Pain and Local Anesthetics

Pain:

• Highly ________

• Strong __________ component.

• Complex neurological pathways involved with both ______ and ______ receptors.

variable

emotional

peripheral and central

Basic Pain Pathway:

• What are the 5 steps?

1. Noxious stimulus

2. Nocieptors

3. Nocieption

4. Consciousness

5. Pain

Inflammatory mediators:

• Activate/sensitize nerve __________

• Increase in spontaneous ________

• Decrease in _________

• All of these can cause what?

terminals

activity

threshold

Hyperalgesia

How do local anesthetics work?

Prevent the generation and propagagtion of nerve action potentials by blocking the sodium channel to prevent sodium influx.

To be effective, local anestheics must penetrate the ______

nerve

_____ helps determine how well an anesthetic can penetrate a nerve

pka

Inflamed tissues tend to have decreased ____, therefore there is a tendency for local anesthetics to be in the _______ _______ form.

pH

charged hydrophillic

pka determines the % of what?

Molecules that are charged

What is the best local anesthetic for inflammed environments?

Mepivacaine

What local has the lowest and highest aka and what are they?

Meptivicaine: 7.6

Procaine: 9.1

What is induction time?

The time from when anesthetic is delivered to when pulpal aneshtsia is achieved.

Induction time is affected by:

• Concentration of __________

• ___ of the tissues to be anesthetized

• ___ of the anesthetic

• ______ of the tissue and _____ of the nerve

• ______ supply to the area

• ______ of the anesthetic

anesthetic

pH

PKA

thickness, size

blood

potency

Time during which the patient has pulpal anesthesia?

Duration of action

Duration of action:

• ______ supply other the area

• degree of ________ binding

• ___________ activity of the agent

• _____________ activity

• Patient to patient ____________

blood

protein

vasodilating

vasoconstrictor

variability

Remember that local anesthetics are non __________

They can interfere with impulse conduction in any body _______

selective

system

What 3 systems can be affected by local anestheic toxicity?

CNS

PNS

Muscle (skeletal, cardiac, or smooth)

Toxicity is more likely to occur with _______ agents and in ________ patients.

topical

pediatric (or small)

Toxicity is ________ dependent

dose

Preventing systemic toxicty by good technique:

• ____________

• Careful __________

• Beiong aware of ___________ considerations

• Being aware of drug ____________

aspiration

dosing

medical

considerations

Methemoglobinemia:

• Local anestheic metabolites can sometimes oxidate _________ to _________ is susceptible individuals.

hemoglobin to methemoglobin

Methemoglobinemia presnets with what?

Does it improve with oxygen?

Is it fatal?

Cyanosis, blue lips, nail beds

No

Rarely

Methemoblobinemia:

• Seen with __________, _______ and the topical agent _________.

• What do you treat it with?

prilocaine, articaine, benzocaine

intravenous methylene blue

Patient reports of local anestheic allergy are farily common? True of false?

True

True local anestheic allergies are exceedingly _______

rare

Be very careful not to tell a pt what about loal anestheic?

Tell them they have an allergy if they simply have a bad experience (syncope, palpatiaions, anxiety attack)

Esters more commonly cause allergy as a result of the formation of ____________ acid.

p-aminobenzoic acid

If a patient is allergic to an ester, the patient is allergic to all ________

esters

Most investigators consider amides essentially what?

non allergic

If concerened about allergy to one amid, it is ok to try what?

Another because there is no cross reactivity.

It is inconsistent with life to be allergic to what?

epinephrine, it is simply impossible

What to do if someone has a true loal anestheic allergy? (4)

Confirm with an allergist

Infiltrate with 50 mg of Benadryl (diphenhydramine)

Oral sedation and nitrous oxide

IV sedation or general anesthetic

used in local anestheics with vasoconstrictor?

Metabisulfites

How may be hyperreactive to sulfites when they are inhaled or ingested? (But not injected)

Asthmatics

Allergies to metabisulfites are not ___________ in nature.

immunologic

If very severe asthmtics or persons with metabisulfite allergy, better to avoid what?

local with vasoconstrictors

There is no contraindication to the use of local aneshteics which contain metabisulfite in patients with a history of allergy to _________ __________ (so called ____ allergy)

sulfomnamide antibiotics

sulfa

Is methylparaben an issue for dentists?

No

What is methylparaben used for?

Only used as a perservative in multi-dose vials

No longer used in dental single use packaging

Malignant Hyperthermia:

• Previously thought to be induced by local anesthetics.

