Inhalants Flashcards
(118 cards)
1
Q
Name the organic inhalants
A
Iso, sevo, des
2
Q
What kind of inhalant are iso, sevo and des
A
Organic ethers
3
Q
What kind of inh is halothane
A
Organic aliphatic hydrocarbon
4
Q
What kind in inh is NO
A
Inorganic
5
Q
Define halogenation
A
Adding Cl, Br or F
6
Q
What does halogenation do
A
Decreases reactivity, increases potency, makes non-flammable
7
Q
Is toxicity still possible with halogenation
A
Yes- esp with F
8
Q
What effects do Br and Cl have on inh’s
A
Increases potency
9
Q
Which halogens increase potency
A
Br and Cl
10
Q
What effect does F have
A
Improves stability (less decomp) but reduces potency and solubility
11
Q
Halo vs iso
A
halo requires preservative and can cause dysrhythmias but is more potent
12
Q
What preservative is used in halo
A
Thymol
13
Q
What inh properties determine administration
A
Vapor pressure, BP, density/SG
14
Q
What properties determine how inh travel in body
A
Solubility and blood gas partition co-efficient
15
Q
What can change the physical state of matter of inh
A
motion and degree of intramolecular attraction
16
Q
Define inh gas
A
Exist in this form at room temp and atmospheric pressure
17
Q
Which inh is a gas
A
NO
18
Q
Define inh vapor
A
Exists as liquid at room temp/atmos. pressure
19
Q
Which inh is a vapor
A
Iso, sevo, des
20
Q
T/F Vapors and gases have same physical properties
A
Yes- still follow gas laws
21
Q
Define partial pressure
A
Pressure a gas exerts on walls of closed container
22
Q
Define dalton’s law
A
Total pressure of a gas mix equals the sum of all of their partial pressures
23
Q
3 ways to quantify inh’s
A
Pressure (mmHg), **Concentration (%), mass (g or mg)
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
25
Describe changes in vol%
Vol % changes in response to atmospheric pressure and may be different in different body compartments
26
Define vapor pressure
Pressure molecules exert when liquid and vapor phases are in equilibrium
27
Define saturated vapor pressure
Max concentration of molecules in vapor state for a liquid at a certain temp
28
Gas vs vapor differences in administration amounts
Gas administered from a % concentration, vapor is delivered as a max concentration that depends on saturated vapor pressure
29
As temp decreases, vapor pressure ________
decreases
30
Why does vapor pressure decrease with temp-
Cooling (rather than evap) decreases delivered vapor concentration due to decreased vapor pressure
31
Define BP
Temp where vapor pressure = atmos temp
32
BP decreases as altitude _________
Increases
33
What is the BP of des
Close to room temp
34
Rank inh's by BP low to high
Des
35
Which inh has the highest vapor pressure
Des
36
Iso in sevo vaporizer - what happens
Iso vapor pressure 238 is greater than sevo 157, overdose likely due to more iso being delivered
37
Inh vapor pressures (actual and rank low to high)
Iso- 238; Sevo- 157; des- 669; halo- 243;
Sevo
38
Def inh solubility, how is it expressed
Total number of gas molecules dissolved into a solvent- Blood: gas partition coefficient
39
What factors influence solubility (3)
Molecular weight of gas, chem nature of solvent, partial pressure gradient between gas and solvent
40
Does solubility change with temp?
Yes
41
Partition coefficient of 2% blood and 1% gas
2.0 (blood:gas)
42
Partition coefficient of 1% blood and 2% gas
0.5 (blood:gas)
43
What does partition coefficient predict
Speed of induction, recovery, change in depth
44
_______ (lower/higher) B:G PC = faster onset and recovery
Lower
45
The majority of modern inhs are
halogenated organic vapors
46
What determines how many molecules of inhalant are available to produce anesthesia
Vapor pressure
47
What determines max concentration of inhalant that can be delievered
Saturated vapor pressure
48
What determines speed of onset and recovery
Solubility
49
Temperature effects ____ and _______
Vapor pressure and solubility
50
B:G PC determines
% inhalant in blood vs alveoli when partial pressure between compartments are in equilibrium
51
Which in (iso, sevo, des, NO) has fastest onset (also, rank)
NO (0.41) > Des (0.45) > Sevo (0.68) > Iso (1.4)
52
3 theories of mech of action
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
What are the principal sites of action
Brain (amnesia) and spinal cord (immobility)
54
What produces anesthesia
Partial pressure of anesthetic in brain and spinal cord
55
What is potency
Dose required to reach desired effect
56
Does potency equal efficacy
No
57
MAC
Minimum alveolar concentration - the min that prevents purposeful gross movement in 50% pf patients; describes the dose of anesthetic being delivered
58
MAC =
ED50
59
1/MAC =
Potency - higher the mac, lower the potency
60
MAC of iso in dogs/ most mammals
1.3 %
61
MAC of sevo
2.5%
62
Which is more potent- iso or sevo
Iso
63
NO MAC in animals vs people
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
Factors effecting Mac
Age, disease, other drugs
65
Define MAC bar-
Prevent baroreflector reflex (changes in HR or BP)
66
MAC awake-
Concentration needed where person will respond to verbal commants
67
How does temp effect MAC
colder - need less (decreased MAC)
68
What 5 factors do not effect MAC
Gender, time of anesthesia, acidosis/alkalosis, anemia, respiratory gas concentration
69
Inc or decrease MAC ? Hyperthermia
Inc
70
Inc or decrease MAC ? Hypotension
Dec
71
Inc or decrease MAC ? Excitatory neurotransmitters
Increase
72
Inc or decrease MAC ? CNS stimulating drugs
Increase
73
Inc or decrease MAC ? Other anesthetics
Decrease
74
Inc or decrease MAC ? Pregnancy
Decrease
75
Inc or decrease MAC ? Hypernatremia
Increase
76
What PaO2 will decrease MAC
below 40 and above 90
77
Does age effect MAC? how?
