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Local Anesthesia Gary J. Wayne DMD

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1 Local Anesthesia Gary J. Wayne DMD Diplomate American Board Of Oral/Maxillofacial Surgery Boynton Oral & Maxillofacial Surgery and Dental Implant Center Boynton Beach, Florida

2 Review of Neurophysiology
How do local anesthetics work? What are the implications in my choice of anesthetics?

3 Summary Local anesthetics dissociate into the ionic form in order to penetrate the nerve membrane. Anesthetics are available as salts clinical use. Pka-the ability to dissociate into the ionic form in a given ph The ph of a nerve is quite stable. The ph of the extracellular fluid is variable The ph of a local anesthetic (and the surrounding tissue into which it is injected) greatly influences its nerve blocking action. Ph of normal tissue is 7.4, ph of an inflamed area is 5 to 6

4 Summary Local anesthetics containing epinephrine or other vasoconstrictors are acidified by manufacturers to inhibit oxidation of the vasopressor The acidification causes more “burning” on injection Ph of solutions without epinephrine are around 5.5, with epinephrine 3.3 Clinically this lower ph is more likely to produce a burning sensation, as well as a slightly slower onset of action

5 Summary Increasing the ph (alkalinization) of a local anesthetic solution speeds the onset of its action, increases its clinical effectiveness, and makes its injection more comfortable However, the local anesthetic base, because it is unstable, precipitates out of alkanized solutions, and this makes these solutions ill suited for clinical use Adding sodium bicarb to the anesthetic solution immediately prior to injection provides greater comfort and a more rapid onset of anesthesia

6 Local Anesthetics Articaine Bupivacaine Dibucaine Etidocaine Lidocaine
Amides Esters Articaine Bupivacaine Dibucaine Etidocaine Lidocaine Mepivacaine Prilocaine Butacaine Cocaine Benzocaine Hexylcaine Piperocaine Tetracaine

7 Local Anesthetics PABA Type Chloroprocaine Procaine Propoxycaine
Esters Others PABA Type Chloroprocaine Procaine Propoxycaine Quinoline Centbucridine Diphenhydramine Saline

8 Amide Local Anesthetics
Lidocaine “Xylocaine” Mepivacaine “Carbocaine” Prilocaine “Citanest” Articaine “Septocaine” Bupivacaine “Marcaine”

9 Lidocaine Available since 1943, most common
Available with/without vasoconstrictor With 1:100,000 Epi Max dose 7mg/kg not to exceed 500mg Pulpal Anesthesia 60min Soft Tissue Anesthesia 3-5hr Pka 7.9 Onset of action 2-3 minutes

10 Mepivacaine 3 % Common for non-surgical procedures
Used in pediatrics and geriatrics Onset of action minutes Slight Vasodilation < Lidocaine Pulpal Anesthesia minutes Soft Tissue Anesthesia 2-3 hours Pka 7.6 Maximum dose 6.6mg/kg not to exceed 400mg

11 Mepivacaine 2% with vasoconstrictor
1:20,000 Neo-Cobefrin/Levonordefrin 1/5 Vasoconstrictor Activity Rapid onset minutes Soft Tissue/Pulpal Anesthesia Similar to Lidocaine with vasoconstrictor Maximum Dose 6.6mg/kg not to exceed 400mg Is available with 1:100,000 epi (documented lidocaine allergy)

12 4% Prilocaine Vasodilation >Mepivacaine,<Lidocaine Pka 7.9
Onset 2-4 minutes Duration Pulpal 10min infiltration, 60 min block Maximum Dose 6mg/kg not to exceed 400mg

13 4% Prilocaine with 1:200,000 epi Rapid Biotransformation
Safest of all amides Good for “epi sensitive” patients requiring prolonged pulpal anesthesia >60min Duration of action pulpal 60-90min, soft tissue 3-8hrs Maximum Dose 6mg/kg not to exceed 400mg

14 4% Articaine with 1:100,000 epi Newest “wonder anesthetic” in U.S.
Pka 7.8 Onset of action minutes block,1-2 minutes infiltration Claim is that can diffuse more readily, controlled comparisons failed to corroborate Duration of action pulp min, soft tissue 3-6hrs Maximum dose 7mg/kg not to exceed 500mg Available 1:200,000 epi

15 .5% Bupivacaine 1:200,000 epi Good for lengthy procedures as an adjunct/post operative analgesia “Weak” anesthetic Pka 8.1 Onset of action 6-10 minutes Maximum dose 1.3mg/kg not to exceed 90mg Duration pulpal min, soft tissue 4-9hrs (12hr reported)

16 Esters Can Use with documented allergy to Amides Procaine+Propoxycaine
Provides min of pulpal 2-3 hours of soft tissue each cartridge 7.2 mg of Propoxycaine 36mg of Procaine Maximum dose 6.6mg/kg

17 Vasoconstrictors Epinephrine Neo Cobefrin Levonordefrin Levophed

18 When to use/not use Discussion: Cardiovascular disease “allergy”
Pediatrics Elderly Post operative analgesia Hemostasis

19 Vasoconstrictors “Vasoconstrictors should be included in local anesthetic solutions unless specifically contraindicated by the medical status of the patient or by the duration of the planned treatment” S.Malamed

