Anaesthesia in hepatic disease

Question 1

Name two common settings in which a patient in liver failure will present to the theatre

Answer 1

1. Cirrhosis: Upper GI bleed for variceal banding

2. Sepsis: multi-organ failure

Question 2

What is the Child-Pugh score. Describe the interpretation of the score.

Answer 2

It is a score which determines the chance of patient mortality after major surgery.
—> 1 - 3 points for level of severity

Bilirubin
Albumin
INR
Ascites
Encephalopathy

Total possible score is 15

Class A: 5 -6 (10% mortality) - District
Class B: 7 -9 (30% mortality) - Teritiary
Class C: 10 - 15 (75% mortality) - Tertiary

Question 3

Describe the principles of anaesthetic management for a patient in liver failure

Answer 3

1. Avoid drugs metabolized by the liver (ROC)
2. Avoid hepatotoxic drugs (e.g. halothane)
3. Address coagulopathy using Thromboelastography (TEG)
4. Provide glucose containing fluids
5. Reduces doses of sedatives and opioids (Remi safest)
6. Muscle relaxation: cisatracurium
7. Regional anaesthesia if clotting profile allows

Question 4

Define azotemia versus uremia

Answer 4

Elevated levels of urea and other nitrogenous compounds in the blood.

Uremia is the clinical syndrome related to the pathological and symptomatic manifestations of azotemia

Question 5

What investigations demonstrate metabolic and synthetic function of the liver

Answer 5

1. Urea: Low urea synthesis –> hyperammonaemia
2. Albumin (dilution and decreased synthesis)
3. INR

Question 6

What are the effects of anaesthesia on the liver

Answer 6

1. Reduced hepatic blood flow —> reduced drug metabolism
   - Decreased MAP
   - PPV
   - Catecholamines
   - Manipulation of gut near liver
2. Drug-induced hepatitis
3. Opioids: spasm of the sphincter of Oddi

Question 7

What degree of liver disease might exclude a patient from elective surgery

Answer 7

Child-Pugh Class C (10 - 15)

Question 8

How does halothane affect the liver

Answer 8

20% halothane metabolised here (the rest exhaled)

20% of patients with 2nd exposure to halothane within 6 months will develop a transaminitis

Question 9

What is the incidence of true halothane hepatitis

Answer 9

1 : 35 000 —> may develop into fulminant hepatic failure

Question 10

How does the incidence of halothane hepatitis differ in adults and kids

Answer 10

Less common in children

Question 11

Describe the two possible mechanisms of halothane hepatitis

Answer 11

1. Cytotoxic
   - Hypoxic hepatic metabolism of halothane –> hepatotoxic metabolite formation –> binds to hepatocytes –> these hepatocytes now appear as foreign proteins
2. Type 2 hypersensitivity reaction
   - Eosinophilic response
   - -> rash, nausea, jaundice, hepatic failure

Question 12

What is the mortality associated with halothane hepatitis

Answer 12

50 - 75% for those that develop fulminant hepatic necrosis

Question 13

What are the risk factors for halothane hepatitis

Answer 13

1. Family Hx
2. Fat, females over forty
3. Exposure to halothane < 6 months
4. Pre-existing liver disease

Question 14

What is the absolute contraindication to the use of halothane

Answer 14

Previous unexplained postoperative hepatitis