Local Anaesthesia Flashcards
What preservatives are commonly used in LA?
Bisulphite and Propylparaben
What Vasoconstrictors are often used in LA?
Adrenaline and felypresssin
What is the function of adrenaline and felypressin in a LA?
They are vasoconstrictors which provides homeostatic control to the area. This diminishes the blood flow to the area and slows down the absorption therefore prolonging the effect of the anaesthesia.
What is the difference between a nerve infiltration and a block?
Infiltration- anaesthetic deposited around the terminal branches of the nerve
Block- anaesthetic deposited beside nerve trunk
When is it suitable to use an infiltration?
- anaesthetise soft tissues
- pulpal anaesthesia where alveolar bone is thin (Maxilla and lower anterior)
When is it suitable to use a nerve block?
- soft tissue anaesthesia
- anaesthetise teeth where the alveolar bone is too thick to allow infiltration (mandible)
How would you anaesthetise the dental pulp, buccal and palatal gingivae of a maxillary tooth?
Anaesthesia of the dental pulp
-Buccal infiltration
Anaesthesia of the buccal gingivae
-Buccal infiltration
Anaesthesia of palatal gingivae
-Palatal injection
How would you anaesthetise a lower anterior tooth?
Anaesthesia of the dental pulp
-Buccal/ labial infiltration
Anaesthesia of the buccal gingivae
-Buccal/ labial infiltration
Anaesthesia of Lingual gingivae
-Lingual infiltation
How would you anaesthetise Lower Premolars and canines?
Dental pulp - Mental (incisive) nerve block Buccal Gingivae - buccal infiltration or buccal/ mental nerve block Lingual Gingivae - Lingual infiltration
How would you anaesthetise lower molar or second premolar teeth?
Dental Pulp - Inferior alveolar nerve block Buccal gingivae - Buccal infiltration (long) Lingual Gingivae - Lingual nerve block (second part of IAN block if given)
What are the benefits of using a needle with a bigger gauge?
- less deflection through tissues (more accurate)
- easier aspiration
- reduce risk of breakage
What is the bevel of the needle?
Defines the point or tip of the needle, providing cutting surface to penetrate mucosa with as little resistance as possible
> angle of bevel with the long axis of the needle the > will be the deflection as the needles passes through tissue
What length of needle would you use for an infiltration?
25mm (short needle)(blue)
what length of needle would you use for a block?
35mm (long needle)(yellow)
how would you assemble a syringe and anaesthetic ready for use?
- collect syringe handle and needles
- collect LA cartridge (check batch number and expiry date)
- unpack everything and record details for decontamination
- make up syringe handle and attach the rubber bung to end
- Load cartridge of local anaesthetic solution in needle barrel
- Connect Syringe Handle and Local Anaesthetic needle with cartridge
- pull back safety sheath ready for use (clicks into place
- remove plastic needle cap
Injection technique for a buccal infiltration
- dry mucosa with cotton wool and apply topical anaesthesia on cotton wool (1-2 minutes)
- retract tissue with mirror and puncture mucosa with bevel facing towards bone
- needle should be parallel to the axis of the tooth and the needle should puncture the skin in the gingival sulcus adjacent to tooth that you want to be numb
- aim for the apex of tooth if you hit bone retract and reposition
- aspirate and deposit anaesthetic slowly (30s)
- massage anaesthetic and allow a few minutes for it to work (test)
- allow patient to rinse once distributing anaesthetic
Injection technique for a palatal infiltration
- dry mouth with cotton wool and numb with topical anaesthesia
- allow a few minutes for this to work
- select a short needle
- place the bottom end of your mirror in patients mouth and apply pressure behind the injection site
- aim for needle penetration 5-10mm palatally from the centre of the crown
- 45 degree angle to the long access of the tooth (parallel)
- advance until you hit bone and aspirate
- inject no more that 0.2-0.4ml or until you see blanching
injection technique for a IAN Block
- Dry with cotton wool and use topical anaesthesia to numb the injection site
- Thumb placed at coronoid notch and fingers cupping the angle of the mandible
- long Needle entry junction of buccal pad of fat / pterygomandibular raphe
- Syringe lies over contra lateral 5-6
- Advanced to bony contact (1cm of needle visible)
- If no bony contact reposition syringe distally
- If bony contact too soon, reposition syringe barrel mesially
- When in correct position withdraw from bony contact
- Aspirate
- Inject slowly
- For lingual anaesthesia withdraw while injection last 1/3 of solution
Injection technique for a mental nerve block
- numb area
- aim for between the apices of the lower premolars
- aspirate and then inject slowly
How would you gain consent for a LA?
“im going to be extracting your upper right 5 today so in order to do this i will have to numb up your tooth with local anaesthetic “ is that okay?
Lidocaine
Amide type LA Lidocaine HCl 2% Vasoconstrictor: Plain (none) 1:80,000 Adrenaline
Uses – Infiltrations / blocks / others
Max Dose 4.4mg/kg
Prilocaine (citanest)
Prilocaine HCl 3% Amide LA Vasoconstrictor Plain felypressin (octapressin) (1.2micogms)
Uses – Infiltrations / blocks / others
Max Dose - 8mg/kg
Articaine
Amide type LA 4% with Adr 1:100,000 1:200,000 1:400,000
Uses – Infiltrations / blocks?
Max Dose 7mg/kg
What are the systemic complications of local anaesthetic?
- psychogenic
- drug interactions
- allergy
- toxicity
- collapse
- cross infection
What is the cause of psychogenic complications and how would you treat it?
- lack of oxygenated blood to the brain
- lay flat and raise legs above head
- loosen neck clothing
- sugary drink/food
what are the clinical features of psychogenic stress?
