Flashcards in Chapter 4 Deck (27)
Local anesthetics are considered what?
Dilation of the mood vessels causes what?
an increase in blood flow to the site of injection.
The increase in blood flow causes what?
-Increased rate of anesthetic absorption into the bloodstream
-A decrease in the duration of the anesthetic's action
-Higher plasma levels of local anesthetics, increasing risk of toxicity.
-Increased bleeding In the area.
Vasoconstrictor drugs provide beneficial effects that include
-A decrease in the blood flow by constricting the blood vessels at the injection site.
-An increased duration of the anesthetic's effects
-Reduction in systemic toxicity due to the increased duration of the anesthetic, requiring a lower administered dose.
-Hemostasis at the injection site.
What are the two vasoconstrictors the are added to local anesthetics?
Both Epinephrine and levonordefrin are considered what?
Sympathomimetic (adrenergic) drugs
vasoconstrictors participate in what?
"Fight or Flight" response of the sympathetic nervous system.
Absorbed from the site if injection
Endogenous release of epinephrine
Release of epinephrine from within can compound the adverse effects of exogenous administration of epinephrine via the anesthetic injection containing epinephrine.
Epinephrine administered intravenously has a half-life of what?
What patients should not receive vasoconstrictors?
patients with recent myocardial infarction, coronary bypass surgery, or cerebrovascular accident with the past 6 months.
-Patients with uncontrolled hypertension, angina, arrhythmias, diabetes, and hyperthyroidism.
Epinephrine, norepinephrine, and levonordefrine activates what?
Adrenergic receptor sites are divided into two groups
- a receptors: excitatory actions
-b receptors: Inhibitory actions
-a receptors: Vasoconstrictions
-b receptors: Vasodilatation
Stimulation of beta2 receptors by adrenergic drug causes what?
Bronchi of the lungs to dilate
Stimulation of beta1 receptors by adrenergic drugs cause what?
Increased rate and force of heart contractions
1:50,000 of vasoconstrictors means
1 gram of drug contained or dissolved in 50,000mL solution, or 0.005mg/mL
Sodium Bisulfite Preservative Advantages
Increases shelf life
Sodium Bisulfite Preservative Disadvantages
-Further acidify the pH of the anesthetic solution; range 3.8 to 5
-Allergic reactions to sodium bisulfites
Maximum Recommended Dose
-Healthy patient 0.2mg
-Medically compromised patients 0.04 mg
-Use lowest possible dose
-Approximately 1/6 as potent as epinephrine
-Manufactured in higher concentrations
-Contains sodium bisulfite
-Compare mode of action
Levonordefrine: 75% a; 25% b activity
Epinephrine: 50% a: 50% b activity
-produces same systemic actions as epinephrine but to a lesser extent.
Levonordefrin is ONLY available with
2% mepivacaine in 1:200,000 mg/mL
Levonordefrin is terminated by
reuptake by adrenergic nerves and escaped drug is inactivated by enzymes catechol-O-methyltransferase (COMT) but not monoamine oxidase (MAO)
Maximum permissible dose of levonordefrin
-Healthy patient: 0.1 mg
-Medically compromised patient: 0.2 mg
Side Effects or Vasoconstrictors
The body is efficient at removing vasoconstrictors; adverse effects of vasoconstrictors normally only last 5 to 10 minutes.