Inhalants Flashcards

1
Q

Name the organic inhalants

A

Iso, sevo, des

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2
Q

What kind of inhalant are iso, sevo and des

A

Organic ethers

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3
Q

What kind of inh is halothane

A

Organic aliphatic hydrocarbon

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4
Q

What kind in inh is NO

A

Inorganic

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5
Q

Define halogenation

A

Adding Cl, Br or F

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6
Q

What does halogenation do

A

Decreases reactivity, increases potency, makes non-flammable

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7
Q

Is toxicity still possible with halogenation

A

Yes- esp with F

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8
Q

What effects do Br and Cl have on inh’s

A

Increases potency

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9
Q

Which halogens increase potency

A

Br and Cl

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10
Q

What effect does F have

A

Improves stability (less decomp) but reduces potency and solubility

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11
Q

Halo vs iso

A

halo requires preservative and can cause dysrhythmias but is more potent

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12
Q

What preservative is used in halo

A

Thymol

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13
Q

What inh properties determine administration

A

Vapor pressure, BP, density/SG

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14
Q

What properties determine how inh travel in body

A

Solubility and blood gas partition co-efficient

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15
Q

What can change the physical state of matter of inh

A

motion and degree of intramolecular attraction

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16
Q

Define inh gas

A

Exist in this form at room temp and atmospheric pressure

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17
Q

Which inh is a gas

A

NO

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18
Q

Define inh vapor

A

Exists as liquid at room temp/atmos. pressure

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19
Q

Which inh is a vapor

A

Iso, sevo, des

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20
Q

T/F Vapors and gases have same physical properties

A

Yes- still follow gas laws

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21
Q

Define partial pressure

A

Pressure a gas exerts on walls of closed container

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22
Q

Define dalton’s law

A

Total pressure of a gas mix equals the sum of all of their partial pressures

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23
Q

3 ways to quantify inh’s

A

Pressure (mmHg), **Concentration (%), mass (g or mg)

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24
Q

Does concentration change? Does partial pressure change?

A

Conc changes relative to whole gas mixture or to atmospheric pressure; partial pressure is absolute value

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25
Q

Describe changes in vol%

A

Vol % changes in response to atmospheric pressure and may be different in different body compartments

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26
Q

Define vapor pressure

A

Pressure molecules exert when liquid and vapor phases are in equilibrium

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27
Q

Define saturated vapor pressure

A

Max concentration of molecules in vapor state for a liquid at a certain temp

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28
Q

Gas vs vapor differences in administration amounts

A

Gas administered from a % concentration, vapor is delivered as a max concentration that depends on saturated vapor pressure

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29
Q

As temp decreases, vapor pressure ________

A

decreases

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30
Q

Why does vapor pressure decrease with temp-

A

Cooling (rather than evap) decreases delivered vapor concentration due to decreased vapor pressure

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31
Q

Define BP

A

Temp where vapor pressure = atmos temp

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32
Q

BP decreases as altitude _________

A

Increases

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33
Q

What is the BP of des

A

Close to room temp

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34
Q

Rank inh’s by BP low to high

A

Des

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35
Q

Which inh has the highest vapor pressure

A

Des

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36
Q

Iso in sevo vaporizer - what happens

A

Iso vapor pressure 238 is greater than sevo 157, overdose likely due to more iso being delivered

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37
Q

Inh vapor pressures (actual and rank low to high)

A

Iso- 238; Sevo- 157; des- 669; halo- 243;

Sevo

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38
Q

Def inh solubility, how is it expressed

A

Total number of gas molecules dissolved into a solvent- Blood: gas partition coefficient

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39
Q

What factors influence solubility (3)

A

Molecular weight of gas, chem nature of solvent, partial pressure gradient between gas and solvent

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40
Q

Does solubility change with temp?

A

Yes

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41
Q

Partition coefficient of 2% blood and 1% gas

A

2.0 (blood:gas)

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42
Q

Partition coefficient of 1% blood and 2% gas

A

0.5 (blood:gas)

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43
Q

What does partition coefficient predict

A

Speed of induction, recovery, change in depth

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44
Q

_______ (lower/higher) B:G PC = faster onset and recovery

A

Lower

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45
Q

The majority of modern inhs are

A

halogenated organic vapors

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46
Q

What determines how many molecules of inhalant are available to produce anesthesia

A

Vapor pressure

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47
Q

What determines max concentration of inhalant that can be delievered

A

Saturated vapor pressure

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48
Q

What determines speed of onset and recovery

A

Solubility

49
Q

Temperature effects ____ and _______

A

Vapor pressure and solubility

50
Q

B:G PC determines

A

% inhalant in blood vs alveoli when partial pressure between compartments are in equilibrium

51
Q

Which in (iso, sevo, des, NO) has fastest onset (also, rank)

A

NO (0.41) > Des (0.45) > Sevo (0.68) > Iso (1.4)

52
Q

3 theories of mech of action

A

Altering structure of membrane proteins by binding, prevention of GABA breakdown (neurotransmission), meyer-overton - distortion of CNS membrane proteins via agents occupying hydrophobic regions

53
Q

What are the principal sites of action

A

Brain (amnesia) and spinal cord (immobility)

54
Q

What produces anesthesia

A

Partial pressure of anesthetic in brain and spinal cord

55
Q

What is potency

A

Dose required to reach desired effect

56
Q

Does potency equal efficacy

A

No

57
Q

MAC

A

Minimum alveolar concentration - the min that prevents purposeful gross movement in 50% pf patients; describes the dose of anesthetic being delivered

