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Local Anaesthesia2
description
Transcript of Local Anaesthesia2
Presented byDr. Mehreen riaz
Demonstrator, omfsiidh
LOCAL ANAESTHESIA
DEFINITION
Loss of sensation in a circumscribed area of the body caused by a depression of excitation in nerve endings or an inhibition of the conduction process in peripheral nerves.
OTHER METHODS:-1) Mechanical trauma2) Low Temperature3) Anoxia4) Chemical Irritant5) Neurolytic agents6)Chemical agents
CLASSIFICATION
ACCORDING TO SITE:-1)Topical2)Infiltration3)Regional Block • ACCORDING TO CHEMICAL COMPOSITION:-1)Amides2)Esters3)Alcohols4)Others e.g oxathazin, chlorbutol, Clove Oil, Eugenol
CLASSIFICATION
ESTERS:-Esters of Benzoic acid:-
Butacaine Cocaine Ethyl aminobenzoate (benzocaine) Hexyclaine Piperocaine Tetracaine
Esters of PABA:-• Chloroprocaine• Procaine• Propoxycaine
AMIDES:-• Articaine• Bupivacaine• Dibucaine• Etidocaine• Lidocaine• Mepivacaine• Prilocaine• Ropivacaine
MECHANISM OF ACTION
Displacement of Ca ion from Na channel receptor
Binding of the L.A mol. To this
receptor site which thus produces
Blockade of the Na channel and a…
Dec in Na conductances Depression of the rate of electrical depolarization and a….
Failure to achieve the threshold potential with a… Lack of development of propogated action potential
which is called…. Conduction Blockade
which permits
PHARMACOLOGY
PHARMACOKINETICS:- Uptake:- L.A produce a degree of vasoactivity . Most producing
vasodilatation except Cocaine. Procaine is the most potent vasodilator.
Topical route:- Tracheal Mucosa:- Absorption is as rapid as IV Pharyngeal Mucosa :- Absorption is slower Eosaphagus and Bladder mucosa :- Uptake is even slower
IV:- It’s the most rapid route of administration. Used in PVC’s
PHARMACOKINETICS
DISTRIBUTION:- Distributed throughout the body Highly perfused organs Not highly perfused organs e.g. skeletal muscles Cross BBB Cross Placental Barrier Procaine and Chloroprocaine shortest half life ( 0.1 hrs) Etidocaine Longest Half Life ( 2.6 hrs )
PHARMACOKINETICS
METABOLISM (BIOTRANSFORMATION):- ESTERS:- Hydrolyzed in plasma by the enzyme pseudocholinesterase Chloroprocaine ……most rapidly hydrolyzed Tetracaine …………16 times more slowly and is toxic Allergic reaction due to PABA Atypical Pseudocholinesterase Difficulty during previous GA should be taken
AMIDE LOCAL ANESTHETICS:-• Primary site is liver• Prilocaine gets metabolized in liver Primarily but
also in lungs• Liver disease …. Rate of biotransformation
anesthetic blood levels in blood toxicity
PHARMACOKINETICS
EXCRETION:- Kidneys Primary organ for L.A and its metabolites Renal Impairment eg glomerulonephritis , pyelonephritis, renal
dialysis.
SYSTEMIC ACTIONS CNS:-• Depression • Anticonvulsant properties ( procaine, lidocaine, mepivacaine)
CVS:- Myocardium:- Myocardial depression Dec. electrical excitability Dec . Conduction rate Dec. force of contraction Therapeutic advantage in cardiac arythmias , PVCs, Vtech.
(lidocaine)
Blood Vessels:-Cocaine VasoconstrictionAll other vasodilationHypotension ( procaine more effective) due to
myocardial depression and vasodilation .LOCAL TISSUE TOXICITY:-Skeletal muscles Longer acting LA such as EtidocaineMuscle regenerates after 2 wks after LA inj.
Respiratory Sys:-• Non Over dose levels direct relaxant effect• Overdose Respiratory arrest may occur
VASOCONSTRICTOR
Catecholamines Noncatecholamime
Epinephrine AmphetamineNor Epinephrine MethamphetamineLevonordefrin EphedrineIsoproterenol MephentermineDopamine Hydroxuamphetamine
MethoxaminePhenylephrine
*Fellypressin .
EPINEPHRINE
Source:- Available as synthetic Adrenal Medulla of animals
Mode of action :- α and β adrenergic receptors. β effects predominate
Systemic Actions:-Cardiovascular dynamics:- Inc in systolic and diastolic pressures Inc in Cardiac output• Inc in stroke Vol.• Inc in strength of contraction Inc in Myocardial O2 consumption
Hemostasis:- Used as a hemostatic agent Initial action on α receptors and vasoconstriction and as
tissue conc dec. its affect will be on β receptors and vasodilation occurs.
