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Exodontia > LA difficulties and complications > Flashcards

LA difficulties and complications Flashcards

1
Q

Is LA safe?

A

Extremely safe - average dentist gives approx 15 patients LA per day
=1/4 million/ day
=approx 70 million/year in UK
Major complications very rare

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2
Q

Failure to obtain anaesthesia: agitated patient

A

Has it failed? Is px feeling pain or pressure

Consider premedication, sedation or GA

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3
Q

Failure obtain anaesthesia: faulty technique

A

Wrong place, too small a volume (usually IAN), therefore repeat

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4
Q

Failure to obtain anaesthesia: anatomical variations

A

Zygomatic buttress over first molar roots

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5
Q

Failure to obtain anaesthesia: alternative pathways of pulpal fibres

A

Supply from lingual, buccal, mylohyoid, cervical plexus, therefore infiltrates around tooth

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6
Q

Failure to obtain anaesthesia

A 
Agitated px
Faulty technique
Anatomical variation
Alternative pathways of pulpal fibres
Inability to place needle appropriately
Local infection
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7
Q

Failure to obtain anaesthesia: inability to place needle appropriately

A

Trismus
Unwillingness of px
Gagging

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8
Q

Failure to obtain anaesthesia: local infection

A

pH changes (but only small so may not be cause) reduced lipophilic component
> vascularity, LA dispersed
Receptor or neural pathway sensitisation?
Why significant with regional block?
Therefore inject remote from site - avoid spread

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9
Q

Pain during injection

A 
Tissues not taut
Excessive p in tight tissues
Subperiosteal injection
Solution cold - use at room T
Wrong solution - never refill LA cartridges
Penetration of nerve = 'electric shock'
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10
Q

Penetration of nerve

A

‘electric shock’
‘anaesthesia did not wear off’
Prolonged (usually partial) impairment of sensation
-worse with articaine 4% and prilocaine 3% therefore given as IAN blocks
Recovery dependent upon degree of injury, usually <3 months
No treatment

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11
Q

Cartridge breakage

A 
Rare, due to misalignment of syringe or blocked needle (always test and inject slowly)
Beware glass (usually plastic sleeved, or plastic cartridges)
Use sleeved glass cartridges for intraligamentary injections
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12
Q

Needle breakage

A

Rare (do not insert to hub)
At site of bending, metal fault or hub
Remove immediately with artery forceps
If not possible, refer to oral surgeon for removal under GA (or may move in tissues, cause pain, trismus and worry)
Radiographs at 2 angles and localising needles
Keep all details and hub of needle

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13
Q

Facial nerve paralysis

A

LA within parotid
May be partial or complete, resolves after LA wears off
Protect eye if lids affected

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14
Q

Visual disturbance

A

Very rare - visual loss/ diplopia/ squint
Due to intravascular LA to eye/orbit or diffusion from maxillary injection site
Recovery after LA wears off

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15
Q

Vascular problems

A

Aspiration suggests entry into vessel in 2-12% of injections
If positive aspiration, reposition needle
Haematoma
Blanching at distant site
Intravascular injection (greater potential for drug toxicity - see below, LA failure)

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16
Q

Haematoma

A

Dependent upon site - posteriorsuperior dental worst
Results in:
-swelling and subsequent bruising
-possibly trismus if in medial pterygoid (IA block)
-may become infected, leading to severe trismus

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17
Q

Haematoma treatment

A

Pressure
Prophylactic antibiotics
Trismus slowly resolves
If not infected, exercises

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18
Q

Blanching at distant site

A

Due to intra-arterial vasoconstrictor or effect of needle on vessel
May be up to half-hour, reassure

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19
Q

Self-induced trauma

A

Hot drinks/ cig on lip

Biting (children)

20
Q

Needle track infection

A

Very rare with sterile disposable needles in absense of haematoma
Treat as for any other infection

21
Q

Allergy

A

Higher incidence with procaine/ amethocaine (esters)
Take careful history
Allergen usually preservative but most LA now preservative free
Care with latex allergy (latex in cartridges)
Responses range: delayed hypersensitivity, acute oedoma, anaphylaxis

22
Q

Treatment of allergy

A 
Dependent on severity
Antihistamines
Adrenaline
Hydrocortisone sodium succinate
Can refer to sensitivity tests
If negative undertake test infiltration
23
Q

Allergy: contact dermatitis

A

Dentist/ nurse - most likely with procaine/ amethocaine/ benzocaine (esters)
Avoid agent and wear gloves

