Inhaled anesthetics 1: pharmacokinetics 2

Question 1

_______ is the tendency of a solute to dissolve in a solvent

Answer 1

Solubility

Question 2

In the case of inhalation anesthetics, solubility is the ability of the

Answer 2

anesthetic agent to dissolve into the blood and tissues

Question 3

___________ describes the relative solubility of an inhalation anesthetic in the blood vs. in the alveolar gas when the partial pressures between the two compartments are equal.

Answer 3

The blood:gas partition coefficient

Question 4

Blood: gas coefficient for sevoflurane.

Answer 4

0.65

Question 5

Blood: gas coefficient for isoflurane.

Answer 5

1.46

Question 6

Blood gas coefficient for desflurane.

Answer 6

0.42

Question 7

Blood gas coefficient for nitrous oxide is

Answer 7

0.46

Question 8

How easily a solute will dissolve into a solvent depends on the

Answer 8

physiochemical characteristics of both compounds- “like dissolves like”

Question 9

A polar solute will be more soluble in a

Answer 9

hydrophilic solvent

Question 10

A nonpolar solute will be more soluble in a

Answer 10

liphophilic solvent

Question 11

An anesthetic gas with low blood:gas solubility is

Answer 11

less likely to be taken up into the blood
as a result, more of the agent is available to exert a partial pressure in the alveoli and brain

Question 12

An anesthetic gas with high blood: gas solubility is

Answer 12

more likely to be taken up into the blood;
as a result, less of the agent is available to exert a partial pressure in the alveoli and brain

Question 13

While administering a volatile anesthetic, we produce a state of anesthesia by

Answer 13

building up a partial pressure of anesthetic agent inside the patient’s brain and spinal cord

Question 14

These three factors determine anesthetic uptake into the blood:

Answer 14

agent solubility
partial pressure difference between the alveoli and the blood
cardiac output

Question 15

The amount of anesthetic agent inside the alveoli is a balance between

Answer 15

input (the setting on the vaporizer) and uptake into the blood

Question 16

The Fa/Fi curve helps us appreciate the speed at which

Answer 16

FA equilibrates with Fi (speed of induction)

Question 17

The concentration of an agent inside the alveoli is proportional to its

Answer 17

concentration inside the brain
for this reason, we use alveolar partial pressure (FA) as a surrogate for the brain partial pressure

Question 18

Describe how low solubility affects Fa/Fi.

Answer 18

Faster equilibration of Fa/Fi–> faster onset

Question 19

Describe how high solubility affects Fa/Fi.

Answer 19

slower equilibration of Fa/Fi–> slower onset

Question 20

Determinants of alveolar delivery include

Answer 20

setting on the vaporizer
time constant of the delivery system
anatomic dead space
alveolar ventilation
volume of the FRC

Question 21

The Fa/Fi curve approximates the

Answer 21

speed at which Fa will approximate Fi

Question 22

Describe which inhalational anesthetic has the highest Fa/Fi in order

Answer 22

N20> des>sevo>iso

Question 23

Which group is the first group to become saturated with anesthetic?

Answer 23

vessel rich group

Question 24

Fa is the

Answer 24

partial pressure of the anesthetic inside the alveoli

Question 25

Fi is the

Answer 25

concentration of the anesthetic exiting the vaporizer

Question 26

Which factor reduces the rate of rise of Fa/Fi? (select 3)
a. increased cardiac output
b. decreased time constant
c. increased FRC
d. decreased anatomic dead space
e. decreased fresh gas flow
f. increased alveolar ventilation

Answer 26

a. increased cardiac output
c. increased FRC
e. decreased fresh gas flow

Question 27

Factors that influence the rate of anesthetic delivery to the alveoli:

Answer 27

setting on the vaporizer
time constant of the delivery system
anatomic dead space
alveolar ventilation
functional residual capacity

Question 28

Factors that influence the removal of anesthetic from the alveoli (uptake):

Answer 28

agent solubility
partial pressure difference between the alveoli and the blood
cardiac output

Question 29

For Fa/Fi to increase, there must be

Answer 29

greater wash in or reduced uptake

Question 30

Increased Fa/Fi means that there is

Answer 30

a faster onset or the curve is pushed up

Question 31

Factors that lead to an increased wash in include

Answer 31

high fresh gas flow
high alveolar ventilation
low FRC
low time constant
low anatomic dead space

Question 32

Factors that lead to reduced uptake include

Answer 32

low solubility
low cardiac output
low Pa-Pv difference

Question 33

Decreased Fa/Fi means that

Answer 33

there is slower onset; curve is pushed down

Question 34

Factors that lead to decreased wash in include

Answer 34

low fresh gas flow
low alveolar ventilation
high FRC
high time constant
high anatomic dead space

Question 35

Factors that lead to increased uptake include

Answer 35

high solubility
high cardiac output
high Pa-Pv difference

Question 36

What percentage of body weight is accounted for by the vessel rich group?
a. 20%
b. 50%
c. 10%
d. 75%

Answer 36

C. 10%- the vessel rich group accounts for only 10% of the body weight, yet it receives 75% of the cardiac output

Question 37

Tissue uptake is dependent on

Answer 37

tissue blood flow
solubility of the anesthetic in the tissue
arterial blood: tissue partial pressure gradient

Question 38

The vessel rich group consists of the

Answer 38

heart, brain, kidneys, liver and endocrine glands

Question 39

The muscle/skin group is ____ of the body mass but receives _____ of the cardiac output.

Answer 39

50%; 20%

Question 40

The fat group is ____ of the body mass but receives ____ of the cardiac output.

Answer 40

20%; 5%

Question 41

The vessel poor group is_____ of the body mass but receives ____ of the cardiac ouptut.

Answer 41

20%; <1%

Question 42

The vessel-poor group includes

Answer 42

bone, tendon & cartilage

Question 43

The uptake of nitrous oxide by any of these groups is

Answer 43

minimal; it partitions nearly the same into all of the compartments