Hepatic Part 3 Flashcards
Preoperative considerations for the patient with acute hepatitis include
postpone elective surgery until resolved as determined by normal liver function test
-increased periop morbidity & mortality during acute phase
Perioperative considerations for patients with acute alcoholic hepatitis includes
risk with alcoholic hepatitis may not be as great
but patients could suffer from withdrawal during surgery and this is associated with a high mortality rate
Patients with hepatitis are at risk for further hepatic dysfunction and hepatic failure include
encephalopathy, coagulopathy, & hepatorenal syndrome
For patients who are chronic alcoholics, hypomagnesemia may occur
which predisposes to dysrhythmias
Lab evaluation of the patient with acute hepatitis includes
BUN, creatinine, bilirubin, electrolytes, glucose, transaminases, alkaline phosphatase, albumin, prothrombin time (INR), platelet count
serum HBsAg
blood alcohol level
Elevated transaminases do not
correlate well with the degree of cellular necrosis
bilirubin & alkaline phosphatase are usually only moderately elevated except with the cholestatic variant
For patients with acute hepatitis, describe levels of ALT & AST
ALT>AST
For patients with alcoholic hepatitis, describe levels of ALT & AST
AST> ALT
Hypoalbuminemia is usually not present except in
protracted cases with severe malnutrition (or chronic hepatitis)
The best indicator of synthetic function of the liver with hepatitis is
PT
prolongation> 3 to 4 seconds following administration of Vitamin K is indicative of severe liver dysfunction
Preoperative evaluation of the emergent patient with acute hepatitis should include:
determination of the cause & degree of hepatic impairment
record drug exposures
presence of N/Vā> may necessitate cricoid pressure
correction of dehydration & electrolyte abnormalities
mental status changes suggest severe hepatic impairment
premedication generally is not given to minimize drug exposure and confounds encephalopathy in patients with advanced liver disease
Recording of drug exposures for the acute hepatic patient should include
alcohol intake, recreational drug use, recent transfusions, & prior anesthetics
For alcoholics with acute hepatitis, the preoperative evaluation includse
inappropriate behavior or obtunded patient is a sign of acute toxicity
irritability, tremulousness, HTN, and tachycardia are signs of withdrawal
Vitamin K may be necessary to correct
a coagulopathy
The goal of intraoperative management of acute hepatitis is
to preserve existing hepatic function
avoid factors that may be detrimental to the liver
Intraoperative management of the patient with acute hepatitis includes
drug selection & doses should be individualized
acute viral hepatitis may produce increased CNS sensitivity to anesthetics
Intraoperative management of the alcoholic patient includes:
display cross-tolerance to IV and volatile anesthetic agents
requires CV monitoring due to the additive depressant effects of anesthetics & alcohol, possible presence of alcoholic cardiomyopathy
Patient classification of the patient with hepatitis is based on three distinct syndromes and is determined by
liver biopsy
chronic persistent hepatitis, chronic lobular hepatitis, & chronic active hepatitis
Chronic hepatitis is defined as
persistent hepatic inflammation for longer than 6 months as evidenced by elevated serum aminotransferases
In patients with acute hepatitis, intraoperative considerations include avoiding things known to reduce hepatic blood flow such as
hypotension, excessive SNS stimulation, high mean airway pressures during controlled ventilation
Intraoperative considerations for the patient with acute hepatitis include using āstandardā induction doses of IV agents since their action is
terminated by redistribution versus metabolism or excretion
-prolonged duration of action may occur if large or repeated doses of IV agents are administered (particularly opioids)
The volatile agent of choice for the patient with acute hepatitis is
isoflurane as it has the least effect on hepatic blood flow
-inhalation agents are generally preferable to IV agents due to the dependence on liver metabolism and elimination
Additional considerations for the intraoperative management of the acute hepatitis patient includes
fewest number of anesthetic agents should be used
regional anesthesia can be used in the absence of coagulopathy
Describe chronic persistent hepatitis.
present with acute hepatitis (usually B or C) that has a protracted course but eventually resolves
characterized by chronic inflammation of the portal tracts with preservation of the normal cellular architecture (donāt have a lot of cell death with this)
usually does not progress to cirrhosis
Describe chronic lobular hepatitis.
present with acute hepatitis that resolves but followed by recurrent exacerbations
-characterized by FOCI of inflammation and cellular necrosis in the lobules
usually does not progress to cirrhosis
Describe chronic active hepatitis.
