Anesthesiology 3
A pregnant woman was given an epidural anesthetic for pain relief during labor. The drug selected had a slow onset, but a longer duration of action than most of other local anesthetics. Unfortunately, some of the drug was inadvertently injected intravenously and caused a marked drop in blood pressure and an arrhythmia.
Questions and tasks:
1. Explain the classification of local anesthetic according their structure and list examples of drugs in each group.
2. What are the major ways of local anesthesia?
3. The drug used in above mentioned case was most likely:
a) benzocaine
b) bupivacaine
c) cocaine
d) lidocaine
e) procaine
4. Properties of local anesthetics do not include:
a) an increase in membrane refractory period
b) blockade of voltage-dependent sodium channels
c) effects on vascular tone
d) preferential binding to resting channels
e) slowing of axonal impulse conduction
5. The pKa of bupivacaine is 8.3. In infected tissue at pH 6.3, the percentage of the drug in the non-ionized form will be 1%. Explain the pharmacokinetic properties of local anesthetics.
6. Factors that influence the action of local anesthetics do not include:
a) activity of acetylcholinesterase in the region of injection site
b) amount of local anesthetic injected
c) blood flow through the tissue in which the injection is made
d) the use of vasoconstrictors
e) tissue pH
7. Which statement about the toxicity of local anesthetics is correct?
a) the toxicity of local anesthetics in CNS is only rare
b) in overdosage, hyperventilation (with oxygen) is helpful to correct acidosis and
to lower extracellular potassium
c) intravenous injection of local anesthetic may stimulate ectopic cardiac pacemaker activity
d) most local anesthetics cause vasoconstriction
e) serious cardiovascular reactions are more likely to occur tertacaine than with bupivcacaine