Principles and Pharmacology

Question 1

what composes the triad of anaesthesia?

Answer 1

• hypnosis
• paralysis
• analgesia

Question 2

Outline the drugs used in phase 1: Induction

Answer 2

• inhalation: volatile (sevoflurane) or nitrous oxide
• intravenous: propofol +/- opioid
• +/- muscle relaxant

Question 3

Outline the drugs used in phase 2: Maintenance

Answer 3

• inhalational: volatile (sevoflurane) +/- opioid
• intravenous: propofol +/- opioid = TIVA
• +/- muscle relaxant

Question 4

how does propofol/sevoflurane work?

Answer 4

Propofol and sevoflurance bind to and activate the GABAa receptor, activating the channel, allowing lots of Cl- ions to enter the cell.
- The influx of Cl- means membrane potential remains below resting potential of-70mV, so cannot get to threshhold of excitation (-55 mV) > therefore stops any forward transmission of neural signals and pathways.
- Pharmacologically induced state of narcosis.

Question 5

how does fentanyl work?

Answer 5

Opioids inhibit propagation of pain impulse from peripheral tissue up to the brain.
- morphine and fentanyl act on MOP receptor type.

Question 6

what opioids are commonly used by anaesthetists?

Answer 6

Question 7

how does rocuronium work?

Answer 7

• muscle relaxant
• act at NMJ
• block acetylcholine receptors on post-synaptic membrane, blocking acetylcholine from binding and stimulating a muscle contraction

Question 8

what are the types of muscle relaxants used by anaesthetists?

Answer 8

• non-depolarising - competitive antagonists at ACh receptor e.g. rocuronium, atracurium
• depolarising - ACh receptor agonist e.g. suxamethonium

Question 9

what agents are used to reverse muscle relaxants?

Answer 9

• neostigmine - ACh inhibitor + glycopyrrolate - muscarinic anticholinergic
• suggamadex

Question 10

what do anaesthetics do to all components of these two equations?
what drugs can help combat this?

Answer 10

decrease
- sympathetic nervouse system agonists, alpha receptors > vasculature and beta receptors > heart.

Question 11

THE ONE BIG ANAESTHETIC EMERGENCY THAT EVERYONE LEARNS ABOUT BUT NO ONE SEES?

Answer 11

• malignant hyperthermia
• lethal unless given dantrolene

Question 12

how does local anaesthetic work?

Answer 12

• can be ionised or unionised
• have to be unionised to cross the cell membrane where they bind to a protein, becoming ionised.
• they then block the sodium channel intracellularly, preventing depolarisation.