Exam 3 (Gas laws / MAC / VAs)

Question 1

Boyles law

Answer 1

at a constant temperature, pressure and volume of gas are inversely proportional

Question 2

Diffusion is described by ______ Law and describes what 3 factors that influence diffusion

Answer 2

Fick’s Law
1. partial pressure gradient
2. solubility of the gas
3. thickness of the membrane

Question 3

Effusion is described by ______ law and it describes what process?

Answer 3

Graham’s (cracker lol)
describes the process by which molecules pass through pores and channels without colliding (smaller molecules effuse faster)

Question 4

Henry’s Law is the gas law that is applied when we ________ to increase the speed of induction

Answer 4

overpressurize

Question 5

Henry’s Law states that the amount of gas in a liquid is proportional to

Answer 5

it’s partial pressure above the liquid

Question 6

Halothane B:G Partition Coefficient

Answer 6

2.54

Question 7

Enflurane B:G Partition Coefficient

Answer 7

1.90

Question 8

Isoflurane B:G Partition Coefficient

Answer 8

1.46

Question 9

Nitrous Oxide B:G Partition Coefficient

Answer 9

0.46

Question 10

Desflurane B:G Partition Coefficient

Answer 10

0.42

Question 11

Sevoflurane B:G Partition Coefficient

Answer 11

0.69

Question 12

Which volatile has the highest Fat:Blood coefficient?
A. Isoflurane
B. Desflurane
C. Sevoflurane

Answer 12

C. Sevoflurane
Note: halothane has the highest of the volatiles, but since we don’t use it seems a little silly to include it

Question 13

From high to low organize the volatiles based on Fat:Blood coefficient Isoflurane, halothane, sevoflurane, desflurane, enflurane

Answer 13

High to low: Halothane, Sevoflurane, isoflurane, enflurane, desflurane

Question 14

Volatile: Nitrous oxide
MAC: _____

Answer 14

104

Question 15

Volatile: Halothane
MAC: ___

Answer 15

0.75

Question 16

Volatile: Enflurane
MAC: ___

Answer 16

1.63

Question 17

Volatile: Isoflurane
MAC: ___

Answer 17

1.17

Question 18

Volatile: Desflurane
MAC: ___

Answer 18

6.6

Question 19

Volatile: Sevoflurane
MAC: ___

Answer 19

1.8

Question 20

What is the MAC required for general anesthesia?

Answer 20

1.3

Question 21

What is awake MAC

Answer 21

0.3-0.5

Question 22

What two factors affect MAC the most?

Answer 22

Body temperature and age

Question 23

What percentage per decade after the age of 55 should we decrease our MAC?

Answer 23

6%

Question 24

What 4 factors increase MAC?

Answer 24

hyperthermia, increased catecholamines, hypernatremia, excess pheomelanin production (redheads)

Question 25

What factors DECREASE MAC

Answer 25

Hypothermia
Preoperative medication, intraoperative opioids
Alpha-2 agonists
Acute alcohol ingestion
Pregnancy
Post partum (early…12-72 hours)
Lidocaine
PaO2 <38 mm Hg
Mean BP < 40mm Hg
Cardiopulmonary bypass
Hyponatremia

Question 26

Spinal cord depression is achieved by inhibiting what two receptors?

What channels are blocked pre-synaptically?

What neurotransmitter is increased?

Answer 26

NMDA and AMPA (glutamate receptors).

Na+ channel inhibition pre synaptic that decreases release of glutamate

Glycine (inhibitory transmitter) is enhanced

Question 27

Loss of consciousness is thought to be achieved by increasing _____ in the CNS, particularly in the _______. VAs may also potentiate _____ in the brainstem.

What is not effected in the brain via VAs?

Answer 27

GABA; RAS ;Glycine

No effect of volatiles on AMPA, NMDA, or kainate

Question 28

Sum of partial pressures = Ptotal is described by ______ law

Answer 28

Dalton’s

Question 29

Vapor pressure of Halothane

Answer 29

243 torr

Question 30

Vapor pressure of Enflurane

Answer 30

175 torr

Question 31

Vapor pressure of Isoflurane

Answer 31

238 torr

Question 32

Vapor pressure of Desflurane

Answer 32

669 torr

Question 33

Vapor pressure of Sevoflurane

Answer 33

157 torr

Question 34

How do you calculate Fi[gas]

Answer 34

P[gas] / P[total]

Question 35

Flow-over increases vaporization by increasing _____ ____ and achieves this via ____

Answer 35

surface area; wicks