local anaesthetic

Question 1

what axons are most susceptible to local anaesthetic and what do they do

Answer 1

a - delta - mechano , thermo (cold), nociception, chemoreception
c fibres - mechano, thermo (hot), nociception
a - beta - mechano
a - alpha - proprioception

Question 2

in what form is local anaesthetic active

Answer 2

partly dissosciated (B.HCl) 
can only pass through membrane in unionised form (B + H + Cl)

Question 3

why do local anaesthetic preparations contain vasoconstrictors

Answer 3

most LAs are vasodilators and this increased blood flow will wash away the LA therefore decreasing the duration of action
vasoconstrictors include adrenaline and felypressin

Question 4

what do vasoconstrictors work on and what do they do

Answer 4

adrenoreceptors
alpha receptors - vasoconstriction
beta 1 receptors - increase HR
beta 2 receptors - vasodilation

Question 5

common composition of lignocaine

Answer 5

2% lignocaine HCl with 1:80000 adrenaline

Question 6

what does 3% prilocaine mean

Answer 6

3g per 100ml

Question 7

benefits of using vasoconstrictor

Answer 7

longer duration
less LA in bloodstream to kept to a localised area
aids haemostatic control

Question 8

symptoms of allergic reaction

Answer 8

red itchy rash , red itchy eyes, runny nose, sneezing, wheezy, coughing

Question 9

symptoms of anaphylaxis

Answer 9

breathing difficulties, tachycardia, faint , confusion, collapse

Question 10

where is LA deposited during an infiltration technique

Answer 10

terminal end branches

Question 11

where is LA deposited during a block technique

Answer 11

beside nerve trunk

Question 12

bevel

Answer 12

tip of needle

Question 13

hub

Answer 13

base of needle, most prone to fracture

Question 14

is the LA cartridge inserted into the open end of the needle with the gold end or the clear end towards the needle

Answer 14

gold end

clear end has the wee gap for the twist safety mechanism

Question 15

method of assembling an ultra safety plus twist

Answer 15

1 - insert LA cartridge into open end of needle with gold end towards needle
2 - attach handle and do the safety twist
3 - pull needle safety cover and ensure is covers safety lock
4 - remove needle sheath

Question 16

gauge number

Answer 16

tells us size of needle lumen

smaller gauge number = larger lumen e.g 30 gauge needle has smaller lumen than 25 gauge

Question 17

how much solution is in an LA cartridge

Answer 17

2.2ml

Question 18

what should you do before applying topical

Answer 18

dry area you will be applying it to

Question 19

buccal infiltration injection site

Answer 19

gingival sulcus above tooth apex and slightly distal

Question 20

palatal infiltration injection site

Answer 20

5-10mm palatal to crown (middle of crown and top of mouth)
insert needle at 45 degree angle to bone
advance until hit bone then withdraw slightly

Question 21

how long is a short needle and what are they used for

Answer 21

20-25mm

buccal / palatal infiltration , blocks at front of mouth

Question 22

how long is a long needle and what are they used for

Answer 22

30-35mm

IANB, long buccal infiltrations

Question 23

mental nerve block location

Answer 23

between apices of lower pre molars

Question 24

important landmarks for a IANB

Answer 24

coronoid notch- where thumb of non working hand sits
posterior border of mandible - where fingers or non working hand sit
pterygomandibular raphe - stringy bits
occlusal plane of molars - 6-10mm above
lower pre molars on opposite side - where LA barrel should be

Question 25

implications of an IANB given too low

Answer 25

increased lingual nerve injury

increased onset time

Question 26

IANB injection point

Answer 26

about 6-10mm above occlusal plane
in between coronoid notch and raphe (about 2/3 raphe direction)
LA barrel over contra lateral pre molars
advance until bony contact then withdraw 1mm and inject

Question 27

what should be done if you don’t hit bone when giving a IANB

Answer 27

move barrel more distally in relation to pre molars

Question 28

what should be done if you hit bone too fast when giving a IANB

Answer 28

move barrel more mesially in relation to pre molars

Question 29

how much LA should be deposited in a IANB

Answer 29

3/4 in IAN region then remaining quarter to achieve lingual nerve block as you retract needle

Question 30

lidocaine max dose

Answer 30

4.4mg/kg

Question 31

prilocaine max dose

Answer 31

6mg/kg

Question 32

articaine max dose

Answer 32

7mg/kg

Question 33

what patients should LA containing adrenaline not be used/ be used cautiously on

Answer 33

hyperthyroidism
hypertension
cardio vascular disease
some drug interactions e.g beta blockers

Question 34

why might prolonged anaesthesia occur

Answer 34

direct trauma from needle

chemical trauma from needle

Question 35

why may trismus appear in a patient who has recieved a IANB

Answer 35

due to an injection given to low / too forceful/rapid

will present within a few hours and may last weeks/ months

Question 36

why may facial palsy appear in a patient who has recieved a IANB

Answer 36

injection been given too far posteriorly and LA has entered the parotid gland and anaesthitised the facial nerve
will present within a few minutes and last until the LA wears off

Question 37

topical jet injectors pros and cons

Answer 37

pros - no needle

cons - soft tissue damage , loud noise, unpleasant taste

Question 38

what depth of tissue can topical anaesthesia reach

Answer 38

2-3mm

Question 39

is the mandibular foreamen located in the same place in children as adults

Answer 39

no it is slightly lower

Question 40

why should you be mindful of a ptx with liver disease when choosing what LA to use

Answer 40

amide LAs are metabolised in the liver so liver disease will impair this ability.