10- Local anaesthesia Flashcards
What does the conduction of a nerve depend on?
changes in the electrophysical status of the nerve
How does an impulse travel through a nerve
Impulse stimulates neurone, Na+ channels open, Na moves into cell depolarising the membrane, triggers action potential
What does local anaesthetic do?
Blocks the sodium channels, stopping the depolarization of the nerve
What are 2 categories of local anaesthetic?
- Amino-esters
2. Amino-amides
Give an example of amino-ester?
- procaine
Give an example of amino-amides?
- lidocaine
- mepriocaine
- prilocaine
What category is lidocaine?
Amino-amide
What is potency?
the minimum concentration of local anaesthetic needed to produce the same effect
What is the most potent LA?
Lidocaine
What is the least potent LA?
Procaine (amino-esters)
Where are amino-esters metabolised?
in the blood
Where are amino-amides metabolised?
In the liver
Which LA would you give to a patient with liver problem?
amino ester i.e. procaine
Name the three branches of the trigeminal?
V1 - Ophthalmic branch
V2 - Maxillary branch
V3 - Mandibular branch
What does the ophthalmic branch innervate?
sensory innervation to :
- lacrimal gland
- conjunctiva
- skin between nose and eyes
- skin of upper eyelid
- forehead
What does the maxillary branch innervate?
sensory innervation to:
- teeth of maxilla and soft tissue
- buccal gingiva of upper jaw
- mucous membrane of cheek
- interdental papilla
- periodontal ligament
- hard palate
- side of the nose
- upper lip
What does the mandibular branch innervate?
- motor branches for muscles of mastication
- skin of anterior temple
- lower teeth
- gingiva of lower teeth
- skin of lower lip
- chin
- taste buds
- submandibular and subgingival glands
- lingual gingiva
What position should you put the patient in when injecting maxilla?
Flat/ supine (should be perpendicular to the floor)
What position should you put the patient in when injecting mandible?
Semi-supine
What must you do to the soft tissue before you apply topical anaesthetic?
must dry the soft tissue
What 4 things should be written on the LA Cartridge
1, LA drug
- Vasoconstrictor
- Expiry date
- Batch number
What is unique about the ultra-safety plus XL?
can be resheathed
What are the different types of anaesthesia of the upper jaw?
- infiltration
- posterior, middle, anterior alveolar nerve block
- greater palatine nerve block
- nasopalatine nerve block
- anterior, middle, superior nerve block
- 2nd division nerve block
What are the different types of anaesthesia of the lower jaw?
- infiltration (soft tissues)
- mental nerve block (mental foramen)
- inferior alveolar nerve block
- long buccal nerve
- lower anteriors
- lower first premolar and anteriors
- lower molars and second premolar
Where should you aim when injecting upper jaw?
Aim for root of tooth, inject on mucogingival line
How much should you inject when infiltrating the upper jaw?
1/2 cartridge
What teeth does does the greater palatine nerve block cover?
all upper molars and premolars (i.e. area distal to canine) 4-8
What teeth does the nasopalatine nerve block cover?
Canine to canine 3-3
What LA would you use when doing restorative work in the maxillary teeth?
Buccal infiltration
What LA would use when extracting maxillary teeth?
(SINGLE TOOTH) = buccal and palatal infiltration
(MULTIPLE TEETH) = nasopalatine and greater palatine nerve block
What is unique about the maxilla that makes it easier to inject?
maxilla is a spongey bone, easier for LA to reach
Why is it harder to inject the lower jaw?
Mandible made up of cortical bone which is extremely dense
What does infiltration in mandible cover?
only soft tissues
What does the mental nerve block in the mandible cover?
premolars and anterior teeth
Where should you aim inferior alveolar nerve block?
around lingula (do this by finding coronoid notch, internal oblique ridge, pterygomandibular raphe
How much of the cartridge do use when doing iD block?
at least one whole cartridge
What does the long buccal nerve block cover in mandible?
Only soft tissues around molars/wisdom teeth
Where do you inject long buccal in mandible?
slightly anterior to coronoid notch depression
What injection should you do when working on lower anterior teeth?
- Buccal infiltration (pulp)
- Lingual infiltration (lingual soft tissues)
What injection should you do when working on lower first premolar and anterior?
- Mental nerve block (pulp)
- Lingual infiltration (lingual soft tissue)
What injection should you do when working on lower molars and second premolar?
- ID nerve block
- Lingual nerve block (can be done when doing ID)
- Long buccal nerve block
What are some of the general complications of LA?
- Psychogenic
- Toxic
- Allergy reaction
- Drug reaction
Name some psychogenic reactions?
-palpitations
-restlessness
-fainting
-cold sweat
-excittion
(ATYPICAL= clonic convulsions, rolling of eyes, rigidity)
(HYPOXIA= blood pressure drops, patient holding breath)
Name some Toxic reactions?
- convulsions
- loss of consciousness
- respiratory disease
How do toxic complications occur?
overdosing i.e injecting more than patient can take
- consider patient having a liver problem (unable to break down anaesthetic)
Why would an allergic reaction occur?
often due to the presence of sodium metabisulphate
What might LA have a drug interaction with?
non cardio-selective beta blockers
Name some local complications
- contaminated needles
- infected area
- trismus
- laceration of nerve or blood vessels
- facial paresis
- LA injected too fast or too much
