Case 33 - Major hepatic Resection Flashcards

1
Q

What is liver cirrhosis?

A

Can be due to cholestatic diseae and hepatocellular disease.

Cholestatic Disease

  • primary biliary cirrhosis
  • primary sclerosing cholangitis

Hepatocellular Disease

  • infectious (Hep C)
  • autoimmune
  • steatohepatitis
  • alcoholic
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2
Q

what does liver cirrhosis do to the CNS system?

A

Hepatic Encephalopathy

  • variable manifestations
  • confusion, personality changes, coma
  • can be preciptated by anesthesia or sx if hepatic perfusion is impaired (hypotension, hypoxemia)
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3
Q

what does liver cirrhosis do to the Cardiovascular system?

A

Hemodynamic State

  • decrease SVR due to nitric oxide effects (not metabolized due to poor functioning liver)
  • increase CO
  • normal to low BP

Cardiomyopathy

  • s/sx of CHF

Altered Blood Flow

  • incrase splachnic blood flow with central hypovolemia
  • AV collateralization –> increase MVO2
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4
Q

what does liver cirrhosis do to the portal system?

A

Portal HTN

  • results in collateral flow around liver –> portosystemic collateral development
  • caput medusa, esophageal varices, spinger angiomas
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5
Q

what does liver cirrhosis do to the pulmonary system?

A

**Atelectasis **

  • ascities
  • pleural effusion

pulmonary shunting

  • impaired hypoxic pulmonary vasoconstriction

Hepatopulmonary syndrome

  • Intrapulmonary vascular dilation and shunting
  • Dyspnea and hypoxemia are worse in the upright position (which is calledplatypnea and orthodeoxia, respectively).

Portopulmonary HTN

  • pulmonary vascular remodeling due to imbalance between vasoconstrictor and vasodilator mediators
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6
Q

What is hepatorenal syndrome?

A
  • HRS is prerenal failure from advanced chirrhosis
  • due to lack of blood flow to the renal artery due to imbalance between vasoconstrictor and vasodilator mediators. Flow increased in splachnaic circulation, but decreased to renal arteries.
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7
Q

Describe edema and ascities in liver cirrhotic pts

A

Edema and ascities

  • ascities due to portal HTN, backflow of blood
  • central hypovolemia due to edema/third spacing/ascites causes activation of RAA which leads to sodium and water retention
  • pts on diuretic and salt restricted diet
  • albumin is mainstay of tx
  • infection of ascitic fluid = spontaneous bacterial peritonitis –> renal failure and sepsis
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8
Q

what does liver cirrhosis do to the coagulation system?

A
  • clotting and fibrinolysis is impaired
  • PT/INR, PTT elevated
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9
Q

How does liver cirrhosis casue thrombocytopenia?

A

portal HTN causes increase flow to collateral circulation, one of which is to the spleen

  • portal HTN induces splenomegaly
  • splenomegaly sequesters PLT (decrease circulation of PLT)
  • bone marrow suppresion also decrease PLT
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10
Q

What is esophageal varicies

A
  • long term portal HTN will cause collateral flow to the lower esophagus
  • superficial veins lining the esophageal mucosa, drain into the left gastric vein (coronary vein), which in turn drains directly into theportal vein. These superficial veins (normally only approximately 1 mm in diameter) become distended up to 1–2 cm in diameter in association with portal hypertension.
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11
Q

how is MELD score different from Child-Pugh Score?

A

MELD Score (CBP)

  • creatinine
  • bilirubin
  • PT/INR
  • more useful in transplant selection; no subjective data

Child- Pugh Score (A&E ABP)

  • ascites (subjective)
  • encephalopathy (subjective)
  • Albumin
  • Bilriubin
  • PT/INR
  • straifying risk in cirrhotic patients for non-transplant procedures
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12
Q

Would you consider an LMA for a cirrhotic patient undergoing surgery?

A

NO!

  • decrease dose or avoid premeds (BZD) in setting of even mild encephalopathy
  • full stomach due to ascities and decreased GI motility
  • ET intubation to secure airway (avoid facemasks and LMAs)
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13
Q

Do you have any concern with the pharmacokinetics when giving anestheia meds to a cirrhotic patient?

A

YES!

  • cirrhosis is associated with abnormalities in protein binding, protein concentration, volume status, volume of distribution, metabolism from hepatocyte derangment
  • all meds given to these patients should be titrated to effect
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14
Q

What happens to cirrhotic patients using inhaled anesthetics? Do you need a change in dose?

A

No change in dose necessary

  • encephalopathic pts may require less inhaled anes
  • high dose inhaled anes can cause hypotension, exacerbate disease state through hypoperfusion
  • sev, des, iso presever hepatic blood flow well
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15
Q

what happens to cirrhotic patients using induction agents like prop, etom, ket?

A

no change in dose necessary

  • modest impact on hepatic blood flow and post op liver function when arterial blood pressure is maintained
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16
Q

do you need to change opoid dose in cirrhotic patients?

A

fentanyl and remifentanil

  • no change
  • fentanyl undergoes rapid redistribution
  • remifentail not affected by liver (non-specific tissue and plasma esterases)

Rest of opioids (morphine, dilaudid, etc)

  • reduce dose
  • accumulation and prolong or profound effects
17
Q

Neuromuscular blocks dose needs to be changed in cirrhotic patients, Yes Or NO?

A

Sux

  • NO change
  • beware liver dz assoc with decrease colinesterase level (due to decrease synthesis from dz)

NMBDs

  • Atra and CisAt - no change - hoffman elimination
  • vec, roc, miv
    • increase dose for induction due to increase volume of distribution
    • decrease incremental maintenance dose (decrease hepatic clearance)
18
Q

What preoperative preparations would you do for a patient undergoing liver resection?

