Liver anatomy, physiology and imporatance to anesthesia

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Liver anatomy and physiology imporatnat considerations from anesthesia point of view

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Liver anatomy, physiology and imporatance to anesthesia

  1. 1. LIVER ANATOMY & PHYSIOLOGY DR. PRIYANKA Ruby Hall Clinic Pune
  2. 2. ANATOMY OF LIVER & BILIARY SYSTEM <ul><li>1.5 kg or 1% body wt </li></ul><ul><li>5% in neonates </li></ul><ul><li>Holds 10 to 20 % of blood volume </li></ul><ul><li>Reservoir of blood </li></ul>
  3. 3. GROSS ANATOMY OF LIVER
  4. 4. LIGAMENTS OF LIVER <ul><li>Ligamentum teres </li></ul><ul><li>Falciform ligament </li></ul><ul><li>Coronary ligament </li></ul><ul><li>Triangular ligament </li></ul>
  5. 5. LOBES OF LIVER <ul><li>French (Couinaud) system </li></ul><ul><li>Each segment : own vascular supply & biliary drainage </li></ul><ul><li>Improved surgical outcome in neoplasm & traumatic liver injury </li></ul>
  6. 6. HEPATIC LOBULE
  7. 7. HEPATIC LOBULE
  8. 8. BLOOD SUPPLY <ul><li>25% of cardiac output </li></ul><ul><li>1ml/ gm of liver </li></ul><ul><li>Hepatic artery : 25-30 % of blood flow & 45-50% of oxygen </li></ul><ul><li>Portal veins : valveless nutrient vessel , 70-75% blood flow, 50-55% of oxygen </li></ul>
  9. 9. SPLANCHNIC BLOOD FLOW
  10. 10. BLOOD FLOW IN LIVER <ul><li>Terminal branches : sinusoids ( capillaries in liver) </li></ul><ul><li>Central vein : terminal hepatic venules </li></ul><ul><li>Hepatic veins </li></ul><ul><li>Inferior vena cava </li></ul>
  11. 11. HEPATIC SINUSOIDS
  12. 12. HEPATIC MICROCIRCULATION
  13. 13. HEPATIC ACINUS <ul><li>ZONE 1 : PERIPORTAL </li></ul><ul><li>ZONE 2 : MIDZONE </li></ul><ul><li>ZONE 3 : PERICENTRAL </li></ul><ul><li>Receives blood that has gases & metabolites exchanged with zone 1 & zone2 G lutamine synthase ( urea) </li></ul>
  14. 14. INTRENSIC REGULATION OF BLOOD SUPPLY <ul><li>1 . Pressure flow regulation : </li></ul><ul><li>Myogenic , Not in portal system </li></ul><ul><li>Maximum in postprandial, Absent in fasting state </li></ul><ul><li>2. Metabolic control : </li></ul><ul><li>Decrease in pH & O2 tension </li></ul><ul><li>3. Hepatic arterial buffer response : </li></ul><ul><li>Adinosine (vasodilator) </li></ul>
  15. 15. EXTRENSIC REGULATION OF BLOOD FLOW <ul><li>Neural control : </li></ul><ul><li>Splanchnic nerves ie postganglionic sympathetic T6-T11,vagus, phrenic nerves </li></ul><ul><li>Sympthoaderanal stimulation </li></ul><ul><li>Humoral control : HA( α 1 β 2 α 2) PORTAL( α ) </li></ul><ul><li>Epinephrine - vasoconstriction </li></ul><ul><li>Dopamine – no influence </li></ul><ul><li>Glucagon - vasodilatation </li></ul><ul><li>Angiotensin 2 - vasoconstriction </li></ul>
  16. 16. FACTORS AFFECTING HEPATIC BLOOD FLOW <ul><li>INCREASE IN HEPATIC BLOOD FLOW </li></ul><ul><li>Hypercapnia </li></ul><ul><li>Acute hepatitis </li></ul><ul><li>Supine posture </li></ul><ul><li>Food intake </li></ul><ul><li>Drugs : β Agonist </li></ul><ul><li>Phenobarbitone </li></ul><ul><li>Enzyme inducers </li></ul><ul><li>DECREASE IN HEPATIC BLOOD FLOW </li></ul><ul><li>IPPV </li></ul><ul><li>Hypocapnia </li></ul><ul><li>Hypoxia </li></ul><ul><li>Cirrhosis </li></ul><ul><li>α Stimulation </li></ul><ul><li>β Blocker </li></ul><ul><li>Halothane , volatile & anesthetics </li></ul><ul><li>Vasopressin </li></ul>
