Local anaesthetic Flashcards
Which type of analgesic is this the definition of;
- a drug or agent which reversibly blocks neuronal transmission in the applied region causing a temporary loss of sensation/pain, without affecting consciousness
local anaesthetic
Which type of analgesic is this the definition of;
- a drug or agent which produces loss of response to painful stimulation (analgesia) and loss of reflexes (motor and autonomic), with reversible loss of consciousness
general anaesthetic
What is this the definition of?
- a drug or agent which relieves and prevents pain without loss of consciousness
analgesic
What is this the definition of?
- a drug or agent which reduces irritability, excitement, or nervousness
sedative
What are the 2 types of local anaesthesia?
local and regional
Which type of local anaesthesia is being described?
- injection of local anaesthetic near nerves branches innervating a small, specific area of the body near surgical site
local
Which type of local anaesthesia is being described?
- injection of local anaesthetic near major nerve bundles innervating larger, specific area of the body
regional
What duration of cocaine use can cause the following?
CNS: headache, nausea, vomiting, muscle tremors, pseudohallucinations
Cardio: vasoconstriction, hypertension, tachycardia
Resp: increase in breathing rate & depth
Temp: elevation
Behaviour & other: euphoria, elation, excitation, restlessness, alert, energetic, strong paranoia
short term use
What duration of cocaine use can cause the following?
CNS: generalised seizures, hallucinations, gross muscle tremors&twitching, decreased responsiveness to stimuli, incontinence
Cardio: hypertension, tachycardia, cardiac dysrhythmias, peripheral cyanosis
Resp: abnormally rapid breathing, shortness of breath, irregular breathing pattern
Temp: severe hyperthermia
Behaviour & other: paranoia, depression, agitation, violent or suicidal tendencies, difficulties in emotion and impulse control
long term use
What duration of cocaine use can cause the following?
CNS: generalise convulsions, cerebral infarction & haemorrhage (stroke), pupils fixed and dilated, loss of vital support functions, coma
Cardio: aortic dissection, heart failure, cardiac arrest
Resp: resp depression, resp failure, gross pulmonary oedema, paralysis of respiration
Temp: severe hyperthermia
Behaviour & other: death
overdose
What are the names of the 2 groups of synthetic local anaesthetics?
ester and amide
What is a simple way of differentiating which synthetic local anaesthetics fall into esters or amides?
all amides have an ‘i’ before the ‘caine’ (lidocaine, bupivacaine) and all esters don’t (cocaine, procaine)
What metabolises ester local anaesthetics?
plasma esterases
What metabolises amide local anaesthetics?
hepatic enzymes
Protonated forms of weak acids are … so therefore …
- lipophilic
- can cross the lipid bilayer
Protonated forms of weak bases are … so therefore …
- not lipophilic
- cannot cross lipid bilayer as easily
What percentage of lidocaine exists at an unionised form?
25%
What percentage of bupivacaine exists at an unionised form?
15%
The clinical performance of all local anaesthetics correlated with 4 principle properties: A?
property: lipid solubility
correlate: potency
The clinical performance of all local anaesthetics correlated with 4 principle properties: B?
property: dissociation constant (pKa)
correlate: time of onset
The clinical performance of all local anaesthetics correlated with 4 principle properties: C?
property: chemical linkage
correlate: metabolism
The clinical performance of all local anaesthetics correlated with 4 principle properties: D?
property: protein binding
correlate: duration
Which nerve fibres are myelinated and have fast conduction and conduct sharp pain?
A delta fibres
Which nerve fibres are unmyelinated and have slow conduction and conduct dull pain?
C fibres
A delta and C fibres (nociception, temp, touch) blocked … A beta fibres (touch, pressure, proprioception)
before
Myelinated nerve fibres blocked … unmyelinated nerve fibres
before
Nerve fibres associated with pain are blocked … other sensory modalities
before
What are the 4 factors that impact the absorption of local anaesthetics?