20 Local Complications Needle Breakage Pain on Injection
Burning on Injection Persistent Anesthesia or Paresthesia Trismus Hematoma Infection Edema Sloughing of Tissues Soft Tissue Injury Facial Nerve Paralysis Post Anesthetic Intraoral Lesions

21 Systemic Complications

22 Overdose Patient Factors Age Weight Other Drugs Sex (pregnancy)
Presence of Disease Genetics Mental Attitude and enviroment

23 Overdose Drug Factors Vasoactivity Concentration Dose
Route of Administration Rate of Injection Vascularity of the Injection Site Presence of Vasoconstrictors

24 Overdose “Many local anesthetic overdose reactions occur as a result of the combination of inadvertant intravascular injection and too rapid rate of injection, both of which are virtually 100% preventable” S. Malamed

25 Minima/Moderate Overdose Levels
Signs Talkativeness Apprehension Excitability Slurred Speech Generalized Stutter Euphoria Dysarthria Nystagmus Sweating Vomiting Failure to follow commands Disorientation Loss of response to pain ^Blood Pressure ^Heart Rate ^Respiratory Rate

26 Minimal/Moderate Overdose Levels
Symptoms (progressive with increasing blood levels) Light-Headedness and dizziness Restlessness Nervousness Numbness Sensation of twitching, before observed Metallic Taste Visual Disturbances Auditory Disturbances Drowsiness and disorientation Loss of consciousness

27 Moderate/High Overdose Levels
Tonic-Clonic seizure activity followed by Generalized CNS Depression Depressed blood pressure, heart rate, and respiratory rate

28 Management of Mild Overdosage>5min
Reassure patient O2 via nasal cannula or hood Monitor and record vital signs IV if able Self Limiting, discharge when recovered

29 Mild Overdose-Slower Onset>15min
Biotransformation trouble All of the previous methods plus Anticonvulsant Summon medical assistance Patient to be examined by physician or hospital

30 Severe Overdose BLS Anticonvulsant Terminate treatment Summon Help

31 Epinephrine Overdose More common in gingival retraction cord Symptoms
Fear,Anxiety Respiratory difficulty Tenseness Palpitations Restessness Pallor Throbbing Headache Dizziness Tremor Weakness Perspiration

32 Epinephrine Overdose Signs of epinephrine overdose
Sharp elevation in blood pressure, systolic Elevated heart rate Possible cardiac dysrhythmias (PVC,Vtach,Vfib)

33 Management of Epinephrine Overdose
Terminate procedure Position patient –Semisitting or erect Minimized CNS Effect Monitor Blood Pressure Administer O2 (except hyperventilation) Recover-Most are self limiting

34 Allergic Reactions Rare with amides
Seen with topical anesthetics-esters Sodium metabisulfites-only with vasoconstrictors Treatment BLS Oral Histamine Blocker Sub Q epi IM Histamine Blocker Bronchial Treatment Laryngeal Treatment

35 Maxillary Anesthesia Field Block Infiltration Nerve Block Intraseptal
Intraosseous Periodontal Ligament

36 Infiltration Area of treatment is flooded with local anesthesia Periodontal treatment Selective restorative procedures

37 Field Block Anterior Superior Middle Superior Posterior Superior

38 Nerve Blocks Maxillary (Second Division)
Junction of Vertical/Horizontal Shelves Second Molar Long Needle 2cc of solution Greater Palatine Nasopalatine Infra-orbital

39 Infraorbital

40 Problems with Maxillary Anesthesia
Few Related to inflammation/infection Posterior teeth Use Nerve Blocks Infraorbital-Extra/Intra Oral Nasopalatine Secondary Division

41 Mandibular Anesthesia

42 Mandibular Anesthesia

43 Inferior Alveolar Block
80-85% Successful Related to Greater Density of Bone Limited Accessibility Wide Variation of Anatomy Solution Depot within 1mm Most Important Block Variations Accessory Innervation

44 Inferior Alveolar Block
Deepest Part of Ascending Ramus Parallel to Occlusal Plane Lateral To Raphe Hit bone Pull Back? Bevel aimed away, assist in needle deflection and direction of liquid

45 Accessory Innervation
Determine Objective Anesthesia of IAN Mylohyoid Accessory Foramina Cervical Branches

46 Mental Nerve Block Does not anesthetize incisive branch
Angle needle anterior Second Premolar High risk of nerve injury

47 Buccal Nerve Block Bevel Toward Bone
Distal and buccal to most distal molar

48 Gow-Gates Anesthetizes all branches
IAN,lingual,mylohyoid,mental, incisive auriculotemporal and buccal High Success >95% Low Aspiration Parallel tragus to anterior border of ramus Mesiolingual cusp of maxillary second molar Hit neck of condyle and back off 1mm Stay open 1-2 minutes-bite block

49 Gow-Gates Target

50 Vazirani-Akinosi Closed Mouth Block
IAN, Incisive, Mental, Lingual and Mylohyoid Mucogingival of Maxillary Third or Second Molar Parallel Maxillary Occlusal Plane Medial of Anterior Ramus Approximate 25mm (midway)

51 Supplemental Aids Ligamentary Injections Intraosseous Injections
Intrapulpal Electronic Hypnosis Nitrous Oxide IV/General Anesthesia Always reduces local anesthesia “Gizmos”

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