occurs most commonly as a sequela of hepatitis B or C
characterized by chronic hepatic inflammation with destruction of cellular architecture
evidence of cirrhosis present initially or eventually develops
Patients with hep B or C infection usually have a favorable response to
antiviral medications
Hep B: antiviral + immune modulator drugs (interferon)
Hep C: antiviral can cure more than 95% of affected patients
Anesthetic management for the patient with chronic hepatitis includes:
patients with chronic persistent or chronic lobular hepatitis should be treated similar to those with acute hepatitis
patients with chronic active hepatitis should be assumed to have cirrhosis and treated as such
For the patient with chronic hepatitis, laboratory test may show
only mild elevation of serum aminotransferases and generally these correlate poorly with severity of the disease
Cirrhosis is a progressive disease that eventually results in
hepatic failure
Most common causes of cirrhosis include:
alcohol abuse, NALFD, chronic active hepatitis (B & C), chronic biliary inflammation or obstruction
Regardless of the cause of cirrhosis, the result is
hepatocyte necrosis followed by fibrosis and nodular regeneration (scar tissue)
Destruction of the livers normal cellular and vascular architecture in the patient with cirrhosis produces:
obstruction of the portal venous flow leading to portal hypertension
impairment of normal synthetic and metabolic functions leading to multisystem disease
3 major complications associated with cirrhosis include
variceal hemorrhage from portal hypertension
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 and some may eventually develop hepatocellular carcinoma
Manifestations of the patient with cirrhosis include
jaundice & ascites
other manifestations include: spider angiomas, palmar erythema, gynecomastia, spleenomegaly
Patients with cirrhosis are at increased risk for further deterioration of liver function due to
detrimental effects of anesthesia and surgery on hepatic blood flow
already limited hepatic reserve
Successful anesthetic management depends on recognizing the multisystem dysfunction with cirrhosis
GI, circulatory, pulm, renal, hematological, infections, metabolic, & neurological
the goal is to prevent or limit complications
Preoperative considerations for the patient with cirrhosis include
surgical risk is correlated with the degree of hepatic impairment
severity of hepatic impairment and surgical risk can be estimated used the Childs-Turcotte-Pugh scoring system
The Childs=Turcotte-Pugh score measures:
total bilirubin, serum albumin, INR, ascites, & hepatic encephalopathy
-assigning points based on levels and this helps determine survival
Gastrointestinal manifestations of the cirrhotic patient includes
portal hypertension leads to development of extensive venous collateral channels: gastroesophageal, hemorrhoidal, periumbilical, & retroperitoneal
The preoperative sign of portal hypertension is
abdominal wall veins
Massive bleeding from gastroesophageal varices is a major cause of morbidity & mortality and medical treatment includes
replace blood loss with IV fluids & blood products
vasopressin, somatostatin, & propranolol to reduce the rate of blood loss
balloon tamponade
endoscopic sclerosis or ligation of the varices is about 90% effective
bleeding continues or reoccurs then emergency surgery is indicated
Patients with cirrhosis may present with
anemia, thrombocytopenia/coagulopathy, leukopenia
For the patient with cirrhosis who has anemia, it is associated with
blood loss, increased RBC destruction, bone marrow suppression, & nutritional deficiencies
Thrombocytopenia/coagulopathy in the patient with cirrhosis is associated with
congestive spleenomegaly due to portal hypertension
decreased hepatic synthesis of clotting factors
enhanced fibrinolysis due to reduced elimination of factors that activate the fibrinolytic system
Leukopenia in the patient with cirrhosis is associated with
congestive spleenomegaly due to portal hypertension
Cirrhotic cardiomyopathy may be present due to
arteriovenous shunts & decreased blood viscosity
contribute to increased CO: above normal filling pressures, below normal SVR
Superimposed alcoholic cardiomyopathy may readily lead to
CHF
Circulatory manifestations of cirrhosis include
cirrhosis is typically associated with a hyperdynamic circulatory state
CO is often increased and generalized peripheral vasodilation is present
AV shunts can develop in the systemic and pulmonary circulation
Preoperative blood transfusion consideration sinclude:
protein breakdown from excessive blood transfusion can precipitate encephalopathy
coagulopathy should still be corrected before surgery
clotting factors should be replaced with blood products such as FFP & cryo
platelet transfusion should be considered immediately prior to surgery for platelet count < 100,000
Describe the respiratory manifestations for a patient with cirrhosis.
hyperventilation is common resulting in resp alkalosis
hypoxemia is frequent due to right to left shunts
decrease lung volumes (particularly FRC) due to ascites fluid elevation of the diaphragmā> results in atelectasis
Describe why hypoxemia occurs in patients with cirrhosis.
shunting is due to increased anomalous AV communication
also have V/Q mismatch
up to 40% of CO involved
Describe preop labs/procedures that should be performed related to the respiratory manifestations of the patient with cirrhosis.