- LIGHTHEADEDNESS
- PALLOR
- BEADS OF SWEAT (LIPS:NOSE:TEMPLE)
- BRADYCARDIA (SLOW PULSE)
- NAUSEA
- PUPIL DILATION
what drugs could have interactions with local anaesthetics?
M.A.O.I.s MOST EXOGENOUS ADRENALINE IS METABOLISED VIA CATECHOL –A-METHYL TRANSFERASE SYSTEM. MAO SYSTEM OF LESSER SIGNIFICANCE.
TRI-CYCLICS THEORETICAL RISK OF HYPERTENSION DUE TO INHIBITION OF UPTAKE OF ADRENALINE AT SYMPATHETIC NERVE TERMINALS. MAY BE PRUDENT TO LIMIT QUANTITY TO 2 CARTRIDGES OF 1:80,000 (i.e. 50mcg)
β BLOCKERS PRESSOR INCREASE AS VASODILATORY β2 ADRENERGIC RECEPTORS BLOCKED. AGAIN, MAY BE WISE TO RESTRICT QUANTITY.
NON POTASSIUM SPARING DIURETICS
RELATIVELY LOW K+ MAY BE FURTHER ENHANCED BY ADRENALINE’S POTASSIUM LOWERING ACTION.
COCAINE: INCREASED ADRENERGIC ACTIVITY
What medical conditions do you need to take into account when using adrenaline in LA?
- cardiovascular disease (< 3 x 2.2ml cartridges)
- pheochromocytoma
- hyperthyroidism (thyroid crisis)
What are some local complications of using Local Anaesthesia?
- failure to achieve anaesthesia
- prolonged anaesthesia
- trismus
- facial paralysis
- needle breaks
- soft tissue damage
- haematoma
- pain at injection site
- intra-vascular injection
- blanching
- infection
- contamination
What causes trismus and how is it treated?
- it is caused when the medial pterygoid muscle is damaged during injection (injection too low or rapid)
- reassure patient and give them a muscle relaxant and anti inflammatory
What causes facial palsy and how is it treated?
- LA injection into parotid gland where the facial nerve lies (injection to posteriorly)
- reassure and cover eye with a patch until blink reflex returns
How can you distinguish a facial palsy from a stroke?
- usually occurs within minutes after the injection
- test facial nerve
- get patient to try raise their eyebrows
- temporal branches are affected indicating lower motor neuron disturbance where as in a stroke usually only the lower face is affected
What would be the clinical features of a intra-vascular injection?
PALPITATION. (OTHERS INCLUDE ANXIOUSNESS, RESTLESSNESS, HEADACHE, SWEATING, PALLOR)
Describe the intraligamentary technique?
- use a peri press syringe
- inject LA in the periodontal ligament space
What does the efficacy of a periodontal ligament anaesthesia depend on?
Procedure
Tooth
Resistance to injection
Anaesthetic solution
Intraosseous injection
Inject LA straight into the alveolar bone
What are the advantages of topical jet injectors?
Bleeding diatheses, where deep
injections contraindicated
Sole means achieving LA
Prior to conventional techniques
What are the disadvantages of topical jet injectors?
-Expensive
-Could cause soft tissue damage
if careless
-Frightening sight and sound
-Taste of solution
What are the two different alternative IAN block techniques?
Gow Gates
- Open mouth technique
- Patient lying flat
- Aim for neck of condylar process
Akinosi Technique
-Closed mouth technique
what are the two types of surface anaesthesia?
physical and pharmalogical anaesthesia
Name a physical anaesthesia?
Ethyl chloride
- this is rarely used as LA in practice as it is difficult to direct stream and may come into contact with vital teeth
name a pharmalogical anaesthesia?
benzocaine (20%) gel
lidocaine (2%) gel
What are topical anaesthesia used for?
- anesthetise surface of skin and mucous membranes
- 2-3mm depth of tissue
- used before LA injection, rubber dam placement, suture removal, subgingival scaling, incision of an abscess etc
Name two non-pharmalogical pain controls?
TENS (Transcutaneous electrical nerve stimulation)
blocks large myelinated nerve fibres and closes the gate to central transmission of smaller unmyelinated pain fibres
Controlled by patient (over 10yrs old)
Uses: restorations, primary extractions, pre- LA
Hypnosis
An altered state of mind such that suggestions are accepted more readily and acted upon more powerfully
adjunct to LA by decrease pulse rate
What is the max dose that should be given per route when doing an intraligamnetal injection?
0.2ml
What are the advantages and disadvantages of a mental nerve block?
Advantages
very good soft tissue anaesthesia
Disadvantages
Incisive nerve anaesthesia not as reliable as IDB
Incisors may get crossover supply across midline so need a labial infiltration adjacent to tooth as well as this block
What behavioural techniques can you use to on children worried about a LA?
- empathetic
- allow control (hand signals)
- ask how there feeling
- create a safe environment
- positive reinforcement
- tell show do
- acclimatisation
- decentralisation
- voice control
- distraction
- role modelling
How would you explain the procedure to the patient when doing a LA?
-Firstly I’m going to use some topical gel on a bit of cotton wool and apply it to your gum. ill let this work for a few minutes and then i will numb up your tooth using the local anaesthetic this might cause a bit of discomfort for a few seconds but then it’ll go numb. ill explain what I’m doing as I’m going if that helps you. Ill then test to make sure your tooth is completely numb.
How would you discus the side effect of LA with your patient?
There are a few common side effects with LA which is prolonged anaesthesia so your face may feel numb for a few hours after the procedure until the anaesthetic wears off. You may get blanching but again this will go once the anaesthetic wear off
What LA would you not use on a pregnant women?
Prilocaine
Why can you not use prilocaine on pregnant women?
- it contains octapressin which can induce labour
