Local Analgesia Flashcards
What topical preparations of lidocaine are available ?
2% gel
10% spray
5% ointment
What topical preparations of benzocaine are available ?
20% gel
How does topical lidocaine impact total LA dose ?
Lidocaine is well absorbed so must be included in total dosage
What does topical anaesthetise ?
Non keratinised mucosa
2-3 mm into soft tissues
What doesn’t topical anaesthetise ?
Limited use on palatial mucosa or attached gingivae
Pain produced by rapid injection
What is the difference between analgesia and anaesthesia ?
Analgesia is absence of pain sensation
Anaesthesia is absence of all sensation
What skin preparations are available ?
Amitop and EMLA
Amitop takes 60 mins to work
EMLA takes 45 mins to work
Lidocaine …
2% and adrenaline 1:80000
2-3 mins to effect
45-60 min duration
Max dose is 4.4 mg/kg up to 300mg max
Prilocaine …
4% and felypressin 0.03IU/ml Less effective than lidocaine Used when adrenaline contraindicated Max dose is 6mg/kg up to 400 mg Latex free
What is the association between felypressin and scheming heart disease ?
Causes coronary arteries to constrict
Limit of 3 cartridges for those with ischemic heart disease
Mepivocaine …
2 or 3% with 1:100000 adrenaline Least vasodilation so can be used plain 30 min duration Max dose is 4.4mg/kg up to 300 mg More effective for block than infiltration
Articaine vs lignocaine
Articaine more effective for buccal infiltration next to molars and upper lateral incisors
Safer
But causes more post injection pain
What anaesthetic agents can be used as topical anaesthetics ?
Lidocaine
Benzocaine
Where is infiltration anaesthesia deposited ?
Around nerve terminals
Which sized needles are used for infiltration and nerve block anaesthesia ?
Infiltration is 25mm
Nerve block is 35mm
Where is the needle placed for mental block ?
Between the apices of premolars
Where is the needle placed for palatial anaesthesia ?
Distal to the tooth being treated
Except for incisors and premolars and third molars
Use chasing technique
What is the target for the long buccal block ?
Supra periosteal distal and buccal to the last standing molar
2-4 mm depth
Can also inject in cuscus distal to tooth being treated
What are the anatomical landmarks for the inferior alveolar nerve block injection ?
Thumb placed at anterior notch
Needle entry is junction of buccal pad of fat and pterygomandibular raphe
advance to bony contact there should be 1 cm needle showing
If no bony contact move the needle distally
If contact too early move mesially
For lingual anaesthesia withdraw while injecting final 1/3 of solution
What are the contraindications to LA?
Bleeding diasthesis Incomplete root formation Susceptibility to endocarditis Pademaker Epilepsy Trismus Cerebrovascular disease
What are the local complications with LA?
Pain on injection Pain after injection Vascular problems Failed anaesthesia Localised neurological problems Infection Interference with wound healing Self inflicted trauma Trismus
What causes pain on injection ?
Subperiosteal injection Intraepithelial injection Too rapid injection Direct contact with nerve trunk Solution factors ph and temperature
What causes post injection pain ?
Sub periosteal injection
Forceful intraligamentary injection
Muscle damage
What causes neurological effects in relation to LA?
Prolonged anaesthesia due to nerve trunk damage, repeat injections, solution concentration
Facial paralysis due to injection into parotid gland
Auditory and visual disturbances
What vascular problems can be caused by LA?
Intravenous injection - haematoma
Intra arterial injection - localised blanching
What effects can LA have on would healing ?
LA decreases cell motility
Adrenaline reduces oxygen tension
Increased risk of dry socket with LA with adrenaline
What systemic effects unrelated to LA agent can occur ?
Psychogenic effects eg fainting
Infection eg hiv, hepatitis
What systemic effects related to LA agent can occur ?
Toxicity
Methemoglobinaemia
Drug interactions
Allergy
What is methaemogloninaemia ?
Prilocaine, benzocaine and articaine metabolites convert iron in Hb to ferric state
Decreases oxygen carrying capacity
Which drugs can interact with LA?
Procaine and prilocaine and sulphonamides can produce metheamoglonilinaemia
Lidocaine prolongs suxamethonium
Lidocaine and membrane stabilising agents
La and beta blockers
Which drugs can the adrenaline in some LA s react with ?
MAOIs, TCAs, phenothiazine, beta blockers, non potassium sparing diuretics, drugs of abuse
What measures should be takes if a patient is having repeated system is post treatment effects ?
Check weight and dosage
Check blood pressure
Check anxiety
What are the signs of LA overdose ?
Tonic clonic seizure activity then generalised CNS depression, depressed blood pressure, heart rate and respiratory rate
