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NUNA 681 Pharm II > inhalational agents - MOA, effects on ventilation, and circulation > Flashcards

inhalational agents - MOA, effects on ventilation, and circulation Flashcards

1
Q

what defines anesthesia

A
  • muscle relaxation
  • unconsciousness
  • analgesia
  • suppression of autonomic reflexes
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2
Q

what is absolutely essential according to Eger?

A
  • immobility
  • amnesia
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3
Q

immobility site of action

A

spinal cord

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4
Q

not exactly sure where in the cord, but one suggestion is the _____ _____

A

motor neuron

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5
Q

there is a theory about the effect on receptors - not _____

A

directly

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6
Q

depression of excitatory ______ _____

A

NMDA & AMPA

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7
Q

enhancement of inhibitory -

[in the cord and brainstem]

A

glycine receptors

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8
Q

Na+ ion channels - ________, inhibit release of ________

[Immobility theory]

A

hyperpolarization, inhibit release of glutamate

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9
Q

MOA - immobility theory: site is likely ______ ______ of the membrane

A

lipid portion

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10
Q

meyer-overton hypothesis states

A

that there is a direct correlation between the anesthetic potency and the lipophilicity (oil:gas partition coefficient)

this suggests that the site of action is on the neuronal lipid bilayers

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11
Q

an indirect relationship between _____ and ____ ______ _____ _____

[meyer-overton]

A

MAC
oil:gas partition coefficient

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12
Q

membrane expansion theory (M-O): agent moves into the ______ portion of the lipid bilayer causing a disruption of _________ _______ or ________ ________

A

lipid
synaptic transmission or receptor function

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13
Q

1950s study showed that anesthetized animals could be awakened by ___________ them to _________ which restored the ________ ________ to the preanesthesia density

A

hyperpressurizing them to 100 atm
cell membranes

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14
Q

problem was that some ________ _______ take much higher concentrations than M-O would suggest to cause immobility

A

transitional agents

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15
Q

also, other ______________, never cause immobility although M-O would suggest that it could

A

nonimmobilizers

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16
Q

________ have a greater potency than M-O would suggest

A

alcohol

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17
Q

all three of these have a ______-solubility or ___________ component

A

water-solubility
hydrophilicity

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18
Q

immobility modified theory - anesthetic agents must be ________ and ________ to work on both lipid and water portion of the lipid bilayer membrane

A

lipophilic and hydrophilic

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19
Q

in doing so, inhalation agents change the amount or order of the motion of the lipid constituents. This changes the ______ ________ and the ________ and ________ function

A

surface tension
cellular and membrane

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20
Q

5-angstrom theory - the site of action may actually be _____ _____ of action at either ______ of the molecule

A

2 sites
end

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21
Q

maximum potency is achieved with a molecule ___ _______ long with ____ active sites at each end

A

5 carbons long with 2 active sites at each end

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22
Q

(CF2)

[Immobility-MOA]

A

no anesthetic effect itself

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23
Q

increased potency up to _____ ______, then started ______

[MOA-Immobility]

A

5 carbons
decreasing

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24
Q

amnesia MOA - Not at the

A

spinal cord

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25
Q

possible site:

[MOA-Amnesia]

A

reticular activating system

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26
Q

enhance inhibitory synaptic transmission especially involving ______, the major _______ NT in the brain

A

GABA
inhibitory

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27
Q

hippocampus, ______, ______ _______, and parts of the cerebral ________

[MOA-Amnesia]

A

hippocampus, amygdala, caudate putamen, and parts of the cerebral cortex

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28
Q

_______, inhibitory NT in the cord and brainstem, is ________

A

glycine
enhanced

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29
Q

may be due to inhibition of release of _________ _______, specifically _______.

