Local Anesthesia 1 Flashcards by Casey Kariya

Nerve type classification

A, B, C and subtypes

A: large, myelinated
Alpha, beta, gamma = motor, proprioception
Delta = sensory

B: preganglionic autonomic (otherwise same as Aδ)

C: small, unmyelinated

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Sodium channel activation gate:

Inactivation gate?

Act: m
Inact: h

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Steps in impulse propagation

Na influx causes rapid depolarization

Na channels close, K permeability increases

Polarity restored

Wave of depolarization

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_ is responsible for depolarization

Na channel inactivation

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Distance b/t nodes is proportional to _+

Diameter

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How does local anesthetic act on nerves

Blocks influence of stimulation on Na permeability

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Specific receptor vs. membrane interaction theories

SR: anesthetic receptor in channel, from intracellular side

MI: agent molecules associated with hydrophobic membrane

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_ is the common ester LA. Almost all other injectables are _

Procaine

Amides

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Q is the _ constant

pKa is the _ constant

Aqueous distribution constant - ability to penetrate hydrophobic tissue

Dissociation constant - proportion of ionized to unionized molecules

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Susceptibility to blockade
From most to least affected

DWCSTPP

Dull pain
Warmth
Cold
Sharp pain
Touch
Pressure
Proprioception

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5 things in an anesthetic compound, common examples

Local anesthetic
Vasoconstrictor
Antioxidant (w VC) - Na metabisulfite
Preservative - methylparaben
PH adjusting agents - HCl,NaOH

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Typical pH of anesthetic compound

4-6, especially with vasoconstrictor

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Vascular uptake (systemic distribution) depends on what 3 things

Vascularity of area
Vasodilation of agents
Quantity

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More lipophilic = _ % bound

Higher

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Conditions that increase plasma binding (5)

Conditions that decrease plasma binding

MI, cancer, trauma, surgery, chronic pain

Pregnancy, oral contraceptive, estrogen, acidosis, increasing dose

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How long does it take the following to uptake unbound drug:

Lungs
Brain, heart, liver, kidneys
Muscle
Fat

Lungs - 1 min
BHLK - 5 min
Muscle - 15 min
Fat - 1-2 hrs

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_ breaks down ester anesthetics

Psudocholinesterase

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CNS effects of lidocaine in low, moderate, mod/high, high conc.

Low: anticonvulsant, relaxation, analgesia

Mod: euphoria, drowsiness, slurred speech

Mod/High: disorientation, tremor, unconsciousness, seizures

High: coma, Resp arrest

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High conc of anesthetic decrease what in the heart

Conduction velocity
Automaticity
Myocardial contractility
Cardiac output
Blood pressure

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More _ an anesthetic is, the greater proportion of cardiovascular to CNS effects

Lipophilic

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Adrenergic receptors:
α1
α2
β1
β2

α1: increases BP
α2: inhibits NE release
β1: Increases HR
β2: Decreases BP

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Plain LA are _ by nature

Vasodilator

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3 reasons for vasoconstrictors in LA

Hemostasis
Lower toxicity by lowering CV absorption
Increased duration

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3 modes of action of VC

Direct - act on adrenergic receptors
Indirect - use NE release
Mixed - both

1:1000 conc. Means what

1gm of solute in 1000 ml of solvent 1,000 mg in 1,000 ml

How much epinephrine is in each of the following: 1: 50,000 1.7 ml cartridge 1: 100,000 1.7 ml c 1: 200,000 1.7 ml c

0. 034 mg 0. 017 mg 0. 0085 mg

Maximum epinephrine dose per appointment for healthy person? Pt. With cardiovascular disease?

Healthy: 0.2 mg Diseased: 0.04 mg or 2 cartridges of 1:100,000 epinephrine

Antioxidant Most used with epinephrine

Sodium bisulfite

4 things that determine which vasoconstrictor to use

Length of dental procedure Hemostasis requirements Post-op pain control requirement Medical status

An alpha blocker would cause what two effects

Hypotension and tachycardia

Non-selective β blocker would cause _

Increased blood pressure and bradycardia

If a patient is taking TCAs, what can epinephrine do? Why?