chest film & ABG to diagnose hypoxemia & atelectasis as they may not be evident from clinical examination
paracentesis should be considered for massive ascites with pulmonary compromise
Alterations in fluid & electrolyte balance are manifested as
ascites, edema, electrolyte abnormalities, & hepatorenal syndrome
The following methods are believed to be responsible for ascites:
portal hypertension
hypoalbuminemia
seepage of protein-rich lymph fluid from the surface of the liver
avid renal sodium (& often water) retention
Describe how portal hypertension leads to ascites.
increased hydrostatic pressure favors fluid transudation across the intestine into the peritoneum
Describe how hypoalbuminemia leads to ascites.
decreases plasma osmotic pressure favors fluid transudation
Describe how seepage of protein-rich lymph fluid from the surface of the liver leads to ascites.
secondary to distortion and obstruction of lymphatic channels
Describe how avid renal sodium (and often water) retention lead to ascites.
hepatorenal syndrome
In relation to renal manifestations & fluid balance, patients with cirrhosis and ascites have
decreased renal perfusion
altered intrarenal hemodynamics
enhanced proximal and distal tubule Na+ reabsorption
impairment of free water clearance
Describe the electrolyte abnormalities of the patient with cirrhosis and ascites.
hyponatremia is common- dilutional
hypokalemia is common- excessive K+ loss secondary to hyperaldosteronism or diuretics
The renal manifestations and fluid balance abnormalities in cirrhosis are most severe with the onset of
hepatorenal syndrome
Hepatorenal syndrome is afunctional deficit in patients with cirrhosis that usually follows:
gastrointestinal bleeding
aggressive diuresis
sepsis
major surgery
Hepatorenal syndrome is characterized by
progressive oliguria, avid Na+ retention, azotemia, intractable ascites, & very high mortality rate
Treatment for hepatorenal syndrome is
supportive in nature and often unsuccessful unless a liver transplant is performed
The anesthetic management of the cirrhotic patient with renal manifestations and fluid balance includes:
judicious use of periop fluid management
use colloid infusion for fluid correction
avoid overzealous preop diuresis
importance of preserving renal function periop is critical
diuresis of ascites and edema should be accomplished over several days
Loop diuretics should only be used after
bed rest, Na restriction, and spironolactone therapy have failed
Hepatic encephalopathy is characterized by
alterations in mental status
fluctuating neurological signs- asterixis, hyperreflexia
EEG changes
some patients also have increased ICP
Metabolic encephalopathy may be related to the amount of
hepatocellular damage and degree of shunting of portal blood directly into the systemic circulation
Accumulation of toxins originating in the GI tract and normally metabolized in the liver that may cause hepatic encephalopathy include:
ammonia
methionine metabolites
short chain fatty acids
phenols
Encephalopathy should be treated
preoperatively
It is recommended to avoid ____ in patients with encephalopathy
sedatives
Factors known to precipitate hepatic encephalopathy include
GI bleeding, increased dietary protein intake, hypokalemic alkalosis from vomiting or diuresis, infections, worsening liver function
The drug response to agents is unpredictable due to changes in
CNS sensitivity, volume of distribution, protein binding, drug metabolism & drug elimination
The most important thing we can do with our drugs for liver patients include
titration!
Volume of distribution of highly ionized NMBAs is increased & therefore
it requires greater than normal loading doses
hepatic elimination of NMBAs is decreased and therefore requires
lower than normal maintenance doses
The cirrhotic liver is very dependent on
hepatic arterial blood flow due to reduced portal blood flow
Preservation of hepatic arterial blood flow is critical in the cirrhotic patient and we can do this by
avoiding anesthetic agents that potentially reduce hepatic arterial blood flow
Regional anesthesia can be used in cirrhotic patients without
thrombocytopenia or coagulopathy but must take great care to avoid hypotension
The most highly recommended anesthesia for the cirrhotic patient is
propofol induction with isoflurane maintenance in oxygen or air-oxygen with Cisatricurium as the NMBD
Cardiovascularly unstable patients and those with active bleeding should have
awake intubation or RSI with cricoid pressure using ketamine or etomidate and succinylcholine
RSI with cricoid pressure may be indicated for the liver patient because
preoperative nausea, vomiting, GI bleeding, and abdominal distension
Opioid supplementation for the cirrhotic patient will
reduce the volatile agent requirement but have prolonged half life leading to prolonged respiratory depression
Monitoring of the cirrhotic patient includes:
monitor 5 lead EKG to detect ischemia (particularly in patients receiving vasopressin as they may have cirrhotic and alcoholic cardiomyopathy)
- supplement pulse ox with ABGs to evaluate acid base status