58
Q

MAC =

A

ED50

59
Q

1/MAC =

A

Potency - higher the mac, lower the potency

60
Q

MAC of iso in dogs/ most mammals

A

1.3 %

61
Q

MAC of sevo

A

2.5%

62
Q

Which is more potent- iso or sevo

A

Iso

63
Q

NO MAC in animals vs people

A

Much higher in animals (115% to 200%)- NO can’t be used as sole agent in animals- but helps decrease MAC of other inh

64
Q

Factors effecting Mac

A

Age, disease, other drugs

65
Q

Define MAC bar-

A

Prevent baroreflector reflex (changes in HR or BP)

66
Q

MAC awake-

A

Concentration needed where person will respond to verbal commants

67
Q

How does temp effect MAC

A

colder - need less (decreased MAC)

68
Q

What 5 factors do not effect MAC

A

Gender, time of anesthesia, acidosis/alkalosis, anemia, respiratory gas concentration

69
Q

Inc or decrease MAC ? Hyperthermia

A

Inc

70
Q

Inc or decrease MAC ? Hypotension

A

Dec

71
Q

Inc or decrease MAC ? Excitatory neurotransmitters

A

Increase

72
Q

Inc or decrease MAC ? CNS stimulating drugs

A

Increase

73
Q

Inc or decrease MAC ? Other anesthetics

A

Decrease

74
Q

Inc or decrease MAC ? Pregnancy

A

Decrease

75
Q

Inc or decrease MAC ? Hypernatremia

A

Increase

76
Q

What PaO2 will decrease MAC

A

below 40 and above 90

77
Q

Does age effect MAC? how?

A

Decreased with increased age

78
Q

How do inh’s get delivered to action site for anesthesia

A

Movement along partial pressure gradient

79
Q

What produces anesthesia in the brain- partial pressure or concentration

A

Partial pressure

80
Q

Brain partial pressure moves towards or away from alveolar

A

Towards

81
Q

Brain partial pressure equilibrates quickly or slowly with alveolar partial pressure

A

Quickly

82
Q

Delivery is _____ to alveoli

A

Input

83
Q

Uptake is ____ from alveoli

A

Loss

84
Q

What is the depot and delivery agent to site of action

A

Blood

85
Q

Define uptake

A

Inhalants removed from alveoli by pulmonary blood

86
Q

What 3 factors influence uptake

A

Solubility, cardiac output, alveolar-venous anesthetic partial pressure difference

87
Q

Delivery depends on (2)

A

Inspired anesthetic concentration and alveolar ventilation

88
Q

What effects whether the agent will remain in the blood

A

Solubility

89
Q

Less or more soluble agents readily leave blood to reach equilibrium in tissues

A

Less

90
Q

Less or more soluble is more reluctant to leave blood

A

More

91
Q

Low B:G PC leads to

A

Rapid induction, precise depth, rapid elimination

92
Q

Increased CO =

A

Greater amount of blood carrying inhalant from alveoli to tissue

93
Q

Increased CO =

A

Less blood through lungs to remove anesthetic

94
Q

T/F some inh will remain in venous blood

A

T

95
Q

What must exist for uptake to occur

A

P_A - P_V gradient

96
Q

What effect does decreasing alveolar partial pressure have on gradient

A

Reverses gradient from blood to alveoli so elimination can leave through lungs

97
Q

What three factors effect elimination-

A

Solubility, CO and duration of anesthesia

98
Q

Less solubility will eliminate less/more quickly

A

more

99
Q

An inhalant which is more soluble will induce quicker or slower induction than a less soluble

A

Slower- more soluble will want to stay in blood more

100
Q

T/F MAC is a measure of potency

A

T

101
Q

T/F MAC is a measure of speed of induction

A

FALSE

102
Q

T/F MAC is additive among multiple inhalants

A

T

103
Q

Metabolism of sevo leads to

A

Compound A toxic metabolite

104
Q

Metabolism of iso/des/enflurane leads to

A

Carbon monoxide metabolite

105
Q

Inh decrease or increase cerebral blood flow? How?

A

Increase (decreased ventilation leads to increased CO2 leads to vasodilation, inh also leads to vasodilation of intracranial vessels)

106
Q

Inh effect on ICP

A

Increase- parallels increase in CBF

107
Q

All inhalants inc/dec CO? Why?

A

Increase - negative inotropic effect, decrease peripheral resistance (dec BP)

108
Q

Increased ICP will occur at what level

A

Above 1 MAC

109
Q

Two effects of inh on cardio system

A

Negative inotrope, decreased BP through decreased peripheral resistance

110
Q

Describe the pulmonary effects of inh

A

Dose related decrease in ventilation- pressure in brain increases, leading to decreased ventiliation, which leads to decreased uptake, which lowers brain pressure

111
Q

Increase in inh dose leads to inc/dec of spontaneous ventilation

A

Dec

112
Q

Increase in inh dose leads to inc/dec of arterial CO2

A

Inc

113
Q

Where does respiratory arrest occur

A

MAC 1.5-3

114
Q

Decreased CO has what effect on liver

A

Decreased flow, decreased metabolism of co-administered drugs

115
Q

What inhalant is most likely to miantain hepatic blood flow

A

Iso

116
Q

Describe malignant hyperthermia

A

Increase in CO2, very hot- blocks Ca outflow due to RYR1- muscle contraction

117
Q

Breeds affected by malignant hyperthermia

A

Swine, greyhounds

118
Q

Tx for malignant hyperthermia

A

Dantrolene sodium muscle relaxant