Final_Hepatic Flashcards
Hepatic blood flow is provided by
hepatic artery + portal vein (dual afferent blood supply)
Hepatic arterial blood flow is controlled by
arterial smooth muscle and autonomic regulation
Reduction in portal vein flow is compensated by
hepatic arterial buffer response
Acute liver failure - signs and symptoms
● Fatigue ● Lethargy ● Anorexia ● Nausea/ vomiting ● Jaundice ● RUQ tenderness ● Change in liver span ● Ascites ● Encephalopathy ● Cerebral Edema (↑ICP)
Hepatic drug metabolism
Hepatic biotransformation
○ Phase I: + oxygen or - hydrogen carried out by mixed function oxidase (Oxidation, Reduction, Hydrolysis (involves breaking of ester bonds))
○ Phase II: Involves conjugation of active metabolites with glutathione, sulfate, glycine or glucuronic acid into inactive substrates (Conjugation)
- Hepatic Microsomal Enzymes – CYP450
- inducers: ETOH, phenobarb, st johns wort
- inhibitors: Cimetidine, ritonivir, grapefruit juice, CCBs, erythromycin, itraconazole, nefazodone
normal hepatic blood flow is
25% of CO
portal vein flow is
not regulated
-vulnerable to: systemic HOTN, dec CO
reduction in portal vein flow is compensated by
hepatic arterial buffer response
hepatic arterial buffer response
○ ↓ portal vein flow leads to ↑ hepatic arterial flow
○ Stimulated by ↓ pH + O2 levels, ↑ CO2
portal vein
- Supplies 3x blood flow as hepatic artery (75% of blood flow)
- Venous blood - but still supplies 45-50% O2 to liver
portal triad
- hepatic artery
- hepatic portal vein
- bile duct
Hepatitis etiology
Chronic Liver disease - one cause = Chronic viral hepatitis
- Persistent hepatic inflammation > 6 m
- result of infxn with hepatitis B or C
Chronic Liver disease - categories
- Cirrhosis of the liver
a. Functioning liver tissue replaced by scar tissue
b. Progressive decrease in hepatic blood flow - Fibrosis of the liver
a. Overgrowth of scar tissue d/t infxn, inflammation, injury, or healing
b. Can inhibit the organs proper functioning
chronic liver disease - s/s
-Non-specific symptoms (Anorexia, weight loss, weakness, fatigue)
- Jaundice
○ Portal HTN → diverts blood away from liver, lower albumin levels → lead to a buildup of bilirubin → causes jaundice
○ Normally: RBCs broken down in spleen into indirect bilirubin (very lipid soluble, hard for kidneys to remove) → indirect bilirubin goes to liver for conjugation → turns into direct bilirubin
○ Direct bilirubin: water soluble, easy for kidneys to remove
○ Albumin = plasma protein that binds to direct bili, keep in circulation
○ ↓albumin levels + ↑bilirubin → leaking bilirubin→ jaundice
- Spider angioma
- Palmar erythema
- Hepatomegaly
- Splenomegaly
gastroesophageal varices
-Can lead to massive bleeding r/t portal hypertension
-Varice - large vein that became distended d/t collapsed valves
-Major cause of morbidity and mortality
Can Precipitate Encephalopathy From Blood In GI tract
(Risk of GI bleed → upper GI bleed → digesting too much protein (blood) → hepatic encephalopathy)
-Management: Balloon tamponade, vasopressin, somatostatin (octreotide), propranolol
-Sclerotherapy, variceal banding/hemoclip, electrocoagulation
complications of liver disease
- hyperdynamic circulation
- gastroesophageal varices
- hepatic encephalopathy
- pulm: hepatopulmonary syndrome, portopulmonary HTN
- ascites
- hematologic: anemia, thrombocytopenia leukopenia, coag factor deficiencies
- renal: hepatorenal syndrome, hyponatremia/hypokalemia
- hypoalbuminemia
perioperative anesthetic management of liver disease - goal
preserve hepatic blood flow/existing hepatic function
perioperative anesthetic management of liver disease - premedication
○ Judicious use of sedatives (or skip)—may prolong CNS depression + worsen hepatic encephalopathy
○ For EtOH patients: Need benzodiazepines
perioperative anesthetic management of liver disease - induction
○RSI for ascites, delayed gastric emptying (intoxicated), bleeding
○ Propofol induction followed by IAs
○ Induction may cause profound HOTN (IV volume replacement, small dose of pressors)
perioperative anesthetic management of liver disease - maintenance
○ Sevo-, iso- and des- have limited liver metabolism
○ Opioids should be used judiciously (Remifentanil)
○ Cisatracurium or atracurium for NMB maintenance
perioperative anesthetic management of liver disease - emergence
○ Slower emergence + return of neuromuscular fxn d/t reduced ability to clear Rx
○ At risk for aspiration must be wide awake prior to extubation
○ Postop intubation if altered LOC
Liver failure is most common cause of
postop death in patients with cirrhosis
_____ is increased in cirrhotic patients
periop mortality
Goals for periop (liver failure)
○ Maintain liver perfusion and oxygenation
○ Avoid NG/OG tubes (risk of variceal bleed)
○ Avoid LR, use colloids
○ Benzos for Etoh patients
○ Consider admitting to ICU after intermediate or high-risk procedure
Liver biotransformation reactions involve all of the following EXCEPT... ○ Auto-oxidation ○ Conjugation ○ Hydrolysis ○ Oxidation ○ Reduction
Auto-oxidation
● Jaundice may result from all of the following EXCEPT…
○ Defects in bilirubin conjugation
○ Excessive production of bilirubin
○ Increased uptake of bilirubin into hepatic cells
○ Intrahepatic obstruction of ducts
○ Gilbert’s disease
Increased uptake of bilirubin into hepatic cells
● Hepatic blood flow….