24
Q

Toxicity of LA agent

A

Potential risk with inappropriately high dose, particularly with accidental intravascular injection or in small children
Most likely to affect CNS – excitatory at low doses, depressant at high doses
Depressant action on the heart
Prilocaine can cause methaemoglobinaemia (reduces RBC oxygen carrying capacity)

25
Q

Toxic effects of adrenaline

A

Adrenaline in LA can have systemic effects (see earlier lecture)
Inappropriately high, toxic levels would lead to anxiety, trembling, headache, palpitations, sweating, dizziness (very similar to vaso-vagal syncope)

26
Q

Prevention of toxic effects

A

Aspiration
Slow injection
Dose limitation – should have no problems with correct doses

27
Q

Treatment of toxicity

A 
Stop dental treatment
Call for medical assistance
Protect the patient from injury
Monitor vital signs
Provide basic life support
28
Q

Max recommended dose - lignocaine

A

Lignocaine 4.4mg/kg – healthy patient
2% lignocaine will contain 20mg/ml
65kg man may have a total of 65x4.4mg =286mg ~ 14.3ml of 2%
~ 6.5 X 2.2ml cartridges
One tenth of a cartridge per kg in weight

29
Q

Cardiac disease/hypertension

A

Adrenaline increases force and rate of contraction of heart, increases cardiac excitability and ↑ systolic but ↓ diastolic blood pressure
Minimal effects with normal LA doses
Effects equivalent to normal endogenous level of adrenaline with light work
Anxiety produces significant cardiac problems, so therefore use most effective LA – Lignocaine/adrenaline is ‘gold standard’
Sensible to limit to a maximum of two cartridges
In case of unstable angina, recent myocardial infarct or refractory arrythmias, adrenaline is best avoided – use prilocaine or lignocaine plain
Felypressin (with Prilocaine) may cause coronary vasoconstriction, so also restricted to three cartridges

30
Q

Patients taking other drugs

A

Monoamine-oxidase inhibitors (MAOIs): do not affect metabolism of exogenous catecholamines, therefore no effect
Tricyclic antidepressants: inhibit uptake of catecholamines, leading to ↑ intracerebral levels and improved mood
- No clinical evidence of adverse reactions with amount of adrenaline in LA
- May be wise to limit to two cartridges
Phenothiazines: (anti-psychotic)
Non-potassium sparing diuretics

31
Q

Phenothiazines

A

(anti-psychotic) - Adrenaline could potentiate hypotension - No problem with normal dose range

32
Q

Non-potassium sparing diuretics

A

adrenaline exacerbates decrease in circulating potassium, so wise to limit to two cartridges

33
Q

Calcium channel blockers (e.g. verapamil)

A

increase the adrenaline induced hypokalaemia; increases toxicity – limit to two cartridges

34
Q

Anti-Parkinson drugs

A

the drugs entacapone and tolcapone affect the metabolism of adrenaline – limit to one cartridge

35
Q

General anaesthesia (Halothane)

A

increases sensitivity to adrenaline – therefore reduce maximum dose by 50%

36
Q

Recreational drugs within the past 24 hours

A

reduce the amount, or avoid, local anaesthetic agents

37
Q

Beta-blockers

A

increase the toxicity by reducing hepatic blood flow and inhibiting liver enzymes; may also lead to unopposed increase in systemic BP by adrenaline. Limit to two cartridges

38
Q

Tricyclic antidepressants

A

reduces reuptake of adrenaline at nerve endings, increase effect of adrenaline (little evidence) – limit to two cartridges

39
Q

Pregnancy

A

Minimise all drugs during pregnancy
Bupivacaine should be avoided as it causes more maternal cardiac problems and foetal hypoxia in animal models
Felypressin theoretically could lead to uterine contraction and a decrease in placental blood flow
Prilocaine crosses placental barrier more readily than lignocaine
Lignocaine/adrenaline is the LA of choice

40
Q

Liver disease

A

Reduce dose of amide LAs

41
Q

Irradiation

A

Caution using vasoconstrictors in an area that has previously been irradiated

42
Q

Bleeding diatheses

A

Avoid IAN blocks

43
Q

Pseudocholinesterase deficiency

A

Avoid ester local anaesthetic agents

44
Q

Phaeochromocytoma

A

Catecholamine producing tumour – avoid adrenaline

45
Q

Susceptibility to endocarditis

A

Avoid intraligamentary injections

46
Q

Methaemoglobinaemia

A

Prilocaine – conversion of haemoglobin to methaemaglobin – may cause cyanosis

Exodontia (21 decks)

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