hepatic pathophysiology and anesthesia implications Flashcards
what typically causes liver carcinoma?
hepatitis c
clinical manifestations of hepatic disease are often
absent until extensive damage has occurred
acute hepatitis is usually the result of
viral infection, drug reaction, exposure to a hepatotoxin
clinical manifestation of acute hepatitis depends on
severity of the inflammatory reaction and amount of cellular necrosis
acute hepatitis caused by viral infection are due to
hepatitis a, b, or c viruses
hepatitis a is transmitted by the
oral-fecal route
hepatitis b and c are transmitted primarily
percutaneously and by contact with body fluids
hepatitis A
least severe, most recover in weeks to months, transmission through fecal contamination
hepatitis E
similar to A, mostly in 3rd world countries, transmission through fecal contamination
hepatitis D
does not produce hepatitis by itself
only occurs as a co-infection with acute hep B or super infection with chronic hep B
which hepatitis does not cause jaundice?
hepatitis B
hepatitis B can lead to
fulminant hepatic necrosis or chronic hepatitis
hepatitis C
antibodies not present for long periods, rarely produces fulminant hepatic failure
hepatitis C produces
asymptomatic carries
concerning acute hepatitis caused by viral infection patients often have a
prodromal illness for 1-2 weeks with fatigue, malaise, low grade fever, N/V
incidence of chronic active viral hepatitis is more common in
hepatitis C (50% at least)
things to consider if someone is an infectious carrier
avoid direct contact with blood and secretions
immunization is effective against hep b
prior infection with hep c does not mean they have immunity when re-exposed
post-exposure prophylaxis with hyperimmune globulin if effective for hep B
drug induced acute hepatitis results from
direct dose-dependent toxicity of a drug or a metabolite, idiosyncratic drug reaction, combination of the two
most common cause of drug induced acute hepatitis
alcohol
chronic alcohol ingestion can result in
fatty infiltration as a result of impaired fatty acid oxidation, increased uptake and esterification of fatty acids, diminished lipoprotein synthesis and secretion
drugs that can cause acute hepatitis
alcohol, acetaminophen, volatile anesthetics, sulfonamides, amiodarone
should patients with acute hepatitis have surgery?
no, d/t high mortality rate
should be postponed until resolved with normal liver function test
alcohol withdrawal during surgery is associated with
a mortality rate of as high as 50%
patients with hepatitis are at risk for further hepatic dysfunction and hepatic failure including
encephalopathy, coaguolopathy, hepatorenal syndrome
which lab values should be done for someone with acute hepatitis?
BUN/creat, bilirubin, albumin, PT/INR, electrolytes, glucose, transaminases, alk phos, platelet count
what electrolyte abnormality and acid base deficiency is most common with acute hepatitis?
hypokalemia and metabolic alkalosis usually d/t vomiting
chronic alcoholics may have which electrolyte disturbance?
hypomagnesemia which predisposes them to dysrhythmias
in acute hepatitis which is higher ALT or AST?
ALT
om alcoholic hepatitis which is higher ALT or AST?
AST
which lab is the best indicator of synthetic function of the liver with hepatitis?
PT prolonged >3-4 seconds (>1.5 INR) after administration of vitamin K = severe liver dysfunction
hypoalbuminemia is usually not present except in
protracted cases with severe malnutrition or chronic hepatitis
preop evaluation of emergent patient with acute hepatitis includes:
determining cause and degree of hepatic impairment, recording drug exposures (alcohol, recreational drugs, recent transfusions, prior anesthetics), N/V, correction of dehydration/electrolyte abnormalities, mental status changes, if alcoholic
acute intoxication of alcohol manifests as
inappropriate behavior or obtunded
withdrawal from alcohol manifestations
irritability, tremulousness, hypertension, tachycardia
goal of intraoperative management in acute hepatitis is to
preserve existing hepatic function, avoid factors that may be detrimental to the liver
acute viral hepatitis may produce increased ____ to anesthetics
CNS sensitivity
which anesthetic is typically preferred in acute hepatitis patients?
