Medical Pharmacology: Practice Questions on Local Anesthetics

Agent(s) that may prolong local anesthetic duration of action:
1. dextran
2. epinephrine
3. both
4. neither
Primary side effect(s) of local anesthetics:
1. Allergic reactions
2. Systemic toxicity
3. both
4. neither
Allergic reactions to local anesthetics: characteristics
1. common
2. mainly associated with amide-type agents
3. may be caused by preservatives
Cross-sensitivity to local anesthetics:
1. could be caused by a common metabolite profile
2. not observed between ester-& amide-local anesthetic agents
3. both
4. neither
Basis/evidence for local anesthetic allergies:
1. clinical history
2. intradermal testing
3. both
4. neither
Patient presentations which is suggestive of local anesthetic allergy:
1. rash
2. urticaria
3. laryngeal edema
4. bronchospasm
5. all the above
Hypotension with syncope & tachycardia following epinephrine-containing local anesthetic injection could be due to accidental intravascular injection
1. true
2. false
Most common cause of toxic plasma local anesthetic concentrations
1. dosage too high
2. accidental direct intravascular injection during peripheral nerve block or epidural anesthesia
3. excessive absorption from injection site
Factor(s) which influence the extent of local anesthetic systemic absorption
1. initial dose administered
2. injection site vascularity
3. whether or not epinephrine was used to provide local vasoconstriction
4. properties of the drug itself
5. all the above
Earliest symptom associated with local anesthetic toxicity
1. tonic-clonic seizures
2. skeletal muscle fasciculation
3. tongue and circumoral numbness
4. tinnitus, vertigo, restlessness
Characteristics of, clonic seizures associated with local anesthetic CNS toxicity
1. Duration: 1-2 minutes
2. Consciousness:loss of consciousness
3. Generalized seizure with alternating contractions and relaxations
4. B & C
5. A, B & C
Factors influencing local anesthetic CNS toxicity:
1. rate of injection -- injection rate more important than total amount of drug injected
2. direct relationship between PaCO2 and local anesthetic seizure thresholds
3. hypokalemia: increased local anesthetic toxicity
4. Reduced lidocaine (Xylocaine) toxicity in patients treated perioperatively with mexiletine (Mexitil)
Local anesthetic-induced seizure suppression:
1. IV diazepam (Valium)
2. IV midazolam (Versed)
3. flumazenil (Romazicon)
4. A & B
5. B & C
Neurotoxicity characteristics of local anesthetic injection into subarachnoid or epidural spaces
1. transient radicular irritation
2. cauda equina syndrome
3. long-lasting, isolated myotomal weakness
4. B & C
5. A, B & C
Local anesthetic Neurotoxicity symptoms: moderate/severe lower back, buttocks, posterior thigh pain
1. cauda equina syndrome
2. transient radicular irritation
3. anterior spinal artery syndrome
Local anesthetic neurotoxicity symptoms: sensory anesthesia; bowel & bladder sphincter dysfunction
1. transient radicular irritation
2. cauda equina syndrome
3. anterior spinal artery syndrome
Possible mechanisms of anterior spinal artery syndrome:
1. hypotension/vasoconstrictor drugs
2. thrombosis
3. anterior artery spasm
4. all the above
Possible predisposing conditions for anterior spinal artery syndrome:
1. advanced age
2. peripheral vascular disease
3. both
4. neither
Cardiotoxicity at elevated local anesthetic plasma concentrations:
1. greater cardiotoxicity compared to CNS toxicity
2. less cardiotoxicity compared to CNS toxicity
Cardiovascular toxicities associated with elevated lidocaine (Xylocaine) concentrations (5-10 ug/mL)
1. hypotension
2. increased conduction velocity
3. QRS complex prolongation
4. A & C
5. A, B & C