LA Delivery Flashcards
How do you assemble a LA syringe?
- open sterile packaging
- check batch no and expiry date
- insert LA cartridge into sheath
- insert plunger into sheath with the handle at the top of the plunger
- twist plunger into locked position
- pull back sheath until click sound is heard
- remove needle cap
- needle is ready for use
How do you aspirate?
- a light push of the needle
- if any blood is seen then retract slightly and aspirate again
How do you dispose of a LA syringe?
- orange lidded sharps box if the entire cartridge was used
- blue lidded sharps box if there is still LA left over
- ensure the sheath has been locked in place
How do you close a syringe for disposal?
- double click the sheath
- the needle cannot be used after this point
What is the IANB used for?
- inferior alveolar nerve block
- used to numb the mandibular teeth on one side (to the midline), also numbs lower lip, parts of the tongue and chin
How do you administer the IANB?
- LH thumb placed intra-orally
- LH fingers placed extra-orally on the posterior border of the ramus
- LH thumb feels for the coronoid notch
- the needle advances from the opposing premolars, parallel to the occlusal plane
- needle should be inserted into the mucosa at the centre of the V created by the coronoid notch and the pterygomandibular raphe, around 5-10mm above the last molar
- the needle should contact bone, pull back slightly, aspirate, and deposit LA slowly
What is a palatal infiltration used for?
- numbing the associated palatal soft tissues
How do you administer a palatal infiltration?
- apply firm pressure posterior to the area to the injected
- insert the needle at a 90 degree angle to the site, slightly distal to the tooth be anaesthetised
- advanced needle until bone is contacted and withdraw slightly
- aspirate
- inject LA quickly due to high discomfort in this area, not much is required
- when area blanches sufficient LA has been deposited
What is a buccal infiltration used for?
- numbing the maxillary teeth and the anteriors in the mandibular
- numbing associated buccal soft tissues
How do you administer a buccal infiltration?
- stretch cheek
- puncture mucosa in the deepest part of the sulcus, slightly distal to the apex of the tooth being anaesthetised
- advance the needle until bone is contacted
- pull back slightly and aspirate
- deposit LA slowly
What are the contraindications for LA?
- felypressin and a pregnancy, can induce labour
- infection can have an effect of on the efficacy of LA
- some heart conditions can contradict the use of LA which contains adrenaline
- LA with adrenaline is absolutely contraindicated in patients with hyperthyroidism
- IDB severely contraindicated in haemophiliacs
- true allergy is very rare, these patients should be sent for testing and not treated in general clinic, some allergies relate to the preservative
What are the different types of LA?
Amides (more common) - lidocaine - prilocaine - articaine Esters - cocaine - procaine - benzocaine
What is the typical preparation of lidocaine?
- 2% lidocaine
- 2% lidocaine with 1:80,000 adrenaline
What is the typical preparation of prilocaine?
- 4% prilocaine
- 3% prilocaine with 0.03U/ml felypressin
What is the maximum safe dose of lidocaine for a healthy adult?
- max safe dose = 4.4mg/kg bw
- assuming the adult is 70kg => 308mg is max dose
- 2% lidocaine = 44mg per cartridge
=> 7 cartridges max
What is the maximum safe does of articaine for a healthy adult?
- max safe dose = 7mg/kg bw
- assuming the adult is 70kg => 490mg is max dose
- 4% articaine = 88mg per cartridge
=> 5 cartridges max
What is the typical preparation of articaine?
- 4% articaine with 1:100,000 or 1:200,000 adrenaline
What is the maximum safe dose of prilocaine?
- max safe dose = 8mg/kg bw
- assuming the adult is 70kg => 560mg is max dose
- 3% prilocaine = 66mg per cartridge
=> 8 cartridges max
What are some local complications of LA?
- failure to anaesthetise
- prolonged anaesthesia
- pain
- trismus
- Bell’s palsy
- soft tissue damage
What complications are associated with articaine?
- due to its potency nerve damage can occur in blocks
- articaine should only be used for infiltrations
How do you differentiate between Bell’s palsy and a stroke?
- Bell’s palsy = full side paralysis, caused by peripheral lesion
- stroke = forehead wrinkles , caused by central lesion, stroke on one side affects opposite side of the face
Why is it difficult to achieve anaesthesia during infection?
- low pH affects the efficacy of the LA
Describe the wand.
- uses controlled and regulated speed and pressure for LA delivery which makes it much more comfortable for the patient
- smaller needle which is beneficial in children or the needle-phobic
- pencil grip is used which can make it easier to manoeuvre
Why are topical anaesthetics used?
- make the procedure more comfortable for the patient
How long should topical anaesthetic be applied for?
- 1-2 minutes
- applied using a cotton wool roll
What kind of topical anaesthetic is used?
- 20% benzocaine
- 2% lidocaine
How do you test for anaesthesia?
- ask the patient how they feel, should feel “fat” or “swollen”, “tingly”
- sensation to the patient should only be different on the side LA was administered
- percuss the tooth
- apply a cold stimulus to the tooth
How much of a cartridge is required for a palatal infiltration?
1/8 cartridge
How much of a cartridge is required for a buccal infiltration?
1/4 cartridge
How much of a cartridge is required for a lingual block?
- the remaining 1/3 of the cartridge that has been used for IDB, deposit as you retract the needle from the tissues
How much of a cartridge is required for a lingual block?
- the remaining 1/3 of the cartridge that has been used for IDB, deposit as you retract the needle from the tissues
How long does infiltration anaesthesia last?
60 minutes
How long does block anaesthesia last?
90 minutes
What are systemic complications of LA?
- psychogenic / stress
- drug interactions
- cross infection
- allergy
- collapse
- toxicity
What are the symptoms of psychogenic stress?
- fainting (syncope)
- palpitations
- pallor
- sweating
- bradycardia
- nausea
How do you treat psychogenic stress?
- lay flat and raise legs
- sweet drink
- loosen neck clothing
What are common drug interactions with LA?
- antidepressants (MAOIs and tricyclics)
- hypertensive drugs (beta blockers and non-potassium sparing diuretics)
- cocaine, increased adrenergic activity
What typically causes allergy in LA?
- preservatives (methylparaben)
How does LA toxicity present?
- convulsions
- loss of consciousness
- respiratory depression
- circulatory collapse
What is a contraindication for lidocaine?
- liver problems
- heart block without a pacemaker
What is a contraindication for articaine?
- sickle cell anaemia or disease
How do you numb the maxillary teeth?
- buccal infiltration
