Inhalation Induction

Question 1

Fi

Answer 1

inspired concentration of volatile agent

Question 2

Fa

Answer 2

concentration of volatile agent in alveoli (and expiratory tubing)

Question 3

inhalation induction mechanism

Answer 3

1. volatile agent on
2. Fi increases
3. Fa increases
4. agent diffuses into blood
5. agent diffuses from blood to brain
6. pt asleep when conc in brain is sufficient

Question 4

how does concentration gradient effect diffusion speed?

Answer 4

the greater the conc gradient from the lungs to blood the faster the diffusion to the blood

Question 5

T/F diffusion is slow at first and then rapid.

Answer 5

false, rapid at first then slows as the concentration gradients decrease

Question 6

Fa/Fi ratio

Answer 6

how concentrated the alveoli are compared to machine

Question 7

why is the Fa/Fi ratio less than one?

Answer 7

b/c blood is always absorbing agent from the lungs

Question 8

list the volatile agents in order from fastest to slowest for Fa/Fi ration approaching 1

Answer 8

nitrous oxide
des
sevo
iso
halo

Question 9

what does a steep slope on the Fa/Fi curve mean?

Answer 9

Fa is rapidly increasing and leads to faster diffusion and faster induction

Question 10

why is low blood solubility important?

Answer 10

slower initial diffusion into blood and Fa builts up, rapidly diffuses to brain b/c low blood solubility

Question 11

high blood solubility

Answer 11

quickly diffuses to blood, slow to the brain bc wants to stay in the blood

Question 12

If Desflurane has a lower blood gas coefficient than nitrous oxide, why does nitrous oxide have a steeper Fa/Fi curve?

Answer 12

Because N2O is typically used in much higher concentrations

Question 13

how to speed up inhalational induction

Answer 13

higher % poison
higher FGF rate
decrease circuit volume
agent with lowest blood solubility

Question 14

how much oxygen does a patient need?

Answer 14

250mL

Question 15

When do you need to run at least 2L/min?

Answer 15

sevo is used

Question 16

advantages of low FGF

Answer 16

cost effective
preserves heat and moisture
slows drying of CO2 granules
preserves pt temp

Question 17

disadvantages of low FGF

Answer 17

slower induction

slower emergence

Question 18

advantages of high FGF

Answer 18

faster induction

faster emergence

Question 19

disadvantages of high FGF

Answer 19

expensive
dries out airway
accelerates drying of granules

Question 20

what are the patient factors that affect the speed of induction?

Answer 20

cardiac output
minute ventilation
FRC

Question 21

low cardiac output

Answer 21

faster buildup of agent conc in blood
faster buildup of agent conc in lungs
faster induction

Question 22

high cardiac output

Answer 22

slower buildup of agent conc in blood
slower buildup of agent conc. in lungs
slower induction

Question 23

T/F low cardiac output quickens the intravenous induction?

Answer 23

false, it slows the intravenous induction (how long it takes to travel to the brain)

Question 24

higher minute ventilation

Answer 24

alveoli are open longer
deeper breath= more surface area
faster breaths = more gas

Question 25

low FRC

Answer 25

less space in alveoli higher conc of agent in lungs faster induction ***peds pts

Question 26

high FRC

Answer 26

more space in alveoli lower conc agent in lungs slower induction

Question 27

where do volatile agents go in the body other than the brain?

Answer 27

vessel rich group, fat group, muscle group

Question 28

what are the vessel rich organs

Answer 28

``` brain heart liver kidney endocrine glands ```

Question 29

what percent of cardiac output do the vessel rich organs get?

Answer 29

75%

Question 30

clinical implications of vessel rich group

Answer 30

saturate quickly | desaturate quickly

Question 31

muscle group includes

Answer 31

muscle and skin

Question 32

how much cardiac output does the muscle group get?

Answer 32

20%

Question 33

how much cardiac output does the fat group get?

Answer 33

5%

Question 34

clinical implications of fat group

Answer 34

slow to saturate | slow to desaturate

Question 35

wake up mechanism

Answer 35

1. turn vapor off 2. conc in machine and lungs decrease 3. agent diffuse from blood to lungs 4. conc agent in blood decrease 5. diffuse out of tissues (brain) into blood 6. conc in fat decreases and blood conc further decrease 7. blood and brain conc decrease enough pt wakes

Question 36

what are the factors that affect wakeup

Answer 36

``` age (geriatric=longer) amount of agent in fat FGF rate blood solubility of agent minute ventilation (higher=faster) amount of narcotic (more=longer) body temp- hypothermia (longer) cardiac output (low=longer) lung disease/decreased alveolar diffusion (longer) APL valve FRC (low=faster) ```

Question 37

when will there be more agent dissolved in fat?

Answer 37

obesity time surgery time high conc of agent

Question 38

if you want your patient to wake up faster do you want your APL valve open or closed?

Answer 38

OPEN