question

what do Vasoconstrictors in Local Anesthetics do?

answer

1. Decrease blood flow (perfusion) 2. Absorption of LA is slowed 3. Lower LA levels decrease risk of toxicity 4. Higher volumes of LA remain thereby increasing duration and effect 5. Decrease bleeding at the site

question

what are Reason for Adding Vasoconstrictors

answer

Must weigh side effects of the use of vasoconstrictors against elevated local anesthetic blood levels. It is currently thought that the cardiovascular effects of conventional epinephrine doses are of little practical concern even in patients with heart disease. However even following usual precautions (aspirations, slow injection), sufficient epinephrine can be absorbed to cause sympathomimetic reactions such as apprehension, tachycardia, sweating, and pounding in the chest (palpitations), the so called "epinephrine reaction"

question

Levonordefrin is a synthetic _________ (chemical structure of vasoconstrictors)

answer

catecholamine

question

Epinephrine, norepinephrine, and dopamine are naturally occurring ____________

answer

catecholamines

question

3 categories of sympathomimetic amines

answer

1. Direct acting-epinephrine, norepinephrine, levonordefrin 2. Indirect acting-amphetamines 3. Mixed acting-ephedrine (cause release of norepinephrine) Epinephrine exerts its action directly on adrenergic receptors found in most tissues of the body

question

Activation of _____________ causes contraction of smooth muscle (blood vessels)

answer

alpha receptors

question

Activation of _____________ produces smooth muscle relaxation (vasodilation and bronchodilation) and cardiac stimulation

answer

beta receptors

question

What are the three vasodilating activities of a Local Anesthetic?

answer

1. Increased rate of absorption of LA 2. Higher plasma levels of LA (toxicity) 3. Decreased duration of action and decreased depth of anesthesia

question

Do vasoconstrictor increase or decrease perfusion?

answer

decrease

question

What is an epinephrine reaction?

answer

Sweating

question

How is levonordefrin different from epinphrine?

answer

synthetic

question

What are the two adrenergic receptors?

answer

alpha, beta

question

what are the Dilutions of Vasoconstrictors?

answer

1:100,000 dilution contains 0.01 mg/ml cartridge of 1:100,000 has 0.018 mg/ml

question

The benefits to be gained from adding a vasoconstrictor to a local anesthetic must be weighed against any __________

answer

risks

question

Epinephrine (adrenaline)

answer

Epinephrine (adrenaline): Available in both a synthetic form and from the adrenal medulla Acts on both alpha (contraction) and beta (relaxation) receptors with beta predominate Sodium bisulfite added to slow oxidation Must weigh epinephrine dose against elevated local anesthetic dose

question

Systemic Actions of Epinephrine Cardiovascular:

answer

Increased systolic and diastolic pressures Increased cardiac output and stroke volume Increased heart rate, strength of contraction Increased myocardial oxygen consumption These actions lead to an overall decrease in cardiac efficiency

question

Systemic Actions of Epinephrine vascular:

answer

Smaller doses beta receptors predominate, larger doses produce vasoconstriction because alpha receptors are stimulated Injection of epinephrine directly into tissues produces primarily vasoconstriction (alpha) and as tissue levels decrease, beta dominates (vasodilation)

question

Systemic Actions of Epinephrine respiratory:

answer

Epinephrine is a potent dilator (smooth muscle of bronchioles), drug of choice for management of acute asthma (bronchospasm)

question

Side Effects and Overdose of Epinephrine

answer

"Epinephrine reaction" -even following normal precautions sufficient epinephrine can be absorbed to cause sympathomimetic reactions such as apprehension, tachycardia, sweating, and pounding in the chest (palpitations) Other clinical manifestations-headache, tremor, weakness, dizziness, pallor, respiratory difficulty, restlessness, tension

question

What is the most common concentration of epinephrine used and how many milligrams is in one cartridge of anesthetic?

answer

1:100,000 dilution contains 0.01 mg/ml .009

question

List 4 cardiovascular systemic reactions to epinephrine

answer

Increased systolic and diastolic pressures Increased cardiac output and stroke volume Increased heart rate, strength of contraction Increased myocardial oxygen consumption These actions lead to an overall decrease in cardiac efficiency

question

What effect does epinephrine have on the respiratory system?

answer

Respiratory system-epinephrine drug of choice for management of acute asthma

question

What are some other reactions besides an epinephrine reaction that may occur?

