11b. Drugs used in radiology II: anaesthetics and analgesics - Anasthetics

Question 1

what is anasthetics

Answer 1

controlled and reversible loss of conciousness, loss of pain perception and/or amnesia

Question 2

what 5 reversible effects do general anaesthesia typically require

Answer 2

immobility
analgesia
amnesia
unconciousness
supression of stress response

Question 3

what is local anasthesia

Answer 3

blockade of pain perception from peripheral nerves

Question 4

what are the 2 ways that GA is administered

Answer 4

IV or inhalation

Question 5

what 4 agents does GA require

Answer 5

induction
maintenance
analgesia
+/- paralysis

Question 6

what is induction of GA

Answer 6

going off to sleep

Question 7

what is maintenance of GA

Answer 7

staying asleep

Question 8

how is GA induced - 2 ways

what is the most common way

Answer 8

IV or inhalation

generally IV as in inhalation you get agitation which is hard to deal with in adults

Question 9

how is GA maintained - 2 ways

Answer 9

IV or inhalation

Question 10

do acute patients get GA via IV or inhalation

Answer 10

IV

Question 11

do paeds patients get GA via IV or inhalation

Answer 11

inhalation

Question 12

how does GA work

Answer 12

no unifying theory of how GA works

Question 13

are current GA agents selective for a single ion channel

Answer 13

no

Question 14

many IV anesthetics do what to the inhibitory effects

what is an exception

Answer 14

enhance inhibitory effects by acting on GABA receptors leading to unconsciousness and amnesia

ketamine is an exception

Question 15

what receptors does ketamine target

Answer 15

NMDA receptors

Question 16

how do inhalation anaesthetics work in terms of where does it act

Answer 16

act on both brain and spinal cord

Question 17

what does inhalation anaesthetics do to inhibitory pathways and how

Answer 17

increase inhibitory pathways through GABA neurotransmitter release and increased GABA receptor activity

Question 18

what does inhalation anaesthetics do to excitatory pathways and how

Answer 18

suppress excitatory pathways through reduced glutamate release and increased GABA receptor activity

Question 19

what is the IV anaesthetic agent for propofol

Answer 19

diakeylphenol

Question 20

what is the most widely used IV anaesthetic

Answer 20

propofol

Question 21

what is propofol used for in terms of anesthesia

Answer 21

induction or maintenance and sedation

Question 22

propofol’s action is mostly via what

Answer 22

GABA

Question 23

how is propofol formulated

Answer 23

formulated in lipid emulsion as it has low water solubility

Question 24

what is propofol’s onset time and return to consciousness time like following bolus dose

Answer 24

fast for both

Question 25

can propofol be used as infusion and why

Answer 25

yes due to rapid clearance via kidney resulting in reasonable recovery times

Question 26

what does propofol appear white

Answer 26

poor solubility

Question 27

what happens to the time it takes to wear off if you give propofol as an infusion

Answer 27

accumulates in body so if you give it as infusion eg for 8hrs, itll take 40 mins to wear off

Question 28

can you give GA as intramuscular, what is the downside of this

Answer 28

yes but will only transiently cause anaesthesia and will need something else to keep it going

Question 29

does propofol offer analgesia

Answer 29

no

Question 30

what are the 5 side effects of propofol

Answer 30

pain on injection and increase in microbial growth respiratory depressant loss of airway reflexes lowered BP HR effects as rate drops with bolus, increased with low BP

Question 31

why do you need to give propofol slowly

Answer 31

due to its BP effects

Question 32

what does propofol do to your breathing and is this intentional

Answer 32

stops breathing and is intentional

Question 33

how can propofol help heart functions

Answer 33

it increases HR with low BP

Question 34

what is thiopentone's IV anaesthetic agent

Answer 34

barbituate

Question 35

what is thiopentone used for

Answer 35

induction no longer used for maintenance

Question 36

why is thiopentone no longer used for maintenance

Answer 36

metabolism is slow and repeated doses have a cumulative effect and recovery is much slower has very long recovery time if given as infusion