inhalational agents over IV agents d/t metabolism
things to avoid that reduce hepatic blood flow
hypotension, excessive SNS stimulation, high mean airway pressures during controlled ventilation
chronic hepatitis definition
persistent hepatic inflammation for longer than 6 months as evidenced by elevated serum aminotransferases
what are the 3 patient classifications of chronic hepatitis and how are they determined?
chronic persistent, chronic lobular, and chronic active
determined by liver biopsy
chronic persistent hepatitis present with
acute hepatitis (B or C) that has a protracted course but eventually resolves
chronic persistent hepatitis is characterized by
chronic inflammation of the portal tracts with preservation of the normal cellular architecture
which chronic hepatitis classification(s) DO(ES) NOT progress to cirrhosis?
chronic persistent and chronic lobular
chronic lobular hepatitis presents with
acute hepatitis that resolves but is followed by recurrent exacerbations
chronic lobular hepatitis is characterized by
foci of inflammation and cellular necrosis in the lobules
chronic active hepatitis occurs most commonly as
a sequela of hepatitis B or C
chronic active hepatitis is characterized by
chronic hepatic inflammation with destruction of cellular architecture (more global)
which chronic hepatitis classification(s) does lead to cirrhosis?
chronic active hepatitis
in hepatitis C antivirals can
cure more than 95% of affected patients
patients with chronic persistent or chronic lobular hepatitis should be treated similar to
those with acute hepatitis
patients with chronic active hepatitis should be treated as
that they have cirrhosis
most common causes of cirrhosis
alcohol abuse, NAFLD, chronic active hepatitis (B and C), chronic biliary inflammation or obstruction
Cirrhosis leads to
hepatocyte necrosis –> fibrosis and nodular regeneration
destruction of the livers normal cellular and vascular architecture produces
obstruction of the portal venous flow leading to portal hypertension, impairment of normal synthetic and metabolic functions leading to multisystem disease
what 2 things eventually develop in most patients with cirrhosis
jaundice and ascites
other manifestations of cirrhosis include
spider angiomas, palmar erythema, gynecomastia, spleenomegaly
3 major complications with cirrhosis
variceal hemorrhage from portal HTN
intractable fluid retention in the form of ascites
hepatic encephalopathy or coma
approximately 10% of patients with cirrhosis have at least one episode of
bacterial peritonitis
severity of hepatic impairment and surgical risk can be estimated using the
childs-turcotte -pugh scoring system which consists of 2 clinical features and 3 lab assessments
Class A from Childs-Turcotte-Pugh Score
5-6 points
one year survival 100%
two year survival 85%
Class B from Childs-Turcotte-Pugh Score
7-9 points
one year survival 80%
two year survival 60%
Class C from Childs-Turcotte-Pugh Score
10-15 points
one year survival 45%
two year survival 35%
sign of portal hypertension preoperatively is
dilated abdominal wall veins
what is a major cause of morbidity and mortality of cirrhosis
massive bleeding from gastroesophageal varices
medical treatment for variceal bleeding includes
replace blood loss with IV fluids and blood products, vasopressin, somatostatin, propranolol, balloon tamponade, endoscopic sclerosis or ligation of the varices, emergency surgery if continues to bleed
hematological manifestations with cirrhosis
anemia, thrombocytopenia/coagulopathy, leukopenia
thrombocytopenia/coagulopathy associated with
congestive spleenomegaly d/t portal hypertension
decreased hepatic synthesis of clotting factors
enhanced fibrinolysis d/t reduced elimination of factors that activate the fibrinolytic system
leukopenia associated with
congestive spleenomegaly d/t portal hypertension
cirrhosis is typically associated with a
hyperdynamic circulatory state
cardiac output is often ___ in cirrhosis
increased and generalized peripheral vasodilation is present
what kind of shunt can develop with cirrhosis
arteriovenous shunt can develop in the systemic and pulmonary circulation
cirrhotic cardiomyopathy may be present due to
av shunt, decreased blood viscosity which both contribute to increased CO, above normal filling pressures, and below normal SVR
respiratory manifestations with cirrhosis
hyperventilation is common leading to respiratory alkalosis
hypoxemia d/t R–> L shunt
decreased lung volume (especially FRC) d/t ascites elevating diaphragm leading to atelectasis
When an AV shunt is involved with cirrhosis what are the consequences?