Produce exaggerated effects TCAs block reuptake of NE and E

Epinephrine is metabolized by what two enzymes

MAO | COMT

5 contraindications to using VCs

``` ASA IV Acute MI Angina at rest (unstable angina) Cardiac dysrhythmias Uncontrolled hyperthyroidism ```

Avoid _ in patients with methemoglobinemia

Prilocaine

Local infiltration vs nerve block

LI: Tx in same area in which local an was deposited NB: an. Deposited close to main nerve trunk, away from tx

What 6 factors determine selection of LA technique

1. Area (bone differences) 2. Procedure(s) performed 3. Duration and profoundness needed 4. Age 5. Hemostasis 6. Presence of infection

PSA and MSA innervate which teeth

MSA= premolars and MB root of first molar PSA= molars except MB root of first molar

Which nerves innervate palatal mucoperiosteum

Anterior teeth: nasopalatine nerve | Premolars and molars: greater palatine

``` Supra-periosteal injection: Used for what Where Needle Contraindications ```

Pulpal anesthesia in maxillary teeth Outside maxilla at level of root apex 25 or 27 gauge needle CI for large areas

PSA block: Injection site Angulation

Height of MB fold over second molar | Up, in and back all at 45˚ angle

MSA block: | Point of insertion

Height of Mucobuccal fold above max 2nd premolar

Infraorbital block: Which nerves are anesthetized Point of infiltration Depth and orientation of needle:

ASA, MSA, infraorbital nerve Over max 1st premolar Needle touches roof of foramen and bevel is towards foramen

Palatal anesthesia requires _

Topical and pressure anesthesia

``` Greater palatine nerve block: Which teeth Point of insertion Pressure where: Depth ```

PM and molars Anterior to GP foramen Pressure at junction of alveolar process and HP 5mm

Incisive nerve block: Needle insertion: Depth

Lateral to incisive papilla | 5mm

``` V2 nerve block high tuberosity technique: Where Depth Amount Risk ```

Same as PSA 30mm Deposit 1.8 ml Risk of hematoma formation

V2 greater palatine approach Where Problems

Up through greater palatine foramen | Close to eye, can have vision problems

``` Volume of LA injected: infiltration: PSA MSA ASA IO Palatal infiltration Greater palatine Nasopalatine V2 nerve block ```

``` I: 0.6 PSA: 0.9-1.7 MSA: 0.9-1.2 ASA: 0.9-1.2 Palatal inf: 0.2-0.3 GP: 0.45-0.6 NP: 0.45 V2: all of it ```

IAN supplies:

Teeth to midline (24/25 cross over) Body of mandible Buccal mucoperiosteum, mucous membrane ant. To mand 1st molar

LB nerve supplies

Buccal mucoperiosteum of mandibular molars

Lingual nerve supplies

Ant. 2/3 of tongue and floor of mouth | Lingual mucoperiosteum

IAN block: Height: Depth: Angle

Height: Index finger in coronoid notch 6-10 mm above occlusal plane Finger on coronoid Lateral to pterygomandibular raphe Tip located slightly superior to mandibular foramen Depth: To the BONE (20-25 mm, 2/3 to 3/4 of long needle) From opposite premolar region

Lingual nerve block

From IAN, withdraw 5mm and inject 0.3 ml

Accessory mandibular innervation (mylohyoid nerve) block location

Lingual surface of tooth posterior to tooth in question

Long buccal n. Block: Insertion Angle Depth

Mucous membrane distal and buccal to most distal molar in arch Parallel and lateral to occlusal plane Bone contact, 2-4 mm

Mental nerve block: Affected tissue: Needle insertion:

Muc membranes ant to mental foramen and skin of lower lip and chin MB b/t apices of 1/2 premolars

Gow-Gates V3 block: Insertion: Target area Depth

Distal to max 2nd molar Target: lateral side of condylar neck, just below lat. pter muscle insertion To BONE

vazirani ankinosi V3 block (closed mouth) Who? Why Insertion

Pt with trismus Relieve muscle spasm (V3 innervates muscles of mastication Medial border of ramus at height of MGJ next to max 3rd molar