[MOA-Amnesia]

A

excitatory NTs
glutamate

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30
Q

which may be due to action on _______ _____ _______ or _______ _______ channels

[Inhibition of glutamate]

A

presynaptic Na+ channels or calcium ion channels

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31
Q

MOA - amnesia, unconsciousness, and immobility are not a single continuum of increasing anesthetic depth but rather

A

separate phenomena

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32
Q

analgesia has a biphasic dose response - volatiles at very low concentrations (approx. 10% MAC) increases response to ______ ______ and at higher doses they ________ the response

A

nociceptive pain
decrease

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33
Q

MOA amnesia theory - inhaled agents bind to specific sites on the membranes of _______ as opposed to disrupting ______ ________

A

proteins
lipid bilayers

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34
Q

sites may be _______ and _______ receptors

[MOA amnesia]

A

GABAa and glycine

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35
Q

guedel’s stage 1 (analgesia)

A

ends with loss of eyelash reflex and unconsciousness

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36
Q

guedel’s stage 2 (excitement) - _________ breathing, struggling, ______ _____, susceptible to _________, ________, ________, and ends with the onset of ______ _______ and the loss of _______ reflex

A

irregular breathing, struggling, dilated pupils, susceptible to vomiting, coughing, and laryngospasm. ends with onset of automatic breathing and the loss of eyelid reflex

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37
Q

guedel’s stage 3 is preferred for _____ _____

A

surgical anesthesia

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38
Q

stage 3, plane 1 - until eyes ______ with loss of _______ _________, pupils normal or small, ________ increased, _________ reflex abolished

A

until eyes central with loss of conjunctival reflex, pupils normal or small, lacrimation increased, pharyngeal reflex abolished

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39
Q

stage 3, plan II - until onset of ______ _______, deep regular ________, ________ ________ abolished, loss of _______ reflex, pupils larger

A

intercostal paralysis
breathing
laryngeal reflexes abolished
loss of corneal reflex
pupils larger

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40
Q

stage 3, plane III - until complete ______ ______, shallow _______, _______ depressed

A

intercostal paralysis
shallow breathing
lacrimation depressed

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41
Q

stage 3, plane IV - until _______ _______, _______ reflexes abolished

A

diaphragmatic paralysis, carinal reflexes abolished

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42
Q

guedel’s stage 4 is considered _______

A

overdose

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43
Q

stage 4 involves _____ and ______ ______

A

apnea and dilated pupils

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44
Q

indications that a patient is light:

A
  • lacrimation, tearing
  • tachycardia
  • HTN
  • sweating
  • reactive, dilated pupils
  • movement and laryngospasm
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45
Q

dose related _______ _______

[ventilation]

A

respiratory depression

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46
Q

depress the ventilatory response to an increase in CO2 is

A

dose dependent

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47
Q

depress the ventilatory response to a decrease in oxygenation (oxyhemoglobin saturation) is

A

NOT dose dependent

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48
Q

light anesthesia - _____ ______ and irregular depths and patterns of _________

A

breath holding
breathing

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49
Q

as anesthesia deepens, breathing changes to ________, ______ ______, and smaller _____ ______

A

regular, faster rate, and smaller tidal volumes

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50
Q

At an even deeper plane, ______ ______ _______ fails

A

intercostal muscle function fails

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51
Q

minute ventilation may not change, but ________ _______ decreases with increased _______ _______ ventilation

A

alveolar ventilation
dead space

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52
Q

respiratory rate may be

A

increased

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53
Q

tidal volume is

A

decreased

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54
Q

thus, PaCO2 ________ during spontaneous ventilation in proportion with the ______ in the ________ of _______ ________.

A

increases
increase in the concentration of inhaled agent

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55
Q

the ratio of ____ _____ ventilation to ______ ventilation increases

A

dead space
total

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56
Q

with spontaneous ventilation, the response to increasing _______ is diminished

A

CO2

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57
Q

N2O ______ ______ increase the CO2

A

DOES NOT

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58
Q

if N2O is used and the concentration of volatile is decreased, there is less _______ _______ compared to the equivalent ________ of the volatile alone.

A

ventilatory depression
MAC

(true with all volatiles)

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59
Q

______ patients will likely have an exaggerated increase in PaCO2

A

COPD

60
Q

in an unanesthetized patient, the increased PaCO2 would stimulate ______ _______ ______

A

increased minute ventilation

61
Q

in patients under inhaled anesthesia, that response is _________
[Ventilation]

A

decreased

62
Q

the response curve is shifted to the ______ - it takes a higher ______ to produce an increase in _______

A

right
CO2
MV

63
Q

des and sevo lead to apnea:
[response curve shift to R]

A

between 1.5 and 2.0 MAC

64
Q

with surgical pts, this decreased response may:

A

not be so evident

65
Q

studies have shown that the stimulation of surgery increases _____ ______ by ______ and decreases ________ only by _______

