Chapter 6 - Vasoconstrictors in Dentistry Flashcards

1
Q

Q6-1: How do vasoconstrictors enhance the effects of local anesthetic drugs?

A

A6-1: Vasoconstrictors constrict local vessels, increasing safety by slowing systemic absorption. This constriction also prolongs the local actions of the drugs, provides hemostasis, and increases the profoundness of anesthesia.

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2
Q

Q6-2: When are vasoconstrictors useful in dental settings?

A

A6-2: Vasoconstrictors are useful in dental settings where long durations and more profound anesthesia are routinely required.

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3
Q

Q6-3: Name two vasopressors that are routinely included in dental local anesthetic drugs in North America.

A

A6-3: There are two vasoconstrictors, also known as vasopressors, which are routinely included in dental local anesthetic drugs in North America — epinephrine and levonordefrin.

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4
Q

Q6-4: Define epinephrine.

A

A6-4: Epinephrine is a naturally occurring catecholamine. It is both a hormone and a neurotransmitter. It is a direct-acting sympathomimetic drug, and is used in some local anesthetic solutions.

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5
Q

Q6-5: Define levonordefrin.

A

A6-5: Levonordefrin is a synthetic catecholamine. It is a direct-acting sympathomimetic drug, and is used in some local anesthetic solutions.

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6
Q

Q6-6: Are vasoconstrictors used in dentistry direct-acting, indirect-acting, or mixed-acting sympathomimetics?

A

A6-6: Vasoconstrictors used in dentistry are direct-acting sympathomimetics.

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7
Q

Q6-7: Using Table 6-1, provide the names of common sympathomimetic amines.

A

Catecholamines Noncatecholamines **
Epinephrine* Amphetamine
Norepinephrine* Methamphetamine
Levonordefrin Ephedrine
Dopamine* Phenylephrine
*Naturally occurring chemicals
** All are examples of chemicals found in street drugs, diet pills, and cold medications

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8
Q

Q6-8: Explain why the lack of profound anesthesia can result in a spike in blood pressure.

A

A6-8: The lack of profound anesthesia can result in unmanageable pain, which in turn can lead to a spike in blood pressure due to the release of endogenous epinephrine in response to the pain. This endogenous release may be much greater than doses of exogenous epinephrine typically administered.

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9
Q

Q6-9: What are the possible local and systemic effects of adrenergic vasoconstrictors?

A

A6-9: Adrenergic vasoconstrictors used in dental procedures typically do not produce noticeable effects but are capable of causing undesired local and systemic reactions. Local effects may include ischemia and necrosis while systemic effects may include changes in arterial blood pressure, palpitations, dysrhythmias, and even permanent injury or death due to ventricular fibrillation, heart attack, or stroke. Overdose, intravascular administration, drug interactions, and intolerance increase the likelihood of adverse events.

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10
Q

Q6-10: Why are most adverse events related to the use of vasoconstrictors short-lived?

A

A6-10: Most adverse events related to the use of vasoconstrictors are short-lived due to their efficient reuptake in synapses, and the rapid removal and biotransformation of any residual portions that enter the bloodstream.

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11
Q

Q6-11: Name the types and subcategories of adrenergic receptors.

A

A6-11: Two types of adrenergic receptors were identified by Ahlquist in 1948, alpha (α) and beta (β). Since that time, subcategories have been identified which explain specific actions of vasoconstrictors

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12
Q

Q6-12: Which receptors are responsible for smooth muscle contraction in peripheral arterioles and veins?

A

A6-12: Alpha (α) receptors are responsible for smooth muscle contraction in peripheral arterioles and veins throughout the body (peripheral vasoconstriction).

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13
Q

Q6-13: Which receptors are responsible for smooth muscle relaxation such as bronchodilation and vasodilation?

A

A6-13: Beta 2 (β2) receptors are responsible for smooth muscle relaxation such as bronchodilation and vasodilation.

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14
Q

Q6-14: What concentrations of epinephrine are available in local anesthetic solutions in North America?

A

A6-14: Epinephrine is added to local anesthetic solutions in North America in concentrations of 1:50,000, 1:100,000, and 1:200,000.

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15
Q

A6-15: A patient calls the office approximately six hours after a tooth extraction to report an increase in bleeding. What is a likely cause of increased bleeding?

A

A6-15: Epinephrine provides nearly equal α and β effects, but not at the same time. Initial α vasoconstriction of peripheral vasculature allows time for the anesthetic drugs to bind to receptor sites. Later, β2 vasodilation predominates. This has been observed before and after surgery where epinephrine has been administered. Initially, α effects enhance profound, durable anesthesia and reduce hemorrhaging at surgical sites. Postoperatively, the dominant β2 effects can result in increased bleeding approximately 6 hours after surgery.

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16
Q

A6-16: What is the maximum dose of epinephrine for use in dentistry in a healthy individual?