Decreased with increased age
78
How do inh's get delivered to action site for anesthesia
Movement along partial pressure gradient
79
What produces anesthesia in the brain- partial pressure or concentration
Partial pressure
80
Brain partial pressure moves towards or away from alveolar
Towards
81
Brain partial pressure equilibrates quickly or slowly with alveolar partial pressure
Quickly
82
Delivery is _____ to alveoli
Input
83
Uptake is ____ from alveoli
Loss
84
What is the depot and delivery agent to site of action
Blood
85
Define uptake
Inhalants removed from alveoli by pulmonary blood
86
What 3 factors influence uptake
Solubility, cardiac output, alveolar-venous anesthetic partial pressure difference
87
Delivery depends on (2)
Inspired anesthetic concentration and alveolar ventilation
88
What effects whether the agent will remain in the blood
Solubility
89
Less or more soluble agents readily leave blood to reach equilibrium in tissues
Less
90
Less or more soluble is more reluctant to leave blood
More
91
Low B:G PC leads to
Rapid induction, precise depth, rapid elimination
92
Increased CO =
Greater amount of blood carrying inhalant from alveoli to tissue
93
Increased CO =
Less blood through lungs to remove anesthetic
94
T/F some inh will remain in venous blood
T
95
What must exist for uptake to occur
P_A - P_V gradient
96
What effect does decreasing alveolar partial pressure have on gradient
Reverses gradient from blood to alveoli so elimination can leave through lungs
97
What three factors effect elimination-
Solubility, CO and duration of anesthesia
98
Less solubility will eliminate less/more quickly
more
99
An inhalant which is more soluble will induce quicker or slower induction than a less soluble
Slower- more soluble will want to stay in blood more
100
T/F MAC is a measure of potency
T
101
T/F MAC is a measure of speed of induction
FALSE
102
T/F MAC is additive among multiple inhalants
T
103
Metabolism of sevo leads to
Compound A toxic metabolite
104
Metabolism of iso/des/enflurane leads to
Carbon monoxide metabolite
105
Inh decrease or increase cerebral blood flow? How?
Increase (decreased ventilation leads to increased CO2 leads to vasodilation, inh also leads to vasodilation of intracranial vessels)
106
Inh effect on ICP
Increase- parallels increase in CBF
107
All inhalants inc/dec CO? Why?
Increase - negative inotropic effect, decrease peripheral resistance (dec BP)
108
Increased ICP will occur at what level
Above 1 MAC
109
Two effects of inh on cardio system
Negative inotrope, decreased BP through decreased peripheral resistance
110
Describe the pulmonary effects of inh
Dose related decrease in ventilation- pressure in brain increases, leading to decreased ventiliation, which leads to decreased uptake, which lowers brain pressure
111
Increase in inh dose leads to inc/dec of spontaneous ventilation
Dec
112
Increase in inh dose leads to inc/dec of arterial CO2
Inc
113
Where does respiratory arrest occur
MAC 1.5-3
114
Decreased CO has what effect on liver
Decreased flow, decreased metabolism of co-administered drugs
115
What inhalant is most likely to miantain hepatic blood flow
Iso
116
Describe malignant hyperthermia
Increase in CO2, very hot- blocks Ca outflow due to RYR1- muscle contraction
117
Breeds affected by malignant hyperthermia
Swine, greyhounds
118
Tx for malignant hyperthermia
Dantrolene sodium muscle relaxant
