Hepatic Lecture Flashcards
the liver is the largest organ, making up what % of body weight in adults and neonates?
2% adults (1.5 kg)
5% neonates
the liver has __ segments
8
the liver has __ lobes
2
the functional units of the liver are what? (2)
1) lobule
2) acinus
what % of the total blood volume goes to the liver?
10-15%
the liver holds ___ ml of blood per 100gm of tissue
25-30 ml
the liver holds blood that is ___% venous blood
70% venous blood
hepatic blood flow is _____ ml/min
1200-1400 ml/min
hepatic blood flow receives ___% cardiac output
25%
where is there more blood flow; the portal vein or the hepatic artery?
portal vein (70-80%) over hepatic artery (20-30%)
what is the hepatic acinus?
the functional microvascular unit of the liver
what does the hepatic acinus consist of? (4)
- terminal portal venule
- hepatic arteriole
- bile duct
- lymph vessels and nerves
describe hepatic blood flow
high flow, low resistance
how large of a blood reservoir is the liver?
normal 450ml (10% TBV) expandable to 0.5-1 L in cases of CHF
the liver contains ____ of all lymph in the body
half
the hepatic artery is dependent on _______ to perfuse the liver
systemic arterial pressure
a highly compliant liver has ____ ml/mmHg for each 100g of liver weight
2-3 ml/mmHg
raising hepatic venous pressure by 1mm/hg results in an increase of ____ ml in a highly compliant liver
40-50 ml
regulation of hepatic blood flow is done intrinsicly by
- autoregulation
- metabolic control
regulation of hepatic blood flow is done extrinsically by
- neural control
- humoral control
how will anesthetics affect hepatic blood flow?
decrease
how does controlled ventilation affect portal venous blood flow?
decrease
regional anesthesia will have what affect on hepatic blood flow?
decrease, along with decreasing systemic blood pressure
how will controlled hypotension by sodium nitropresside alter hepatic blood flow?
no change, due to an increased portion of blood flow to the portal vascular bed
can the site of surgery affect hepatic blood flow?
yes, upper abdominal surgery decreasing flow up to 60%
the liver synthesizes all proteins with the exception of what?
gamma globulin
where is albumin produced?
the liver
what does albumin do?
maintains intravascular oncotic pressure
what is used as a indicator of chronic liver disease?
serum albumin
what is a normal serum albumin?
3.5-6 g/dl
the liver produces what coagulation factors? (9)
vitamin K dependent factors
- II, VII, IX, and X
non-dependent factors
- V, XI, XII, XIII, fibrinogen
what factors are NOT produced byt the liver?
- III (tissue thromboplastin)
- IV (calcium)
- VIII (von willebrands)
what is a good indicator of acute hepatic dysfunction?
- PT (prothrombin time)
what % liver function is needed to maintain adequate coagulation?
20-30%
what is a byproduct of deaminating amino acids by the liver?
ammonia
* can also be produced by GI bacteria
how does the liver remove ammonia?
by forming urea
the liver stores large amounts of carbohydrates in the form of what?
glycogen
how long until liver glycogen is depleted while NPO
24 hours
how does the liver help regulate blood glucose?
- stores glucose as glycogen
- converts carbohydrates, amino acids and TAGs
in PTs with impaired liver function, will glucose go up or down?
up, higher than post-meal levels found in normal hepatic function
the majority of cholesterol synthesized in the liver is converted to…
bile salts, then secreted in the bile
what phagocytize bacteria entering the liver from the intestines?
kupffer cell (macrophages)
how much bacteria does the liver trap using Kupffer cell macrophages before the bacteria can enter systemic circulation?
over 99%
red blood cell life span is how long?