  17. 17. EFFECT OF VOLATILE AGENTS ON HEPATIC BLOOD FLOW <ul><li>Halothane : Causes hepatic arterial constriction, microvascular vasoconstriction </li></ul><ul><li>Enflurane: Increase in hepatic vascular resistance </li></ul><ul><li>Isoflurane : Increase in microvascular blood velocity </li></ul><ul><li>Sevoflurane & Desflurane : Preservation of hepatic blood flow & function </li></ul>
  18. 18. EFFECT OF INTRAVENOUS AGENTS ON HEPATIC BLOOD FLOW <ul><li>THIOPENTONE & ETOMIDATE : Hepatic arterial blood flow reduction, reduced cardiac output </li></ul><ul><li>KETAMINE : Little effect on hepatic blood flow </li></ul><ul><li>PROPOFOL : Significant splanchnic vasodilator </li></ul><ul><li>Increases both hepatic arterial & portal venous blood flow </li></ul>
  19. 19. REGIONAL ANESTHESIA & HEPATIC BLOOD FLOW <ul><li>Reduction in hepatic blood flow in high spinal & epidural anesthesia </li></ul><ul><li>Secondary to hypotension </li></ul><ul><li>Reversed by vasopressors like dopamine, ephedrine </li></ul>
  20. 21. CARBOHYDRATES & PROTEIN METABOLISM <ul><li>Protein synthesis </li></ul><ul><li>Albumin </li></ul><ul><li>Coagulation </li></ul><ul><li>Acute phase reactent </li></ul><ul><li>Hormone prcursors </li></ul><ul><li>Transport proteins </li></ul><ul><li>Protein catabolism </li></ul><ul><li>Ammonia -> urea </li></ul>
  21. 22. CARBOHYDRATE METABLOLISM <ul><li>GLYCOGENESIS </li></ul><ul><li>GLYCOGENOLYSIS </li></ul><ul><li>24-48 Hrs OF STRAVATION </li></ul><ul><li>GLUCONEOGENESIS </li></ul>
  22. 23. FATTY ACID SYNTHESIS & OXIDATION
  23. 24. BILE PRODUCTION <ul><li>Bile acid production </li></ul><ul><li>Absorbtion </li></ul><ul><li>Transportation </li></ul><ul><li>Solubilizing effect on lipids </li></ul><ul><li>Activates lipases </li></ul><ul><li>Cholesterol synthesis </li></ul>
  24. 25. MICELLE <ul><li>Micelle needed for absorption of </li></ul><ul><li>Cholesterol </li></ul><ul><li>Fat soluble vitamines </li></ul><ul><li>Lipids </li></ul><ul><li>Opioids : spasm of spincor of oddi , interfere with bile flow </li></ul>
  25. 26. COAGULATION & LIVER ACTIVATION
  26. 27. ERYTHROPOIESIS & HEME SYNTHESIS <ul><li>9-24 wks of gestation </li></ul><ul><li>Major organ till 2 yrs </li></ul><ul><li>Heme synthesis </li></ul><ul><li>5 aminolevulinic acid </li></ul><ul><li>Prophyrias : </li></ul><ul><li>Barbiturates </li></ul><ul><li>Etomidate </li></ul><ul><li>Enflurane </li></ul>
  27. 28. BILIRUBIN METABOLISM
  28. 29. DRUGS METABOLISM
  29. 30. DRUGS EXCREATED THROUGH LIVER <ul><li>EFFICIENTLY EXCRETED </li></ul><ul><li>Amitryptiline </li></ul><ul><li>Desipramine </li></ul><ul><li>Imipramine </li></ul><ul><li>Labetolol </li></ul><ul><li>Lidocaine </li></ul><ul><li>Meperidine </li></ul><ul><li>Metoprolol </li></ul><ul><li>Mophine </li></ul><ul><li>Pentazocine </li></ul><ul><li>Propranolol </li></ul><ul><li>Verapamil </li></ul><ul><li>Zydovudine </li></ul><ul><li>POORLY EXCRETED </li></ul><ul><li>Acetaminphen </li></ul><ul><li>Amobarbital </li></ul><ul><li>Aspirin </li></ul><ul><li>Clindamycin </li></ul><ul><li>Diazepam </li></ul><ul><li>Digitoxin </li></ul><ul><li>Ethanol </li></ul><ul><li>Penobatbital </li></ul><ul><li>Phenytoin </li></ul><ul><li>Tolbutamide </li></ul><ul><li>Warfarin </li></ul><ul><li>Tolbutamide </li></ul>
