Orthotopic Liver Transplantation

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Orthotopic Liver Transplantation
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Orthotopic liver transplantation

• Approximately 2500 liver transplants per year in
  the United States
• 1 yr survival approx 76
• Majority are orthotopic ( native hepatectomy with
  donor implantation in RUQ )
• Typically reserved for non-malignant ESLD that
  will not recur in hepatic graft

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Indications

• Post necrotic cirrhosis 35
• Post hepatitis
• Alcoholic (Laennecs cirrhosis)
• Cryptogenic
• Auto-immune
• Primary biliary cirrhosis
  12
• Malignancy (isolated) 12
• Biliary Atresia 10
• Acute fulminant failure 8
• Sclerosing choangitis 6

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Contraindications

• Have evolved over the last several years
• Now generally include
• Widespread malignancy
• Uncontrolled infection
• Severe cardiac / neurologic disease
• Inability to maintain appropriate
  immunosuppression

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Pre-Anesthetic considerations

• Vast array of physiologic derrangements
• Many are not correctable until after
  transplantation
• Identify most important areas of physiologic
  compromise and treat only those that threaten the
  safe induction of anesthesia ( ie. Pleural
  effusions, coagulopathy )

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Pathophysiology

• GI portal HTN, Esophageal Varices, Ascites
• Renal Oliguria (pre-renal v. hepatorenal v.
  other )
• CV Hyperdynamic circulation ( low SVR, high CO
  )
• Pulmonary ( Intrapulmonary shunting, pleural
  effusions, decreased FRC, atelectasis, decreased
  compliance, pulmonary HTN )
• CNS Encephalopathy /- increased ICP
• Heme Coagulopathy (thrombocytopenia, synthetic
  dysfunction, fibrinolysis, DIC )

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Monitoring

• Standard ASA /- institutional variations
• Fundamental goals are the same
• Sufficient IV access to administer rapid
  infusions, drips, other products
• Arterial line(s)
• Central Line ( /- PAC)

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Anesthetic management

• Induction RSI vs. awake
• Maintenance Isoflurane opioids muscle
  relaxants (Nitrous Oxide?)
• Also
• Renal dose Dopamine
• CaCl infusion

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OLT terminology

• Pre-anhepatic Stage Dissection of the porta
  hepatis and mobilization of the native liver
• Anhepatic Stage Begins after clamping of native
  livers blood supply
• Neo-hepatic Stage Reperfusion of the allograft,
  biliary reconstruction

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Preanhepatic (dissection) stage

• Pre-anhepatic Stage Dissection of the porta
  hepatis and mobilization of the native liver

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Pre-anhepatic Stage

• HD instability -secondary to acute loss of
  ascites, hemorrhage from abdominal venous
  collaterals, excessive retraction, pericardial
  effusions
• Electrolytes citrate toxicity, rapid
  transfusion/ hemolysis

• Coagulopathy- factor deficiencies,
  thrombocytopenia, hemodilution, fibrinolysis,
  hypothermia
• Metabolic Acidosis
• Hypothermia
• Oliguria
• Air embolism

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Pre-anhepatic Stage

• Increased risk in patients with
• preop coagulopathy (significant)
• previous abdominal surgery (ie. Kasai
  procedure in pediatric pt.s)

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Anhepatic Stage

• Anhepatic Stage Begins when native liver is
  removed after clamping of its blood supply

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Anhepatic Stage

• Clamping hepatic artery, portal vein,
  infrahepatic vena cava, suprahepatic vena cava
• Typically lasts 60 90 minutes
• Typically requires venovenous bypass

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Anhepatic Stage

• Clamping and Veno-venous bypass related
  complications
• Air embolism
• Thromboembolism
• Hypotension
• Hypothermia
• Vericeal Hemorrhage (Sengstaken-Blakemore tube)
• Hyperkalemia ( liver is primary site of insulin
  action, even in ESLD)
• Hypocalcemia (total lack of citrate metabolism)
• Continued problems associated with all stages of
  OLT (hypothermia, coagulopathy, acidosis and
  other metabolic derrangements, atelectasis, HD
  instability, hemorrhage)

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Venovenous Bypass

• Blood from femoral and portal vein bypasses liver
  via extracorporeal circulation and returns to
  heart via axillary / subclavian vein.
• Helps maintain HD stability
• Improves renal perfusion
• Reduce portal venous pressures
• In pt.s gt 15 kgs
• No heparinization needed
• Bypass flow should be gt25 CO (gt 1 L/Min)

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Neohepatic (post-anhepatic) stage

