Types of local anasthetic

Name: nur A’isyah binti idris Serial no.: 61

INTRODUCTION

• The local anaesthesia is designated according to the technique or anatomical site where it is injected or applied

• It allows patients to undergo surgical and dental procedures with reduced pain and distress.

Types of local anasthetic

Surface anaesthesia

Infitration anaesthesia

Conduction block

anaesthesia

Central nerve block

anaesthesia

Intravenous regional

anaesthesia

Surface anaesthesia

• Topical application to mucous membrane & abraded skin.

• Do not work well on intact skin.

• The sensory nerve endings are the chief nerve affected.

• Only superficial layer is anaesthetised.

• Form: solution, oitments, cream , sprayed

• Drug Used:• Tetracaine (2%)• Lidocaine(2-5%)• Eutectic mixture (5%)• Benzocaine(5%)• Dyclonine(0.5-1%)• Promaxine(1%)

Uses:• to facilitate endoscopic

procedures• to reduce pain of

hemorroids/ anal sphincter.• On eyes:

For tonometry, surgeryTo remove foreign bodies

from corneal & conjunctiva

For preoperative preparation.

• Others:• Nasal lesion• Tonsilectomy• Burns • Protoscopy• Stomatitis• Sore throat

Surface anaesthesia

Infitration anaesthesia• Dilute solution of LA

produced by injection of the anesthetic solution in the area of sensory nerve endings

• Aims: to block sensory nerve terminals.

• Onset of action: immediate

• Duration of action: shorter than nerve block

• Adrenaline / felypressin added to retard absorption

• Uses: minor surgical

procedures ( incision & excision)

HydroceleHerniation

Advantages• Possible to provide

anesthesia without disruption of normal body function

Disadvantage• In major surgeries-

systemic toxicity

Drugs used:• Lidocaine (1%)• Bupivacaine(0.25%)• Etidocaine(0.5-1%)• Ropivacaine(0.5-1%)• Mepivacaine(1-3%)• Prilocaine(1-4%)

Infitration anaesthesia

Conduction block anaesthesia

• Injected around the nerve trunk, so the area distal to site of injection is anaesthetised & paralysed.

Field block• Injected sc• All other nerve coming to a

particular field are blockedUses:• Applied to scalp & ant.

abdominal walls where nerve travel superficially to supply the area.

• Advantage: small dose of drug provided for larger area

• Drugs used: Lidocaine Bupivacaine, Ropivacaine Mepivacaine, prilocaine

Nerve block• Injected around appropriate

nerve trunks or plexuses.• Provide large area of

anaesthesia .• Muscle supplied by injected

nerve/ plexus are paralysed.

• Duration depends on lipid solubility & protein binding

• Frequently performed nerve block:Lingual IntercostalUlnar SciaticFemoralBrachial plexusTrigeminalFacial Inferior alveolar

• Uses:Tooth extractionOperation on eye, limb ,

abd. WallFracture settingTrauma to ribsneuralgias

• For block of 2 to 4 hr, intermediate acting like LAs like lidocaine or mepivacaine can be used.

• Longer duration -bupivacaine

Conduction block anaesthesia

Central nerve block anaesthesia

• Includes: epidural & spinal block

A)Epidural block anaesthesia• LA is injected in the dural

space which is filled with semiliquid fat through which nerve is travel.

• Acts on nerve roots & small amount of permeates

• Aims: to produce multiple paravertebral blocks.

• Drug used: Lidocaine, Bupivacaine , Ropivacaine

• 3 categories depends on site of injection:

Thoracic• Injection in midthoracic region• Epidural space narrow : small

volume of drugs is needed• Wide segmented band of

analgesia is produced• uses: pain reliever – upper

abd. surgery

Central nerve block anaesthesia

Lumbar• Epidural space wide :

large volume of drug needed

• Produce anaesthesia of L. abdomen, pelvis & hinds limbs

• Uses: similar to spinal anaesthesia

Caudal• Injection in sacral canal

through sacral hiatus • Produce anaesthesia of

pelvic & perineal region• Uses: vaginal delivery,

anorectal, genitourinary operations.

Central nerve block anaesthesia• B) Spinal block anaesthesia• Injected LA in the spinal

subarachnoid space between L2 and L3, or L3 and L4

• Primary site of action is the nerve roots in cauda equina rather than spinal cord.

• Drug used: lidocaine, tetracaine, Bupivacaine

• Advantages• Safe, affords good analgesia ,

muscle relaxation & no loss of consciousness

• Preferred to be used in cardiac, pulmonary & renal disease

• Uses:• Surgical procedure on L. limb,

pelvis, L. Abdomen, obstetrics & C-section procedures.

Complication• Hypotension• Resp. paralysis• Headache • Cauda equina syndrome• Septic meningitis• Nausea & vomitting

Intravenous regional anaesthesia

• Also reffered to Bier’s block

• Useful for rapid anaesthetization of an extremety.

• Uses: For the upper limb and for orthopaedic procedures

Drug used: • Lidocaine • Prilocaine also preffered

because of its higher safety index.

• Bupivacaine is avoided because of its higher cardiac toxicity.

Procedure :1. The limb first is elevated to

ensure venous drainage and then tightly wrapped by an elastic bandage for maximal exsanguination.

2. Tourniquet then applied proximally and inflated just above systolic BP.

3. Then elastic bandage removed, lidocaine is injected IV.

• Normally the cuff is inflated for at least 20min to minimise systemic toxicity.

Adverse effects

• CNS : • low dose: tongue numbness, sleepiness, mild headache,

visual & auditory disturbances• High dose: nystagmus, muscular twitching• CVS : depress abnormal cardiac pacemaker activity• Blood : large dose of prilocaine accumulation of

metabolite orthotoluidine oxidised HB to methHB cyanosis• Allergic reaction: ester LA metabolised to PABA derivative.

Conclusion

• There are 5 types of LA.

Surface anaesthesia

Infitration anaesthesia

Conduction block

anaesthesia

Central nerve block

anaesthesia

Intravenous regional

anaesthesia

Thank you