Inhaled Anesthesia Gas

Question 1

What are the actions of Inhaled Anesthesia Gas?

Answer 1

Produces immobility and amnesia

Question 2

What are two things that Inhaled Anesthesia Gases do NOT provide?

Which gas is the exception?

Answer 2

Do NOT provide any significant analgesia NOR increase/affect skeletal muscle tone (some lower)

Nitrous Oxide provides analgesia AND increases skeletal muscle tone.

Question 3

What is the mechanism of action for inhaled anesthesia gases?

Answer 3

Produce immobility –> via actions on the spinal cord

Produce anesthesia –> by enhancing inhibitory channels and attenuating excitatory channels (unknown whether this occurs through direct binding or membrane alterations)

Question 4

What is MAC?

Answer 4

Minimum Alveolar Concentration

MAC of an inhaled anesthetic is the alveolar (end expiratory) concentration at which 50% of patients will not show a motor response to a standardized surgical incision.

Question 5

What is the standard deviation of MAC and what does this mean?

Answer 5

The standard deviation of MAC is ~10%
thus 95% of patients will respond to 1.2 MAC
and 99% will respond to 1.3 MAC.

Question 6

What do standard MAC values assume?

Answer 6

Standard MAC values assume the absence of all other potentially sedative or hypnotic drugs.
Temp 37, 1 ATM, 30-55yo.

Question 7

True or False?

According to rat data, MAC values are NOT additive in terms of preventing movement to incision (0.5 MAC of nitrous oxide plus 0.5 MAC of isoflurane ≠ 1.0 MAC of any other agent)

Answer 7

FALSE

MAC values ARE ADDITIVE in terms of preventing movement to incision (0.5 MAC of nitrous oxide plus 0.5 MAC of isoflurane = 1.0 MAC of any other agent)

Bonus Question: What Law is this?

Dalton’s Law.

Question 8

What are the four anesthesia gases we commonly talk about and what are their corresponding brand names?

Answer 8

Desflurane/Suprane
Isoflurane/Forane
Sevoflurane/Ultane
Nitrous Oxide

Question 9

Which inhaled anesthesia gas is the most expensive?

Answer 9

Desflurane

Question 10

Which inhaled anesthesia gas is the least expensive?

Answer 10

Isoflurane

Question 11

Which gas is most commonly used?

Answer 11

Sevoflurane

Question 12

Which gas requires a special heated vaporizer?

Answer 12

Desflurane

Question 13

Which gas has very low solubility making it good for obese patients?

Answer 13

Desflurane

Question 14

Which gas is an airway irritant and smells bad?

Answer 14

Desflurane

Question 15

Which gas can increase heart rate?

Answer 15

Desflurane

Question 16

How is Desflurane absorbed and eliminated?

Answer 16

QUICKLY

Question 17

Which gas is good for pediatric induction?

Answer 17

Sevoflurane

Question 18

What are three downsides to Sevoflurane?

Answer 18

1. Can cause emergence delirium in kids
2. Can hang around longer in obese patients
3. Has been indicated to cause nephrotoxicity in rats (not proven in humans)

Question 19

Is sevoflurane irritable to the airway?

Answer 19

No

Question 20

Which gas is not used very often, but is still very effective if used correctly?

Answer 20

Isoflurane

Question 21

Which gas is very lipid soluble?

How does this effect emergence?

Answer 21

Isoflurane

LONGER Emergence

Question 22

What kind of case is Isoflurane very suitable for?

Answer 22

Long cases where quick extubation is not expected
For example: a sick ICU patient going to stay on a ventilator

Question 23

Which gas must be used as an adjunct and is NOT considered a solo anesthesia gas?

Answer 23

Nitrous

Question 24

Which gas allows decrease of primary anesthesia agents?

Answer 24

Nitrous

Question 25

Which gas provides analgesia?

Answer 25

Nitrous

Question 26

How can Nitrous be used?

Answer 26

Can be used in many different fashions (ex: help wakeup) 1. 2nd gas effect 2. Reduction of narcotic 3. Reduction of other anesthetic agents

Question 27

In which two types of cases would we NOT use Nitrous?

Answer 27

neuro ( head ?) or most bowel cases

Question 28

What is the most mentioned negative trait of Nitrous?