• Neo-hepatic Stage Reperfusion of the allograft,
  biliary reconstruction
• Allograft is flushed of air, debris, and
  preservative solution
• Subsequent unclamping can release significant
  load of Potassium and Metabolic Acids into
  circulation

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Neohepatic Stage

• Continued pre-anhepatic, anhepatic problems
• Hemodynamic changes hypotension, bradycardia,
  supraventricular and ventricular arrythmias,
  cardiac arrest.
• Hemorrhage
• Continued risk of air or thromboembolism

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Postreperfusion Syndrome

• Aggarwal et al. defined as decreased MAP of at
  least 30 from baseline for at least one minute
  within five minutes of reperfusion
• Labile SVR, and CO
• Incidence as high as 30
• Lower incidence in non VVB cases (attributed to
  increased intravascular volume before
  reperfusion)

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Mechanism(s) of PRS

• Isolated RV dysfunction (as detected by echo
  paradoxical motion of IVS, etc.)
• Impaired LV function
• Endotoxemia , Cytokine release (TNF, IL-1,
  IL-6 , and other vasoactive substances following
  decompression of the portal circulation
• Most likely multifactorial in nature

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Other factors affecting post reperfusion
hemodynamics

• Hyperkalemia
• Hyocalcemia
• Continued blood loss
• Air embolism
• If graft function is adequate, hemodynamic
  stability generally occurs within 15 min
  following reperfusion

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Treatment of Post -Reperfusion instability

• Inotropic support
• Calcium
• Sodium Bicarbonate
• 100 Oxygen
• Aggressive electrolyte management pre-reperfusion
• ACLS

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Hyperkalemia

• ECG changes generally seen at gt 6.0 meq/L
• Immediate tx with Calcium salt
• Then
• Insulin with glucose ( 10 U with 50 ml of 50
  glucose)
• B agonist ( 10-20 mg nebulized albuterol )
• Sodium Bicarbonate
• K removal (Loop diuretic, Kayexelate,
  Dialysis)

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UW or Belzers Solution

• K lactobionate 100 mmol
• Dihydrogen Phosphate 25 mmol
• Adenosine
  5 mmol
• MgSO4 5 mmol
• Glutathione 3 mmol
• Raffinose 30 mmol
• Allopurinol 1 mmol
• Insulin 100 U
• Penicillin 40 U
• Dexamethasone
  8 mg
• Hydroxyethyl starch
  50 g
• Osmolality
  320-330 mOsm
• pH 7.4

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UW Solution

• Cell impermeant agents Lactobionic Acid,
  Raffinose, Hydroxyethyl starch
• Glutathione Antioxidant
• Adenosine Cellular metabolism

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Autologous Flush

• Prior to reperfusion
• All vascular anastamoses completed except for
  infrahepatic IVC
• Graft perfused via unclamping Portal Vein, and
  Hepatic Artery
• 500 cc of blood allowed to flow out of partially
  anastamosed infrahepatic IVC, then into cell
  saver
• Blood supply then reclamped, and infrahepatic IVC
  anastamosis completed
• Associated increase in HD stability, decreased
  serum K levels, improved early graft function,
  increased patient and graft survival ( Fukazawa
  et al., 1994)

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Reperfusion Hyperglycemia

• Massive release of glucose from donor liver
• Gradually resolves with return of hepatic
  function
• Persistent hyperglycemia is indicator of impaired
  glucose utilization
• May be prognostic factor for liver viability

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Reperfusion Coagulopathy

• Related to release of heparin from the donor
  liver
• Reversible with protamine
• Accompanied by diminished platelet count, factor
  V, and VIII.
• 80 of patients experience primary fibrinolysis
  from release of TPA from liver
• 20 require specific treatment with
  cryoprecipitate and platelets
• Continued refractory coagulopathy indicates high
  likelihood of graft failure

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Thromboelastography

• Monitors entire coagulation process
• This includes clot formation and lysis
• Valuable in directing blood product replacement
  and pharmacologic intervention

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Thromboelastography 101

• R (reaction time) denotes time to onset of the
  start of coagulation ( 6-8 min )
• Prolonged R time represents factor deficiency, tx
  with FFP
• Coagulation time (r k ) is time from start of
  TEG to the generation of an amplitude of 20 mm,
  and measures speed of clot formation
• Alpha angle (clot formation rate) Normally
  greater than 50 degrees. Abnormalities represent
  plt dysfunction, fibrinogen, IP. Tx with
  Cryoprecipitate
• MA (max amplitude) Most indicative of plt
  function (normally 50-70 mm) Treat with
  platelets