Anaesthetics

Question 1

Fasting rules for GA

Answer 1

• 6 hours of no food or feeds before the operation
• 2 hours of no clear fluids (fully “nil by mouth”)

Question 2

Purpose of preoxygenation before GA

Answer 2

gives pt an oxygen reserve for the period between when they lose consciousness and are successfully intubated and ventilated (in case the anaesthetist has difficulty establishing the airway)

Question 3

Triad of GA

Answer 3

• Hypnosis
• Muscle relaxation
• Analgesia

Question 4

IV hypnotic agents

Answer 4

• Propofol (the most commonly used)
• Ketamine
• Thiopental sodium (less common)
• Etomidate (rarely used)

Question 5

Inhaled hypnotic agents

Answer 5

• Sevoflurane (the most commonly used)
• Desflurane (less favourable as bad for the environment)
• Isoflurane (very rarely used)
• Nitrous oxide (combined with other anaesthetic medications – may be used for gas induction in children)

Question 6

Use of IV vs inhaled hypnotic agents, what is TIVA?

Answer 6

• IV used as induction agent, inhaled used to maintain GA (IV work more quickly)
• Total intravenous anaesthesia (TIVA): using IV for both induction and maintenance

Question 7

How do muscle relaxants work

Answer 7

• Work on neuromuscular junction
• Acetylcholine neurotransmitter is released by the axon but is blocked from stimulating a response from the muscle - muscle relaxants act as competitive inhibitors on ACh receptors

Question 8

2 types of muscle relaxants and examples

Answer 8

• Depolarising (e.g., suxamethonium) - short-acting (work quickly, wear off quickly)
• Non-depolarising (e.g., rocuronium and atracurium) - long-acting (take longer to work, last longer)

Question 9

How to reverse muscle relaxants

Answer 9

• Cholinesterase inhibitors (e.g., neostigmine)
• Sugammadex used specifically to reverse non-depolarising muscle relaxants

Question 10

Acute respiratory syndrome definition