Local Anaesthesia in Children Flashcards
Two types of LA
- Amides - majority
- Esters
- Amides less allergenic
- Lidocaine is most common
Mechanism of function
- Chemical roadblock between source of pain and brain
- Electrical signals in form of action potentials
- Local anaesthetic blocks the sodium channels
- Vasoconstrictor slows removal of anaesthetic from vicinity of nerve - prolonged action
Contraindications?
Lidocaine
Adrenaline
Prilocaine
• Lidocaine - hypersensitivity - acute porphyria - heart block • Adrenaline - cardiac arrhythmia - hyperthyroidism • Prilocaine - known allergy
Other contraindications
• Bleeding disorders
- block is more likely to cause a bleed - haematoma
• Infection at injection site
- consider block instead - may neutralise infection
Topical anaesthetic
• Xylonor gel (5% lidocaine) • Benzocaine gel (20%) • EMLA cream - mixture of LA - lignocaine and prilocaine - usually skin, pre-iv access
LA solutions
• 2% (20mg/ml) lidocaine with 1:80,000 adrenaline
- gold standard
- pulpal anaesthesia 45 mins
- soft tissue anaesthesia 2-3 hours
• 3% (30mg/ml) prilocaine/Citanest with felypressin
- similar spectrum of activity
- also found in 4% (40mg/ml) solution
Articaine
• 4% articaine with 1:100,000 or 1:200,000 adrenaline
- aka septanest
- metabolised quicker
- good for mandibular infiltration
not for <4s
- used for paed buccal infiltration
• Contraindicated in patiens with know hypersensitivity to amide LA or hypersensitivity to sodium metabisulfite
• Intravascular injection is strictly contra-indicated and associated with convulsions
• Anti-convulsant meds can be used
Maximum doses Lidocaine Prilocaine Articaine Bupivicaine
- 4mg/kg
- 0mg/kg
- 0mg/kg
- 0mg/kg
Method for quick calculation of weight
1 cartridge/10kg of body weight on average
body weight (kg) = (age +4) x 2 e.g. 3 year old (3 + 4) x 2 =14kg
1 year old = 10kg
5 year old = 20 kg etc.
e.g Maximum dose for 3 year old
14kg
Max dose of lidocaine: 4.4mg/kg Max dose for 3 year old = 4.4x14 = 62mg 2% lidocaine = 2 parts per 100 = 20 parts per 1000 = 20mg/ml 1 cartridge = 2.2ml = 44mg 62mg/44mg = 1.4 cartridges
Equipment
- Adv safety plus vs traditional syringes
- Sterile single use, aspirating syringe system prevent needle stick injuries
- No recapping necessary
- Bevel indicator in orientating the bevel to the bone
- Transparent barrel to allow visualisation of aspiration
Needle selection
Infiltration
Block
Intraligamental
- 30 gauge - 2cm
- 27 gauge - 3mm and aspiration
- 30 gauge 1cm around gingival cuff
Behaviour management
- Verbal and non-verbal communication
- TLC
- Tell-show-do
- Positive renforcement
- Control
- Distraction
- Relaxation
Anatomical considerations
ID blocks in children
ID foramen is more posterior and inferior
Parallel to occlusal plane
Apply from contralateral side across D
Halfway between coronoid notch and pterygomandibular raphe
LA delivery
- Apply topical for sufficient length of time (1 min)
- Pull mucosa taut
- Establish rest for barrel
- Rotate needle round long access for easier penetration
- Inject very slowly
Infiltration
- Pulpal analgesia
- Topical
- Retract mucosa so it’s taught
- Advance needle and perforate mucosa
- Slow injection - 1ml/15-20 secs (ant. region)
- Routine aspiration
- Smooth withdrawal and protective sheath replaced
Maxillary molars
- Thick malar buttress
- Molar roots on buccal aspect
- Infiltration injections
- Mesial and distal to roots - more permeable
- Block if infiltration not possible or failed
Maxillary molar block
- If infiltration not poss or failed
- Primary and permanent molars
- Post +/- middle superior dental nerves
- Palpate max-zygomatic buttress