- patients with large R to L shunts may not tolerate N2O & may require PEEP
- catheter to monitor UO- consider mannitol for persistent low urine output
Most patients with cirrhosis should have intrarterial monitoring due to rapid changes in BP as a result of
excessive bleeding, rapid intercompartmental fluid shifts & surgical manipulations
Intravascular volume is difficult to assess in cirrhotic patients and therefore they may need
CVP or PAP monitoring
When evacuating ascites fluid, consider that removal of large amounts of ascites fluid may require
IV colloid solutions to prevent profound hypotension
Fluid shifts can occur in patients who have
prolonged surgical procedures & evacuation of ascites fluid
Intraabdominal procedures in the patient with cirrhosis are often associated with
excessive bleeding due to venous engorgement from portal hypertension, adhesions from previous surgery, coagulopathy
For fluid replacement in the cirrhotic patient, most patients are on Na+ restriction preoperatively. Intraoperatively preservation of intravascular fluid volume and urinary output
takes precedence
use of predominantly colloid solutions may be preferable to avoid Na+ overload and to increase plasma osmotic pressure
Most patients are anemic & have a coagulopathy and therefore require
RBC transfusion preoperatively
Significant transfusions can result in citrate toxicity because
citrate is normally metabolized by the liver
cirrhosis impairs citrate metabolism
citrate binds to serum Ca++ and leads to hypocalcemia
IV Ca++ is often necessary to reverse the negative inotropic effects of decreased ionized Ca
Treatment of extrahepatic obstruction is usually
surgical
Treatment of intrahepatic cholestasis is
medical
Both extrahepatic & intrahepatic obstruction produce a
predominantly conjugated hyperbilirubinemia and marked elevation in alk phos
Patients with symptomatic gallstone disease (cholelithiasis) usually present with
biliary colic secondary to obstruction of the cystic duct
Cholangitis is suggestive due to
concomitant chills or high fever suggesting an ascending bacterial infection of the biliary system
Gallstones can obstruct the
pancreatic duct and cause acute pancreatitis
The most common cause of cholestasis is
extrahepatic obstruction of the biliary tract (obstructive jaundice)
Extrahepatic obstruction can be due to
gallstones, stricture, & tumor in the common hepatic duct
Cholestasis can also be caused by
intrahepatic obstruction
Intrahepatic obstruction can be due to
suppression or stoppage of bile flow at the level of the hepatocyte or bile canaliculus
most commonly results from viral hepatitis or idiosyncratic drug reaction
Hepatobiliary disease is characterized by
cholestasis- suppression of stoppage of bile flow
Patients with hepatobiliary disease most commonly present to the OR for
cholecystectomy
Patients with acute cholecystitis should be treated
medically before coming to the OR
Treatment for acute cholecystitis includes
nasogastric suction, IV fluids, antibiotics, and opioid analgesics
Patients suffering from serious complications related to hepatobiliary disease may require
emergency cholecystectomy as it is resulting in destruction of hepatocytes
Patients with extrahepatic biliary obstruction from an cause readily develop
vitamin K deficiency
- should be given vitamin K (requires 24 hours for a full response)
- failure of the PT to correct prior to surgery may necessitate FFP
High bilirubin levels for the patient with hepatobiliary disease may be associated with
renal failure
Long standing extrahepatic biliary obstruction is associated with secondary
biliary cirrhosis & portal hypertension
Laparoscopy cholecystectomy will accelerate
recovery
Describe the use of opioids when an intraoperative cholangiogram is to be performed.
can be problematic
opioid induced spasm of the sphincter of Oddi may theoretically result in a false-positive cholangiogram
-some clinicians withhold opioids until after the cholangiogram has been performed
sphincter of Oddi spasm can be treated with naloxone or glucagon
In patients with a biliary tract obstruction expect a prolonged
duration of action of drugs that are dependent on biliary excretion
agents dependent on renal excretion are preferable
Common hepatic surgeries include
repair of lacerations, drainage of abscesses, & resection of tumors
How much of the liver can be resected?
80 to 85%
Cirrhosis greatly complicates anesthetic management and increases periop mortality, preparation includes
multiple large bore IVs, fluid & blood warmers, rapid infusion devices, direct arterial & CVP monitoring advisable, & avoidance of hypotension
Postoperative complications of hepatic surgery include
bleeding, sepsis, & hepatic dysfunction
Postoperative __________ may be necessary in patient undergoing extensive resection
mechanical ventilation
______ may occur following large liver resections
hypoglycemia
Drainage of an abscess may be complicated by
peritoneal contamination
Administration of ____ may reduce blood loss.
antifibrinolytics; aprotinin, aminocaproic acid, tranexamic acid
