Case 33 - Major hepatic Resection

Question 1

What is liver cirrhosis?

Answer 1

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

Question 2

what does liver cirrhosis do to the CNS system?

Answer 2

Hepatic Encephalopathy

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

Question 3

what does liver cirrhosis do to the Cardiovascular system?

Answer 3

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

Question 4

what does liver cirrhosis do to the portal system?

Answer 4

Portal HTN

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

Question 5

what does liver cirrhosis do to the pulmonary system?

Answer 5

**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

Question 6

What is hepatorenal syndrome?

Answer 6

• 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.

Question 7

Describe edema and ascities in liver cirrhotic pts

Answer 7

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

Question 8

what does liver cirrhosis do to the coagulation system?

Answer 8

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

Question 9

How does liver cirrhosis casue thrombocytopenia?

Answer 9

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

Question 10

What is esophageal varicies

Answer 10

• 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.

Question 11

how is MELD score different from Child-Pugh Score?

Answer 11

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

Question 12

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

Answer 12

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)

Question 13

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

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

no change in dose necessary

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

Question 16

do you need to change opoid dose in cirrhotic patients?

Answer 16

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

Question 17

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

Answer 17

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)

Question 18

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

Answer 18

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

Question 19

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

Answer 19

• 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.)

Question 20

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

Answer 20

• 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

Question 21

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

Answer 21

• 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.

Question 22

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

Answer 22

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

Question 23

Briefly describe liver blood supply and lobes of liver?

Answer 23

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

Question 24

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

Answer 24

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

Question 25

Please describe the segmental anatomy of the liver?

Answer 25

• 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.

Question 26

What is the difference between right and left liver lobectomies?

Answer 26

• 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

Question 27

Why is avoidance of transfusion a resonable request?

Answer 27

• 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)

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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)

Question 30

What is the Pringle Maneuver?

Answer 30

• 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