answer

Other clinical manifestations-headache, tremor, weakness, dizziness, pallor, respiratory difficulty, restlessness, tension

question

Clinical Applications of Epinephrine

answer

1. Management of acute allergic reactions 2. Management of bronchospasm 3. Treatment of cardiac arrest 4. Hemostasis 5. Vasoconstrictor in local anesthetics 6. Produce mydriasis (dilation of pupils)

question

Epinephrine-Maximum Doses for Pain Control Normal healthy adult patient

answer

= 0.2 mg 20 ml of 1:100,000 (20 ml X 0.01 mg/ml) Equals 11 cartridges

question

Epinephrine-Maximum Doses for Pain Control Patient with clinically significant cardiovascular disease (ASA III or IV)

answer

0.04 mg (2 cartridges)

question

Norepinephrine (Levophed)

answer

Not recommended for use in dentistry (tissue sloughing due to vasoconstriction)

question

Levonordefrin (Neo-Cobefrin)

answer

Available in 1:20,000 (0.05 mg/ml) dilution, clinical effect similar to 1:100,000 epinephrine Maximum dose = 11 cartridges (1.0 mg)

question

what to consider when Selection of a Vasoconstrictor and its Concentration

answer

1. Length of the dental procedure 2. Need for hemostasis 3. Medical status of patient

question

why are Vasoconstrictors important additions to local anesthetic solutions

answer

They slow rate of absorption Lower systemic blood level Prolong duration Intensify depth of anesthesia Reduce incidence of adverse systemic reactions

question

Vasoconstrictors facts

answer

An often-repeated and essentially true statement is that the cardiovascularly impaired patient is more at risk from endogenously released catecholamines than from exogenous epinephrine administered in a proper manner Unless specifically contraindicated by a patients medical status or by the required duration of treatment (short), the inclusion of a vasoconstrictor should be considered

question

Contraindications for Using Vasoconstrictors

answer

Patients with uncontrolled hyperthyroidism Less than six months after a myocardial infarction, cerebrovascular accident, or post coronary artery bypass Daily episodes of angina pectoris or cardiac dysrhythmias

question

If the maximum recommended dose for epinephrine is 11 cartridges then what is the maximum recommended dose of 1:100,000 epi and 1:200,000 epi for a cardiac impaired patient?

answer

2 cartridges

question

What is the ratio of epi in neo-cobefrin?

answer

1:20,000 (.05 mg)

question

How do I decide whether to add a vasoconstrictor to an local anesthetic?

answer

1. Length of the dental procedure 2. Need for hemostasis 3. Medical status of patient

question

Name 5 reasons for adding a vasoconstrictor to a Local Anesthetic.

answer

They slow rate of absorption Lower systemic blood level Prolong duration Intensify depth of anesthesia Reduce incidence of adverse systemic reactions

question

Which is worse for a cardiovascular patient: The natural catecholamines released from anxiety or a vasoconstrictor that was added to the local anesthetic?

answer

An often-repeated and essentially true statement is that the cardiovascularly impaired patient is more at risk from endogenously released catecholamines than from exogenous epinephrine administered in a proper manner

question

What are three contraindications for administering a local anesthetic with a vasoconstrictor?

answer

Patients with uncontrolled hyperthyroidism Less than six months after a myocardial infarction, cerebrovascular accident, or post coronary artery bypass Daily episodes of angina pectoris or cardiac dysrhythmias

question

Factors that influence the duration and depth of anesthesia

answer

1. Individual variation in response to drug 2. Accuracy in the administration technique 3. Status of the tissues-healthy, infection 4. Anatomic variation 5. Type of injection

question

Maximum Doses of Local Anesthetics based on:

answer

Based on body weight mg of drug/unit of body weight Maximum doses based on 150 pound (lb) adult which approximates 70 kilograms (kg) Usually see "kg" with drug formulas, divide pounds by 2 for approximate "kg" weight

question

The maximum calculated drug dose should always be ______________ in medically compromised, debilitated, or elderly persons

answer

decreased

question

Hyporesponders

answer

those who will not experience adverse reactions until the blood level is above the normal threshold

question

Hyperresponders

answer

those who experience adverse reactions when the blood level is way below the normal threshold

question

MRD 2% Lidocaine

answer

2.0 mg/lb 75 lb patient = 2.0 mg/lb X 75 lb = 150 mg 1 cartridge = 36 mg (150 divided by 36 = 4.2) 4 cartridges is MRD

question

MRD 3% Mepivacaine

answer

2.0 mg/lb 40 lb patient = 2.0 mg/lb X 40 lb = 80 mg 1 cartridge = 54 mg (80 divided by 54 = 1.5) 1.5 cartridges is MRD

question

When using more than one type of local anesthetic solution, a rule of thumb is that the total dose of both anesthetics should not exceed the __________ of the two maximum doses for the individual agents

answer

lower example:Used 2 cartridges 4% Prilocaine = 144 mg Max dose 2% Lidocaine = 200 mg (100 lb) If switch to Lidocaine, can use 56 mg

question

What is the calculation for figuring a person's maximum recommended dose?

