Hepatobiliary Flashcards
Define hepatic encephalopathy
spectrum of neuropsychiatric abnormalities seen in patients with liver dysfunction after exclusion of other known brain diseases
What are the classifications used by people and vets for HE
A: acute liver failure in the absence of pre-existing liver disease
B: associated with portal systemic bypass
C: associated with cirrhosis and portal hypertension
What are the subcategories of veterinary HE
0- None
1 - Mild decrease mobility, apathy, or both
2- severe apathy, ataxia, or both
3- hypersalivation, severe ataxia, head pressing, blindness, circling
4. seizures, stupor, coma
How is ammonia handled in the liver
Net Loss- ammonia detoxification
1) Urea cycle- converts NH3 to urea: Low affinity but high capacity, occurs during alkalosis
2) Glutamine production: High affinity, low capacity occurs during acidosis
How is ammonia handled in the intestines
Net gain
Microgranisms break down urea to produce ammonia
Enterocytes breakdown glutamine to make glutamate and NH3
How is ammonia handled in the skeletal muscle
Sink
Glutamine production
How is ammonia handled in the cerebrum
Glutamine made in astrocytes, broken down in the neurons
NH3 freely crosses BBB
What role to astrocytes place in HE
Glutamine re-enters astrocyte and metabolized back to NH3 leads to mitochondrial damage, ROS and osmotic swelling
Glutamate release cuases aggitation confusion and seizures
What are the contributors to HE development
Aromatic amino acids, altered neuroreceptors Bile acids, endogenous benzodiazipines False neurotransmitters Mercaptans- toxic metabolits Gaba, Glutamine
What are common underlying causes of HE in veterinary patients and their class
Conginetal PSS (B) Developemnt of PSS (c) ALF (A) Congenital urea recycling disorders- dogs Arginine deficiency in Hepatic lipidosis
What are 10 precipitating factors for HE development
High protein diet. GI hemorrhage, Hypokalemia, azotemia/dehydration, alkalosis, diuretic admin, blood transfusion, sedative use, SIRS/Sepsis, arginine deficiency in cats
How does ammonia play in the diagnosis of HE
Fasting concentrations rarely predict severity. Not run in people. But still recommended vet.
Sample handling important EDTA/Lithium heparin tube
run in 30 minuts
RBCs can release NH3 ex vivo
What is the number one goal of treatment for HE
Treat underlying cause of HE
When should enemas be given with HE
if constipated, or if severely neurologically affected
Warm water as good as lactulose
What are the diet recommendations for HE
Dogs: Protein limited
Cats: need protein especially with hepatic lipidosis
Which anticonvulsants are recommended for HE
Levetiractam,- renally excreted
Pheno okay for short term shown to control seizures with CPSS; get profound sedation
Why are benzodiazepines not recommended for HE
Liver metabolize, Can get ALF in oral admin to cats
May cause excessive sedation
How is albumin production by the liver increased
decreased COP, Adquate nutrition increase
Carbs, and increased COP decrease production
What is the net charge of albumin and the half life
66Kda
Negative
D 7-10 days, C 6-9 days
How does total plasma protien indicate hypoalbumenima and hypoprotienemia
< 5.8 g/dl strongly indicates hypoalbum and hypoprotienemia
What can falsely increase total plasma protien measurements by refractometer
hyperglycemia and hypercholesteremia
Define acute liver injury
acute hepatocellular damage and necrosis with retained hepatic function
Define acute liver failure
occurs once hepatocelluar damage is so extensive that it compromise hepatic synthetic, excretory and regulatory functions
