MAC

Question 1

2 main differences in modern anesthetics from ether/chloroform/nitrous?

Answer 1

fluorinated and nonflammable

Question 2

why do we like low solubility of volatile agents?

Answer 2

low solubility means drug wants to stay in gas form in alveoli rather than moving to blood so med reaches side of effect and is able to be blown off
[we want these in gas form so they work]

Question 3

What is added to decrease flammability of ether?

Answer 3

halogens - fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts).

Question 4

what halogen is in all modern anesthetics

Answer 4

flourine

Question 5

advantages of halothane compared to ether?

Answer 5

nonflammable, less pungent, less soluble (quicker off), less toxic

Question 6

disadvantages of halothane compared to ether?

Answer 6

decrease CO, increased arrythmias, hepatotoxic

Question 7

main advantage of flourination?

Answer 7

decreased solubility
[dont want these meds to hang on]

Question 8

effects of increased flourination?

Answer 8

1. nonflammable
2. decreased solubility
3. decreased potency
4. less toxic r/t degradation
5. decreased % metabolized

Question 9

list inhaled anesthetics

Answer 9

nitrous, halothane, enflurane, isoflurane, desflurane. sevoflurane

Question 10

list volatile anesthetics

Answer 10

halothane, enflurane, isoflurane, desflurane, sevoflurane

Question 11

explain MAC

Answer 11

minimum alveolar concentration of inhaled agent that prevents mvmt in response to stimulus in 50% of patients

Question 12

how are MAC and potency related

Answer 12

higher the MAC, lower the potency
lower the MAC, higher the potency

Question 13

How to do you get to a MAC of 95% or ED95?

Answer 13

multiply MAC by 1.3

[ex: sevo MAC 1.8 so ED95 is 2.34]

Question 14

What determines MAC?

Answer 14

spinal cord

Question 15

Why do we use alveolar concentration?

Answer 15

it reflects concentration at cord and brain more accurately r/t equilibration

Question 16

law of overpressurization?

Answer 16

Henry’s

Question 17

how does age alter MAC?

Answer 17

as age increases, MAC decreases [6% per decade] meaning: increased age, less drug given to produce immobility

Question 18

What does nitrous do to MAC?

Answer 18

decreases MAC in all ages, especially geri

Question 19

list MAC by age from highest MAC to lowest MAC

Answer 19

infants - children - neonates - adults

Question 20

60% nitrous causes how much of a reduction in MAC?

Answer 20

60%

Question 21

how does body temp affect MAC?

Answer 21

decreased body temp causes decreased MAC
[hypothermia basically anesthesia]
[lower body temp causes vapors to hang on]

Question 22

Why does pregnancy decrease MAC?

Answer 22

progesterone, decreases 30% thru early postpartum then normalizes 12-72 hours

Question 23

What does low sodium do to MAC?

Answer 23

decreases! Low sodium is CNS depressant.

Question 24

What medications decrease MAC?

Answer 24

-opioids (ceiling effect)
-benzos dd
-barbiturates
-prop
-acute ETOH
-LA

Question 25

how much does small dose fentanyl decrease MAC of des?

Answer 25

50% but not dd. ceiling effect so won't see a big decrease with additional dosing

Question 26

Other drugs used that decrease MAC?

Answer 26

-clonidine and precedex -some BB -some CCB -adenosine

Question 27

how to clonidine and precedex decrease MAC?

Answer 27

by decreasing CNS catecholamines (norepi) and hyperpolarization of cns cell membranes

Question 28

Factors that decrease MAC?

Answer 28

neuraxial opioids pao2 <38 mmhg bp <40 mmhg cardiopulm bypass

Question 29

Factors that increase MAC

Answer 29

red hair increased cns catecholamines (cocaine, amphet, ketamine) hyperthermia hypernatremia

Question 30

why does red hair increase MAC?

Answer 30

pheomelanin production (19%)

Question 31

factors that do NOT alter MAC?

Answer 31

gender duration of anesthesia body mass pao2 >50 paco2 <80 hematocrit >10 bp > 40

Question 32

explain MAC awake

Answer 32

% MAC where pt can move and FOLLOW COMMANDS

Question 33

Nitrous MAC and MAC awake

Answer 33

MAC 104% MAC awake .64

Question 34

halothane MAC and MAC awake

Answer 34

MAC .76% MAC awake 55%

Question 35

isoflurane MAC and MAC awake

Answer 35

1.17% awake 38% of MAC

Question 36

desflurane MAC and MAC awake

Answer 36

MAC 6.6% awake 34% of MAC

Question 37

sevoflurane MAC and MAC awake

Answer 37

1.8% awake 34% of MAC

Question 38

explain trend of ratio of MAC awake

Answer 38

the higher the ratio number, the shorter the distance between MAC and MAC awake and the quicker patient will be able to follow commands. Lower the ratio, more drug you will have to get out of system in order for pt to follow commands.

Question 39

explain ratio MAC and MAC awake and amnesia

Answer 39

the higher the ratio number (nitrous) the worse amnestic drug is and the quicker the patient will wake

Question 40

list different MACs from highest to lower

Answer 40

MAC bar MAC te MAC MAC awake MAC amnesia

Question 41

what % MAC of halothane is MAC awake

Answer 41

50%

Question 42

what % MAC of nitrous is MAC awake?

Answer 42

60% [poor amnestic]

Question 43

1/3 of MAC is MAC awake with these three drugs

Answer 43

isoflurane, sevoflurane, desflurane

Question 44

the higher the ratio the..

Answer 44

faster the recovery worse the amnestic

Question 45

how do low dose opioids affect MAC awake?

Answer 45

minimally affects MAC awake, but does decrease MAC so the ratio increases and awakening should be quicker

Question 46

very important concept to know about MAC awake?

Answer 46

does not ensure return of esophageal sphincter tone or pharyngeal function, cannot always protect a/w

Question 47

what concentration of inhaled agent provides pt safety?

Answer 47

less than .1 MAC

Question 48

What is MAC te

Answer 48

MAC that will not allow tracheal stimulation to occur, exceeds or equal to MAC

Question 49

what is MAC bar?

Answer 49

blocks autonomic responses to surgical stimulus

Question 50

MAC bar of des with and w/o 60% nitrous

Answer 50

1.3 with 1.9 w/o add fent .4 and 1

Question 51

MAC bar of iso with and w/o 60% nitrous

Answer 51

1.3 with 1.9 w/o add fent and .55 and 1.15

Question 52

mac bar of sevo

Answer 52

2.2 of MAC