involves 40% of the CO!!
will have a V/Q mismatch and hypoxemia!
what are some preop labs/tests that would be useful in someone with cirrhosis concerning respiratory manifestations?
chest xray, abg
if someone has a large amount of ascites what would be something to consider preoperatively?
performing a paracentesis
alterations in fluid and electrolyte balance are manifested as
ascites, edema, electrolyte abnormalities on lab results, hepatorenal syndrome
mechanisms responsible for ascites include:
portal HTN
hypoalbuminemia
seepage of protein rich lymph from the surface of the liver
avid renal sodium retention and water reabsorption
how does portal HTN lead to ascites?
increases hydrostatic pressure favors fluid transudation across the intestine into the peritoneum
how does hypoalbuminemia lead to ascites?
decreases plasma osmotic pressure which favors fluid transudation
patients with cirrhosis and ascites have
decreased renal perfusion
altered intrarenal hemodynamics
enhanced proximal and distal tubule Na+ reabsorption
impairment of free water clearance
what electrolyte abnormalities are common with cirrhosis
hyponatremia (dilutional)
hypokalemia (excessive loss from hyperaldosteronism or diuretics)
hepatorenal syndrome
is a functional deficit in patients with cirrhosis that usually follows GI bleeding, aggressive diuresis, sepsis, or major surgery
hepatorenal syndrome is characterized by
progressive oliguria, avid Na+ retention, azotemia, intractable ascites, high mortality rate
perioperative fluid management in someone with cirrhosis
be judicious
albumin or some kind of colloid is better choice
loop diuretics should only be used
after bed rest, sodium restriction, and spironolactone have failed
hepatic encephalopathy is characterized by
alterations in mental status fluctuating neurological status asterixis, hyperreflexia EEG changes increased ICP potentially
metabolic encephalopathy
related to the amount of hepatocellular damage and degree of shunting of portal blood directly into the systemic circulation so toxins from the GI tract that normally are metabolized in the liver will accumulate into systemic circulation
factors known to precipitate hepatic encephalopathy include
GI bleed increased dietary protein intake hypokalemic alkalosis from vomiting/diuresis infection worsening liver function
response to medications is unpredictable due to changes in
CNS sensitivity, volume of distribution, protein binding, drug metabolism, drug elimination
volume of distribution of highly ionized NMBAs is increased requiring
greater than normal loading doses
hepatic elimination of NMBAs is decreased requiring
lower than normal maintenance doses
in someone with cirrhosis the liver is very dependent on
hepatic arterial blood flow d/t reduced portal blood flow
how do we preserve hepatic artery blood flow to the liver?
avoid anesthetic agents that potentially reduce the arterial blood flow (agents that cause hypotension)
What is the most commonly used anesthetic for cirrhotic patients?
propofol induction and isoflurane maintenance
What is NMBA of choice in someone who has cirrhossi?
cisatracurium
opioid supplementation reduces the volatile agent requirement but will have a prolonged
T1/2 B (elimination) leading to prolonged respiratory depression
if someone is having N/V, GI bleeding, and abd distention what will we probably have to do
RSI with cricoid pressure
if a cirrhosis patient is cardiovascularly unstable and with active bleeding how should we proceed with inducing them?
awake intubation
RSI with cricoid pressure using ketamine or etomidate and succinylcholine
why should you monitor someone with 5 leads that has cirrhosis?
