Overdose, children and LA

Question 1

Brief the difference between infiltration and nerve blocks

Answer 1

An infiltration is injecting local to site being numbed. to numb only the end of the nerve branch which is supplying that single tooth. So you can give a buccal infiltration in the maxillary region, and the anaesthetic will penetrate the bone (as it is quite thin) and numb that region.

A nerve block is when you inject much further up the nerve branch and anaesthetise more of the nerve.

Question 2

State how LA toxicity is reduces in adults.

Answer 2

LAs preferentially binds to α-1 acid glycoprotein (AAG) found in plasma.

Question 3

State how LA toxicity is induced in children

Answer 3

AAG Levels:

• Levels in neonates are 20-40% % than in adults
• Low AAG levels lead to higher levels of unbound LA

Metabolism and excretion:
* Infants have decreased clearance and longer elimination 1⁄2 life

Myelination:

• Myelination not complete until 12 years of age
• Incomplete myelination= better penetration into nerve fibres
• Therefore reduced doses can provide complete block

Anatomy:
* Loose fascial attachments around nerves facilitate spread of LA