Liver Disease
Liver disease is a high-risk group for anesthesia
Classification system to assess risk
Ascites
Encephalopathy
Bilirubin
Albumin
Prothrombin time
Pharmacokinetics
Distribution
Unbound portion is able to distribute widely therefore the volume of distribution (Vd) increases
Detoxification
Decreased hepatic clearance of drugs (benzodiazepines and opioids)
Elimination
Decreased biliary excretion
Other problems
Ascites: could decrease functional residual capacity (FRC)
Coagulopathy: decreased production of vitamin K clotting factors (II,VII,IX,X) and non-vitamin K (V,XI,XII,XIII) and altered platelet function
Renal: hepato-renal syndrome and acute tubular necrosis. Increased plasma volume
Cardiac: high cardiac output and low SVR (severe)
Respiratory: V/Q mismatch reduces PaO2
Metabolic
Hypoglycemia and sodium retention
Neurology
Encephalopathy
Drugs
Corticosteroids
Assessment
Optimize condition by hepatologist
May take several weeks (esp. nutrition)
CBC, electrolytes, clotting factors, LFTs, glucose, ABG
ECG, CXR & hepatitis B status
Vitamin K and mannitol may be needed pre-op
Conduct
Monitoring: CVP, arterial, capnography, urinary output, temperature, nerve stimulator, PAWP if severe myocardial abnormalities
Regional – could be best option
General - lower doses required: increased volume of distribution (Vd)
Careful titration of drugs, i.e. atracurium, sodium thiopental, and isoflurane
Increased FiO2 and careful fluid balance
Perioperative mannitol to maintain urinary output
Avoid lactate and sodium fluids, give 5% dextrose
Warm pt adequately
Post-operatively
ICU may be required
Accurate fluid balance
Analgesia carefully
Risk of infection: prophylactic antibiotics