EDAIC Hepatic, Renal and Endocrine Anesthesia 4 — Questions and Answers
Question 1: A patient with hepatic encephalopathy grade III requires emergency surgery. Which agent is MOST appropriate for induction?
- Ketamine 1-2 mg/kg
- Propofol 1-2 mg/kg with cautious titration (Correct answer)
- Thiopental 4-5 mg/kg
- Etomidate 0.3 mg/kg
Correct answer: Propofol 1-2 mg/kg with cautious titration
Propofol, carefully titrated to effect, is preferred in hepatic encephalopathy as it reduces cerebral metabolic rate without significantly worsening encephalopathy; ketamine raises ICP and thiopental/etomidate are less favorable.
Question 2: Which coagulation factor is synthesized exclusively in the liver and has the shortest half-life, making it the most sensitive marker of acute hepatic synthetic failure?
- Factor VIII
- Factor VII (Correct answer)
- Fibrinogen
- Von Willebrand factor
Correct answer: Factor VII
Factor VII has the shortest half-life (~4-6 hours) and is exclusively hepatically synthesized, making PT/INR the most sensitive early indicator of acute liver failure.
Question 3: A patient on chronic lithium therapy for bipolar disorder presents for elective surgery. What is the primary anesthetic concern regarding renal function?
- Lithium causes acute tubular necrosis requiring dialysis pre-operatively
- Lithium-induced nephrogenic diabetes insipidus causes hypovolemia and hypernatremia (Correct answer)
- Lithium accumulates in the renal cortex causing chronic interstitial nephritis
- Lithium blocks aldosterone receptors causing hyperkalemia
Correct answer: Lithium-induced nephrogenic diabetes insipidus causes hypovolemia and hypernatremia
Chronic lithium causes nephrogenic diabetes insipidus by antagonizing ADH in collecting ducts, leading to polyuria, dehydration, and hypernatremia that must be corrected before anesthesia.
Question 4: During laparoscopic cholecystectomy in a patient with Child-Pugh C cirrhosis, which hemodynamic pattern is characteristic of the hepatorenal syndrome type 1 that may develop perioperatively?
- High SVR, low CO, normal renal blood flow
- Low SVR, high CO, marked renal vasoconstriction (Correct answer)
- Normal SVR, normal CO, prerenal azotemia
- High SVR, low CO, renal tubular dysfunction
Correct answer: Low SVR, high CO, marked renal vasoconstriction
HRS type 1 occurs in the context of cirrhotic hyperdynamic circulation (low SVR, high CO) with paradoxical intense renal vasoconstriction, causing rapid deterioration of renal function.
Question 5: A patient with a known pheochromocytoma is inadequately alpha-blocked prior to emergency appendectomy. Intraoperative hypertensive crisis occurs. What is the FIRST-LINE treatment?
- IV labetalol 20 mg bolus
- IV phentolamine 1-5 mg bolus titrated (Correct answer)
- IV nicardipine infusion
- IV esmolol 500 mcg/kg loading dose
Correct answer: IV phentolamine 1-5 mg bolus titrated
Phentolamine, a short-acting non-selective alpha-blocker, is first-line for acute hypertensive crises from pheochromocytoma; beta-blockers like labetalol must never be given before adequate alpha-blockade as they worsen hypertension.
Question 6: Which inhalational anesthetic is MOST associated with fluoride-mediated nephrotoxicity, particularly after prolonged exposure or in patients with pre-existing renal disease?
- Desflurane
- Sevoflurane
- Isoflurane
- Methoxyflurane (Correct answer)
Correct answer: Methoxyflurane
Methoxyflurane undergoes extensive hepatic defluorination producing serum fluoride concentrations above the nephrotoxic threshold (>50 µmol/L), historically causing high-output renal failure; sevoflurane's defluorination is modest and renal impact minimal.
Question 7: A 58-year-old with diabetic nephropathy (eGFR 18 mL/min) requires lower limb revascularization. Postoperative potassium rises to 6.8 mEq/L with ECG changes. What is the MOST immediate treatment?
- IV sodium bicarbonate 50 mEq
- IV calcium gluconate 10 mL of 10% solution (Correct answer)
- Insulin 10 units IV with 50 mL 50% dextrose
- Salbutamol 10-20 mg nebulized
Correct answer: IV calcium gluconate 10 mL of 10% solution
IV calcium gluconate is the most immediate treatment for hyperkalemia with ECG changes as it stabilizes the myocardial membrane within 1-3 minutes, though it does not lower serum potassium.
EDAIC Hepatic, Renal and Endocrine Anesthesia 4
A patient with hepatic encephalopathy grade III requires emergency surgery.
Which agent is MOST appropriate for induction?