Complications of LA

Question 1

What problems can occur by injecting LA into muscles

Answer 1

This will increase the diffusion distance and barrier, making anaesthetic time and success more variable - aim to inject as close to the bone as possible

Question 2

When doing a mandibular block, why should you ask yourself whether or not there is bone contact

Answer 2

The needle may be lying in the medial pterygoid muscle

Question 3

When doing a mandibular block, why should you ask yourself whether the needle is too deep

Answer 3

The needle may be sitting in the parotid gland

Question 4

How deep should the needle be in the average adult

Answer 4

2.5cm

Question 5

How much LA will you need to inject to achieve sufficient anaesthesia in a mandibular block

Answer 5

a whole cartridge

Question 6

What complications related to LA can arise when trying to anaesthetise an infected area

Answer 6

• Infected tissues tend to have a lower pH so the LA is less effective
• There is also greater tissue vascularity, so more LA is taken away from the site it is needed

Question 7

What can cause pain when delivering LA

Answer 7

• Too rapid injection and fast tissue expansion ± laceration of the periosteum
• Neuralgic pain as a result of laceration of the nerve sheath

Question 8

What can be done to minimise the pain felt by the patient when administering LA

Answer 8

• use a slow technique
• Ensure the mucosa is pulled tight, needle is sharp
• Can use a point of pressure next to the injection site (like a mirror handle pressed against the palatal mucosa)

Question 9

How can cheek swelling occur from administering LA

Answer 9

Damage to the pterygoid venous plexus during a posterior SAN block (haematoma)

Question 10

How can a rapid black eye form from administering LA

Answer 10

Damage to the infra orbital venous plexus

Question 11

How can trismus develop from administering LA

Answer 11

Bleeding into the pterygomandibular space during an IAN block

OR from an intramuscular injection

Question 12

What can result from intravascular injections

Answer 12

• Transient tachycardia
• Temporary blindness
• Blurred vision
• Seizures

Aspiration is therefore essential

Question 13

How can facial paralysis occur from administering LA

Answer 13

• If the solution is deposited into the parotid gland and therefore affects the branches of the facial nerve
• When the needle is inserted too far back behind the ramus within the parotid during an IAN block

Question 14

How long does facial paralysis usually last if it does occur

Answer 14

2-3 hours

Question 15

Which LA should be avoided for IAN blocks due to risk of nerve damage

Answer 15

4% articaine

Question 16

What should be done if a needle fractures during a block

Answer 16

This is unlikely but you should ask the patient to keep their mouth open and retrieve the needle using needle holders

Question 17

What can you do to reduce the risk of fainting/vaso-vagal attack

Answer 17

Can administer LA with the patient lying flat

Question 18

What accounts for the majority of complications from LA

Answer 18

Psychogenic reactions like palpitations, cold sweats, restlessness, excitation and fainting

Question 19

If a patient has hereditary methaemoglobinaemia what precautions should be taken

Answer 19

Try not to use prilocaine, articaine or benzocaine