A

Preop prepration

  • History, examination, laboratory studies review
  • Assess risk using MELD or Child-Pugh Score
    • severe liver disease (high risk) portends poor outcome because of increased morbidity and mortality from hepatic problems
  • discuss with surgical staff size of lesion, location of lesion, vascular involvement of tumor
  • presence of esophageal varicies
  • thrombocytopenia, large varices, significant anemia, and coagulopathy preoperatively should be corrected preoperatively
19
Q

How would be your intraop management for all patients undergoing hepatic resection?

A
  • General Anesthesia is required
    • RSI for large volume ascitic patients
    • inhalation better than TIVA due to slight decrase in hepatic blood –> limit bleeding
    • NMBD (roc/vec) if liver has good function
    • Cis-At if severe liver disease (hoffman elim)
  • Two large bore IV catheters ( 14g, 16g, RIC)
    • risk of sudden and brisk blod loss
  • +/- Central venous cannulation
    • patient with poor peripheral access, or extremely sick and may require BP support
  • A-line (pre or post induction)
    • close hemodyamic monitoring, frequent blood sampling (ABG, coags, CBC, etc.)
20
Q

What are post-op pain managment options for a patient undergoing hepatic resection?

A
  • spinal morphine
    • single dose, limited duration of action, n/v + pruritis, coagulation profile
  • epidural catheter with continuous infusion pump/PCEA
    • coagulation profile (hematoma), ASRA guidelines
  • intraop IV opioids, post-op PCA infusion. Consider long acting opioids (dilaudid, morphine)

Patients should be monitored in ICU/step down –> resp depression can occur

21
Q

What happens when the surgeon compresses the vena cava during hepatic resection?

A
  • surgeon may need to compress the vena cava to mobilize and retract the liver.
  • acute decrease venous return –> decrease preload –> decreased LVEDP –> decrease CO –> hypotension (profound)
  • always have vasoactive medications (phenyl, norepi, vaso) on standby to treat this.
22
Q

what is your emergence and post-op plan for a patient underoging hepatic surgery?

A

Emergence

  • resumption of spont ventilation
  • titrate analgesics to RR 12-20 breaths/min
  • antagonize neuromuscular blockade
  • extubation criteria
  • step-down vs ICU to monitor for resp depression (residual narcotics or splinting from pain), rebleed, acute liver failure
23
Q

Briefly describe liver blood supply and lobes of liver?

A

Liver blood supply

  • portal vein supplies 80% of total heaptic blood flow
  • hepatic artery 20% of total hepatic blood flow
  • Venous drainage - 3 hepatic veins which dump into IVC

Lobes

  • four lobes: right lobe, left lobe, two posterior lobes
24
Q

what’s the maximum percentage of liver resection one can have before ensuing liver failure?

A
  • 75% of liver mass can be resected without leading to liver failure
  • liver cells replicate rapidly, expect complete compensation in a few weeks.
25
Q

Please describe the segmental anatomy of the liver?

A
  • liver is divided into 8 segments, labeled 1 to 8
  • segment 1 = caudate lobe
  • segments 2-4 = left lobe
  • segments 5-8 = right lobe
  • center of each segment there is a branch of the portal vein, hepatic artery and bile duct.
26
Q

What is the difference between right and left liver lobectomies?

A
  • lobe/segment to be resected & number of segments resected –> anticipate blood loss
  • # of segments resected anticipate morbidity/mortaility (more segments resected leads to increased risk)

Right Lobe

  • more vascular than left lobe
  • multiple small venous branches from IVC to liver as well as large accesory hepatic veins must be isolated/ligated (requires extensive caval dissection)
  • larger blood loss
    • arterial line, +/- CVC vs two large bore periphreal IVs

Left Lobe

  • does not lie on vena cava, therefore extensive caval dissection is unnecessary
27
Q

Why is avoidance of transfusion a resonable request?

A
  • liver resection for malignant lesions carries risk of increased blood loss
  • blood transfusion is essential to maintain intravascular volume

Negative effects of blood transfusion

  • patients with tumor who get blood transfusion –> immunosuppresion and subsequent tumor recurrence
  • blood transfusion has its own adverse effects (TRALI, hemolysis, TACO, infectious transmission)
28
Q

What are risks vs benefits in low CVP during hepatic surgery?

A

Low CVP controversy

  • low CVP may minizmize blood loss from hepatic veins or vena cava (signif contribute bleeding during resection)
  • low CVP balanced with potential risk of organ hypoperfusion and air embolus
  • CVP value altered by mech vent, ascities, surgical retractors in thorax and R atrium, zero-reference point
29
Q

How would you manage the fluids for hepatic resection cases while avoiding blood transfusion?

A

Arterial line

  • estimate volume status through pulse pressure variation, systolic pressure variation

Mgmt

  • target normovolemia (not hypo) during resection
  • Before Resection
    • limit fluids to < 1L crystalloid (limit bleeding).
    • maitain MAP > 70 with vasopressor
  • After Resection
    • volume resuscitate (no superiority of colloids vs crystal)
30
Q

What is the Pringle Maneuver?

A
  • Sx may use pringle maneuver during hepatic surgery
  • extrahepatic approach - hepatic artery and portal vein branches are isolated and clamped to limit inflow to liver before resection
    • bleeding will be a result of hepatic venous pressure (decreaes with low CVP and MAP)

SE

  • clamping/unclamping leads to liver ischemia and reperfusion injury
  • keep clamp under 45 min to prevent ischemia
  • Hypotension
    • clamp –> decrease venous return
    • unclamp –> reperfusion injury
    • unclamp –> release of ischemic mediators leading to cardiac depression and vasodilation
    • unclamp –> lactic acidemia
    • Tx: pressors/inotropes, fluids, electrolyte correction
31
Q
A