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NUNA 681 Pharm II > inhalational agents - history and MAC > Flashcards

inhalational agents - history and MAC Flashcards

1
Q

ideal inhaled anesthetic characteristics:

A
  • nonflammable
  • easily vaporized at ambient temperature
  • potent
  • low blood solubility to assure rapid induction and recovery from anesthesia
  • minimal metabolism
  • compatible with epinephrine
  • skeletal muscle relaxation
  • suppresses excessive sympathetic nervous system activity
  • not irritating to airways
  • bronchodilation
  • absence of excessive myocardial depression
  • absence of cerebral vasodilation
  • absence of hepatic and renal toxicity
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2
Q

the modern drugs were possible because with the _________ ________, development of the ________ _______, came advances in discoveries ________ _______.

A

manhattan project
atomic bomb
in fluorine chemistry

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3
Q

after 1950, all introduced drugs except ____ ______ ______ have contained _______

A

ethyl vinyl ether
fluorine

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4
Q

first of the modern agents was ______, but limited use due to ______

A

Fluroxene
PONV

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5
Q

halothane - an alkane - advantages:

A

nonflammable
less pungent
less soluble
decreased toxicity

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6
Q

halothane - an alkane - disadvantages:

A

decreased CO
increased arrhythmias
(hepatotoxicity)

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7
Q

enflurane - methyl ethyl ether

[Discovery #]

A

still has chlorine #347

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8
Q

isoflurane -

A

isomer #469

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9
Q

desflurane #653 - couldnt be used in ______ _______ due to its ______ _______ near atmospheric pressure at 699 and ______ ________ making it more expensive

A

conventional vaporizers
vapor pressure
low potency

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10
Q

sevoflurane - no perceived need, more __________ and _______ to synthesize

A

expensive
difficult

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11
Q

effects of increased fluorination

A
  • nonflammable
  • decreased solubility (main advantage)
  • decreased potency/increased MAC
  • less toxic due to resistance to degradation: desflurane = yes, sevoflurane = no
  • decreased percentage metabolized
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12
Q

MAC

A

minimal alveolar concentration (partial pressure) of an inhaled agent at 1 atm that prevents skeletal muscle movement in response to a noxious stimulus in 50% of patients

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13
Q

10-30% greater concentration than MAC produces immobility in

A

90-95% of patients

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14
Q

why 50% immobile versus 95% immobile?

A

less variability
takes fewer subjects to determine MAC

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15
Q

what portion of the CNS determines MAC?

A
  • spinal cord excitability is decreased resulting in immobility
  • perfusion of the brain alone with ordinary concentrations does NOT produce immobility (took up 3-6X MAC)
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16
Q

alveolar reflects the _______ at the ______ or the ______ most accurately

A

concentration at the cord or the brain

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17
Q

must allow for ____________ (generally about ____-____ minutes)

A

equilibration
10-15 minutes

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18
Q

dependent on agent -

[alveolar reflects concentration at cord or brain]

A

3-4 time constants

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19
Q

as age increases,

A

MAC decreases about 6% per decade

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20
Q

N2O decreases MAC in ____ _____, but more so the ______

A

all ages
the elderly

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21
Q

MAC is greatest in patients less than _____________ and decreases by nearly ________ in the elderly years

A

less than a year of age
50%

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22
Q

MAC greatest to least populations

A

infants > children > neonates > adults

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23
Q

reduction caused by __________ is further enhanced with _______ patients

A

N2O
older

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24
Q

___% N2O causes about a ___% reduction in MAC normally - more so in the ________

A

60%
60%
elderly

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25
Q

____ __________ reduction causes MAC reduction

A

body temp

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26
Q

MAC of __________ is decreased almost in half by a 10 degree C decrease in temp

A

desflurane

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27
Q

MAC of _______ is not as affected

[w/body temp reduction]

A

N2O

28
Q

pregnancy ________ MAC due to increased concentrations of _________

A

decreases
progesterone

29
Q

MAC decreases nearly ______ through early postpartum, normalizing within ____-____ _____

A

30%
12-72 hours

30
Q

Decreased CNS Na leads to _______ MAC

A

decreased

31
Q

possible CNS Na causes:

A

dehydration, absorption of irrigant

32
Q

MAC and opioid effects

A

synergistic effect

33
Q

_____ dose opioids (fent 3mcg/kg) cause ____ decrease in MAC

A

small dose opioids
big decrease in MAC

34
Q

opioids have a

A

ceiling effect on MAC

35
Q

benzos cause a

A

dose dependent decrease in MAC

36
Q

barbiturates, propofol, and acute ETOH ingestion cause

A

decrease in MAC

37
Q

local anesthetics

A

lidocaine IV decreases MAC

38
Q

N2O - 0.5 MAC of N2O + 0.5 MAC of isoflurane are __________ to ___ MAC of either drug alone

A

additive
1 MAC

39
Q

_________ and ________ decrease MAC by decreasing CNS catecholamines and by hyperpolarization of CNS membranes

A

clonidine and precedex

40
Q

some ______ _______ and some _______ _______ decrease MAC
[drug classes]

A

beta blockers
calcium-channel blockers

41
Q

Adensosine

A

decreases MAC

42
Q

factors that decrease MAC (4)

A
  • neuraxial opioids
  • PaO2 < 38mmHg
  • BP < 40 mmHg
  • cardiopulmonary bypass
43
Q

red hair

A

increased MAC due to excess pheomelanin production - 19%

44
Q

drug induced increases in CNS catecholamine levels:

A

cocaine, ketamine, amphetamines

45
Q

_______ and _______ increase MAC

A

hyperthermia and hypernatremia

46
Q

factors that do NOT alter MAC

A
  • gender
  • duration of anesthesia *iso decreases
  • body mass
  • arterial PaO2 > 50 mmHg
  • arterial PaCO2 < 80 mmHg
  • hematocrit > 10%
  • BP > 40 mmHg
47
Q

loss of ________ and the __________ (MAC) are not a “single continuum of increasing anesthetic depth but rather two separate phenomena”

A

consciousness and the immobility

48
Q

MACawake

A

the average of the concentrations immediately above and below those permitting voluntary response to command

49
Q

MACawake usually exceeds ___________

A

MACamnesia

50
Q

MACawake is affected by _____ (______) and ______ ______

A

age (decreases) and inhalation agent

51
Q

the ratio of MACawake/MAC is not affected by age as _____ _______

A

both decrease

52
Q

for des/iso/sevo, MACawake is about

A

1/3 of MAC

53
Q

for halothane, MACawake is more than

A

50% of MAC

54
Q

for N2O, MACawake is more than

A

60% of MAC

55
Q

comparison of MACawake/MAC is important. the higher the ratio, the ______ ___ ______, and the higher the ratio, the poorer the ______ _______

A

the faster the recovery
the poorer the amnestic value

56
Q

low dose opioids (2-3 mcg/kg of fent) minimally affects _________. however, it does bring MAC down so the ratio of MACawake/MAC becomes higher and awakening should be more _______.

A

MACawake
quickly

57
Q

MACawake does not ensure return of ______ ______ ______ or return of ________ ________

A

esophageal sphincter tone or return of pharyngeal fxn

58
Q

concentrations of inhaled agent may require levels of less then _________ for patient safety

A

0.1 MAC

59
Q

_________ ________ is impaired even at very low concentration - lower than MAC awake.

A

sphincter tone

60
Q

MACte - to allow for ______ ______

A

tracheal stimulation

61
Q

MACte - no _________ or _________ during suctioning of pharynx

A

coughing or bucking

62
Q

MACte - no movement or coughing within ___ ____ of ______

A

1 minute of extubation

63
Q

MACte is equal to or _______ MAC

A

exceeds

64
Q

MACbar - minimum alveolar concentration that ______ _______ _______ to surgical stimulus

A

Blocks Autonomic Responses

65
Q

with 60% N2O - des 1.3 MAC (________) - iso so 1.3 MAC (______)

A

des (1.9 MAC total)
iso (1.9 MAC total)

66
Q

fentanyl of 1.5-3mcg/kg decreases it to 0.4 MAC (des) ________MAC total and 0.55 MAC (iso) ________MAC total.

[w/ 60% nitrous oxide]

A

des 1.0 MAC total
iso 1.15 MAC total

67
Q

sevo 2.2 MAC (“less potent”) - with 67% N2O, _______ (2.2 MAC total) - with fent 3mcg/kg alone decreases it by ______

A

1.45 MAC
83%

[the info here is incorrect and she acknowledged that this info is an error]
MAC should be 1.53
The percentage is off as well!

NUNA 681 Pharm II (12 decks)

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