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4th yr- CMS- Pharmacology and drugs > Local anaes > Flashcards

Local anaes Flashcards

1
Q

Define local anaesthesia

A

Loss of sensation to specific anatomical area

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2
Q

What are the 2 main uses of LA in dentistry

A
  1. Enable surgical procedures to be undertaken

2. Provide analgesia

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3
Q

Name the different way we can produce local anaesthesia

A
  1. Cooling sensation of topical application of ethyl chloride
  2. Pressure
  3. Try LA agents injected into nerve fibres
  4. Irreversabel blockades
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4
Q

How can we administer local anaesthesia

A
  1. Topical
  2. Subcutaneous injection
  3. Nerve blockers
  4. Epidural
  5. Intrathecal
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5
Q

What is an Intrathecal injection

A

Injecting directly into the subarachnoid space

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6
Q

Name the first known substance used as LA

A

Cocaine

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7
Q

Give examples of different local anaesthetics

A
  1. Lidocaine
  2. procaine
  3. Pilocaine
  4. Mepivicaine
  5. Ropivacaine
  6. Bupivicaine
  7. Articaine
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8
Q

What do we often give alongisde the anaesthetic agents

A

A vasoconstrictor

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9
Q

What are the benefits of administrating a vasoconstrictor

A
  1. Longer duration of LA
  2. Can reduce risk of CNS effects
  3. Greater anaesthetic affect so lower dose can be given
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10
Q

Where should we not administer LA with a vasoconstrictor? why?

A

into extremities as there is a risk of significant local tissue hypoxia

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11
Q

Name the 2 most common vasoconstrictors use din dentistry

A
  1. Adrenaline

2. Felypressin

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12
Q

What us another name for adrenaline

A

Epinephrine

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13
Q

What is another name for felypressin

A

Vasopressin

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14
Q

How do adrenaline work

A

It stimulates alpha adrenoreceptors to constrict blood vessels

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15
Q

Name the most common dental LA solution

A

2% lidocaine with 1:80,000 adrenaline

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16
Q

What dow e mean by 2% lidocaine

A

20mg per ml

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17
Q

When might LA with adrenaline be contraindicated

A

In patients with severe hypotension or an unstable cardiac rhythm

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18
Q

If we can’t use adrenaline as a vasoconstrictor what can we use instead

A

Felypressin

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19
Q

List the ideal properties of an LA

A
  1. Be reversible
  2. Have a high therapeutic index
  3. Have a short time of onset
  4. Last for a suitable amount of time for treatment
  5. Not have local irritant effects
  6. No side effects
  7. No potential to induce allergy
  8. Be applicable to any site
  9. Be cheap to manufacture, stable and soluble
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20
Q

List some possible adverse effects of LA

A
  1. Hypersensitivity
  2. CNS effects
  3. Cardiac arrest
  4. Methaemoglobinaemia
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21
Q

What is an allergic reaction to LA usually due to

A

The preservatives rather than the local

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22
Q

List some early CNS effects LA can have

A
  1. light-headedness,
  2. dizziness,
  3. tinnitus,
  4. circumpolar numbness,
  5. abnormal taste,
  6. confusion,
  7. drowsiness
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23
Q

List some late CNS effects LA can have

A
  1. tonic-clonic seizures,
  2. loss of consciousness,
  3. respiratory depression
  4. arrest
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24
Q

What is Methaemoglobinaemia a very rare side effect to

A

Felypressin

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25
Q

What are the symptoms of Methaemoglobinaemia

A
  1. Cyanosis
  2. lethargy
  3. Respiratory distress
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26
Q

When can Methaemoglobinaemiabe more risky

A

In a patient With angian or anaemia

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27
Q

How do we treat Methaemoglobinaemia

A

Be treated as a medical emergency give oxygen and call an ambulance

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28
Q

What is the max dose of lidocaine we can give for infiltration

A

4mg/kg

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29
Q

What is the max dose of lidocaine with adrenaline we can give for infiltration

30
Q

What is the max dose of Bupivicaine we can give for infiltration

31
Q

What is the max dose of Bupivicaine with adrenaline we can give for infiltration

32
Q

What is the max dose of Prilocaine we can give for infiltration

33
Q

What is the max dose of Prilocaine with adrenaline we can give for infiltration

34
Q

What is LA made up of

A
  1. Aromatic ring
  2. Intermediate linkage
  3. Terminal amine
35
Q

What does the aromatic ring do

A

It determines the degree fo solubility in the lipid membrane

36
Q

What is the intermediate linkage

A

It usually consist of the amide or ester portion of the molecule

37
Q

How can the terminal amine exist

A

In 2 forms:

  1. Unionised
  2. Ionised
38
Q

What does an unionised terminal amine suggest

A

Lipid soluble molecule

39
Q

What does an ionised terminal amine suggest

A

A water soluble molecule

40
Q

Is LA an acid or base

A

A chemical weak base

41
Q

What is the pKa of LA

42
Q

What does pKa mean

A

The pH at which half the molecule is ionised and half is unionised

43
Q

What does a pKa of 8 suggest

A

The the solution is mostly ionised at physiological pH.