answer

...

question

Procaine (Novocain)

answer

First injectable local anesthetic synthesized, no longer available for dental use Ester, therefore is hydrolyzed rapidly in plasma by plasma cholinesterase Incidence of allergy significantly greater than amides but still not extremely common Profound vasodilating properties, provides virtually no pulpal anesthesia

question

Lidocaine (Xylocaine)

answer

Amide mostly metabolized in the liver Available in 2% concentration with or without epinephrine pH plain is ~ 6.5 pH with vasoconstrictor is ~ 5.0-5.5 Onset of action ~ 2-3 minutes Topical form is 5% concentration

question

Lidocaine Malamed MRD:

answer

With or without vasoconstrictor-2.0 mg/lb not to exceed 300 mg (8 cartridges) Duration: 2% lido plain ~ pulpal 5-10 min/soft 1-2 hrs 2% lido w epi ~ pulpal 60 min/soft 3-5 hrs

question

Mepivacaine (Polocaine, Carbocaine)

answer

Amide metabolized in the liver Produces only slight vasodilation pH plain ~ 4.5 pH with vasoconstrictor ~ 3.0-3.5 Effective dental concentration is 3% with out vasoconstrictor, 2% with vasoconstrictor Anesthetic half-life ~ 1.9 hrs Onset of action ~ 1.5-2 min

question

Mepivacaine Malamed MRD:

answer

3% without vasoconstrictor - 2.0 mg/lb not to exceed 300 mg (5.5 cartridges) 2% with vasoconstrictor - 2.0 mg/lb not to exceed 300 mg (8 cartridges) Duration: 3% plain ~pulpal 20-40 minutes/soft 2-3 hrs 2% w 1:20,000 levonordefrin ~ pulpal 60 min/soft 3-5 hrs

question

Prilocaine (Citanest)

answer

Amide hydrolyzed by hepatic amidases into orthotoluidine and N-propylalanine with carbon dioxide as a major end-product of prilocaine transformation Orthotoluidine can induce formation of methemoglobin producing methemoglobinemia with large doses Prilocaine undergoes biotransformation more rapidly and completely than lidocaine Biotransformation in liver and to a smaller extent in the plasma and lungs Plasma levels of prilocaine decrease more rapidly than lidocaine and is considered less toxic systemically Signs of CNS toxicity with prilocaine are briefer and less severe than lidocaine Prilocaine produces more vasodilation than mepivacaine but less than lidocaine pH plain ~ 4.5 pH with vasoconstrictor ~ 3.0-4.0 Effective dental concentration = 4% Onset of action ~ 2-4 min Anesthetic half-life ~ 1.6 hrs

question

Prilocaine (Citanest) Malamed MRD:

answer

Manufacturer (and Malamed) MRD: 4% plain - 2.7 mg/lb not to exceed 400 mg (5 cartridges) 4% with 1:200,000 epi - 2.7 mg/lb not to exceed 400 mg (5 cartridges) Duration: 4% plain- infiltration~ pulpal 10 min/soft 1.5-2.0 hrs nerve block~ pulpal 40-60 min/soft 2-4 hrs 4% w 1;200,000 epi (Citanest Forte)- pulpal ~ 60-90 min/soft 3-8 hrs

question

prilocaine considerations

answer

Should consider Prilocaine plain or with epinephrine (1:200,000) for epinephrine sensitive individuals or ASA III cardiovascular compromised patients requiring prolonged pulpal anesthesia Can use up to 4 cartridges with 1:200,000 Prilocaine is rapidly biotransformed and considered by some to be the safest of all amide local anesthetics Prilocaine is a relative contraindication in patients with methemoglobinemia and patients receiving acetaminophen and phenacetin (both produce elevations in methemoglobin), sickle cell anemia, anemia Would need 6-7 cartridges to approach cyanosis Some suggest using prilocaine with heavy caffeine usage, smokers, and druggies as it may work in a more acidic tissues somewhat better?

