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Flashcards in Anaesthesia and anaesthetics Deck (39)
1

How is regional and general anaesthetic administered

regional - intrathecal
general - inhilation / iv

2

what does local/regional anaesthetic target?
what does general anaesthetic target?

L/R = afferent sensory reflex
G = central neural processing

3

when would you use local anaesthetic

1. hand/foot/gum - suturing / dental procedures

4

describe the mechanism for local anaesthetic

Weak bases - cross the membrane uncharged then ionise and block the channel
Lipid soluble/ uncharged - dissolves in the membrane and blocks the channel from within

5

Lidocaine, Benzocaine, Tetracaine.. what type are they

lido = weak acid
benzo uncharged
tetra lipid sol

6

Name the two types of regional anaesthetic and when you would use them

spinal - c section/ bladder surgery (subarachnoid)
epidural - child birth (epidural)

7

What would you give if a patient is nervous for general anaesthetic and why would they be

patient stays awake - benzodiazepine

8

what is bupivicaine and how would you administer it? how long would it last?

into epidural space at L4 - lasts 2-3 hours

9

IV general anaesthetic describe the mode of action
1. Propofol, etomidate, thiopental (barb)
2. Ketamine

describe the 2 main types

1. at gaba receptor
2. blocks NMDA glutamate receptor

barbiturates ad non barbiturates

10

inhilation GA - mechanism of action?
1. halothane isoflurane
2. nitrous oxide

1. volatile liquide - act on gaba receptor
2. inorganic gases - unclear

11

Difference between
1. anaesthetic
2. hypnotic
3. tranquilliser

1. loss of consciousness, amnesia, inhib sensory reflexes, skm relax
2. induces sleep
3. eases anxiety WITHout causing sleep

12

when would you want to put a patient in a medically induced coma

used to protect the brain following major neurosurgey
decreases E requirements of the brain and allows for healing and swelling to go down

13

what is used to control a medically induced coma

barbiturates / propofol

14

List the 5 main stages of anaesthesia

induction
1. analgesia
2. excitation
3. surgical anaethesia
4. medullary depression

15

anaesthesia - induction ?

autonomic reflexes progressively depressed
control the airway, 02 levels, vent, and circilation

16

anaesthesia - stage 1 ?

consciousness NOT lost - thoughts blurred
reflexes present
smell and pain lost by the end

17

which stage of anaesthesia is child birth limited to ?

stage 1

18

anaesthesia - stage 2?

become unconscious
comiting, temp control lost, EEG desynchronised, resp irreg, increased muscle tone, incoherent speech
DANGEROUS

19

anaesthesia - stage 3?

slow synchronised EEG , reg slow breathing, reflexes lost, pupils dilates,

20

anaesthesia - stage 4?

resp arrest, CV collapse, EEG small/ lost
death

21

what is boyles apparatus used for?

inhilation anaesthesia
mixes 02 anaesthetic and ambient air

22

pros of inhilation anaesthesia

Levels are easily controlled
Rapid elimination from body
Doesn't cause post op resp depression
Few drug interactions

23

why isnt halothane used?

toxic to liver

24

what is MAC? what decreases MAC?

the minimum alveolar concentration - potency of inhailed anaesthetic
mix air with N20 and decreases MAC therefor need to use less anaesthetic

25

Name 3 factors that alter MAC

n20
age
pregnancy (alcohol abuse, some drugs)

26

describe the uptake of inhalation anaesthetics

lipid soluble molecules rapidly absorbed across pul memb, pass into blood into tissue, BBB freely permeable to GAs

27

describe the elimination of inhalation anaesthetics

diffuses out of the brain into muscles and fat
inert therefor undergos little metabolism
eliminated via lungs
rate mirrors uptake

28

problem with some inhalation anaesthetics during elimination

some are metabolised by liver and some metabolites are toxic

29

how do inhaled anaesthetics cause anaesthesia

uncharged molecules conc in lipid membrants causing effects on the structure - membrane expansion! effects membrane spanning proteins e.g. ion channels

30

how are inhilation anaesthesia reversed?

decompression chamber 200 ATM

31

How long do iv anaesthetics last for?

20 minutes - short acting

32

when is the ideal time to use IV anaesthetics in anaesthetics

induction - then maintain with GA

33

negatives and 1 +ve to barbiturates

enter brain quickly,
no analgesia, small therapeutic window ,short lasting, slow metabolism, irritant , resp depression

34

example of barbiturates

thiopentone

35

1. examples of 2 non barbiturates used for GA
2. which causes neausea

ketamine and propofol
ketamine causes nausea on recovery

36

2 main sites of action of general anaesthetics and why they target these areas

RAS - reticular activating system ( medullary area involved in sleep and wake)
hippocampus (inhibit Ach release - amnesic effects)

37

what is the lipid theory in general anaesthesia

GAs potency directly correlates with lipid solubility (proposed)

38

How to GAs work..

increased fluidity of membrane..
decrease NT release pre synaptically
decrease excitability post synaptically

39

Name some side effects of GAs

vomiting
resp depression
drug interactions
CV effects
renal failure
hepatotoxicity
malignant hyperpyrexia (release ca from skn, rigidity acidosis )