○ Is closely regulated by dopamine
○ Is closely regulated during surgery and anesthesia
○ Is decreased with sympathetic stimulation
○ Increases with arterial hypoxemia
○ Responds slowly to bodily needs
Is decreased with sympathetic stimulation
● Unconjugated bilirubin... ○ Breaks down to biliverdin ○ Is conjugated with glucuronic acid ○ Is nontoxic ○ Is secreted into the intestinal tract ○ Is the product of white cell breakdown
Is conjugated with glucuronic acid
● Ascites…
○ Follows chronic decreased portal vein pressure
○ Follows periods of hyperalbuminemia
○ Is usually accompanied by hypernatremia
○ May have adverse cardiopulmonary effects
○ Should be removed rapidly to avoid reaccumulation
May have adverse cardiopulmonary effects
● In the patient with cirrhosis…
○ Excessive sodium is lost in the urine
○ Less thiopental is required for induction
○ Pancuronium is more effective
○ Serum gamma globulin level will be low
○ The serum albumin level will be elevated
Less thiopental is required for induction
● The patient with acute viral hepatitis…
○ Is an acceptable candidate for general anesthesia for elective surgery
if the degree of liver enzyme elevation is mild
○ Is at high risk for perioperative mortality
○ Is not affected by surgical procedures
○ Should have an inhalational induction to avoid thiopental
○ Should never have a general anesthetic
Is at high risk for perioperative mortality
Albumin…
○ Has a half-life of approximately 3 weeks
○ Is necessary for maintenance of oncotic pressure
○ Is the major plasma protein
○ Levels are lower in a neonate
■ Select all that apply
○ Has a half-life of approximately 3 weeks
○ Is necessary for maintenance of oncotic pressure
○ Is the major plasma protein
○ Levels are lower in a neonate
The blood supply to the liver is by two vessels, the hepatic artery and portal vein. These vessels differ in that …
○ 60% of the blood supply comes from the hepatic artery
○ The portal vein blood is more fully saturated than the hepatic artery
○ The portal vein provides 50% of the oxygen supply
○ The portal vein supplies the bulk of the nutrients to the liver
■ Select all that apply
○ The portal vein provides 50% of the oxygen supply
○ The portal vein supplies the bulk of the nutrients to the liver
*The liver has a dual blood supply. Only 25% of the blood is supplied by the hepatic artery. The oxygen supply is evenly divided by the two vessels, even though the portal vein blood is more Unsaturated. Most of the nutrients come from the portal vein.
The autoregulation of the hepatic blood flow…
○ Involves the hepatic artery
○ Involves the portal vein
○ Is via the sympathetic nervous system
○ Is via the parasympathetic nervous system
Select all that apply
○ Involves the hepatic artery
○ Is via the sympathetic nervous system
ALF is seen in which race the most? Least?
Acute liver failure is seen among all races
Most: Whites
Least: Latin Americans
○ Whites (74%) ○ Hispanics (10%) ○ Asians (5%) ○ African Americans (3%) ○ Latin Americans (2%)
hepatitis A etiology
contaminated food/water
hepatitis B etiology
infected blood, needles, unprotected sex
hepatitis C etiology
blood + needles
hepatitis D etiology
infected blood, needles, unprotected sex
-must be + hepB
Hepatitis E etiology
contaminated water