• No current ________ in the literature to support this.

• Is is now considered ____ to use all local anestheics in patients with a history of MH?

evidence

safe

Where are amides metabolized?

The liver

Where are esters metabolized?

By plasma pseudocholinesterases

Para-aminobutryic acid is a metabolite (allergen)

Does liver disease effect the duration of local anestheic?

No, remember what actually determines duration of action.

**Only important with significant liver disease.

Liver disease and local:

• Best ot limit dosing to ______ dentistry when dealing with patients with ________ liver disease.

quadrant

severe

Liver disease and local:

• Also important for _______ since plasma __________ are synthezied in the liver.

esters

pseudocholinesterases

Vasoconstrictors:

• Prolong __________

• Antagonize __________ of local anesthetics

• Decrease ________

• Decrase ________ toxicity.

duration

vasodilation

bleeding

systemic

How do vasconstrictors work? (2)

Alpha 1 agonists

Produces vasoconstriction

What are the 3 vasoconstrictor agents?

1. epinephrine

2. levonordefrin (neo cobefrin)

3. Norepinephirne

What vasoconstrictor possibly has less cardiac and pressor side effects than epi?

Levonordefrin

Sympathomimentics activate what?

The sympathetic nervous system

What are the 4 contraindications to vasoconstrictors?

1. Untreated pheochromocytoma

2. Uncontrolled or unstable angina

3. Uncontrolled hyperthyroidism

4. MI within last 6 months

Limit epi use to what?

In who?

0.04mg, 2 carpules of 1:100,000

Moderate to severe cardiovascular disease

CVA history

Moderate to severe hypertension

Low dose epi reaction?

Can produce syncope like symptoms

High dose epi reaction?

Palpitations

What does B1 target?

B2?

Heart

Skeletal muscle

What 2 receptors does low dose epi target?

Effect on PP and DBP?

B1 and B2

Increased PP and decrased DBP

What receptors does high dose epi target?

Affect on PP, SBP, and DBP?

a1, b1, b2

Increased all

Selection of anesthetic is based upon:

• Patient _________ history

• Duration of _______ desired

• Need for ___________

• Clinical __________ (active infection)

• _____________

medical

action

vasoconstrictor

situation

availability

What are the 3 nonselective beta blockers?

Propranolol, nadolol, and timolol

Nonselective beta blockers can cause an increased _______ respoonse from systemic epi dose resulting in systemic __________ with incrased ____.

alpha

vasoconstriciton

BP

Are selective beta blockers a problem?

What are the 4 selective beta blockers?

No

Atenolol, metoprolol, acebutolol, betaxolol

What does alpha one target?

Constricitdon, arterioles, and veins

What does beta 1 target?

Heart, increased rate, contractility, conduction, and automaticity

What does beta 2 target?

Trachea and bronchiole relaxation

Arterole and vein dilation (except brain and skin)

Lidocaine/Xylocaine:

• Class?

• Onset?

• Duration?

• Max dose?

• Available as?

• Why is it populat?

amide

2-4 min

60-120 min (180-240 with epi)

4.4 mg/kg

2.0% ± 1:100,000 or 1:50,000 (36mg per 1.8cc) (available without epi but not effective)

Cheap, effective and safe.

Bupivicaine/ Marocaine:

• Class?

• Onset?

• Duration?

• Max dose?

• Available as?

• May not be ideal for who?

• Great for what procedures?

Amide

2-10 minutes

240-540 min

1.3mg/kg

0.5% ± 1:200,000 epi (9mg per 1.8cc)

pediatric patients

significant post operative pain like 3rd molars

Mepiviacaine/ Carbocaine:

• Class?

• Onset?

• Duration?

• Available as?

• Nice drug for what?

Amide

Rapid 1-2 minutes

120-180 min Max dose 4.4mg/kg

3% without vasconstrictor

2% with 1:20,000 ne cobefrin (120-240 min)

Cardiovascular compromised (less vasodilation) patients and infected tissues (PKA 7.6)

Prilocaine/ Citanest:

• Class?

• Onset?

• Duration?

• Max dose?

• Available as?

• Risk for?

Amide

2-5 minutes

100-240 min (120-240+epi)

6 mg/kg

4.0% without epi

4% (citanest forte) with 1:200,000 epi

Methemoglobemia

Etidocaine/ Duranest:

• Class?

• Onset?

• Rapid?

• Duration?

• Max dose?

