LA Flashcards
Define local anaesthesia
Loss of sensation in circumscribed area of the body caused by depression of excitation in nerve endings or inhibition of conduction process in peripheral nerves
Why must you give LA with GA
GA no alagesic effect, without LA, must give more GA to put patient into even deeper sedation
Larger needle gauge = greater or smaller diameter?
Smaller diameter
If you see blood when you aspirate, is it good technique
Yes, because you DID aspirate
Means that blood vessel is near target
What is the soft tissue target when trying to numb buccal nerve
Buccal soft tissue adjacent to 3rd mandibular molar just above occlusal plane
Relationship of lingual nerve to IDN
Lingual nerve is medial to IDN
What are the important branches of the maxillary nerve
Nasopalatine, greater palatine, lesser palatine nerve
Anterior, middle, posterior superior alveolar nerve
What do the greater palatine nerves supply
Mucosa of the hard palate
Palatal gingiva of maxillary alveolar process
What do lesser palatine nerves supply
Soft palate
What does the posterior superior alveolar nerve supply
Maxillary molars and buccal gingiv
What do anterior superior alveolar nerves supply
Maxillary canines and incisors
Anterior division of mandibular nerve is sensory or motor
Motor, except long buccal nerve which is sensory
Posterior division of mandibular nerve is sensory or motor
All sensory except nerve to mylohyoid
Articaine is an amide or ester. What is it often used for
Amide. Used in perio. Diffuses through bone better
Name 4 amide LAs
Articaine Bupivacaine Lidocaine Mepivacaine Prilocaine Etidocaine Dibucaine Ropivacaine
Name examples of esters
Benzocaine, procaine
What is the mode of action of LA
Bind to specific sites of channel protein, stabilise inactivated conformation of sodium channel
Block influx of sodium ions into neuron, reduce depolarisation, block conduction of impulses
3 functions of vasoconstrictors
Increase length and depth of action
Reduce toxicity (because delay absorption into blood stream)
Haemostatic effect
Contraindications for use of LA with adrenaline
Unstable angina
Recent myocardial infarction
Recent coronary artery bypass surgery
Untreated/uncontrolled severe hypertension
Orange LA carpule has or does not have vasoconstrictor
Has vasoconstrictor
What colour LA carpule to be used in pregnant patients
Green ie no vasoconstrictor
Maximum dose of adrenaline for healthy patient and for patient with significant cardiovascular history
Healthy patient: 0.2mg
Cardiovascular: 0.04mg
How many carpules of 2 lidocaine with 1:100 000 epi maximum for patient with significant cardiovascular history?
1 carpule = 1.8cc
1:100 000 = 1mg/100ml
1 carpule contains 1.8 x 0.01 = 0.018mg epinephrine
0.04÷0.018=2.22
What is the maximum dose of LA that can be given
7mg/kg
Maximum number of carpules that can be given to a 23kg patient with significant cardiovascular history. Carpule contains 2% lidocaine with 1:250 000 epinephrine
2% = 2g/dL = 20mg/ml
1.8x20=36mg
Max dose of lidocaine 7mg/kg.
7x23÷36=4.47
1:250 000= 1mg/250ml = 0.004mg/ml
Each carpule 1.8cc
0.04 ÷ (0.004x1.8) = 5.55
Max 4.4 carpules
Maximum dose of lidocaine with vasoconstrictor
7mg/kg, max 500mg
Max dose of lidocaine without vasoconstrictor
4.4mg/kg
Maximum dose of mepivacaine
6.6mg/kg max 400mg
Maximum dose of bupivacaine
1..3mg/kg max 90mg
Why is it very important to aspirate bupivacaine
It is the most cardiotoxic
What is the diameter of the short needle
30 gauge
EMLA cream formed from 2.5% lidocaine and 2.5% prilocaine penetrates skin at what speed
5mm in one hour
Where is local infiltration for tooth deposited
Near or at the apex of the tooth. Diffuse through bone to affect periapical nerves and nerves supplying PDL, adjacent bone, soft tissue
Root length is usually ___ crown height
Twice
Tissue should be ___ when administering LA infiltration
Taut
Palatal LA infiltration give about __cm away from the tooth, ___ to bone
1cm from the tooth
Perpendicular to bone
In IDN block, what is needle tip aiming for
Just above the mandibular foramen just behind the lingula, where IDN inserts into mandibular canal
Why is lingual nerve anaesthesised during IDN block
Lingual nerve is just anterior and medial to IDN
In IDN block, the needle is inserted into
Pterygotemporal depression a the height of greatest depth of coronoid notch
Pterygomandibular raphe is lateral or medial to pterygotemporal depression
Medial
How deep does needle for IDN go
20-25mm
What needle should be used for IDN block
25 gauge long needle
Barrel of syringe rests on ____ during IDN block
Contralateral premolar
How to give buccal nerve block
Injection given immediately after idn block, insert at mucobuccal fold distal to last molar
What does Gow gates mand block anaesthetise
Pulpal anaesthesia Buccal soft tissue and bone Anterior 2/3 of tongue Floor of mouth Periosteum Lingual soft tissue
What does vazirani akinosi mandibular nerve block block (closed mouth)
Pulpal anaesthesia Buccal soft tissue Bone anterior to mental foramen ie 2nd premolar onwards Anterior 2/3 of tongue Floor of mouth Lingual soft tissues
How is gow gates block administered
Needle tip just below mesiolingual cusp of maxillary 2nd molar, just distal to the 2nd molar
How is closed mouth technique administered
Lingual aspect of ramus adjacent to mucogingival junction of last maxillary molar
What does incisive nerve block anaesthetise
In the quadrant: 2PM, canine, 2 incisors
Buccal soft tissue
Bone anterior to mental foramen
Skin of lower lip and Chin
What needle to use for incisive nerve block
27 gauge short
Relationship of long buccal nerve to last molar
Lateral and behind
How long is the long needle
41mm
Relationship of the buccinator to the raphe
Buccinator is lateral to the raphe
Is the needle beveled
No
Greater palatine block will anaesthetise
Only the upper mucosa
What do you anaesthetise for maxillary molar
Posterior superior alveolar
Greater palatine?
What do you anaesthetise for mandibular molar
Inferior alveolar nerve
Lingual nerve
Long buccal nerve
