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

inhalational agents - history and MAC Flashcards

(67 cards)

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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
____ __________ reduction causes MAC reduction
body temp
26
MAC of __________ is decreased almost in half by a 10 degree C decrease in temp
desflurane
27
MAC of _______ is not as affected [w/body temp reduction]
N2O
28
pregnancy ________ MAC due to increased concentrations of _________
decreases progesterone
29
MAC decreases nearly ______ through early postpartum, normalizing within ____-____ _____
30% 12-72 hours
30
Decreased CNS Na leads to _______ MAC
decreased
31
possible CNS Na causes:
dehydration, absorption of irrigant
32
MAC and opioid effects
synergistic effect
33
_____ dose opioids (fent 3mcg/kg) cause ____ decrease in MAC
small dose opioids big decrease in MAC
34
opioids have a
ceiling effect on MAC
35
benzos cause a
dose dependent decrease in MAC
36
barbiturates, propofol, and acute ETOH ingestion cause
decrease in MAC
37
local anesthetics
lidocaine IV decreases MAC
38
N2O - 0.5 MAC of N2O + 0.5 MAC of isoflurane are __________ to ___ MAC of either drug alone
additive 1 MAC
39
_________ and ________ decrease MAC by decreasing CNS catecholamines and by hyperpolarization of CNS membranes
clonidine and precedex
40
some ______ _______ and some _______ _______ decrease MAC [drug classes]
beta blockers calcium-channel blockers
41
Adensosine
decreases MAC
42
factors that decrease MAC (4)
- neuraxial opioids - PaO2 < 38mmHg - BP < 40 mmHg - cardiopulmonary bypass
43
red hair
increased MAC due to excess pheomelanin production - 19%
44
drug induced increases in CNS catecholamine levels:
cocaine, ketamine, amphetamines
45
_______ and _______ increase MAC
hyperthermia and hypernatremia
46
factors that do NOT alter MAC
- gender - duration of anesthesia *iso decreases - body mass - arterial PaO2 > 50 mmHg - arterial PaCO2 < 80 mmHg - hematocrit > 10% - BP > 40 mmHg
47
loss of ________ and the __________ (MAC) are not a "single continuum of increasing anesthetic depth but rather two separate phenomena"
consciousness and the immobility
48
MACawake
the average of the concentrations immediately above and below those permitting voluntary response to command
49
MACawake usually exceeds ___________
MACamnesia
50
MACawake is affected by _____ (______) and ______ ______
age (decreases) and inhalation agent
51
the ratio of MACawake/MAC is not affected by age as _____ _______
both decrease
52
for des/iso/sevo, MACawake is about
1/3 of MAC
53
for halothane, MACawake is more than
50% of MAC
54
for N2O, MACawake is more than
60% of MAC
55
comparison of MACawake/MAC is important. the higher the ratio, the ______ ___ ______, and the higher the ratio, the poorer the ______ _______
the faster the recovery the poorer the amnestic value
56
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 _______.
MACawake quickly
57
MACawake does not ensure return of ______ ______ ______ or return of ________ ________
esophageal sphincter tone or return of pharyngeal fxn
58
concentrations of inhaled agent may require levels of less then _________ for patient safety
0.1 MAC
59
_________ ________ is impaired even at very low concentration - lower than MAC awake.
sphincter tone
60
MACte - to allow for ______ ______
tracheal stimulation
61
MACte - no _________ or _________ during suctioning of pharynx
coughing or bucking
62
MACte - no movement or coughing within ___ ____ of ______
1 minute of extubation
63
MACte is equal to or _______ MAC
exceeds
64
MACbar - minimum alveolar concentration that ______ _______ _______ to surgical stimulus
Blocks Autonomic Responses
65
with 60% N2O - des 1.3 MAC (________) - iso so 1.3 MAC (______)
des (1.9 MAC total) iso (1.9 MAC total)
66
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]
des 1.0 MAC total iso 1.15 MAC total
67
sevo 2.2 MAC ("less potent") - with 67% N2O, _______ (2.2 MAC total) - with fent 3mcg/kg alone decreases it by ______
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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