44
Q

What can affect how well LA is absorbed

A

Presence of infection or inflammation

45
Q

How does the local anaesthetic produce an anaesthesia

A

Binds to the sodium channels so the rate of rise of the action potential is limited
The threshed for the receptor can therefor not be stimulates decreasing the rate of conduction of electrical impulse

46
Q

How can inflammation affect LA effect

A

Can reduce LA effect

47
Q

Why can inflammation affect lA effect

A

As inflammation produces an acidic environment

48
Q

List the order of how LA creates a physical sensation

A
  1. Cold
  2. Warmth
  3. Pain
  4. Touch
  5. Deep pressure
  6. Motor function
49
Q

What does the degree of neuronal blockade depend on

A
  1. Neurone type,
    2, concentration of LA use,
  2. position of the fibres within the nerve
  3. frequency of incoming impulses
50
Q

List some local and regional effects of LA

A
  1. Skin Blanching
  2. Nerve function effected
  3. Cranial nerve 7 effects
  4. Cranial nerve 5 effects
  5. Cranial nerve 6 effects
  6. Further eye effects
51
Q

What can skin blanching immediately upon placement indicate

A

Intrea arterial infection

52
Q

For a fixed dose of LA nerve fibres with a small or large diameter more affected

A

Small diameter

53
Q

Name cranial nerve VII

54
Q

Is cranial nerve 7 sensory or motor

55
Q

When can their be cranial nerve 7 effects in dentistry

A

If you accidentally inject the parotid gland when giving an ID block

56
Q

What can happen if you inject LA into the parotid gland when giving an iD block

A

Facial nerve palsy

57
Q

What do the motor neurones of the facial nerve supply

A
  1. Muscles of pharyngeal arch

2. Secretomotor to lacrimal, submandibular, sublingual and some minor salivary glands

58
Q

What do the sensory neurones of the facial nerve supply

A
  1. Taste fibres to the anterior 2/3rds of the tongue

2, Small area around the external auditory meatus

59
Q

How can we mange facial nerve palsy

A
  1. Recognition
  2. Explain to the patient and reassure them
  3. Protect the eye with an eye patch
  4. Ensure safe discharge from the practice
  5. Follow up
60
Q

Name cranial nerve V

A

Trigeminal nerve

61
Q

Is cranial nerve V sensory or motor

62
Q

What do the motor neurones of cranial nerve V supply

A
  1. Muscles of the 1st pharyngeal arch (muscles of mastication)
  2. Extra-cranial passage to neurones from cranial nerve 7 and 9
63
Q

What do the sensory neurones of cranial nerve V supply

A
  1. Extracranial passafe to neurones from cranial nerve VII
  2. Nociception
  3. Light touch sensation
    4, temperature
  4. Pressure
  5. Proprioception to TMJ and muscles of the face
64
Q

When might cranial nerve V effects occur

A

Inadvertent injection of LA into the lingual or IDN

65
Q

Give examples of cranial nerve V effects

A
  1. Immediate electric shock pain sensation
  2. Direct trauma
  3. Secondary haemorrhage
  4. neurotoxicity
66
Q

How can we mange cranial nerve V effects

A
  1. Recognition
  2. Explain to the patient and reassure them
  3. Protect the eye with an eye patch
  4. Ensure safe discharge from the practice
  5. Follow up
67
Q

Name cranial nerve VI

68
Q

What does cranial nerve VI supply

A

Visceral motor inner action to lateral rectus muscle

Abducts the eyeball

69
Q

When can cranial nerve VI effects occur

A

Inadvertent anaesthesia of the inferior orbital nerve may lead to transient lateral rectus palsy with diplopia

70
Q

During which procedure are we most likely to have cranial nerve VI effects

A

Extraction of the upper third molar where we require LA placement in the posterior superior alveolar nerve

71
Q

How can we manage cranial nerve VI effects

A
  1. Recognise
  2. Explain and reassure
  3. Protect eye with eye patch
  4. Ensure safe discharge
  5. Follow up
72
Q

Name a rare complication if infraorbital nerve block

A

Diminished accommodation of the lens of the eye leading to transient blurred vision

4th yr- CMS- Pharmacology and drugs (7 decks)

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