4. General Anaesthetics

Question 1

What is the patient state index?

Answer 1

developed by comparing large numbers of EEGs through induction, maintenance and emergence. Still being developed.

Question 2

Cerebral function monitor?

Answer 2

Signal filtered, semi-logarithmically compressed, and rectified.
Represents overall electrocortical background activity of the brain.

Question 3

Bispectral index?

Answer 3

Statistically based, complex parameter.

Weighted sum of several EEG parameters including time domain, frequency domain

Question 4

What is the lipid theory? and how does it change the membrane?

Answer 4

That the GA dissolves in the lipid membrane, leading to changes in:

1. bilayer thickness
2. order parameters
3. curvature elasticity.

Question 5

What is the protein theory and which major proteins are implicated?

Answer 5

that GAs bind to specific proteins.

1. GABA a receptor (inhibitory)
2. 2 pore K+ channels (control resting potential)
3. NMDA receptor (excitatory)

Question 6

What is the definition of MAC?

Answer 6

Minimum alveolar concentration- the alveolar partial pressure of an inhaled anaesthetic which prevents movement in response to a standard noxious stimulus in 50% patients.

Question 7

4 examples of intravenous anaesthetics?

Answer 7

Propofol, thiopental, etomidate, ketamine.

Question 8

Commonly used inhaled anaesthetics? 4

Answer 8

halothane, isoflurane, sevoflurane and desflurane