Local anaesthetics and nail surgery

Question 1

Would you go through with nail surgery whilst the infection is present, explain your answer

Answer 1

No

The effectiveness of LA when infection is present might be altered.

The normal inflamatory response causes vasodialation in infected tissue which can wash LA away before it has chance to take effect on the tissue

LA senstivity to PH levels. When infection is present the PH levels drop increasing the acidity. Theres more free hydrogen present in the acidic environment which bind t o the LA too early stopping them from blocking the sodium channels. So sodium continues to enter the nerve and allows for nerve conduction to occur so the LA has less of an effect

We also know that administering LA at the site of infection can actually spread the infection further deeper into the tissue which could lead to ostiomyelitus

Question 2

Define what a Local Anaesthetic is

Answer 2

They supress action potentials blocking voltage gated channels which blocks the transmission of pain impulses

Sensory nerves lose sensation
Motor nerves lose Function

Question 3

What is an Action Potential

Answer 3

An Action Potential is a rapid rise and subsequent fall in the voltage across a cell membrane and its mediated by the difference in the number of ions across a cell membrane.
Muscles and neurons signal via Action potentials.

Question 4

Explain how local aneasthetic works, how does it stop the patient from feeling pain

Answer 4

1. Local anaesthetic stabalises the membrane and prevents the generation of an action potential
2. It stops the influx of sodium ions into the cell by blocking voltage gated sodium channels preventing depolarisation
3. Once the LA agent has been injected it diffuses across the cell membrane (unionised) where it combine with Hydrogen Ions in the axon to become (ionised)
4. In then binds to a receptor on the sodium ion channel causing the channel to close – this prevents the passage of sodium ions