- Deposit anaesthetic distal to buttress
- Massage distal aspect of maxilla
- Ask pt to occlude (coronoid process)
Palatal anaesthesia - initial
• Extraction/rubber dam
• Intrapapillary injections to limit pain
1. Buccal infiltration
2. Test papillae with probe
3. Penetrate to depth of 1-2mm e.g mesial and distal to UR4
4. Syringe barrel is parallel to occlusal plane and perpendicular to line of arch
5. Inject slowly and advance
Palatal anaesthesia - post buccal
- Continue until observe blanching of palate
- Usually takes 20-30 secs
- Repeat with the other papilla until blanching joins
- Anaesthesia of complete gingival cuff achieved
- Can progress to palatal infiltration
- Also useful in mandible (<5years old)
ID blocks
- Inferior dental canal foramen
- More posterior and inferior
- At level of occlusal plane in 6-9 year olds
ID block technique
- TOPICAL
- Open as wide as possible
- Thumb palpates external oblique ridge
- Tauten mucosa between pterygomandibular raphe and the external oblique ridge
- Insert needle from opposite side of mouth
- Barrel over 1st primary molar of other side
ID Block Needle Entry
- Needle enters midpoint between the external oblique ridge and pterygomandibular raphe at level of occlusal plane
- Immediately deposit a small amount of anaesthetic solution
- Gently advance with slow injection and aspiration
- Bony resistance of internal surface of ramus
- Withdraw 1mm and deposit the rest of the solution
ID Block rules - bone is denser with age and infiltration may not be effective
• Count number of tooth from the midline and add tooth number
• Answer is the maximum age at which infiltration alone is likely to give pulpal anaesthesia
if (age of pt) + (tooth #) < 10 = infiltration
(e.g. [4 yrs] + [LLD=4] = 8)
With articane rule of TWELVE
Intraligamental
- If routine infiltration or block techniques fail
- Solution introduced via periodontium
- Majority escapes through lamina dura into cancellous bone
- Potential damage to developing permanent teeth
- Contraindicated in patients at risk from bacteremia
- Caution in acute periodontal inflammation/perio disease
IL Injections
- ‘Peripress’ system - high pressure/shielded barrels/protection
- Intro needle into the inter proximal perio sulcus at 50-60º angle to occlusal plane
- Gently advance until bony resistance felt
- Firm steady pressure to inject
- ‘Back pressure’
- 0.4-0.6ml mesial and distal
- Immediate analgesia
- Lips/tongue not anaesthetised
Alternative delivery systems
• Computer- controlled delivery
- e.g. The Wand
- controls rate of admin
- slow delivery via a line and needle
- especially useful for direct palatal analgesia
• Jet injection
- e.g Index
- ‘needleless’
- jet syringe injects LA solution under pressure through mucosa and bone
- useful for soft tissue analgesia prior to traditional LA methods
Operator safety
- Directive 2010/32/EU - prevention from sharp injuries in the hospital and healthcare sector
- Disposable
- No recapping required
- InSafe safety syringe
- Good positioning
- Calm approach
- Hand rest
Reasons for failure of LA
• Acute infection • Incorrect site - intramuscular - intravascular - dense buccal bone • Insufficient amount • Abnormal nerve supply • Patient immaturity - psychogenic pain
Pain on injection
• Touching the nerve - electric shock - rapid analgesia - permanent damage rare • Subperiosteal injections - extremely painful and unnecessary - internal surface of rams - avoid
Post-injection problems
• Lip/tongue/cheek trauma - painful self-inflicted - warn patient and parent • Haematoma - lacerated vein - like a bruise - resolution fairly rapid • Vasovagal syncope - anxiety driven - early recognition