A

A6-16: The maximum dose of epinephrine for use in dentistry in healthy individuals has been determined to be 0.2 mg per appointment.

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17
Q

Q6-17: Give examples of situations in which the dose of epinephrine should be reduced.

A

A6-17: In individuals with significant cardiovascular compromise (ASA categories III & IV), and other medical situations, including elderly populations and in the presence of a number of specific drug interactions, the dose of epinephrine should be reduced.

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18
Q

Q6-18: What is the maximum appointment dose of epinephrine for individuals at risk?

A

A6-18: The standard maximum dose of epinephrine is 0.2 mg per appointment. For individuals at risk, the dose is reduced to one-fifth, or 0.04 mg maximum dose of epinephrine per appointment.

19
Q

Q6-19: Why does the use of vasoconstrictors increase the risk of subsequent cerebrovascular accident (CVA) or stroke in individuals with a history of previous CVA?

A

A6-19: A history of a cerebrovascular accident (CVA) or stroke increases the risk of experiencing a subsequent CVA due to increases in blood pressure in response to vasoconstrictors.

20
Q

Q6-20: Compare the action of levonordefrin to epinephrine on adrenergic receptors.

A

A6-20: Levonordefrin’s action is primarily α, 75% versus 25% β. Epinephrine is 50% α and 50% β effects. As a weak stimulator of beta adrenergic receptors, levonordefrin is similar to norepinephrine which is approximately 90% α. Despite levonordefrin’s major effect on α receptors, epinephrine is a more powerful vasoconstrictor of peripheral vasculature, thus providing much better hemostasis compared to levonordefrin.

21
Q

Q6-21: Compare the potency of levonordefrin to epinephrine.

A

A6-21: Levonordefrin is less potent compared to epinephrine and is formulated in dilutions of 1:20,000, which is five times more concentrated (less diluted) than a 1:100,000 epinephrine solution.

22
Q

Q6-22: What are the signs and symptoms of high levels of plasma epinephrine?

A

A6-22: The signs and symptoms of high levels of plasma epinephrine include nausea, restlessness, a racing heart, severe headaches, palpitations, tremors, and shakiness. Note that many of these signs and symptoms mimic those observed in anxiety and fear.

23
Q

Q6-23: How is epinephrine removed from the system?

A

A6-23: Epinephrine is uptaken in the synaptic nerve junctions and recycled. The epinephrine that is not recycled is biotransformed by the enzyme catechol-O-methyltransferase (COMT), and further breakdown may occur via monoamine oxidase (MAO).

24
Q

Q6-24: Explain the terms hyper-response versus hypersensitivity.

A

A6-24: The term hyper-response refers to overdose manifestations to less than maximum recommended doses in some individuals. This is the normal response for these individuals and although the doses are below maximum recommended levels, they are dose related. Hyper-response can occur in individuals who experience a rapid, direct, and vigorous stimulation of adrenergic receptors by a vasoconstrictor.
Hypersensitivity refers to an allergic process which involves humoral, cell- mediated, and/or antigen-antibody reactions. These responses are not dose related. A true epinephrine allergy is not possible because epinephrine in local anesthetics is identical to endogenous epinephrine.

25
Q

Q6-25: Give examples of clinical signs and symptoms of an allergic response.

A

A6-25: Hives, rash, bronchospasm, and vasodilation are examples of clinical signs and symptoms that occur with an allergic response.

26
Q

Q6-26: Give examples of vasoconstrictors that are used in regions of the world other than North America.

A

A6-26: Norepinephrine, phenylephrine, and felypressin are not currently available in dental local anesthetic preparations in North America; however, all three vasoconstrictors have been in use in other regions of the world for many years.

27
Q

Q6-27: In the Elena Gagarin case study, the clinician elected to use a local anesthetic without, or with limited, vasoconstrictor. What was the reason for this precaution?

A

A6-27: A severe spike in blood pressure and reflexive bradycardia are more likely to occur in the presence of tricyclic antidepressants in some individuals if vasoconstrictors are used. Epinephrine may be administered, but the total quantities of drug should be limited.

28
Q
  1. Which ONE of the following vasoconstrictors is most useful in providing hemostasis?
    a. Phenylephrine
    b. Epinephrine
    c. Levonordefrin
    d. Felypressin
A

b. epinephrine

29
Q
  1. A patient has significant cardiovascular disease and requires a restorative procedure on tooth #5. Retraction cord and hemostasis are needed in order to keep the restorative site dry. Which One of the following drugs would be most indicated in this situation?
    a. 4% articaine, 1:200,000 epi
    b. 2% mepivacaine, 1:20,000 levonordefrin
    c. 2% lidocaine, 1:50,000 epi
    d. 4% prilocaine plain
A

a. 4% articaine, 1:200,000 epinephrine
- dilutions of 1:200,00 epinephrine contain the least vasoconstrictor
- indicated b/c they are the safest, yet provide hemostasis
- if hemostasis were not needed, plain drugs would work well in shorter treatment times

