on exertion and clubbing
What is acute-on-chronic liver failure?
- it’s when ppl w/stable, well-compensated chronic liver dz develop sudden signs of acute liver failure
- they commonly have established cirrhosis and extensive vascular shunting
- there are significant amounts of parenchyma w/borderline vascular supply that are vulnerable to superimposed insults
