Inhalation Anesthetics

Question 1

Apneic threshold

Answer 1

highest blood CO2 level at which a patient can remain apneic

Question 2

Do anesthetics lower or raise the apneic threshold?

Answer 2

raise, suppresses the drive to breathe

Question 3

Does pain lower or raise the apneic threshold?

Answer 3

lowers, stimulates breathing

Question 4

hypoxic drive

Answer 4

lowest oxygen level a patient can no longer remain apneic

normal patient ~60mmHg

Question 5

for a healthy patient is it hypoxia or hypercarbia that causes them to breathe?

Answer 5

hypercardia

Question 6

for a patient with lung disease is it hypoxia or hypercarbia that causes them to breathe?

Answer 6

hypoxia

less responsive to increase in CO2

Question 7

The CNS chemoreceptors respond to changes in what?

Answer 7

PaCO2

Question 8

The PNS chemoreceptors respond to changes in what?

Answer 8

PaO2

Question 9

minimum alveolar concentration (MAC)

Answer 9

mac of an exhaled gas that will prevent movement in 50% of patients during incision

Question 10

A patient is exhaling 0.8 MAC of Des. What is the percentage they’re exhaling?

Answer 10

4.8%

Question 11

A patient is exhaling 0.3 MAC of Sevo. What is the percentage they’re exhaling?

Answer 11

0.6%

Question 12

1.2% Des + 30% N2O = _____ MAC

Answer 12

0.2 MAC Des + 0.3 MAC N2O = 0.5 MAC

Question 13

MAC awake

Answer 13

0.4 MAC

Question 14

Reliable awareness prevention (with narcotics)

Answer 14

0.8 MAC

Question 15

Reliable awareness prevention (even without narcotics)

Answer 15

1.0 MAC

Question 16

50% chance of movement (w/o paralytics)

Answer 16

1.0 MAC

Question 17

5% chance of movement (w/o paralytics)

Answer 17

1.3% MAC

Question 18

How to know if patients are aware or not when paralyized

Answer 18

vital signs would be high

Question 19

What are the two reasons to give volatile agents?

Answer 19

prevent movement

prevent awareness

Question 20

What are factors that decrease MAC?

Answer 20

1- IV anesthetics
2- Old age (4-6% per decade)
3-ACUTE intoxication
4- pregnancy (progesterone sedative)
5-temperature factors
6- blood factors

Question 21

What are the 4 blood related factors that decrease MAC?

Answer 21

hypoxia
hypercarbia
hypotension
anemia

Question 22

What are the factors that increase MAC?

Answer 22

YOUNG HOT SALTY ALCOHOLICS

young
hot (hyperthermia/ burn pt)
salty (hypernatremia)
alcoholics (chronic)

Question 23

Blood/Gas Partition Coefficients

Answer 23

When you reach equilibrium then it is the % of blood concentrated compared to the lungs

Question 24

If the agent is soluble in the blood, the blood will have more agent than the lungs at equilibrium and the blood gas coefficient will be lower or higher?

Answer 24

Higher

Question 25

What are the neurologic effects of Volatile agents (not N2O)?

Answer 25

1-Dilates the cerebral vasculature, increases CBF, increases ICP 2- emergence delirium in kids 3- decrease seizures 4- decrease cerebral metabolic rate of oxygen

Question 26

What are the cardiac effects of volatile agents?

Answer 26

1-decrease cardiac contractility 2-cause systemic vasodilation 3- cause coronary vasodilation

Question 27

What are the respiratory effects of volatile agents?

Answer 27

1-rapid, shallow breathing (increase in CO2), lower Vd 2- increase apneic threshold 3- decrease hypoxic drive 4- bronchodilation

Question 28

Other effects of volatile agents?

Answer 28

``` 1-decreases renal blood flow 2- decreases hepatic blood flow 3- prolongs muscle relaxant 4- PONV 5- MH 6- inhibits "non-shivering thermogenesis" in peds ```

Question 29

Nitrous oxide

Answer 29

``` 1-analgesic 2-PONV 3-stimulates sympathetic increases PVR 4-dilates cerebral vasculature 5-seizures less likely 6-supports combustion 7- post op diffusion hypoxia 8- expands air containing cavities 9- increases cerebral metabolic rate of oxygen 10- prolonged exposure bad ```

Question 30

What does prolonged exposure to N2O cause?

Answer 30

1-bone marrow depression 2- can inhibit enzymes in DNA synthesis 3-neurological deficiencies

Question 31

How does Nitrous oxide expand air bubbles?

Answer 31

Nitrous oxide will diffuse into air pocket faster than the nitrogen can diffuse into the blood

Question 32

What are the contraindications for N2O?

Answer 32

``` 1- facial or throat surgery with laser 2-ophthalmic surgery 3- severe COPD 4- cardiopulmonary bypass surgeries 5- certain abdominal surgeries (laparoscopic, bowel obstruction) 6- inner ear surgery 7- 1st trimester of pregnancy 8- neurosurgery ```

Question 33

What are the advantages of iso?

Answer 33

mimimal cardiac depression | causes coronary vasodilation

Question 34

what are the disadvantages of iso?

Answer 34

pungent odor | associated with coronary steal syndrome

Question 35

Coronary steal phenomenon?

Answer 35

when iso causes coronary vasodilation the stenotic coronary arteries cannot vasodilate as well as the normal coronary arteries

Question 36

What are the advantages of sevo?

Answer 36

least pungent

Question 37

what are the disadvantages of sevo?

Answer 37

potential risk for nephrotoxicity (free fluoride ions & compound A)

Question 38

What are the effects of compound A thought to be more significant with?

Answer 38

prolonged sevo use high conc of sevo low FGF used

Question 39

desflurane

Answer 39

``` 1- high vapor pressure 2- specialized vaporizer 3- fastest induction and emergence 4- possible sympathetic response 5- pungent ```

Question 40

What are the advantages of xenon?

Answer 40

inert low b:g co minimal cardiovascular effects doesnt trigger MH

Question 41

What are the disadvantages of xenon?

Answer 41

rare and expensive | low potency