Liver disease and anaesthesia:

 

Causes of drug-induced liver injury:

·         Paracetamol

·         Augmentin

·         Anti-TB

·         Sulfa-containing drugs

·         Phenytoin

·         Valproate

·         Herbs

 

Scoring system:

Child-Pugh

Components:

·      Albumin

·      Bilirubin

·      Coag (INR)

·      Distension (ascites)

·      Encephalopathy

Peri-op mortality for major abdo surgery:

·      A: 10%

·      B: 30%

·      C: 80%

But critical care has improved since those studies

MELD

Components:

·      Bilirubin

·      INR

·      Creatinine

·      Log transformations + multiplications etc

Better predictor of overall survival

 

Physiology:

Whole body

·      Many organs not working well

·      Malnourished

·      High risk of disaster

·      Only do surgery if really needed

·      Prefer tertiary HPB centre

·      HDU post-op

Airway

·      Ascites -> risk of aspiration

Respiratory

·      Ascites and hydrothorax-> ↓FRC -> rapid desaturation

Circulation

·      Sepsis-like state: ↓SVR, hyperdynamic (many causes)

·      +/- Cirrhotic cardiomyopathy

·      +/- portopulmonary hypertension (high risk of death)

·      +/- hepatopulmonary syndrome (vasodilation -> shunting- > ↓PaO2. Worse when upright)

·      +/- Prolonged QT

Disability (CNS)

·      Abnormal CNS function

·      Risk of encephalopathy

·      Prevention: lactulose, rifaximin

Coagulation

·      Hypersplenism -> ↓plt

·      Liver failure -> ↓coag and ↓anticoag -> unpredictable

·      ↑Risk of VTE and ↑risk of bleeding

·      FFP doesn’t improve INR

·      Use viscoelastic

·      Look at the actual bleeding

Immunity

·      ↑Risk of infection

Kidneys

·      Hepatorenal syndrome common, but exclude other causes

·      Intravascular depletion despite ascites and oedema is a thing

·      Fluid balance is fraught

·      Multi-electrolyte disturbance common (↓Na, ↓Mg, ↓PO4)
Correct Mg and PO4 but careful with Na

 

Pharmacology:

Sedative-hypnotics

·      Halothane -> hepatitis

·      All volatiles -> hapten -> hepatitis (idiosyncratic and rare)

·      Propofol -> maybe easier on the liver

·      Benzos -> sedation + encephalopathy + slow offset

Local anaesthetics

·      Neuraxial – hell no

·      Regional – hell yes

·      Higher risk of LAST

·      Beware high concentration (ropiv >0.25%, bupiv >0.125%)

·      Beware long infusion (>48 hours)

Analgesics

Tricky!

·      Paracetamol – no (hepatotoxicity)

·      NSAID – no (GIT bleed + plt dysfunction + AKI)

·      COX2i – no (AKI)

·      Opioids – beware. Fentanyl and remi ok

·      Ketamine – no (hepatotoxicity, encephalopathy)

Muscle relaxants

·      Benzylisoquinoliniums – preferred

·      Sux – slower offset due to ↓PChE

·      Sugammadex – alters coag profile, probably unimportant

 

 

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