Answer 28

N/V at higher doses

Question 29

What factors INCREASE anesthetic requirements?

Answer 29

1. Chronic ETOH 2. Infant (highest MAC at 6 mo.) 3. Red hair 4. Hypernatremia 5. Hyperthermia

Question 30

Which factors DECREASE anesthetic requirements? 8

Answer 30

1. Acute ETOH 2. Elderly 3. Hyponatremia 4. Hypothermia 5. Hypoxia 6. HYPERcarbia 7. Anemia 8. Pregnancy

Question 31

True or False We don't really know how anesthesia gases work.

Answer 31

TRUE "We don’t really know how they work…"

Question 32

What are the benefits of using Gas? 5

Answer 32

1. Speed of onset 2. Titratable 3. Very potent 4. Little/no metabolism 5. Available measure (watching contents of breath tells us whats in the patient's brain)

Question 33

Which gas has no effect on the cardiovascular system?

Answer 33

Nitrous

Question 34

Which two gases decrease blood pressure the most?

Answer 34

Isoflurane and Desflurane (Sevoflurane decreases too but not as much as the other two)

Question 35

Which two gases can increase heart rate and of those two which one is more likely to increase heart rate?

Answer 35

Isoflurane and Desflurane Isoflurane is more likely to increase HR while desflurane might cause no change in HR at all.

Question 36

How does Sevoflurane effect the cardiovascular system?

Answer 36

Decrease BP Decrease SVR Decrease CO no change in HR

Question 37

How does Desflurane effect the cardiovascular system?

Answer 37

Substantial decrease in BP Substantial decrease in SVR Decrease (or no change) in CO Increase (or no change) in HR

Question 38

How does Isoflurane effect the CV system?

Answer 38

Substantially decrease BP Substantially decrease SVR Increase HR no change in CO

Question 39

True or False? All anesthesia gases increase respiratory rate

Answer 39

TRUE

Question 40

True or False? All anesthesia gases decrease tidal volume.

Answer 40

TRUE Although, Isoflurane has the greatest impact on tidal volume

Question 41

True or False? All anesthesia gases increase resting PaCO2.

Answer 41

FALSE Nitrous has no change on resting PaCO2

Question 42

Which anesthesia gases increase cerebral blood flow?

Answer 42

All of them (Nitrous, Iso, Des, Sevo)

Question 43

Which anesthesia gases increase intracranial pressure?

Answer 43

All of them

Question 44

Which anesthesia gases decrease cerebral metabolic rate?

Answer 44

Isoflurane, Desflurane, and Sevoflurane Nitrous INCREASES cerebral metabolic rate

Question 45

Which gases decrease seizure activity?

Answer 45

All of them

Question 46

Which two gases have the highest increase in nondepolarizing blockade?

Answer 46

Isoflurane and Desflurane

Question 47

Which two gases have the greatest impact on renal function?

Answer 47

Isoflurane and Nitrous Oxide

Question 48

What do inhaled anesthesia gases do to hepatic blood flow?

Answer 48

Decrease hepatic blood flow

Question 49

What is the MAC % of Sevoflurane?

Answer 49

1.8

Question 50

What is the MAC % of Desflurane?

Answer 50

6.6

Question 51

What is the MAC % of Isoflurane?

Answer 51

1.17

Question 52

What is the MAC % of Nitrous Oxide?

Answer 52

104

Question 53

What is the Blood:Gas of Sevoflurane?

Answer 53

0.69

Question 54

What is the Blood:Gas of Desflurane?

Answer 54

0.42

Question 55

What is the Blood:Gas of Isoflurane?

Answer 55

1.46

Question 56

What is the Blood:Gas of Nitrous Oxide?

Answer 56

0.46

Question 57

What is the vapor pressure of Sevoflurane?

Answer 57

157

Question 58

What is the vapor pressure of Desflurane?

Answer 58

669

Question 59

What is the vapor pressure of Isoflurane?

Answer 59

238

Question 60

What is the vapor pressure of Nitrous Oxide?

Answer 60

Trick Question no vapor! Gas (38,770)

Question 61

Which gases can trigger MH?

Answer 61

Halothane Enflurane Isoflurane Sevoflurane Desflurane