  30. 31. DETERMINANTS OF DRUG METABOLISM <ul><li>Drugs inducers & inhibitors </li></ul><ul><li>Age ,Sex </li></ul><ul><li>Fever, Hypothyroidism </li></ul><ul><li>Halothane reduces blood flow & hence metabolism of fentanyl verapamil, propranolol ,warfarin, phenytoin </li></ul><ul><li>Ketamine induces own metabolism </li></ul>
  31. 32. ALCOHOL METABOLISM
  32. 33. IMMUNE FUNCTION <ul><li>KUPFFER CELLS : 10% </li></ul><ul><li>Phagocytosis of bacteria & inflamatory mediators in splanchnic blood </li></ul><ul><li>Stellate cells : </li></ul><ul><li>Injury </li></ul><ul><li>Fibrosis </li></ul>
  33. 34. Endocrine function <ul><li>Synthesis of Angiotensinogen </li></ul><ul><li>Thrombopoietin </li></ul><ul><li>Insulin like growth factors </li></ul><ul><li>Inactivates aldosteron,estrogen,ADH,androgens </li></ul><ul><li>T4 -> T3 or inactivated </li></ul>
  34. 35. LIVER DYSFUCTION
  35. 36. EFFECTS OF HEPATIC DYSFUNCTION OF ANESTHETIC DRUGS <ul><li>Altered protein binding </li></ul><ul><li>Altered volume of distribution </li></ul><ul><li>Altered drug metabolism due to hepatocyte dysfunction </li></ul>
  36. 37. EFFECTS OF HEPATIC DYSFUNCTION ON ANESTHETIC DRUGS <ul><li>Opioids: exaggerated sedative & respiratory depressant effect </li></ul><ul><li>Half life is almost doubled </li></ul><ul><li>Remifetanyl : </li></ul><ul><li>Synthetic opioid </li></ul><ul><li>Ester linkages </li></ul><ul><li>Rapid hydrolysis by blood, tissue esterases </li></ul>
  37. 38. EFFECTS OF HEPATIC DYSFUNCTION ON ANESTHETIC DRUGS <ul><li>Sedative & hypnotic </li></ul><ul><li>Benzodiazepines : Duration of action increased </li></ul><ul><li>Thiopentone, etomidate propofol ketamine : Repeated doses & prolong infusion causes accumulation of drugs </li></ul><ul><li>Increases risk of hepatic encephalopathy </li></ul>
  38. 39. NEUROMUSCULAR BLOCKING DRUGS <ul><li>Vecuronium, rocuronium, mivacurium : </li></ul><ul><li>Reduced elimination </li></ul><ul><li>Prolong duration of action </li></ul><ul><li>Specially with infusion & repeated doses </li></ul><ul><li>Atracurium & cisatracurium : </li></ul><ul><li>Nondependant of hepatic metabolism </li></ul><ul><li>Can be used without modification of doses in end stage liver disease </li></ul>
  39. 40. HALOTHANE HEPATITIS <ul><li>1 : 6000 , 1: 20,000 </li></ul><ul><li>Mild : focal necrosis, self limited </li></ul><ul><li>Fluminant : repeated exposure, massive necrosis, mortality 50% </li></ul><ul><li>Trifluroacetyl(TFA) antibody formation </li></ul>
  40. 41. TAKE HOME MESSAGES <ul><li>Liver major organ of metabolism </li></ul><ul><li>Liver dysfunction affects pharmacokinetics of anesthetic drugs </li></ul><ul><li>Anesthetic drugs affects liver function </li></ul><ul><li>Neuroaxial blocks : reduction in hepatic blood flow due to hypotension </li></ul><ul><li>Introperative hypotension, hypoxia, hypocapnia, use of hepatotoxic drugs in perioperative period can cause postoperative hepatic dysfunction </li></ul>
  41. 42. THANK YOU THANK YOU

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