2. CONTENTS Definition of LA Classification Composition General structure of LA Mode of action Metabolism Maxium recommended doses Types of injection procedeure Anaesthesia for maxilary and mandibular tissues Mandibular blocks Maxillary blocks Complications Recent advances Conclusion
3. DEFINITION Reversible loss of sensation in a circumscribed area of the body caused by a depression of a excitation in nerve ending or an inhibition of the conduction process in peripheral nerves. MALAMED(1980)
15. 1.Local anesthetic agent Lignocaine hydrochloride 2% is most commony used local anesthetic agent. 2% lignocaine mean……. 2 mg in 100 ml or 20mg in 1 ml USES- CONDUCTION BLOCKADE
16. 2. vasoconstrictor Adrenaline in the concentration of 1:50000 to 1:200000 is commonly used. 1:200000 means…. 1 gm in------------- 200000 ml Or 1mg in-----------------200 ml (0.02 mg/ml) USES Delays absorption of LA from the site Provides blood less field Prolongs the action Reduces the systemic toxicity
17. 3.Reducing agent Sodium metabisulphiteis used to prevent the oxidation of the vasoconstrictor.
18. 4.Preservative Methylparaben It increases the self life of the anesthetic solution Acts as a bacterostatic agent
20. 6.Isotonic agent Sodium chloride is used to make the solution isotonic with the tissues.it makes the solution alkaline.
21. 7.vehicle Modified ringer’s solution or distilled water is used as vehicle. It produces the volume of the solution and act as dilutent.
22. GENERAL STRUCTURE A lipophilic group…usually a benzene ring A Hydrophilic group…usually a tertiary amine These are connected by an intermediate chain that includes an ester or amide linkage LAs are weak bases.
23. HOW LOCAL ANAESTHEICS WORK (mode of action)
24. THEORIES Different theories have been given to explain mode of action of local anesthetic agent:- ACETYLCHOLINE THEORY by Dett Barn in 1967. CALCIUM DISPLACEMENT THEORY by Goldman in 1966. SURFACE CHARGE THEORY by Wei in 1969. MEMBRANE EXPANSION by Lee in 1976 SPECIFIC RECEPTOR
25. SPECIFIC RECEPTOR THEORY It says that the blocking of local anesthetic is due to the binding of the drug to a specific site inside the nerve cell. This decreases the permeability of nerve membrane to sodium ions thus preventing the influx of the sodium ions into nerve. Thus the threshold potential of the nerve is increased which causes the decreased conduction of the impulse.
26. Calcium ions are present in bound form within the nerve cell membrane (sodium ion channel receptor site) LA molecules displaces these calcium ions from the sodium channel receptor site Binding of the LA molecule to this receptor site. Blockade of the sodium channel.. in sodium conductance
27. Depression of the rate of depolarization Failure to achieve the threshold potential level Lack of development of propagated action potential CONDUCTION BLOCKADE
28.
29. METABOLISM
30. ESTER GROUP They are hydrolyzed in the plasma by the enzymes pseudocholinesterase . Allergic reactions that occur in response to ester drugs are usually related to the metabolic product of ester local anesthetic i.eparaaminobenzoic acid.
31. AMIDE GROUP There metabolism is more complex than that of esters. Primary site of biotransformation is in liver. Hence the liver function & hepatic perfusion significantly affect it.
33. Factors affecting the onset pH & pKa of tissue Protien binding of the local anesthetic Use of vasoconstrictor Site of deposition of LA Nerve morphology Concentration of anesthetic agent used
34. ANAESTHETIC AGENT SUITABLE FOR CHILDREN 1.Lidocaine hydrochloride 2% with epinephrine 1:100,000 2.mepivacaine hydrochloride 2% with levonordefin 1:20,000 3.prilocaine hydrochloride 4% with epinephrine 1:200,000
35. POTENCY OF LA AGENTS It depends on-- 1.lipid solubility 2.tissue diffusion characteristics 3.intrinsic vasodilator activity
36. MAXIMUM RECOMMENDED DOSES 4.4 mg/kg body weight with adrenalin 7.5 mg/kg body weight without adrenalin DOSE CALCULATION %CONCENTRATION(mg/ml) x ml/cartage = total mg/cartage
37. example In a 10 kg child If 1 kg-------------=4.4mg Then 10kg-----------=44mg 20 mg------------------=1ml (2% lignocaine) Then 44mg------------2.2 ml So in a child of 10 kg maximum recommended dose of LA is 2.2 ml.
38. POINTS TO BE KEPT IN MIND REGARDING THE DIFFERENCE B/W THE CHILD AND ADULT PATIENT 1.Density and calcification of maxillary and mandibular bone 2.Anatomic structures 3.Penetration of the needle 4.Depth of needle penetration 5.Emotional aspect
39. TYPES OF INJECTION PROCEDURES 1.Nerve block-depositing the LA solution within close proximity to a main nerve trunk 2.Field block-depositing a in proximity to the larger nerve branches 3.Local infiltration-small terminal nerve endings are anaesthetised.
40. ANAESTHESIA FOR THE MANDI BULAR TISSUE 1.infiltration 2.inferior alveolar nerve block 3.mental nerve block
41. INFERIOR ALVEOLAR NERVE BLOCK Nerve anaesthetized- Inferior alveolar nerve and its sub division Mental nerve Incisive nerve Lingual nerve(occasionally)
42.
43. Areas anaesthetized- Body of mandible and an inferior portion of the ramus Mandibular teeth Mucous membrane and underlying tissue anterior to molar
44. Anatomical landmarks
45.
46. Position of the patient-body of the mandible is parallel to the floor. The operator stands to the right side of the patient with left index finger palpates the mucobuccal fold.
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48.
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50.
51. Aspirate slowely Needle depth---8-10 mm Amount deposited-----0.9-1.0 ml LINGUAL NERVE is anterior and medial to ingerior alveolar nerve So withdraw the needlea bout 1mm and deposite the 0.5 ml of LA LONG BUCCAL NERVE can be anaesthtized by infilteration in the buccalsulcus distal to permanent teeth Amount deposited---0.2 ml
57. The infiltration can be of :- Labial infiltration Buccal infiltration Palatal infiltration
58. In local infiltration the nerve endings in the area of the surgery are flooded with local anesthesic solution. The incision is made through the same area in which solution has been deposited. Landmark- Mucobuccal fold. Needle used- 1inch, 25 gauge needle Amount- 0.45 to 0.6 ml
92. 1.IONTOPHORESIS Iontophoresis (a.k.a. Electromotive Drug Administration (EMDA)) is a technique using a small electric charge to deliver a medicine or other chemical through the skin.
94. JET INJECTION This is a technique in which a small amount of local anesthetic solution is propelled as a jet into submucosa without the use of hypodermic needle.
95. COMPUTER CONTROLLED SYSTEM The wand local anesthesia system is a computer controlled injection device. The wnd/compuDent system administers local anesthetic at two specific rates of delivery. The slow rate is 0.5ml/min and fast rate is 1.8ml/min .
96. COMFORT CONTROL SYRINGE The CCS system is an electronic , preprogrammed delivery device that provides the operator with the control needed to make the patient’s local anesthetic injection experience as pleasant as possible.
97. ELECTRONIC DENTAL ANESTHESIA This method of achieving local anesthesia involves the use of the principle of TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION which causes relief of pain.
98. CONCLUSION Local anesthetics are useful for a range of applications in infants and children. Recent research has elucidated developmental pharmacology of local anesthetics and has suggested approaches to safer and more effective use of these drugs. In the future, there may be ways to produce new local anesthetics that expand their utility for treatment of both acute and chronic pain.
