General Anaesthetics

Question 1

What are the stages of anaesthesia?

Answer 1

Analgesia
Excitement
Surgical anaesthesia (loss of consciousness)
Respiratory paralysis

Question 2

What are the 4 levels of surgical anaesthesia?

Answer 2

Eyes roll and become fixed
Corneal and largyngeal reflexes lost
Pupils dilate and light reflex lost
Intercostal paralysis - shallow abdominal breathing

Question 3

Which type of anaesthetic is used for induction and why?

Answer 3

Intravenous - fast stage 2

Question 4

Which factors affect anaesthetic potency?

Answer 4

Increases: unsaturation, halogen substitution, ether group
Decreases: hydrophilic groups (-OH, -NH2)

Question 5

What is the main modern inhalation anaesthetic?

Answer 5

Isoflurane

Question 6

What are the actions of halothane, thiopental, etomidate, and propofol?

Answer 6

Potentiate GABAAR currents

Increase K+ leak channel current

Question 7

What is the action of ketamine, nitrous oxide, and xenon?

Answer 7

Non-competitive antagonists of NMDARs

Question 8

What is the minimum alveolar concentration (MAC)?

Answer 8

Concentration in lungs needed to prevent movement in 50% of subjects in response to nociceptive stimulus

Question 9

What are the properties of an ideal general anaesthetic?

Answer 9

Low MAC (high potency)
Low blood solubility (fast onset and offset)