3. LA Complications

Question 1

Features of lignocaine/lidocaine (4)

Answer 1

Amide
Standard - lidocaine HCl 2%
Vasoconstrictor - none/adrenaline (1:80,000)

Question 2

Features of prilocaine/citanest (3)

Answer 2

Amide
Standard - prilocaine HCl 3%
Vasoconstrictor - plain/felypressin (octapressin - 1.2ug)

Question 3

Features of articaine (4)

Answer 3

Amide
Standard - 4% with varying vasoconstrictor (1:100,000, 1:200,000, 1:400,000)
Uses - infiltration and blocks
Useful if patient has liver disease

Question 4

Length of action of mepivicaine (3)

Answer 4

Infiltration - 20mins
Block - 40mins
Soft tissue - 2hrs

Question 5

Length of action of lignocaine (3)

Answer 5

Infiltration - 60mins
Block - 90mins
Soft tissue - 3-5hrs

Question 6

Length of action of articaine (3)

Answer 6

Infiltration - up to 120mins
Block - 75mins
Soft tissue - 3-5hrs

Question 7

Length of action of prilocaine (3)

Answer 7

Infiltration - 30-45mins
Block - 60mins
Soft tissue - 3-6hrs

Question 8

Systemic complications of LA (6)

Answer 8

Psychogenic/stress
Interactions with other drugs
Cross infection
Allergy
Collapse
Toxicity

Question 9

Psychogenic/stress includes (7)

Answer 9

Fainting
Palpitations
Cold sweat
Restlessness
Excitation
Trembling
Weakness

Question 10

Cause of psychogenic/stress

Answer 10

Lack of oxygenated blood to the brain

Question 11

Clinical features of psychogenic/stress (6)

Answer 11

Light-headedness
Pallor
Beads of sweat (lips/nose/temple)
Bradycardia (slow pulse)
Nausea
Pupil dilation

Question 12

Management of psychogenic/stress (4)

Answer 12

Lay flat and raise legs
Loosen neck clothing
Improve room ventilation
Sweet drink potentially

Question 13

LA interactions with other drugs (5)

Answer 13

MAOI (mono amine oxidase inhibitors)
Tri-cyclics (theoretical risk of HTN)
B-blockers (BP increase_
Non-K sparing diuretics (adrenaline lowers K too)
Cocaine (increased adrenergic activity)

Question 14

Features of LA allergy (2)

Answer 14

True allergy is rare

Most allergies are due to preservatives (methylparaben)

Question 15

Toxicity features (4)

Answer 15

Convulsions
Loss of consciousness
Respiratory depression
Circulatory distress

Question 16

LA and pregnancy (2)

Answer 16

Avoid octapressin (prilocaine)
Has potential to induce labour

Question 17

Max. safe dose of mepivicaine, 3% (3)

Answer 17

Max dose - 3mg/kg
66mg/cartridge
6cartridges/70kg adult

Question 18

Max. safe dose of lignocaine, 2% (3)

Answer 18

Max dose - 5mg/kg
44mg/cartridge
7cartridges/70kg adult

Question 19

Max. safe dose of articaine, 4% (3)

Answer 19

Max dose - 7mg/kg
88mg/cartridge
5cartridges/70kg adult

Question 20

Max. safe dose of prilocaine, 3% (3)

Answer 20

Max dose - 8mg/kg
66mg/cartridge
8cartridges/70kg adult

Question 21

Adrenaline effects on B1-receptors (5)

Answer 21

Increase HR
Increase force of heart contractions
Increase CO
Increase heart muscle excitability
Dilation of coronary BVs

Question 22

Adrenaline effects on B2-receptors (2)

Answer 22

Relaxation of bronchial smooth muscle

Muscle dilation

Question 23

Adrenaline effect on a-receptors

Answer 23

Skin contraction

Question 24

Adrenaline effects on BP (3)

Answer 24

Increases systolic BP
Decreases diastolic BP
Overall little effect on BP

Question 25

Adrenaline contraindications (4)

Answer 25

CVD Hyperthyroidism (thyroid crisis) Phaeochromocytoma (HTN) Drug interactions

Question 26

Adrenaline action (3)

Answer 26

Works by redirecting blood flow (to heart, liver, skeletal muscle from non-essential organs during fight/flight) Binds to B2 receptors causing vasodilation Binds to a1 receptors causing vasoconstriction

Question 27

Local complications of LA (12)

Answer 27

``` Failure to achieve anaesthesia Prolonged anaesthesia Pain during/after injection Trismus (lockjaw) Haematoma Intra-vascular injection Blanching Facial paresis (weakness) Broken needle Infection Soft tissue damage Contamination ```

Question 28

Types of prolonged anaesthesia (3)

Answer 28

Direct trauma from needle Multiple passes with same needle Chemical trauma from direct injection

Question 29

Facial palsy presentation

Answer 29

Usually complete, unilateral nerve paralysis within minutes of IDB

Question 30

Facial palsy confirmation

Answer 30

Temporal branch affected (lower MND)

Question 31

Facial palsy cause

Answer 31

LA into parotid gland (injection too far posteriorly)

Question 32

Facial palsy diagnosis

Answer 32

Test branches of CNVII

Question 33

Facial palsy management

Answer 33

Reassurance, cover eye with paid until blink reflex returns

Question 34

Types of intra-vascular injection (2)

Answer 34

Intra-arterial | Intravenous

Question 35

Features of IA injection (5)

Answer 35

``` Rare Skin blanching Visual disturbances Aural disturbances Transitionary, but persistence requires rapid specialist referral ```

Question 36

Features of IV injection (3)

Answer 36

``` Block injections (IDB) Avoided by careful technique (aspiration) Palpitation, anxiousness, restlessness, headache, sweating, pallor ```