Respiration:- Epi is a potent bronchodilator Asthma drug of choice
CNS:- Not a CNS stimulant in normal doses
In inc doses effects are prominent
Metabolism:-Inc O2 consumption in all tissues
Stimulates Glycogenolysis in the liver and skeletal muscles
Elimination:-Re uptake by adrenergic nerves
Enzyme MAO & COMT ( catechol-O-methyltranferase)
Clinical Application:- Allergic reactions
Bronchospasm Cardiac Arrest Vasoconstrictor
Mydriasis.
CONTENTS
Local anesthetic cartridgePresevative..MethylparabenAntioxidant…Na bi sulphite, NA
metabisulphiteAlkalizing agent …Na hydroxideNaCl isotonicFungicide …Thymol
Maximum Safe Dose of Epi.
Maximum Safe dose for a healthy adult is 0.2 mg or 200µg per app.
Maximum safe dose for a pt. with clinically significant CVS disease is 0.04mg or 40 µg per appointment.
Maximum Safe Dose of L.AMax Safe dose =4.4mg/kg body weight1 kg=4.4mg60kg=4.4 x 60=264mg1 dental cartridge =36mg per 1.8ml 264mg /36=7 cartridges.
TOPICAL ANAESTHETICS
SPRAYS:- JET SPRAY:-• 1 0% lignocaine Punct
wound• 1min onset Surface
anesthesia produced• DOA 10 mins OINTMENTS:-• 5% Lignocaine• 3-4 mins to produce anesthesia• Enzyme hyaluronidase• Amethocaine & Benzocaine• Deep gingival scaling EMULSIONS:-• 2% Lignocaine HCL• Full mouth Impressions• Relief Post op tenderness ETHYL CHLORIDE:-• Refrigeration• Fluctuant abscess• Snow appears
ARMAMENTARIUM
Different techniques of achieving LA
Local infiltrationField blockNerve blockIntraligamentryIntraseptalIntrapulpalIntraosseous injectionJet injector Computer controlled local anesthetic delivery systemElectronic dental anesthesiaTopical anesthesia
Local infiltration
In local infiltration, small terminal nerve endings in the area of the surgery are flooded with local anesthetic solution, rendering them insensitive to pain or preventing them becoming stimulated & creating an impulse.
Incision is made into the same area in which the LA has been deposited.
Field block
Method of securing regional anesthesia consisting of depositing a suitable LA solution in proximity to the large terminal nerve branches so that the area to be anesthetized is circumscribed to prevent the central passage of afferent impulses
Incision is made into an area away from the site of injection
Nerve block
Method of securing regional anesthesia by depositing LA solution within close proximity to a main nerve trunk
Usually at a distance from the site of operative intervention
Periodontal ligament injection
Indications1. Pulpal anesthesia of one or two teeth in a quadrant
2.Treatment of isolated teeth in mandibular quadrant
3. Patient for whom residual soft tissue anesthesia is undesirable
4. Situations in which regional block is contraindicated
Contraindications
1. Infection or inflammation at the site of injection
2. Primary teeth when the permanent tooth bud is present
3. Patient who requires a “numb” sensation for psychological discomfort
Intraseptal injection
IndicationsWhen both haemostasis & pain control are desired for soft tissue & osseous periodontal treatment
Contraindications Infection or severe inflammation at the site of injection
Intrapulpal injection
Deposition of LA directly into the pulp chamber of a pulpally involved tooth provides effective anesthesia for pulpal extirpation & instrumentation where other techniques have failed.
Intraosseous injection
Indications Pain control for
dental treatment on single or multiple teeth in a quadrant
Contraindications Infection or severe inflammation at the site of injection
Jet injector
Principle- based on principle that liquid forced through
very small openings, called jets, at very high pressure
can penetrate intact skin or mucous membrane
The primary use of jet injector is to obtain topical
anesthesia before the insertion of a needle
In addition it may be used to obtain mucosal
anesthesia of palate.
Advantages
1. Does not require use of needle
2. Delivers very small amount of LA
3. Used in lieu of topical anesthesia
Disadvantages
1. Is inadequate for pulpal anesthesia or regional anesthesia
2. May damage periodontal tissue
3. Many patients dislike the feeling accompanying use of the jet injector
4. Post-injection soreness of soft tissue may develop
Computer-controlled local anesthetic delivery system
The system enables a dentist or hygienist to accurately manipulate needle placement with fingertip accuracy and deliver the LA with a foot-activated control
Advantages
1. Precise control of flow rate & pressure, hence a more comfortable injection
2. Increased tactile feel
3. Non-threatening
4. Automatic aspiration
5 Rotational insertion technique minimizes needle deflection
Disadvantages
1. Need for additional armamentarium
2. Increased cost
Electronic Dental Anesthesia
The method of achieving local anesthesia involves the use of the principle of transcutaneous electrical nerve stimulation {TENS} which has been used for the relief of pain
Indications
1. In patients with needle phobia
2. Ineffective LA
3. Instances where LA cannot be administered
Contraindications
1. Cardiac pacemakers
2. Neurological disorders
3. Pregnancy
4. Very young pediatric patients
5. Older patients with senile dementia
Refrences
Stanley F. Malamed –Handbook of local anesthesia, fifth edition, published by Elsevier, page no. 255-268 & 352-358