Question 37

what kind of mixture is thiopentone and what form is more potent

Answer 37

racemic mixture S form is 2x as potent as R form

Question 38

what does thiopentone cause - 4 things

Answer 38

sedation and hypnosis EEG slowing but this is dose dependent anticonvulsant effects respiratory depression

Question 39

what is thiopentone's lipophilicity

Answer 39

highly lipophilic

Question 40

what is the speed of thiopentone's onset of action

Answer 40

occurs quickly after bolus dosing lose consciousness within 30-50sec

Question 41

what dies thiopentone do to neural output and seizures

Answer 41

decreases both

Question 42

what are the 4 side effects of thiopentone

Answer 42

respiratory depressant loss of airway reflexes lowered blood pressure heart rate effects = drops rate with bolus and increases with low BP

Question 43

does thiopentone have analgesia properties

Answer 43

no

Question 44

what kind of sedation does ketamine provide

Answer 44

dissociative sedation

Question 45

does ketamine provide analgesia

Answer 45

yes

Question 46

what does ketamine do to NMDA receptors

Answer 46

antagonist at NMDA receptors in spinal cord and brain to mediate analgesia

Question 47

most anaesthetics do what to sympathetic tone

Answer 47

decreases it

Question 48

what does ketamine do to CO and vasc resistance

Answer 48

increases CO and vascular resistance

Question 49

what does ketamine do to resp drive and muscle tone

Answer 49

maintains respiratory drive and muscle tone with bronchodilation

Question 50

in what conditions should ketamine be avoided and why

Answer 50

neuroanaesthesia due to cerebral blood flow (theoretical risk of increasing intracerebral pressure that can worsen injury)

Question 51

what are 3 side effects of keetamine

Answer 51

intense dreams/nightmares/hallucinations/delirium dose related increase in HR and BP hypersalivation, nausea and vomiting

Question 52

is there loss of airway reflexes and respiratory depression in ketamine use

Answer 52

no, less respiratory depression than other drugs

Question 53

why is ketamine a commonly used field and emergency dept anaesthetic - 4 reasons

Answer 53

can be given intramuscularly via injection if no IV access increases HR and BP by sympathetic stimulation = good for the bleeding unstable patient doesnt depress respiration and maintains airway reflexes provides analgesia provides analgesia

Question 54

what are the 3 classes of inhalational agents

Answer 54

esthers alkanes gases

Question 55

what is the potency of inhalational agents

Answer 55

potency is related to lipid solubility

Question 56

how are inhalational agents taken in body

Answer 56

lungs alveolus -> blood -> brain

Question 57

what is inhalational agents' onset wash in related to 4 things

Answer 57

conc delivered flow rate of gas delivered ventilation cardiac output

Question 58

how is ventilation related to an inhalational agents's onset

Answer 58

increased vent = increase speed of onset

Question 59

how is cardiac output related to an inhalational agents's onset

Answer 59

Low CO = slow delivery blood to lungs = blood has more time to pick up agent = fast onset

Question 60

metabolism of inhalation agents is via what

Answer 60

P450s and metabolised by liver

Question 61

inhalation is commonly used for maintenance for which people

Answer 61

children

Question 62

inhalation agents have an effect on where

Answer 62

brain and spinal cord

Question 63

what is sedation

Answer 63

drug induced state of reduced level of consciousness that allows tolerance of an uncomfortable or painful procedure

Question 64

what is sedation a continuum of

Answer 64

minimal to general anasthesia

Question 65

what are 4 examples of sedative agents

Answer 65

benzodiazepines ketamine Propofol opioids

Question 66

what do benzodiazepines bind to

Answer 66

receptor sites in GABA system

Question 67

what is the most commonly used benzodiazepines

Answer 67

midazolam

Question 68

what are 3 uses of benzodiazepines - midazolam

Answer 68

anxiolysis sedation amnesia

Question 69

what are the 5 side effects of benzodiazepines midazolam

Answer 69

``` no analgesia respiratory depressant loss of airway reflexes lowered BP HR effects ```