Local Anaesthesia in Children

Question 1

Two types of LA

Answer 1

• Amides - majority
• Esters
• Amides less allergenic
• Lidocaine is most common

Question 2

Mechanism of function

Answer 2

• 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

Question 3

Contraindications?
Lidocaine
Adrenaline
Prilocaine

Answer 3

• Lidocaine
- hypersensitivity 
- acute porphyria 
- heart block 
• Adrenaline
- cardiac arrhythmia 
- hyperthyroidism 
• Prilocaine 
- known allergy

Question 4

Other contraindications

Answer 4

• Bleeding disorders
- block is more likely to cause a bleed - haematoma
• Infection at injection site
- consider block instead - may neutralise infection

Question 5

Topical anaesthetic

Answer 5

• Xylonor gel (5% lidocaine) 
• Benzocaine gel (20%) 
• EMLA cream 
- mixture of LA - lignocaine and prilocaine 
- usually skin, pre-iv access

Question 6

LA solutions

Answer 6

• 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

Question 7

Articaine

Answer 7

• 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

Question 8

Maximum doses
Lidocaine
Prilocaine
Articaine
Bupivicaine

Answer 8

4. 4mg/kg
5. 0mg/kg
6. 0mg/kg
7. 0mg/kg

Question 9

Method for quick calculation of weight

1 cartridge/10kg of body weight on average

Answer 9

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.

Question 10

e.g Maximum dose for 3 year old

14kg

Answer 10

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

Question 11

Equipment

Answer 11

• 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

Question 12

Needle selection
Infiltration
Block
Intraligamental

Answer 12

• 30 gauge - 2cm
• 27 gauge - 3mm and aspiration
• 30 gauge 1cm around gingival cuff

Question 13

Behaviour management

Answer 13

• Verbal and non-verbal communication
• TLC
• Tell-show-do
• Positive renforcement
• Control
• Distraction
• Relaxation

Question 14

Anatomical considerations

Answer 14

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

Question 15

LA delivery

Answer 15

• 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

Question 16

Infiltration

Answer 16

• 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

Question 17

Maxillary molars

Answer 17

• Thick malar buttress
• Molar roots on buccal aspect
• Infiltration injections
• Mesial and distal to roots - more permeable
• Block if infiltration not possible or failed

Question 18

Maxillary molar block

Answer 18

• 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)

Question 19

Palatal anaesthesia - initial

Answer 19

• 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

Question 20

Palatal anaesthesia - post buccal

Answer 20

• 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)

Question 21

ID blocks

Answer 21

• Inferior dental canal foramen
• More posterior and inferior
• At level of occlusal plane in 6-9 year olds

Question 22

ID block technique

Answer 22

• 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

Question 23

ID Block Needle Entry

Answer 23

• 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

Question 24

ID Block rules - bone is denser with age and infiltration may not be effective

Answer 24

• 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

Question 25

Intraligamental

Answer 25

• 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

Question 26

IL Injections

Answer 26

• ‘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

Question 27

Alternative delivery systems

Answer 27

• 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

Question 28

Operator safety

Answer 28

• 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

Question 29

Reasons for failure of LA

Answer 29

• Acute infection 
• Incorrect site
- intramuscular
- intravascular
- dense buccal bone 
• Insufficient amount
• Abnormal nerve supply 
• Patient immaturity - psychogenic pain

Question 30

Pain on injection

Answer 30

• Touching the nerve
- electric shock
- rapid analgesia 
- permanent damage rare
• Subperiosteal injections
- extremely painful and unnecessary 
- internal surface of rams
- avoid

Question 31

Post-injection problems

Answer 31

• 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