30
Q
  1. Which ONE of the following statements is true?
    a. Levonordefrin is more potent compared with epinephrine.
    b. Cardiac stimulation from levonordefrin is greater compared with epinephrine.
    c. Cardiac stimulation from levonordefrin is less compared with epinephrine.
    d. Levonordefrin is equal in potency compared with epinephrine.
A

c. Cardiac stimulation from levonordefrin is LESS compared with epinephrine

31
Q
  1. Epinephrine’s metabolism is relatively rapid after LA administration.
    a. True
    b. False
A

a. TRUE

32
Q
  1. Metabolic enzymes for epinephrine include which of the following?
    a. COMT and MAO
    b. Hepatic isoenzymes
    c. Renal isoenzymes
    d. COMT only
A

a. COMT and MAO

33
Q
  1. A diabetic pt requires periodontal therapy on UR and LR quads. She is well controlled and otherwise healthy. Which ONE of the following represents the safest and most effective local anesthesia regime?
    a. 4 cartridges 2% lido w/ 1:100K epi
    b. 2 cartridges 2% lido w/ 1:100K epi and 2 cartridges of 3% mepivacaine plain
    c: 2 cartridges 2% lido w/ 1:100K epi and 2 cartridges 4% articaine, 1:200K epi
    d. 2 cartridges 2% lido w/ 1:100K epi and 2 cartridges 2% mepivacaine w/ 1:20K levonordefrin
A

b. 2 cartridges 2% lido w/ 1:100K epi and 2 cartridges of 3% mepivacaine plain
- Epinephrine can raise blood sugar levels.
- the lowest quantity of epi is found in combination “b” where 1/2 of the adminstered volume has no epinephrine
- the lowest amount of vasoconstrictor should always be used in all individuals
- b/c this pt is a well-controlled diabetic and otherwise healthy, no special precautions are necessary and the default principle applies

34
Q

Consider using “plain” anesthetics on patients with the following medical compromises:

A
  1. Significant CV compromise (ASA III or IV)
  2. Diabetes, thyroid dysfunction, sulfite sensitivity
  3. Receiving MAO inhibitors, tricyclic antidepressants, phenothiazines (= 1st antipsychotics also used to tx extreme nausea, hiccups, extreme excitability in children)
34
Q

Consider using “plain” anesthetics on patients with the following medical compromises:

A
  1. Significant CV compromise (ASA III or IV)
  2. Diabetes, thyroid dysfunction, sulfite sensitivity
  3. Receiving MAO inhibitors, tricyclic antidepressants, phenothiazines (= 1st antipsychotics/tranquilizer also used to tx extreme nausea, hiccups, extreme excitability in children)
35
Q

Hypertension & Vasoconstrictors

A
  • Mild to moderate elevations are okay with or without vasoconstrictor
  • > 200/>115 should not receive any elective tx
36
Q

Cardiovascular Dz & Vasoconstrictors

A
  • ASA I, II and III may safely receive vasoconstrictor
    (ASA III under control and doctor’s care)
  • more compromised ASA III limit vasoconstrictor
  • ASA IVs should NOT receive vasoconstrictor or any
    elective tx
  • Acute MIs (up to 6 months) or daily anginal
    episodes should not receive elective tx. (MI over1
    mo. can have emergency care)
  • Stroke should not have care for 6 months
37
Q

Hyperthyroidism & Vasoconstrictors

A

Sensitive to catecholamines; may exhibit exaggerated responses to vasoconstrictors => keep vasoconstrictors at a minimum
if controlled with Sx or medication, vasoconstrictors are not a problem

38
Q

Drug-drug interactions

A
  • Esters may decrease the bacteriostatic action of sulfonamides
  • Cimetidine (Tagamet) & Lidocaine: relative CI to amides, increases t1/2 of LA (minimal dose of amides should be given)
39
Q

Non-selective Beta Blockers and Epinephrine

A
  • vasopressors increase likelihood of a serious elevation in BP
  • reactions shown with 4 to 32 ml of LA w/ 1:100,000 epi
  • take BP 5-10 min after LA administration
40
Q

Tricyclic Antidepressants and Epinephrine

A
  • rx for management of major depression [also for pain; may improve sleep-wake cycle]
  • may enhance CV action of vasopressors especially levonordefrin
    => avoid levonordefrin; epinephrine may be administered in the smallest effective dose
41
Q

Monoamine Oxidase Inhibitors and Epinephrine

A
  • rx for major depression, phobias, OCD
  • increase action of vasopressors
  • vasoconstrictors used to be CI, but okay to use now
42
Q

Phenothiazines & Epinephrine

A
  • used to manage serious psychotic disorders
  • side effect postural hypotension
  • accidental intravascular administration could lead to hypotension
  • use judicious doses