120 days
heme that is released from the breakdown of hemoglobin is converted into
free bilirubin
free, or unconjugated bilirubin, is conjugated in the liver and secreted where?
into the bile to be transported to the small intestines
what is jaundice?
the yellow-green tint of the body tissue that results from bilirubin accumulation in extracellular fluids
when is skin discoloration of jaundice visibile?
when plasma bilirubin reaches 3x normal value
how can bilirubin accumulation occur? (2)
- increased breakdown of hemoglobin (hemolysis)
- obstruction of bile duct
hemolytic jaundice is associated with what?
an increase in unconjugated (indirect) bilirubin
obstructive jaundice is associated with what?
an increase in conjugated (direct) bilirubin
unconjugated bilirubin (lipid soluble) travels to the liver bound to what?
albumin
what does the liver do to bilirubin to make it exreteable?
conjugates bilirubin to a water-soluble form
how much bilirubin is produced daily?
300 mg
narcotics effect on common bile duct pressure
increases
what narcotic has the greatest effect on common bile duct pressure
fentanyl (increases)
how is an increase in bile duct pressure via narcotics attenuated? (4)
- NTG
- nalonone
- atropine
- glucagone
what is drug biotransformation?
converstion of lipophilic substances to excretable metabolites
phase I enzymatic reactions consists of…
oxidation by cytochrom P-450 (>90%)
phase II enzymatic reactions consist of…
conjugation with glucoronic acid to increase water solubility for biliary excretion
what factors affect drug metabolism? (5)
- HBF
- protein binding
- intrinsic hepatic clearance
- enzyme inducing compounds
- self-induced drugs
what liver enzyme tests are used to evaluate impaired liver function? (4)
- alkaline phosphatase (ALP)
- alanine transaminase (ALT)
- aspartate transaminase (AST)
- gamma-glutamyl transpeptidase (GGTP)
what is the alkaline phosphatase (ALP) test for?
- evaluates liver function
- enzyme levels increased when bile ducts are blocked
what is the alanine transaminase (ALT) test for?
- a liver function test
- best for detecting hepatitis
what is the aspartate transaminase (AST) test for?
evalutates liver function,
not as specific as ALT or ALP
what is the gamma-glutamyl transpeptidase (GGTP) test?
sensitive marker for cholestatic damage
normal alanine aminotransferase (ALT) levels
5-40 IU/L
normal alkaline phosphatase (ALP) levels
13-39 IU/L
what (all) tests can be used to evaluate liver function? (7)
- liver enzymes (ALT, ALP, AST, GGT)
- PT
- total proteins
- albumin
- bilirubin
- platelets
- ammonia
how is serum albumin effected by liver disease (like cirrhosis)?
decreased
what clotting factor is associated with acute liver disease?
factor VII
prothrombin is which factor?
factor II
whats a normal PT?
10-12 seconds
PT can be affected by (5)
- liver disease
- coumarin therapy
- heparin therapy
- vit. K def
- factor VII
what is the normal albumin range?
3.9-5.0 g/dl
conjugated bilirubin is…
water soluble for excretion
unconjugated bilirubin is…
pre-hepatic, not yet processed by liver
increased total bilirubin causes…
jaundice, leading to
- hemolytic anemia
- def. bilirubin metabolism
- bile duct obstruction
if direct bilirubin is elevated, what is going on?
- liver is conjugating bilirubin normally
- liver cannot secrete bilirubin
- bile duct obstruction by cancer or gallstones
if direct bilirubin is normal in a PT with jaundice, what is going on?
- excess of unconjugated bilirubin
- hemolysis, hepatitis, or cirrhosis should be expected
normal total bilirubin range
0.2-1.5 mg/dl
normal direct (conjugated) bilirubin range
0.0-0.03 mg/dl
normal indirect (unconjugated) bilirubin range
0.2-0.8 mg/dl
What are some possible liver diseases?
- hep A, B, C, D, E
- cirrhosis
- cholelitiasis, cholecystitis
- hepatic tumors
Hep A manifests as…
acute viral hepatitis;
- fever, jaundice, painfully enlarged liver
- not common in developed contries
Hep B and C are transmitted by…
- blood transfusion
- needle sticks
- sexual contact
- across placenta
Hep B manifests as…
acute w/ development to fulminant hepatitis and rapid liver destruction
is there an available Hep B vaccine?
yes
what % of hep B will develop chronic hepatitis?
