L6: Clinical Use of Inhalant Anesthetic Agents (Granone)

Question 1

potency of inhalant is an expression of the relationship b/w:

Answer 1

the administered dose of an inhalant and the anesthetic effect that is obtained

Question 2

Minimum Alveolar Concentration (MAC)

Answer 2

• most common expression of potency in inhalant anesthetics
• is the MAC of anesthetic which prevents gross, purposeful movement in 50% of patients exposed to a noxious stimulus
• similar to ED50
• little variation between species, except for nitrous oxide
• mimics the brain partial pressure of the inhalant**

Question 3

mean MAC values for isoflurane, sevoflurane, and desflurane in DOGS***

Answer 3

iso: 1.3% (1.14-1.5)
sevo: 2.2% (2.1-2.4)
des: 8.8% (7.2-10.3)

Question 4

mean MAC values for isoflurane, sevoflurane, and desflurane in CATS***

Answer 4

iso: 1.4% (1.28-1.6)
sevo: 2.8% (2.6-3.1)
des: 10% (9.8-10.3)

Question 5

factors that increase MAC (need more anesthetic)

Answer 5

highhyperthermia
hypernatremia
drugs that cause CNS stimulation
increased levels of excitatory NTs

Question 6

factors that decrease MAC (need less anesthetic)

Answer 6

other anesthetics
hyponatremia
hypotension
hypothermia
low PaO2 
high PaCO2
pregnancy
inc. age

Question 7

factors that don’t affect MAC

Answer 7

gender
normal resp. gas concentrations
duration of anesthesia
metabolic acidosis/alkalosis
mild to moderate anemia (severe WILL affect)

Question 8

highest anesthetic conc. that can be achieved determined by:

Answer 8

saturated vapor pressure of the agent (pressure exerted on the sides of container gas is in)

Question 9

maximum percentage of iso that can be achieved is greater/lesser than the MAC value of iso

Answer 9

greater

Question 10

delivered concentration of anesthetic

Answer 10

corresponds to the percent setting that is on the vaporizer dial

Question 11

inspired concentration of anesthetic

Answer 11

conc. of inhalant that the patient inspires