Pharmacology & Physiology in Anesthesia Flashcards

What is the recommended initial bolus of 20% lipid emulsion for local anesthetic systemic toxicity in an adult over 70 kg?

Answer: 1.5 mL/kg (about 100 mL)

ASRA guidance is a 100 mL bolus over 2-3 minutes for patients over 70 kg (1.5 mL/kg if under 70 kg), followed by an infusion.

Which local anesthetic carries the greatest risk of refractory cardiotoxicity?

Answer: Bupivacaine

Bupivacaine binds cardiac sodium channels avidly and dissociates slowly ('fast-in, slow-out'), which causes hard-to-treat arrhythmias.

Dantrolene treats malignant hyperthermia by acting on which target?

Answer: Ryanodine receptor (RyR1) on the sarcoplasmic reticulum

Dantrolene binds RyR1 and reduces uncontrolled calcium release from the sarcoplasmic reticulum.

Which topical anesthetic is most associated with methemoglobinemia?

Answer: Benzocaine

Benzocaine sprays are a classic cause of methemoglobinemia, along with prilocaine; treatment is methylene blue.

Which adverse effect is a recognized concern with ondansetron?

Answer: QT interval prolongation

Ondansetron, a 5-HT3 antagonist, can prolong the QT interval in a dose-dependent way.

Which sedative gives sedation with minimal respiratory depression through central alpha-2 adrenergic agonism?

Answer: Dexmedetomidine

Dexmedetomidine acts on alpha-2 receptors in the locus coeruleus and produces arousable sedation while largely preserving respiratory drive.

In a patient taking an MAO inhibitor, which opioid is most likely to precipitate serotonin syndrome?

Answer: Meperidine

Meperidine inhibits serotonin reuptake and can cause severe serotonin syndrome when combined with MAO inhibitors.