Flashcards in Anaesthesia (7) Deck (18):
1
Inhalation agents
Sevoflurane, Isoflurane, Desflurane, Nitrous oxide, Xenon
2
IV agents
Propofol, Etomidate, Barbiturates, Ketamine
3
Ideal physical properties of inhalation agent
Non-flammable, stable with materials (e.g. plastic), long shelf life, environmentally friends, easy and cheap to manufacture
4
Ideal biological properties of inhalation agent
Pleasant to inhale (non-irritant), fast onset, high potency, minimal effects to other systems, no biotransformation, non-toxic to theatre personnel
5
Balanced anaesthesia triangle
1. Unconsciousness
2. Analgesia
3. Muscle relaxation
6
Balanced anaesthesia
Usually combination of agents used, safer than large dose single agent, maximises benefit of individual agent, minimises adverse effects
7
Measuring anaesthetic potency - IV
MAC (Minimum Alveolar Concentration), Cp50
8
Producing unconciousness
- Meyer Overton theory
- Related to lipid solubility
- Pertubation of lipid membranes
- Common mechanism of action
- Now shown to be false (lipid membrane effect reproduced by small changes in temp in vitro, differing effects stereoisomers, large molecular weight compounds less potent than predicted)
9
How do anaesthetics work?
Modulate activity of transmitter-gated ion channels
10
Anaesthetics have positive effect on which gated ion channels?
GABAa and Strychine-sesntive glycine
11
Anaesthetics have negative effect on which gated ion channels?
5HT3, neuronal nicotinic and glutamate NMDA/AMPA
12
Inhalation agents
Solubility in blood determines onset/offset, low solubility=fast equilibrium, fast onset and quick recovery
13
Highly fat soluble GA
Given for long time accumulates in fat leading to 'hangover' effect for hours
14
IV agents
Quick onset, short duration (redistribution)
15
Adverse effects (general)
Vasodilation, decreased cardiac contractility, affect organ perfusion
16
Adverse effects (inhalation volatile)
Malignant hyperthermia and hepatotoxicity
17
Adverse effects (IV agents)
Allergy/pain on injection
18