Inhalation agents

Question 1

What happens to the anes effect of a gas of a given concentration when moved to a higher altitude?

Answer 1

The partial pressure of the gas will be less and therefore exert a smaller effect for a given concentration of anesthetic gas

(partial pressure determines effect, not concentration)

Question 2

What effects do the following factors have on rate of rise of FA/FI for inhaled gases?
(FA is alveolar conc)

blood:gas coefficient
cardiac output
minute ventilation
Parterial-Pvenous difference

Answer 2

The following increase FA/FI rate of rise:

Low blood:gas coefficient
Low cardiac output
High minute ventilation
High Parterial-Pvenous difference

Question 3

Effects of sevoflurane on cerebral physiology

Answer 3

Sevoflurane decrease CMRO2

Uncouples CMRO2 and auto regulation

Increases CBF and therefore increases ICP