Hepatic anesthesia considerations Flashcards
Volatile anesthetics and effects on liver
REDUCED HEPATIC BLOOD FLOW!!!!!!
Halothane and the liver
Associated with hepatic toxicity - do not use
“halothane hepatitis”
Isoflurane and the liver
Great choice - very little reduction in HBF at 1 MAC
Dose-dependent reduction at higher doses
Sevoflurane
Good choice - very little reduction of HBF at 1 MAC
Desflurane and the liver
Decrease HBF by 30% at 1 MAC
For volatile anesthetics, what does the degree of hepatic metabolism correlate with?
The likelihood of a toxic reaction
Metabolism to TFA
TFA is a hepatotoxic byproduct
- halothane - 20%
- isoflurane - 0.2%
- desflurane - 0.2%
- sevoflurane - NONE
N2O and the liver
Not known to cause liver injury but can decrease HBF d/t decreased sympathetic stimulation
N2O and vitb12 deficiency
Patients with vitb12 deficiency may be at increased risk for neurotoxicity with exposure to N2O
IV anesthetics and the liver
As long as CO and BP are maintained, prop, etomidate, and midaz do not appear to affect liver function
What are the major determinants of hepatic clearance
Blood flow to the liver
Fraction of drug not bound to plasma proteins
Intrinsic clearance
Vascular architecture
Effects of liver disease on induction agents
Clearance is similar to healthy patients, but you are more sensitive to pharmacodynamic effects of induction agents and clinical recovery times can be prolonged
Effects of liver disease on benzos
Low extraction ratios
Enhanced sedation and prolonged duration of action
Effects of liver disease on dexmedetomidine
Metabolized primarily in liver, so decreased clearance and prolonged half life
Effects of liver disease on opioids
Reduced metabolism so increase dosing intervals, single dose less of a problem than gets
Titrate to effect
Avoid meperidine in cirrhosis because plasma clearance reduced
Remifentanil IS THE OPIOID OF CHOICE
Effects of liver disease on succinylcholine/mivacurium
Plasma cholinesterase can be reduced in advance liver disease prolonging duration of action
Effects of liver disease on roc/vec
Clearance, elimination, and duration are all prolonged
Resistance to initial dose will occur d/t gamma globulin concentration and increase vol of distribution d/t edema and ascities
Effects of liver disease on at/cisat
Not affected by liver disease
Induction for patients with liver disease
They have hyper dynamic circulation (dec SVR, hypotension, inc CO)
MAINTAIN BP DURING INDUCTION AND MAINTENANCE WITH PRESSORS
Vasopressors and patients with liver disease
Pts with liver dx have autonomic dysfunction (may be depleted of endogenous vasopressin)
REDUCED responsiveness to pressors, so you may need higher doses
Goal of abdominal surgery with hepatic patients
Decrease portal pressure to minimize bleeding, consider fluid restriction with CVP monitoring
Serum albumin function and liver patients
Quantitatively and qualitatively decreased in these patients
Choose albumin rather than crystalloid for periop volume expansion
Which g=coat tests may provide more value to ID adequate homeostasis
Fibrinogen and viscoelastic test
They measure the complete process of clot formation, stabilization, and clot dissolution
TEG and ROTEM and liver patients
Have been shown to decrease use of blood products and can confirm preserved hemostatic function despite a prolonged INR