- site of injection - impacts blood levels - areas of high vascularity results in greater uptake and higher blood concentrations
- dose
- addition of vasoconstrictor - most anaesthetics have a direct vasodilator action, increases the rate of absorption into systemic circulation
- pharmacologic profile of the anaesthetic - individual local anaesthetics exhibit different rates of absorption
Patients with which deficiency are at a higher risk of LA toxicity from ester local anaesthetics due to them metabolising the LA more slowly?
pseudocholinesterase deficiency
Patients with dysfunction of what organ may represent a contraindication to amide local anaesthetics due to metabolising LA more slowly and therefore at a higher risk of LA toxicity?
liver dysfunction
Some ester LA (procaine, benzocaine) are hydrolysed to para-aminobenzoic acid (PABA) and are associated with… ???
- allergic reaction
- medical emergencies
- interfere with antibacterial affect of sulphonamides
Large doses of Prilocaine (amide) can lead to which?
methaemoglobinaemia
- metabolite produces methaemoglobinaemia
- patients shortness of breath, cyanosis, can be fatal, but is rare
Allergy to PABA - Esters symptoms?
hypersensitivity - swelling of tongue, throat and face
- onset normally within 5 mins may be delayed up to 40 mins
4 methaemoglobinemia symptoms associated with methaemoglobin levels?
- slight discolouration of the skin
- cyanosis
- headache, lightheadedness
- abnormal cardiac rhythms
What solution is LA prepared as in order to be stable in solution?
hydrochloride salt
What 3 forms do topical anaesthetics come in?
- lignocaine 5%, 10% spray
- benzocaine 20% gel
- EMLA (eutectic mixture of local anaesthetics) 2.5% lidocaine & 2.5% prilocaine
What is the name of the preservatives that can be found in local anaesthetics?
- 0.1% sodium meta-bisulphite
- 1mg/ml methyl para-hydroxybenzoate
Which ingredient in LA acts as a vasoconstrictor?
adrenaline
therefore:
- minimises the vasodilator effect of LA
- decreases the rate at which drug is removed from the site of action by absorption into the systemic circulation
- reduces traumatic blood loss from the site by the same mechanism
Which ingredient is added to LA which increases the pH of the environment when administered?
bicarbonate
therefore:
- more drug is present in its unionised form and speed of onset of anaesthesia is increased
- too much bicarbonate may result in precipitation of the local anaesthetic
- unionised form less soluble in water than the hydrochloride salt
A?
lidocaine (lignocaine)
B?
mepivacaine
C?
bupivacaine
D?
prilocaine
E?
articaine
Which LA has less tendency to cause CNS effects?
lidocaine
Which LA has more tendency for cardiotoxicity?
bupivacaine
What are 5 potential LA complications?
- ischaemic necrosis of tissues and nerve damage may follow injections of local anaesthetics; irritating nature of solution, pressure from large volumes, constriction of vasculature by adrenaline
- vascular damage; haematoma, LA can get into circulation easier leading to systemic toxicity
- drug error; check drug type, concentration, dose, expiry date, check adrenaline content, interactions with other drugs - polypharmacy
- needle breakage and dental cartridge failure - minimised by modern equipment
- no anaesthetic block ‘block failure’;drug, poor delivery, altered anatomy
Branches of trigeminal… A?
ophthalmic nerve
Branches of trigeminal… B?
maxillary nerve
Branches of trigeminal… C?
mandibular nerve
Where does the V2 branch of trigeminal (maxillary nerve) supply?
- lower eyelid
- part of nose and nasal cavity
- upper lip
- upper dentition and gingiva
- palate
Where does the V3 branch of trigeminal (mandibular nerve) supply?
- mandible
- ear
- TMJ
- anterior 2/3 of tongue
- lower dentition
- muscles of mastication
Which branch of trigeminal is being described?
- moves into the pterygopalatine fossa via foramen rotundum
- purely sensory
- 2 types of branches - direct or indirect via a ganglion
- sensation to the mid face, lower eyelid, upper lip, posterior nasal cavity and nasopharynx, palate and the upper dentition/gingiva
V2 - maxillary nerve
What are the 3 direct branches of V2 maxillary nerve?