A

minute ventilation by 40%
PaCO2 only by 10%

66
Q

increased production of ______ offsets increased ____

[Surgical patients, vent]

A

CO2
MV

67
Q

inhaled anesthetics also cause depression of the response to _______, when PaO2 falls below ____

A

hypoxemia
55 torr

68
Q

this response is blunted (50-70% depression) by as little as __________ of halothane/iso/sevo
[ventilation/hypoxemia]

A

0.1 MAC

69
Q

1.1 MAC causes _______ depression of hypoxic response

A

100%

70
Q

_____ has less effect on hypoxic drive than other agents

A

Desflurane

71
Q

all agents cause

A

bronchodilation

72
Q

in dogs, halo/iso/sevo prevented the _________ caused by ________

A

bronchoconstriction caused by histamine

73
Q

bronchodilating effect (in order):

A

sevo > iso > des

“Help! SID needs his bronchodilator!”

74
Q

without preexisting bronchoconstriction, airway resistance is

A

essentially unchanged

75
Q

may see ____ ______ in resistance due to low bronchomotor tone normally

A

5% increase

76
Q

Des causes increased

[ventilation]

A

resistance in smokers

77
Q

irritability of airways with des is blunted by prior admin of _____ or ______, addition of ______ also blunts irritability

A

fentanyl 1 mcg/kg
morphine 0.1 mg/kg
N2O

78
Q

_____ and ______ have been given to patients with asthma without causing bronchoconstriction

A

des and sevo

79
Q

airway diameter is reduced due to reduced _____ ______ and reduced ______ _____ keeping small non-cartilaginous airways open

A

lung volumes
elastic forces

80
Q

______ _____ is a bronchial irritant above ______ but does not cause irritation below _____

A

pungent des
6%
6%

81
Q

Airway irritation increases with concentrations greater than ______ ____ ______

A

MAC of iso

82
Q

higher incidences of airway irritation with

A

smokers

83
Q

minimize irritation by premedicating with an ______ (_________)

A

opioid (fentanyl 1.5 mcg/kg)

84
Q

minimize irritation with slower increases in _______ ______

A

desflurane concentrations

85
Q

induction with ________ also minimizes irritation

A

propofol (vs inhaled agent)

86
Q

_________ of inspired gases also helps

A

humidification

87
Q

increases in ________ activity may reflect the effect of airway irritant _____ > ______ / ______

A

mucociliary
des > iso / halothane

88
Q

cause _______ typically but have little effect on ______ ________

[HPV]

A

vasodilation
pulmonary vasculature (HPV)

89
Q

concentrations that are used ________ of inhaled anesthetics ____ _____ prevent HPV

A

clinically
do NOT

90
Q

dose dependent decrease in ______, at 2 MAC the ______ decreases by _______ without surgical stimulation

[cardiac]

A

MAP
BP
50%

91
Q

surgical stimulation _______ ____ _______

[cardiac]

A

minimizes the decrease

92
Q

lower MAP due to changes in _____ ______, _______ ________, and_______ __________ _______

A

cardiac output
venous capacitance
systemic vascular resistance

93
Q

different agents alter

A

BP by different mechanisms

94
Q

substitution of _______ of the volatile agent decreases the extent of the decrease in MAP compared to the same ________ of the volatile alone

A

N2O
MAC concentration

95
Q

decreases in myocardial contractility and CO

A

halothane

96
Q

decrease in SVR causes decrease in BP

A

iso/des/sevo

97
Q

all agents cause ______ ______ to some degree in a dose-dependent manner
[cardiac]

A

myocardial depression

98
Q

calculated _____ _____ _____ decreased 15-30%

A

LV stroke volume

99
Q

halothane causes _______-_________ decrease in ______ in healthy volunteers

A

dose-dependent
CO

100
Q

decreased LV stroke volume may not translate into _____ _______ due to the ______ and decreased _______ caused by des, iso, sevo

A

decreased CO
vasodilation
SVR

101
Q

the decreased myocardial contractility results in a ______-______ reduction in ______ ______

A

dose-dependent reduction in oxygen demand

102
Q

however, excessive concentrations can cause ______ ______

A

CV collapse

103
Q

N2O increase ______ reflecting mild ____________ effects

[cardiac]

A

CO
sympathomimetic

104
Q

all agents but sevo cause increased

A

RAP

105
Q

decreased forward pump causes higher pressures in the _______ ______ or ______ _____