10%
what % of hep C will develop chronic hepatitis?
50%
hep C increases risk of developing what?
- cirrhosis (20%)
- hepatocellular carcinoma
hep D is a co-infection acquired with…
Hep-B
what is hep D?
an acute infection that can develop into fulminant hepatitis or cirrhosis
what is hep E?
hepatitis related to poor hygiene or contaminated water
which Hepatitis is the greatest risk for anesthesia?
Hep B
how do you asses Hep B?
coagulation pre-op
how do you treat hep B?
- FFP
- monitor glucose
- maintain normal hepatic flow
- avoid hypercarbia
how can drug metabolism be affected by severe hepatitis?
prolonged effect
how are benzos affected by hepatic disease?
prolonged and more intense effect.
- avoid benzos
how are opioids affected by hepatic disease?
prolonged effect of morphine and alfentanil
- fentanyl and sufentanil not affected
how are non-depolarizing muscle relaxants affected by hepatic disease?
prolonged effect
what are good choices for muscle relaxant in PTs with hepatic dysfunction? Why?
cisatricurium or atracurium
- broken down by plasma esterases
what is cirrhosis?
liver disease with distortion of normal hepatic structure caused by cell destruction
- leads to liver failure
who gets cirrhosis?
- chronic hepatitis
- alcoholics
what is cholelitiasis?
the formation of calculus (stones) in the gallbladder via cholesteral crystal precipitation
what is cholecystitis?
inflammation of the gallbladder
what should you consider with PTs coming in for a cholecystectomy?
RSI, may present with recent N/V
why no opioids if the surgeon will be performing a cholangiogram?
may cause sphincter of oddi constriction, preventing contrast dye from flowing out of common bile duct
what will a PT with jaundice look like?
yellowing of the skin and eyes from bilirubin accumulation
how much bilirubin in PRBC?
250 mg
elevation in unconjugated bilirubin can lead to a condition resulting in seizures and brain damage, called what?
kernicterus
what % of hepatic tumors are hepatocellular?
80-90%
what % of hepatic tumors have underlying cirrhosis of usually alcoholic origin?
75%
what are six considerations for hepatic resection?
1 - large bore IV 2 - a-line 3 - central line for CVP 4 - epidural catheter for post-op pain 5 - keep PT hypovolemic during resection 6 - T&C 6 units of blood
what is normal portal vein pressure?
6-12 cmH2O
8-16 mmHg
what is the major clinical manifestation of portal hypertension?
GI bleeding
*bleeding in esophagus means severe
how do you treat portal hypertension?
- stopping the hemorrhage
- decompressing portal venous circulation
- large volume blood transfusion
What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS) used for?
to decrompress portal circulation in the case of portal hypertension
- buys time waiting for liver transplant
what are ascites?
ascites is the accumulation of serous fluid in the peritoneal cavity. It compresses abdominal viscera
What should you watch for following a decompression of fluid caused by ascites?
- hypovolemia
- hypotension
PTs with ascites often present with what?
arterial hypoxmia
- PaO2 (60-70 mmHg)
how do you treat ascites?
induce diuresis with aldactone antagonist (spironolactone)
*1 liter per day max diuresis
how can you minimize hypotension caused by managing ascites?
IV colloids
whats the best treatment of coagulopathy?
FFP
other than FFP, what can one used to normalized a patients PT?
platelets and cryo
what is hepatic encephalopathy?
hepatic coma
confusion, flapping hands, fruity breath, 88% risk mortality
what causes encephalopathy? (3)
- cerebral intoxication (liver not metabolizing GI contents)
- protein byproducts from bacteria
- ammonia (NH3) not converted to Urea by liver
how do you treat encephalopathy?
- protein restriction
- antibiotics (neomycin)
- reduce diuretic therapy
- treat hypokalemia
- restrict sedatives