- meningeal
- zygomatic
- infraorbital
What nerve does the anterior, middle and posterior superior alveolar nerves branch off of?
infraorbital nerve (branch of V2 maxillary nerve)
What are the 3 important indirect branches of V2 maxillary nerve?
- greater palatine
- lesser palatine
- nasopalatine
Where does the greater palatine nerve (branch of V2 maxillary nerve) supply?
hard palate
Where does the lesser palatine nerve (branch of V2 maxillary nerve) supply?
soft palate
Which branch of trigeminal is being described?
- moves into infratemporal fossa via foramen ovale
- mixed sensory and motor
- sensation to the chin, scalp, mandible, lower teeth and gingiva, tongue and oral cavity
- 2 divisions - anterior and posterior
V3 mandibular nerve
Which nerve of the anterior division of V3 mandibular nerve is being described?
- sensory; skin over buccinator, inner surface of cheek and buccal gingiva
long buccal nerve
Which 3 main nerves make up the posterior division of V3 mandibular nerve?
- lingual nerve
- inferior alveolar nerve
- auriculotemporal nerve
Which nerve of the posterior division of V3 mandibular nerve is being described?
- sensory; lingual gingiva and anterior 2/3 of the tongue
lingual nerve
Which nerve of the posterior division of V3 mandibular nerve is being described?
- runs through the mandible via mandibular foramen and canal
- sensory to all lower teeth and gingiva
inferior alveolar nerve
Which nerve of the posterior division of V3 mandibular nerve is being described?
- sensory; angle of the mandible, TMJ and scalp
auriculotemporal nerve
Where is the pterygopalatine fossa in relation to the infra temporal fossa?
on the back wall of the infratemporal fossa
Which branch of V3 mandibular nerve is being described?
- runs along the medial aspect of the mandible, along the floor of the mouth
- then up into the oral cavity to supply the tongue
lingual nerve
Which branch of V3 mandibular nerve is being described?
- runs down the medial aspect of the mandible, enters inside the mandible via the mandibular foramen and into the mandibular canal suppling the lower dentition though little alveolar branches
inferior alveolar nerve
Which branch of the inferior alveolar nerve is being described?
- emerges from the mental foramen and out to supply the lower lip and chin
mental nerve
Which two nerves emerge from the end of the inferior alveolar nerve?
mental nerve and incisive nerve
Part of the inferior alveolar nerve continues to the lower incisors and this is called the…
incisive nerve
Which teeth does the middle superior alveolar nerve (or the superior dental plexus) supply?
- upper premolars
- MB root of upper 6
Some patients do not have a middle superior alveolar nerve, therefore which nerve supplies the upper premolar and the MB pulp of the upper 6s?
combination of the anterior and posterior superior alveolar nerves
Which teeth does the anterior superior alveolar nerve supply?
roots of upper canines and centrals
Where does the nasopalatine nerve innervate?
the anterior part of the hard palate and the mucosa of the nasal septum
Which nerve supplies the roots upper molars (expect MB root of 6s)?
posterior superior alveolar nerve
Which nerve supplies the palatal mucoperiosteum of upper anteriors (123)?
nasopalatine nerve
Which nerve supplies the palatal mucoperiosteum of upper posterior teeth?
greater palatine nerve
Which nerve supplies the roots of the lower anteriors (123)?
incisive nerve
Which nerve supplies the roots of lower premolars and molars (45678)?
inferior alveolar nerve
Which nerve supplies the lower buccal mucoperiosteum for anterior teeth and premolars (12345)?
mental nerve
Which nerve supplies the lower lingual mucoperiosteum for all teeth?
lingual nerve
Which nerve supplies the lower buccal mucoperiosteum for the molars (678)?
long buccal nerve
What are the 5 accessory nerves that can supply sensory to the roots of the lower teeth?
- lingual nerve
- long buccal nerve
- mylohyoid nerve
- auriculotemporal nerve
- cervical nerves
What is the term used to define the following?
- altered sensation
paraesthesia
What is the term used to define the following?
- loss of pain sensation only
analgesia
What is the term used to define the following?
- the loss or abolition of all modalities of sensation which include pain and touch
anaesthesia