Anaesthesia (7) Flashcards Preview

CM Clinical Symposia > Anaesthesia (7) > Flashcards

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

Assessing unconsciousness

Clinical signs, measure level MAC (Minimum alveolar conc), BIS monitor, isolated forearm, evoked potentials