Anaesthesia

Question 1

The 2 types of neuromuscular drugs

Answer 1

Depolarising

Non-depolarising

Question 2

Key chemical property of all anaesthetic agents

Answer 2

highly lipid soluble as they need to cross the BBB

Question 3

General side effects of anaesthetics

Answer 3

• Decreased cardiac contractility
• Respiratory depression
• Sympathetic inhibition

Question 4

Give 3 examples of anaesthetics administered intravenously

Answer 4

Thiopental

Propofol

Ketamine

Question 5

Site of metabolism of IV anaesthetics

Answer 5

Liver

Question 6

Site of metabolism of volatile anaesthetics

Answer 6

volatile agents are NOT metabolised

Question 7

3 examples of volatile anaesthetics

Answer 7

Nitrous oxide

Isoflurane

Sevoflurane

Question 8

Why are local anaesthetics less effective in acidic tissues?

Answer 8

Because they’re weak bases

Question 9

MoA of local anaesthetic drugs

Answer 9

Block voltage sensitive Na+ channels

Question 10

The effect of local anaesthetic agents depends on:

Answer 10

• diffusion gradient
• fibre size
• myelination

Question 11

Why can local anaesthetics potentially be toxic?

Answer 11

they may block Na+ channels in all excitable tissues incl:

• heart - cardiac arrest
• brain - seizures, resp. arrest + loss of consciousness

Question 12

When and why are NMJ blocking drugs given in anaesthesia?

Answer 12

to paralyse patients once sedated

Question 13

Depolarising neuromuscular blocking drug

Answer 13

Suxamethonium

Question 14

MoA of Suxamethonium

Answer 14

binds nicotinic ACh receptor –> depolarisation –> slower ACh hydrolysis –> prolonged depolarisation til no further transmission –> profound relaxation

Question 15

MoA of non-depolarising muscle relaxants

Answer 15

bind cholinergic Rs but do not stimulate them

cause conformational change in R shape tht prevents ACh binding

fewer side effects than depolarising NMJ blocking drugs

Question 16

Side effects of depolarising NMJ blocking drugs

Answer 16

• K+ efflux
• muscle fasciculations
• bradycardia

Question 17

Give examples of non-depolarising neuromuscular blocking drugs

Answer 17

• Turbocurarine
• Rocuronium
• Atracurium
• Vercuronium

Question 18

Why must patients fast before going under general anaesthetic?

Answer 18

to prevent aspiration of gastric contents

Question 19

Why is caution advised when putting smokers or patients w Asthma under general anaesthetic

Answer 19

it may be difficult to intubate + thus ventilate these patients once sedated

Question 20

Reliable clinical signs of anaesthesia

Answer 20

CNS signs:

• movement
• muscle tone
• light reflex
• eyelid reflex
• lacrimation
• eye position

Question 21

Period immediately after adminsitering of induction agent

Answer 21

Induction

Question 22

Features of Excitement stage of anaesthesia

Answer 22

• RR + HR become irregular
• uncontrolled movements
• vomiting
• breath holding

Question 23

4 stages of anaesthesia

Answer 23

Stage 1 - induction

Stage 2 - Excitement

Stage 3 - Surgical/operative

Stage 4 - overdose/danger

Question 24

MoA of Fentanyl

Answer 24

• binds kappa + delta-type opioid receptors
• opens calcium-dependent inwardly rectifying potassium channels
• causes hyperpolarisation + prevents further neuronal excitability