question

Why is Prilocaine considered less toxic than Lidocaine

answer

biotransforms faster

question

Articaine (Septocaine) Malamed MRD:

answer

Only formulation currently approved by FDA is 4% Articaine w 1:100,000 epi, but it is also available in 1:200,00 for cardiac patients Greater penetrability and diffusibility Anecdotal; seems to be more profound Metabolism first in plasma then liver, resulting in more rapid biotransformation Onset is 1-2 minutes for infiltration, 2-3 minutes for nerve blocks

question

Articaine (Septocaine)

answer

MRD (Malamed and manufacturer): 4% Articaine w 1:100,000 epi = 500 mg (7 cartridges) Duration: 60-75 minutes-pulpal 3-6 hours-soft tissue Contraindication with anemia, hypoxia, methemoglobinemia

question

Bupivacaine (Marcaine)

answer

Amide that is 4 times more potent than lidocaine Excellent for lengthy dental procedures or management of post-operative pain Anesthetic half-life ~ 2.7 hrs Onset of action ~ can be 2-4 min but usually longer (6-10 min)

question

Bupivacaine (Marcaine) Malamed MRD:

answer

Manufacturers (and Malamed) MRD: Bupivacaine 0.5% w epi-0.6 mg/lb not to exceed 90 mg (10 cartridges) Duration: Pulpal ~ 90-180 min Soft tissue ~ 4-9 hrs Not recommended for younger patients

question

Etidocaine (Duranest)

answer

Etidocaine similar indications as bupivacaine with a quicker onset of action (about 3 min) Variable results with infiltrations, nerve blocks more predictable Cartridges are 1.5% with 1;200,000 epi No longer marketed

question

Anesthetics for Topical Application

answer

Topical anesthetics are unable to penetrate intact skin but do penetrate abraded skin or any mucous membrane Concentrations greater in topicals Effective only on surface tissues (2-3 mm) Important component of atraumatic injection technique Some are esters, some concern with localized allergic reactions (Angioedema) Spray devices must have measured doses to be used intraorally

question

Benzocaine (Hurricaine)

answer

Is an ester, 20% concentration Poorly soluble in water, remains at site of application longer Systemic toxic overdose reactions unknown Can see localized allergic reactions (angioedema)

question

Dyclonine Hydrochloride (Dyclone)

answer

Unique in that it is a ketone, cross-sensitization does not occur with other LA Onset is somewhat slower (10 min), duration longer (up to 1 hour) Not indicated for use in injectable form as it is irritating to tissues Systemic toxicity very low

question

Topical Lidocaine Available in two forms

answer

1. Lidocaine base (5%)-for use on abraded, ulcerated, or lacerated tissue 2. Lidocaine hydrochloride (2%)-penetrates tissue more readily, however systemic absorption is greater (toxicity) Amide with exceptionally low incidence of allergic reactions

question

Tetracaine Hydrochloride

answer

Long duration ester Onset slow, duration about 45 minutes Rapidly absorbed through mucous membranes, limit to small areas Available as Cetacaine liquid topical anesthetic

question

Selection of a Local Anesthetic Factors to consider:

answer

1. Length of time pain control needed 2. Requirement for pain control post-op 3. Hemostasis 4. Possibility of self-mutilation in post-op period 5. Physical status of patient (absolute & relative)

question

Contraindications for Local Anesthetics Absolute contraindication

answer

offending drug not to be administered to a patient under any condition One absolute contraindication to local anesthetic administration exists: documented, reproducible allergy

question

Contraindications for Local Anesthetics Relative contraindication

answer

preferable to avoid administration of a drug in question because of an increased risk of an adverse reaction. However if no acceptable alternative is available, drug may be used judiciously in minimum volumes

question

Absolute:

answer

Local anesthetic-cross-allergenicity Amides = no, Esters = yes Sulfa allergy-Articaine (recent evidence suggests not) Bisulfite allergy-vasoconstrictor containing local anesthetics

question

Sulfites

answer

Food preservatives, beer, wine, soup mixes, salad bars, sparkling ciders, dried fruit, dehydrated vegetables, sausages, pickles, some cheese mixtures Severe asthmatics (allergy type) consider possibly sulfite allergic as well

question

Relative:

answer

Atypical plasma cholinesterase-esters Methemoglobinemia-Articaine, prilocaine Significant liver dysfunction-amides Significant renal dysfunction-amides/esters Significant cardiovascular disease-no high concentrations of vasoconstrictors (1:100,000 is usually fine) Clinical hyperthyroidism-high concentrations of vasoconstrictors

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