Local Anesthesia Board Exam Review Questions And
Answers
What are the problems associated with the vasodilatory properties of local anesthetics? ANS - An
increased rate of absorption of LA's in the CVS
- A decrease in duration of the anesthetic's action
- higher blood levels of LA's (increase risk in toxicity)
- increase in bleeding
What are the benefits of adding vasoconstrictors to LA solutions? ANS They counteract the
vasodilating properties of LA's:
- decreased blood flow
- slow absorption of LA's
- lower blood levels
- more LA enters the nerve
- decreased bleeding at sight
What are the two vasoconstrictors added to local anesthetics? ANS 1. epinephrine
2. levonordefrin
What is the use of vasoconstrictors in dentistry? ANS Epinephrine is absorbed from the site of
injection and it increases cardiac output and stroke volume
Epinephrine mechanism of action? ANS Activates adrenergic receptors
Epinephrine dilutions ANS 1:50,000 (0.02 mg/mL)
1:100,000 (0.01 mg/mL)
1:200,000 (0.005 mg/mL)
, Sodium bisulfite preservative? ANS Advantage: Increases shelf life
Disadvantages: Further acidify the pH of the anesthetic solution, allergic reactions to sodium
bisulfites
Epinephrine actions on specific systems and tissues ANS - Increases cardiac output and heart rate
- Increases irritability of pacemaker cells: increased incidence of dysrhythmias & tachycardia
- Respiratory system: potent dilator
- Increases oxygen consumption in all tissues
Epinephrine termination of action ANS Terminated by the reuptake of adrenergic nerves
Epinephrine maximum recommended dose ANS Healthy patient: 0.2 mg
Compromised: 0.04 mg
Levonordefrin actions on specific systems and tissues ANS Only 1/6 as strong as epi, so it is used
in a stronger concentration
Levonordefrin dilution ANS Used with Mepivacaine HCL 2% at 1:20,000
Levonordefrin termination of action ANS Reuptake of adrenergic nerves
Levonordefrin maximum recommended dose ANS Healthy patient: 0.2 mg
Max dose: 11 cartridges
Effects, mechanism of action, and uses of: norepinephrine, phenylephrine, and felypressin ANS
Norepinephrine: 1:30,000 (use same as Levonordefrin)
Phenylephrine: not used in dentistry
Felypressin: safely administered with pt's with hyperthryoidism, tricylic antidepressants and MAO
inhibitors
Answers
What are the problems associated with the vasodilatory properties of local anesthetics? ANS - An
increased rate of absorption of LA's in the CVS
- A decrease in duration of the anesthetic's action
- higher blood levels of LA's (increase risk in toxicity)
- increase in bleeding
What are the benefits of adding vasoconstrictors to LA solutions? ANS They counteract the
vasodilating properties of LA's:
- decreased blood flow
- slow absorption of LA's
- lower blood levels
- more LA enters the nerve
- decreased bleeding at sight
What are the two vasoconstrictors added to local anesthetics? ANS 1. epinephrine
2. levonordefrin
What is the use of vasoconstrictors in dentistry? ANS Epinephrine is absorbed from the site of
injection and it increases cardiac output and stroke volume
Epinephrine mechanism of action? ANS Activates adrenergic receptors
Epinephrine dilutions ANS 1:50,000 (0.02 mg/mL)
1:100,000 (0.01 mg/mL)
1:200,000 (0.005 mg/mL)
, Sodium bisulfite preservative? ANS Advantage: Increases shelf life
Disadvantages: Further acidify the pH of the anesthetic solution, allergic reactions to sodium
bisulfites
Epinephrine actions on specific systems and tissues ANS - Increases cardiac output and heart rate
- Increases irritability of pacemaker cells: increased incidence of dysrhythmias & tachycardia
- Respiratory system: potent dilator
- Increases oxygen consumption in all tissues
Epinephrine termination of action ANS Terminated by the reuptake of adrenergic nerves
Epinephrine maximum recommended dose ANS Healthy patient: 0.2 mg
Compromised: 0.04 mg
Levonordefrin actions on specific systems and tissues ANS Only 1/6 as strong as epi, so it is used
in a stronger concentration
Levonordefrin dilution ANS Used with Mepivacaine HCL 2% at 1:20,000
Levonordefrin termination of action ANS Reuptake of adrenergic nerves
Levonordefrin maximum recommended dose ANS Healthy patient: 0.2 mg
Max dose: 11 cartridges
Effects, mechanism of action, and uses of: norepinephrine, phenylephrine, and felypressin ANS
Norepinephrine: 1:30,000 (use same as Levonordefrin)
Phenylephrine: not used in dentistry
Felypressin: safely administered with pt's with hyperthryoidism, tricylic antidepressants and MAO
inhibitors