to detect ischemia because if they are on vasopressin that will cause coronary vasoconstriction which can lead to ischemia
someone who has a large Right to Left shunt
may not tolerate N2O and may require PEEP to treat V/Q mismatch
intraabdominal procedures in cirrhotic patients are often associated with
excessive bleeding d/t venous engorgement from portal HTN, adhesions from previous surgeries, coagulopathy
fluid shifts from evacuation of ascites and prolonged procedure
removal of large amounts of ascites may require
IV colloid solutions to prevent profound hypotension
significant blood transfusions can result in
citrate toxicity
explain citrate and why IV Ca++ is often necessary during a large amount blood transfusions
citrate is metabolized in the liver but if someone has cirrhosis that impairs that metabolism… the citrate binds to serum Ca++ and causes hypocalcemia which will decrease contractility soooo that’s why we give IV Ca++ to reverse the negative effects of the hypocalcemia
typical dose for IV Calcium
1 gram
primary cause of death in acute/fulminant liver failure?
cerebral edema d/t high levels of NH3 (ammonia) in the brain and accumulation of glutamate and neuronal swelling
cirrhosis can lead to
portal HTN (ascites and varices) and/or hepatocellular cancer
hepatocellular death causes
decreased synthesis, decreased clearance, and metabolic derangement leading to encephalopathy and coagulopathy
cholestasis
stoppage of bile flow
hepatobiliary disease is characterized by
cholestasis
most common cause of cholestasis is
extrahepatic obstruction of the biliary tract (obstructive jaundice) d/t gallstone, stricture, tumor in common hepatic duct
cholestasis can also be caused by _____ (not extrahepatic)
intrahepatic obstruction d/t suppression or stoppage of bile flow at hepatocyte or bile canaliculus from either viral hepatitis or idiosyncratic drug reaction
treatment of extrahepatic obstruction is usually
surgical
treatment of intrahepatic obstruction is usually
medical
both extrahepatic and intrahepatic obstructions produce a predominately _____ hyperbilirubinemia and ____ alk phos
conjugated ; increased
symptomatic gallstone disease (cholelithiasis) usually present with
biliary colic secondary to obstruction of the cystic duct
when someone has biliary colic from obstruction and develops chills or high fever that is suggestive of
ascending bacterial infection of the biliary system = cholangitis
medical treatment for someone with acute cholecystitis before going to the OR include
NG to suction, IV fluids, antibiotics, opioids
patients with extrahepatic biliary obstruction from any cause readily develop
vitamin K deficiency so they should get vitamin K and may need FFP
how long does it take to get a full response after administering vitamin K?
24 hours
if someone who has cholecystitis has high bilirubin levels what might that indicate?
renal failure
long standing extrahepatic biliary obstruction is associated with
secondary biliary cirrhosis and portal HTN
what is a consideration regarding opioids and someone undergoing a lap cholecystetomy?
can induce spasm in sphincter of oddi which can result in a false positive on the cholangiogram
so pay attention in the case and don’t give opioid right before they do the cholangiogram
agents dependent on what kind of excretion is preferable in someone with cholecystitis
renal excretion
make sure you monitor urine output through a catheter and maintain periop diuresis
common hepatic surgeries include
repair of lacerations
drainage of abscesses
resection of tumors
what things should you consider having or doing for a hepatic surgery?
multiple large bore IVs fluid and blood warmers rapid infusion devices direct arterial and CVP monitoring avoid hypotension
administration of ____ may reduce blood loss
aprotinin
aminocaproic acid
tranexamic acid
___glycemia may occur following large liver resections
hypo- glycemia
postop complications of hepatic surgery include
bleeding, sepsis, hepatic dysfunction
in someone who has cirrhosis what surgeries have the highest risk of mortality?
peptic ulcer surgery (54%), emergency abdominal surgery (57%), emergency cardiac surgery (80%), abdominal surgery for trauma (47%)
in someone who has acute hepatitis and needs an exploratory laparotomy what is the mortality rate?
100% ……..
