Complications of LA Flashcards
What are some examples of systemic complication of LA?
- psychogenic/stress
- interaction with other drugs
- cross infection
- allergy
- collapse
- toxicity
What is the most common type of LA complication?
psychogenic/stress complications
What is meant by psychogenic/stress complication? (examples)
- fainting
- palpitations
- cold swear
- restlessness
- excitation
- trembling
- weakness
What causes psychogenic/stress complications?
lack of oxygenated blood to the brain
What are some clinical features of psychogenic complications?
- lightheadedness
- pallor
- beads of sweat (lips, nose, temple)
- bradycardia
- nausea
- pupil dilation
How is a patient who experiences a psychogenic complication to LA managed?
- lay flat and raise legs
- loosen neck of clothing
- improve room ventilation
- sweet drink (might be caused due to lack of food)
What are some examples of drugs that can interact with LA?
- MAOI
- Tri-cyclics
- beta blockers
- non-potassium sparing diuretics
- cocaine
How common is a true allergy to LA?
very rare
What were LA allergies historically due to?
the latex bung (no-longer made from latex)
What are most LA allergies due to now?
the preservatives/antioxidant
What are the clinical signs of toxicity complications of LA?
- convulsions
- loss of consciousness
- respiratory depression
-circulatory collaps
always make sure you work out the max dose correctly
What LA’s should you avoid in pregnant women? why?
LA’s that contain oxtapressin (vasoconstrictor) as theoretically it could induce labour
What is the maximum safe does of LA based/calculated on?
a fit healthy adult
Each max dose calculation should be done on what basis for the p?
An individual basis
Toxic effects of LA can be reduced by using what technique?
Aspirating technique
What is the max safe dose of lignocaine ?
5mg/kg (check - might be 4.4)
What is the safe dose of 2% lignocaine in a 70kg man (cartridges)? [assuming max dose = 5mg/kg]
2% = 2g/100ml (2000mg/100ml) = 20mg/1ml
Each cartridge is 2.2ml so will have 44mg actuve component per cartridge
70kg x 5mg = 350mg
350mg/44 = approx 7 cartridges
What is the max dose of Mepivicaine 3% (plain - no vasoconstrictor) ?
3mg/kg
What is the max safe dose of Articaine with adrenaline ?
7mg/kg
What is the max dose of prilocaine with octapressin?
8mg/kg
What are the effects of adrenaline on the heart? What receptors on the heart does adrenaline bind to in order to produce these effects?
Increase in: -heart rate -force -output -excitability
Through Beta 1 receptors
What are the effects of adrenaline on blood vessels? (and therefore skin and muscle) What are the receptors?
- coronary dilation
- skin contraction
- muscle dilation
alpha beta-2
What are the effects of adrenaline on systolic, diastolic and overall blood pressure?
Systolic = increase Diastolic = decrease Overall = little effect
What are the effects of adrenaline on the lungs? What receptors are responsible?
Bronchial muscle relaxation
Beta 2 receptors
What are some dangers of adrenaline?
- Possible danger with cardio-vascular disease
- hyperthryoidism
- pheochromocytoma (hypertension)
- drug interactions
What are some possible local complications of local anaesthesia?
- failure to achieve anaesthesia
- pronlonges anaesthesia
- pain during or after injections
- trismus
- haematoma
- intra-vascular injection
- blanching
- facial paresis
- broken needle
- infection
- soft tissue damage
- contamination
Why might there be prolonged anaesthesia?
- direct trama from needle
- multiple passes with same needle (can become blunt after using the needle more than once)
- chemical trauma from direct injection
- different depending on LA used
With what LA should caution be used when performing an ID block?
Articaine (some suggestions that it may cause more nerve damage)
What is the first-line drug of choice for LA blocks?
Lidocaine 2% with adrenaline
Describe the presentation of trismus? What block is it normally associated with?
Within a few hours of inferior dental block there may be severe restriction of opening which may last for weeks or months
What is the cause of trismus?
Probably damage to the medial pterygoid due to injection being too ‘low’ or too forceful/rapid
How is trismus managed?
-reassurance -muscle relaxant ? -anti-inflammatory
Describe the presentation of LA induced facial palsy.
-usually complete one sided face palsy -Unilateral nerve paralysis within minuted of INF dental blocks
Confirm??
-temporal branch affected i.e. lower motor neurone distribution
What causes LA induced facial palsy?
LA injected into parotid gland - injected toot far posteriorly
How is LA induced facial palsy diagnosed?
test branches of VII nerve (facial nerve)
How is LA induced facial palsy managed?
-reassurance and cover eye with pad until blink reflex returns
What are some clinical symptoms/signs of intra-arterial injection? How common is it?
-skin blanching -visual disturbance -aural disturbances
It is very rare
How are intra-arterial injections managed?
All are transitory but persistence requires rapid specialist referral
What type of LA injection most commonly results in intra-venous injections?
Block injections - most often inferior dental block
How can intra-vascular injections be avoided?
by careful technique: -aspirating system -slow drug introduction -safe quantitiy
What are the features of an intra-vascular injection?
Adrenaline effects most frequently noted: -most likely palpitation
Can also include anxiousness, restlessness, headache, swearing, pallor
