Week 10 MAC and Inhalation Agents

Question 1

What is MAC?

Answer 1

Minimum Alveolar Concentration= the minimum concentration necessary to prevent movement in 50% of patients in response to skin incision

Question 2

MAC amnesia is

Answer 2

25% MAC = concentration that blocks anterograde memory in 50% of awake patients

Question 3

MAC intubation is

Answer 3

130% MAC= concentration required to prevent movement and coughing during endotracheal intubation

Question 4

Factors that increases MAC include

Answer 4

Age: term infant to 6 months= highest MAC requirement

Chronic ETOH abuse

Question 5

Factors that decrease MAC

Answer 5

Pregnancy
Lithium
Cardiopulmonary Bypass

Question 6

Factors that have no effect on MAC

Answer 6

Thyroid gland dysfunction

Question 7

MAC Values:

Answer 7

Sevo 1.1
Iso 2.2
Des 6.6
N2O 105

Question 8

A high inspired concentration of an agent speeds/slows induction

Answer 8

speeds

Question 9

Increased alveolar ventilation increases/decreases rate of rise of agent and speeds/slows induction

Answer 9

increases

speeds

Question 10

The anesthetic system alveolar uptake of agents depends on

Answer 10

volume, solubility of components, gas flow rates- higher rates speed induction

Question 11

Uptake from alveolar space depends on

Answer 11

solubility, cardiac output, and alveolar/ venous partial pressure difference

Question 12

_______ is the important single factor in determining the speed of induction and the rate of emergence

Answer 12

Solubility

Question 13

Blood Gas Coefficients

Answer 13

Sevo 0.69
Iso 1.43
Des .42
N20 .47
Enflurane 1.8
Halothane 2.3

an increased ratio wants to stay in the blood
a decreased ratio wants to be in the gas phase

Question 14

A poorly soluble agent has a faster/slower inhalation induction and a faster/slower emergence

Answer 14

faster

faster

Question 15

A high cardiac output speeds/slows induction

Answer 15

slows

Question 16

A low cardiac output speeds/slows induction

Answer 16

speeds

Question 17

A large alveolar / venous partial pressure difference with an agent enhances uptake and speeds/slows inhalation induction

Answer 17

speeds

Question 18

The ______________ is the ability of a large volume uptake of a first gas (N2O) to accelerate the rate of rise of the alveolar partial pressure of a concurrently administered companion gas (agent) thus speeding induction

Answer 18

second gas law

Question 19

__________ results from the dilution of alveolar O2 concentration by a large amount of N2O “outgasing” or leaving the pulmonary capillary blood at the conclusion of N20 administration
Rapid desaturation can be seen

Answer 19

Diffusion Hypoxia

Question 20

WHy would you not want to extubate while on 70% N2O?

Answer 20

Diffusion Hypoxia

This is avoided by administering 100% O2 following N2O use

Question 21

N2O is a good ______ that can increase ________. Avoid use of N2O with ________________________. N2O increases PVR especially in patients with __________.

Answer 21

good analgesic
increases PONV
avoid in closed gas spaces, PTX, complete bowel obstruction, inner ear, pneumocephalus, air embolism, intraocular bubbles

pulmonary htn

Question 22

N2O is nonflammable but is an _______ source that __________.

Answer 22

O2

supports combustion

Question 23

In rat experiments with N2O given to pregnant rats for greater than 24 hours, N2O inhibited _________, needed for DNA synthesis. Long term use can lead to __________.

Answer 23

Methionine Synthesis

Peripheral neuropathy and megaloblastic anemia

Question 24

Halothane causes a dose dependent decrease in __________. Halothane contains a ____________ preservative, used for inhalation induction in children which may cause a __________ stimulation, and may see ___________ with a MAC>1, pretreat with __________. Halothane sensitizes the heart to ___________. Use _________ with caution.

Answer 24

contractility
thymol preservative
vagal stimulation
bradycardia
atropine
catecholamines, dysrhythmogenic
use epinephrine with caution

Question 25

Iso/Des increase ______ especially when rapidly increasing dose.

Answer 25

heart rate

Question 26

Desflurane is special in that it is ______ and _______.

Answer 26

heated

kept at 2 atm

Question 27

Iso can cause _____________, where normal coronaries dilate and stenotic ones don’t so blood shunted away from diseased vessels.

Answer 27

Coronary steal syndrome (ISO)

Question 28

Sevoflurane has a nonpungent smell, making it good for __________. Children tolerate __________ of sevo. Sevo allows for __________________ (occasional __________ in children). Can react with soda lime to form ____________. Keep FGF at least ________.

Answer 28

inhalation induction
high levels
rapid induction and emergence
delerium
Compound A
FGF at least 2L/min