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Flashcards in Chapter 4 Deck (27)
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1
Q

Local anesthetics are considered what?

A

Vasodilators

2
Q

Dilation of the mood vessels causes what?

A

an increase in blood flow to the site of injection.

3
Q

The increase in blood flow causes what?

A
  • 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.
4
Q

Vasoconstrictor drugs provide beneficial effects that include

A
  • 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.
5
Q

What are the two vasoconstrictors the are added to local anesthetics?

A
  • Epinephrine

- Levonordefrin

6
Q

Both Epinephrine and levonordefrin are considered what?

A

Sympathomimetic (adrenergic) drugs

7
Q

vasoconstrictors participate in what?

A

“Fight or Flight” response of the sympathetic nervous system.

8
Q

Exogenous epinephrine

A

Absorbed from the site if injection

9
Q

Endogenous release of epinephrine

A

Release of epinephrine from within can compound the adverse effects of exogenous administration of epinephrine via the anesthetic injection containing epinephrine.

10
Q

Epinephrine administered intravenously has a half-life of what?

A

1-3 minutes

11
Q

What patients should not receive vasoconstrictors?

A

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.

12
Q

Epinephrine, norepinephrine, and levonordefrine activates what?

A

Adrenergic receptors

13
Q

Adrenergic receptor sites are divided into two groups

A
  • a receptors: excitatory actions

- b receptors: Inhibitory actions

14
Q

Norepinephrine activates

A

a receptors

15
Q

Epinephrine activates

A
  • a receptors: Vasoconstrictions

- b receptors: Vasodilatation

16
Q

Stimulation of beta2 receptors by adrenergic drug causes what?

A

Bronchi of the lungs to dilate

17
Q

Stimulation of beta1 receptors by adrenergic drugs cause what?

A

Increased rate and force of heart contractions

18
Q

1:50,000 of vasoconstrictors means

A

1 gram of drug contained or dissolved in 50,000mL solution, or 0.005mg/mL

19
Q

Sodium Bisulfite Preservative Advantages

A

Increases shelf life

20
Q

Sodium Bisulfite Preservative Disadvantages

A
  • Further acidify the pH of the anesthetic solution; range 3.8 to 5
  • Allergic reactions to sodium bisulfites
21
Q

Maximum Recommended Dose

A
  • Healthy patient 0.2mg
  • Medically compromised patients 0.04 mg
  • Use lowest possible dose
  • Proper aspiration
  • Inject slowly
  • Technique
22
Q

Levonordefrin

A

-Synthetic vasoconstrictor
-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.

23
Q

Levonordefrin is ONLY available with

A

2% mepivacaine in 1:200,000 mg/mL

24
Q

Levonordefrin is terminated by

A

reuptake by adrenergic nerves and escaped drug is inactivated by enzymes catechol-O-methyltransferase (COMT) but not monoamine oxidase (MAO)

25
Q

Maximum permissible dose of levonordefrin

A
  • Healthy patient: 0.1 mg

- Medically compromised patient: 0.2 mg

26
Q

Side Effects or Vasoconstrictors

A

The body is efficient at removing vasoconstrictors; adverse effects of vasoconstrictors normally only last 5 to 10 minutes.

27
Q

Overdose of Vasoconstrictors

A

5 to 10 minutes is too long for the removal of a vasoconstrictor in patients with severe conditions such as unstable angina, recent myocardial infarction (within 6 months), recent coronary bypass surgery (within 6 months), uncontrolled hypertension, uncontrolled hyperthyroidism, uncontrolled diabetes, uncontrolled dysrhythmias, or congestive heart failure.