A

venous side or right atrium

106
Q

_______ increases RAP due to increased PVR

A

N2O

107
Q

inhaled agents decrease the resistance to the ______, _______, and the _____; but increase resistance to the ________ system

A

skin, muscles, and the brain
splanchnic

108
Q

inhaled agents are ________ and can be used to our advantage to dilate _________ _______

A

venodilators
peripheral veins (for IV start)

109
Q

they also attenuate __________ r/t sympathetic stimulation

A

vasoconstriction

110
Q

more exaggerated hypotension is seen with ________ patients over ________ patients

A

hypertensive
normotensive

111
Q

they increase peripheral blood flow (muscle and cutaneous) which has multiple effects: (3)

A
  • temp decrease and heat loss r/t vasodilation (increased risk of shivering)
  • better delivery of NMB to NMJ
  • waster perfusion compared to needs
112
Q

isoflurane has a _____ ______ effect

A

beta agonist

113
Q

N2O does not decrease _____ and may actually cause __________ of cutaneous vessels

A

SVR
vasoconstriction

114
Q

little effect of volatile agents on ______ _______

A

pulmonary vasculature

115
Q

N2O causes increased ____ ______ ______

A

pulmonary vascular resistance

116
Q

_______ are vulnerable
[PVR]

A

neonates

117
Q

congenital ______ _____ / ______

[PVR]

A

heart defects / shunts

118
Q

agent specific effect and concentration specific effect for

[Cardiac]

A

heart rate

119
Q

______ increases HR only at concentrations > 1.5 MAC

A

sevo

120
Q

____ and ____ increase HR at a lower concentration

A

Iso and Des

121
Q

________ does not increase HR - conduction effects

A

halothane

122
Q

increases in HR are more frequently seen with _______ patients and accentuated by ______ agents like _______ and __________

A

younger patients
vagolytic agents
atropine and pancuronium

123
Q

_____ activity, ___ ____ firing, and ______ ______ are all affected by inhalational agents

A

ANS activity, SA node firing, and myocardial conduction

124
Q

_____ can alter the increase in HR

A

opioids

125
Q

increased _____ ______ (______) can enhance increased HR

A

sympathetic activity (anxiety)

126
Q

dose-dependent depression of the ______-______ response

A

baroreceptor-reflex

127
Q

some agents _______the baroreceptor-reflex at low concentrations

A

eliminate

128
Q

_____ attenuates baroreceptor response, but doesnt abolish

A

des

129
Q

______ - studies differ - abolishes baroreceptor reflex at 1.25 MAC v some response at 1.5 MAC

A

iso

130
Q

_____ - increasing to 4% (2 MAC) decreases baroreceptor response

A

sevo

131
Q

when BP decreases, there is no ______ _____ of an increase in ______

A

reflex response
HR

132
Q

this impacts us clinically related to ______ _____ or ____ ______ during anesthesia

A

volume loss or position changes

133
Q

coronary vasodilators acting on small coronary arteries can cause shift of blood from _______ to _______ ______

A

ischemic to non ischemic

134
Q

this shift is called

A

coronary steal syndrome

135
Q

however, the syndrome is

A

clinically insignificant unless MAP < 60

136
Q

preconditioning can be done for

A

cardioprotection

137
Q

brief exposure of the myocardium to volatile agents ________ myocardial ischemia results in _______ recovery after reperfusion of ischemic myocardium and reduction in _____ _____

A

before
faster
infarct size

138
Q

similar effect on ______ _______ may provide protection to other side too

A

vascular epithelium

139
Q

_______ as low as 0.25 MAC may be effective

A

iso

140
Q

______ has been shown to be protective for CPB patients

A

sevo

141
Q

brief exposure to volatile agents can activate ____ ______ resulting in cardioprotection

A

K channels

142
Q

reperfusion injury

A

cellular injury caused by reinstitution of the blood flow, not due to ischemia itself

143
Q

signs of reperfusion injury (3)

A

cardiac dysrhythmias, contractile dysfunction, and microvascular injury

144
Q

the protection probably results from an action on ______ ________ ______ ______

A

ATP dependent potassium channels

145
Q

if given during reperfusion, _____ may slightly increase myocardial ATP

A

sevo

NUNA 681 Pharm II (12 decks)

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