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Flashcards in Inhalation Agents Deck (31)
1

Potency is directly related to what?

lipid solubility

2

what provides a quantitative measure of lipid solubility (aka potency)

oil:gas partition coefficient

3

what is minimal alveolar concentration (MAC)?

the alveolar concentration of an inhalation agent at which 50% of patients do not move in response to skin incision or similar noxious stimuli

4

is MAC inversely or directly proportional to potency (lipid solubility)

inversely proportional
the lower the MAC the higher the potency

5

list the MAC's and put the following in order from least to most potent.
halothane
Des
Sevo
iso
Enf
N20

N20- 104%
Des- 6.6%
Sevo-1.7%
Iso- 1.2 (1.15)%
Enf- 1.6 %
Hal- 0.75%

enflurane is the one exception

6

temp and solubility:
what happens to solubility of gas in a liquid as temp increases

decreases

7

temp and solubility:
the solubility of gas decreases in a liquid as temp increases. how does this apply to out pts

less inhalation agent will dissolve in blood if pt hyperthermic
more inhalation agent will dissolve in blood if pt hypothermic

8

Uptake and elimination:
what determines speed of onset and elimination

blood solubility

9

Uptake and elimination:
what provides a quantitative measure of blood solubility?

blood:gas partition coefficient

10

Uptake and elimination:
which inhalation agents have the faster uptake thus onset the one with a high or low blood:gas

low

11

Uptake and elimination:
what are the 3 determinants of brain uptake and induction speed? and explain how?

- blood solubility- lower blood:gas faster onset
-Alveolar ventilation- the greater the ventilation the faster uptake
-Cardiac output- inversely related- decreased CO faster onset

12

Uptake and elimination:
old people with low CO will their IV inhalation be slow or fast? will there inhalation agent onset be slow or fast?

IV- slow
Inhalation agent- fast

13

Blood:gas partition coefficient:
agents with high blood solubility means they are more soluble where?

in blood
they prefer to be in the blood not gas

14

Blood:gas partition coefficient:
agents with low blood solubility means thay are more soluble where?

in gas
prefer to be in gas

15

Blood:gas partition coefficient:
explain the blood:gas partition coefficent for halothane 2.50 and then nitrous oxide 0.46

halothane 2.50:1 = 250:100 (250 molecules in blood and 100 in gas) - means the affinity (solubility) in blood is 2.5 x's higher than the gas state

nitrous 0.46:1 = 46:100 (46 molecules in blood and 100 in gas)- means solubilty in blood is 0.46 x's that in gas state)

aka nitrous oxide has a much faster onset than halothane

16

Blood:gas partition coefficient:
why is it that the lower the blood:gas the faster the onset

b/c the alveoli or the windows to the brain (AKA more in the alveoli=more in the brain), thus more in the gas phase the more in the alveoli

17

what is the Blood:Gas:
N20

0.46

18

what is the Blood:Gas:
des

0.42

19

what is the Blood:Gas:
sevo

0.7

20

what is the Blood:Gas:
iso

1.46

21

what is the Blood:Gas:
enflurane

1.9

22

what is the Blood:Gas:
halothane

2.5

23

after 30 min, halothane will be how close in % to equilibration?

think 50%
but actual answer 58%

24

after 30 min, isoflurane will be how close in % to equilibration?

think 70's
actual answer 73%

25

N20 is ___ x's more soluble the N2

34 times

26

what law explains why gas bubbles distend when N20 is turned on or collapse when N20 is turned off?

fick's law of diffusion

27

when N20 is turned on, distensible gas spaces expand and non-distensible gas spaces do what?

increase in pressure

28

Concentration effect:
what is it similar to?

a loading dose

29

Concentration effect:
explain it

the higher the concentration of anesthetic agent delivered, the faster the anesthesia is achieved.

30

Concentration effect:
is also referred ti as what?

overpressuring

31

2nd gas effect:
explain

2 anesthetics of varying onset speeds are administered together. a high concentration the fast anesthetic (N20) is administered with a slower (ISO). like the concentration effect w/a friend

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