Chapter 6. Anesthesia
Which of the following drugs should be avoided in patients with inherited atypical pseudocholinesterase?
Answer: A. Both succinylcholine and mivacurium are hydrolyzed by pseudocholinesterase. For example, a single dose of succinylcholine may last hours rather than minutes. Mivacurium is the only nondepolarizing paralytic to be hydrolyzed by pseudocholinesterase. Cisatracurium is broken down in the plasma by Hoffmann elimination.
Which of the following drugs may trigger malignant hyperthermia?
Answer: A. Succinylcholine, a depolarizing muscle relaxant, and all volatile anesthetics (halothane, enflurane, desflurane, isoflurane, and sevoflurane) may trigger malignant hyperthermia.
While providing local anesthesia in a 60-kg patient, what is the maximum volume of lidocaine 1% that can be used?
Answer: B. Calculation of the toxic dose of lidocaine requires the knowledge of 2 things: the toxic dose of lidocaine is ∼5 mg/kg (toxic dose of lidocaine with epinephrine 7 mg/kg; toxic dose of bupivacaine ∼3mg/kg). 1% = 10 mg/mL = 1000 mg/100 mL = 1 g/100 mL for any drug or solution. So, the toxic dose of lidocaine for a 60-kg patient is 60 kg × 5 mg/kg = 300 mg. To calculate the volume of lidocaine 1% that can be given: 300 mg/(10 mg/mL) = 30 mL.
Local anesthetics act on which of the following to block nerve conduction?
A. Na+ K+ 2Cl− transporter
Answer: D. Local anesthetics prevent action potentials from propagating along the nerve by crossing the plasma membrane and stabilizing sodium channels in their closed state. This is a reversible process.
Spinal and epidural block all of the following nerves except:
A. Parasympathetic nerves