• Available as?

• Long duration with relatively quick _______

• No longer avialable where?

amide

2-3 min

240-540 min + epi

6mg/kg

1.5% without epi

1.5% with 1:200,000 epi

onset

US

Articaine/ ultracaine/ septocaine:

• Class?

• Onset?

• Duration?

• Max dose?

• Available as?

• Claims of better what?

• Contraindicated in pt with what allergy?

• What toxicity?

amide

2-3 min

180-300 min + epi

7mg/kg

4% with 1:100,000 or 1:200,000 epi

soft tissue and hard tissue diffusion

sulfa allergy

methemoglobinemia/ neurotoxicity

True of False: the onset and duration of anesthesia compared favorably with other available dental ansthetics

True

How much more is septocaine than lidocaine?

$20 a box

Articaine is clincially associated with a slight increase in what kind of injury?

Nerve

Avoid articaine for what?

IAN blocks

Articaine is great for what?

Minor procedures for maxillary infiltration to avoid palatal injection.

Ex: implant uncovering, rubber damn clamp, operative

Use articaine for what type of extractions in peds?

Maxillary extractions, helps avoid palatal injections

Articaine is also good for what location?

Lower anterior central incisors or back up for failed blocks

When using articaine:

• Be sure to document any __________

• Physical interaction of the needle with what?

• What to do if needle interacts with nerve?

• Balooning the nerve can cause what?

zingers

lingual or IAN

remove needle or move needle without injection, do not want to inject into the structure of hte perineurium

leads to bad outcomes including permanent anesthesia or worse

Benzocaine topical gel:

• __% benzocaiene

• Usually approximately _mg per dose.

• Risk for what?

20

9

methemoglobinemia

Benzocaine spray:

• ___mg benzocaine per metered spray

• Risk for what?

50mg

methemoglobinemia

What can a lidocaine patch or lioderm be used for?

Neuropathic pain'

TMD applications (other transdermal medicaiton for TMD)

What anestheic has the loswet duration of pulpal anesthesia?

What about the highest?

2% lidocaine without epi

0.5% etidocaine with 1:200,000 epi

What local has the lowest and highes vasodilation effect?

Prilocaine 0.5

Etidocaine 2.5

Managing the hot tooth:

• Understanding ____ and local _________

• Understanding ___________

• When it is better to localize, give antibiotics and let things do what?

• Consider ________ _________

pH and local anesthesia

hyperalgesia

cool down

conscious sedation

Is is wrong to assume that all anesthetics are equipotent in all patients?

Yes, there are no drugs that do not have a bell shaped resonse to drug therapy

Anesthetic failures:

• Try a secondary technique?

• Evaluate the anatomy?

• Is sedation an option?

Gow gates, and field blocks, PDL, intraosseous techniques, abort procedure in elective situations

Pan or clincial exam

Oral sedation

Do we generally allow enough time for local to work?

No, especially for profound pulpal anesthesia

Primary Intrasossceous technique % effective?

Secondary?

Vasoconstrictor?

45-93% effective with short duration

80-90% effective with longer duration

40-100% effective

Purpose of buffering local anesthetic?

• Decrease ______ at injection site

• Increase speed of _______ of anesthesia

• Decrease injections _____ pain postoperatively

pain, (local aneshteic pH 3.5-5.9)

onset

site

Buffering local anesthetic:

• How?

Sodium bicarbonate 8.4% that is injected into standard dental carps

What are the disadvantages of buffering local?

1. Staff time to prepare the carps

2. Cost

   1. Mixing pen $300

   2. Connecting cartridges $50 for 4

   3. Bicarb solution $200 for 4

   4. From 5-7$ per carp inital set up

3. Cannot store carps once buffered

Local anesthetic reversal:

• _____________ injection

• Non selective _______ adrenergic receptor _________

• Blocks the effects fo the ___________

• Shortens duration of local anesthteic by what %?

• Can produce __________ and reflexive __________

phentolamine

alpha antagonist

vasoconstrictor

50%

hypotension and reflexive tachycardia

Oraverse:

• Expensive $75 for a 10 pack

• Dosed ___:____ with carps used for local anesthetic

• Careful dosing in _______ compromsised, and extremes of _____.

1:1

medially, age

Intranasal mists:

• Used in otolaryngology for _______ and ______ procedures.

• Has been found useful for what?

• Composition?

nasal and sinus

anterior tooth restoration anesthesia

3% tetrcaine with 0.05% oxymetazoline