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Ten Top Tips for Local Anaesthesia LA

From Mediwikis

Top Tips for Local Anaesthesia (LA)

Dr Rajiv Patel Specialist in Periodontics, St Albans, UK

Michael Edwards FRCS, Author of MHDOS (Masterscript High Detail Operating System


Tip 1 Short acting and Long acting LA

Short acting. Eg. Lidocaine (Lignocaine)
Works in 5 minutes.
Lasts 1 ½ hours.
Long acting. Eg. Bupivacaine (Marcaine).
Works in 20 minutes.
Lasts 8 hours.

Tip 2 Dose

Maximum Dose in mass.
Up to 3mg. per Kg body weight.
Maximum Dose in solution.
For a 70 Kg adult.
Up to 20ml. 1% lidocaine.
Up to 10ml. 2% lidocaine.
NB A 1% solution is 10mg. per ml., NOT 1mg. per ml.

Tip 3 Overdose

Due to unintentional injection into a vein.
Effects are depressive on other systems in the body.
Central Nervous System depression – coma, fits.
Cardio Vascular System depression – bradycardia, cardiac arrest.
Anaphylaxis – flushing, bronchospasm, oedema.

Tip 4 Adrenaline

May make the anaesthetic effect more powerful, last longer and be more localised.
May cause ischaemia if injected into an endartery in a digit, nose, ear, penis.
May cause tachycardia and cardiac fibrillation if injected unintentionally into a vein.
May be selected by mistake if LA ampoules are mixed up.
These hazards will be avoided if adrenaline is never used.

Tip 5 Drawing up the LA into a syringe.

Always check the label and expiry date before drawing up the LA.
Use a green top 21 SWG (Standard Wire Gauge) needle to draw up LA rapidly into the syringe.
Use a 10ml. syringe or smaller to avoid overdoses.
Use a 2 or 5 ml syringe to get more pressure in dense tissues such as scalp or toes.
Change to a finer orange 25 SWG needle to minimise the pain of injecting.
Twist the needle tightly onto the syringe until creaking stops.
This will prevent the needle blowing off when injecting.6 Local application of Lidocaine.

Tip 6 Painfree infiltration

Infiltrating the tissues with LA is painful.
But it can be minimised.
Surface anaesthesia.
Reduces the pain of the initial needling and raising a skin bleb.
Apply Lidocaine 5% to the skin or mucous surface for an hour.
It will not influence the discomfort of distending the deeper tissues with LA.
Pressure.
Before and during injecting, press or pull firmly on neighbouring tissues.
This will counter the needling and infiltrationdiscomfort of the injection.
Inject slowly.
As you inject the LA, advance the needle from infiltrated tissue to non-infiltrated tissue.
This will help the tissues distend painlessly and minimise the pain of the needle.
The needle tip will be advancing into partly anaesthetised tissue.
In the dense tissues of the gums, take 3 minutes to infiltrate 2ml.
In lax skin, take 1minute to infiltrate 2ml.
Wait for the LA to take effect.
Believe patients when they say they can still feel pain.
Wait longer.
Inject more local anaesthetic.

Tip 7 Recovery

At the end of the patient's operation the effects of the LA will still be maximal.
The protection to the patient of pain, touch, temperature sensations will be absent.
Eg. Danger of a dental patient biting the inside of the cheek.
Danger of scalding or biting the tongue.
The LA may affect motor nerves as much as sensory nerves.
Eg. Dribbling from the mouth with dental LA.
Inability to suck on a straw.
The effects will gradually wear off.
Then pain from the operation will be felt.
Analgesics may be needed to control postoperative pain.
Eg After excision of an ingrowing toenail.
NB Severe pain from a bandaged toe of finger may mean too tight a bandage.
Remove all bandages down to the skin.
Do not simply prescribe more analgesics.

Tip 8 Other Points

Buffering the LA.
Local anaesthetics are acidic.
Though not commonly used, adding Sodium bicarbonate to the LA solution may reduce infiltration pain.
Warming the LA to 37% may reduce the pain of infiltration.