Exam2 IAs Flashcards
(111 cards)
1
Q
Isoflurane 1 MAC
A
1.17%
2
Q
Sevoflurane 1 MAC
A
1.80%
3
Q
Desflurane 1 MAC
A
6.6%
4
Q
Nitrous Oxide 1 MAC
A
104%
5
Q
MAC
A
alveolar concentration at which 50% of subjects move in response to a noxious stimuli
6
Q
Factors that increase MAC
A
CNS stimulants alcohol abuser young age (highest 6months) hypernatremia hyperthermia hyperthyroidism red haired females
7
Q
Factors that decrease MAC
A
other drugs, elderly, electrolyte disturbance (hyponatremia), hypercarbic, hypothermic, hypoxic, pregnant, anemia
8
Q
MAC fractions/multiples of inhalation agents are ______
A
additive
9
Q
of MAC that prevents movement in 95% of patients on incision
A
1.3 MAC
10
Q
Non-volatile anesthetics`
A
N2O
11
Q
Volatile anesthetics
A
isoflurane, sevoflurane, desflurane
12
Q
MACawake numeric value
A
1/3 MAC for most IAs
13
Q
MACaware
A
concentration at which pt can remember events
14
Q
MAC-BAR
A
average alveolar concentration which Blunts the Autonomic Response to a noxious stimuli (incision)
15
Q
MAC-BAR is _____ compared to MAC
A
in excess
16
Q
MAC-BAR50 for Sevo (combined with 66% N2O)
A
2.2
17
Q
MAC-BAR50 for Sevo
A
2.2
18
Q
MACaware is related to _____ not ________
A
amnesia not consciousness
19
Q
MACaware numeric value
A
varies per patient
20
Q
Pa measures?
A
partial pressure of agent in alveoli
21
Q
______ is an indirect, yet reliable measure of Pbr
A
Pa
22
Q
Fa
A
fractional concentration of anesthetic in the alveoli
23
Q
Fi
A
fractional concentration of anesthetic in the inspired gas
OR
inspired concentration
24
Q
cardiac output moves agent throughout body
A
distribution
25
evaluating uptake of inhaled anesthetics
Evaluating relationship between Fa and Fi
26
The faster Fa/Fi approaches _____ (#), the faster ______ will occur
1; induction
27
The less soluble the agent, the ____ the rate of rise (induction)
faster
28
Isoflurane Blood:Gas Partition Coeff.
1.46
29
Sevoflurane Blood:Gas Partition Coeff.
0.69
30
N2O Blood:Gas Partition Coeff.
0.46
31
Desflurane Blood:Gas Partition Coeff.
0.42
32
Factors that affect FA/FI
Solubility
Minute Ventilation and FRC
Cardiac Output
Anesthesia circuit characteristics
33
______ FRC will speed induction
decreased
34
________ is the most important factor in the rate of rise of the FA/FI
uptake
35
Uptake_______ the rate of rise of the Fa/Fi
slows
36
As cardiac output ______, Fa is lowered even more
increases
37
An increase in cardiac output will ______ uptake and _____ induction
increase uptake, slow induction
38
A _______ in cardiac output will ______ an inhalation induction
decrease; speed
39
Higher flow rates will ______ induction
speed up
40
Absorption of the circuit: if the circuit itself can absorb the anesthetic, ____ reaches the patient
less
41
Three factors of anesthesia circuit that effect induction speed
1. fresh gas flows > 4LPM
2. absorption by the circuit
3. total circuit volume
42
Factors that increas speed of induction
Increased MV, fresh gas flow rate
| Decreased agent solubility, CO, FRC, circuit volume
43
How do we know Fa?
exhaled concentrations by gas analyzer (mass spectrometry)
44
What is our most distal measurement?
Pa
45
Pa =
delivery into the alveoli (input) minus loss of drug into the blood (uptake)
46
delivery into the alveoli
Input
47
input depends on
- inhaled partial pressure (Pi)
- alveolar ventilation, FRC
- anesthesia breathing machine characteristics
48
A _____ Pi is required during initial administration of an anesthetic to offset the impact of uptake
high
49
overpressure is related to which effect?
concentration
50
All IAs produce _______ of ventilation
dose dependent depression
51
Poorly soluble IAs
sevo
des
N20
52
Intermediately soluble IAs
Iso
53
increased solubility is _______ to the rate of rise of the Pa toward the Pi
inversely proportional
54
ratio that describes how agent distributes between tissues at equilibrium
partition coefficients
55
N2O contributes more to MAC in _______
Advanced age
56
MAC is a form of
ED50
57
Characteristics of the ideal anesthetic
```
Poorly soluble
Non-pungent
Non-flammable
Inexpensive
Easy to produce
Potent
Environmentally safe
No hepatic metabolism
Not a trigger for MH
Not emetogenic
```
58
Average alveolar concentration permitting voluntary response to command
MACawake
59
Pt responds to “Open your eyes!”
MACawake
60
Pt responds to “Breathe!”
MACawake
61
MACawake Isoflurane
38%
62
MACawake Sevoflurane
0.6%
63
MACawake Desflurane
2.2%
64
MACawake N2O
64%
65
The point at which patient loses the ability to learn
MACaware
66
Which happens first:
A. Move and follow commands
B. Make memory
Move and follow commands
67
Addition of _____ mcg/kg fentanyl reduces ______ by _____ %
1.5-3 mcg/kg fentanyl
MAC-BAR
50%
68
MACawake concentrations of Sevo + N2O
Sevo 0.6%
| N2O 60%
69
MAC concentrations of Sevo + N2O
Sevo 1.8%
| N2O 104%
70
MAC-BAR concentrations of Sevo + N2O
Sevo 2.88%
| Nitric - not possible
71
Absorption of IAs
Uptake
72
Uptake of IAs
Occurs when IAs move from alveoli into pulmonary capillary blood
73
Principle objective of inhalation anesthesia
Achieve a constant and optimal brain partial pressure (as reflected by Pa or ET concentration via gas analyzer)
74
Equilibrium occurs when
Partial pressure is equal in both phases
75
% Body mass, % CO of vessel rich group
BM - 10%
| CO - 75%
76
% Body mass, % CO of Muscle group
50% BM
| 19% CO
77
% Body mass, % CO of Fat Group
BM 20%
| CO 5%
78
% Body mass, % CO of vessel poor group
BM 20%
| Blood flow 1%
79
Pharmacokinetics of IAs
```
ADME
Absorption (uptake)
Distribution in body
Metabolism (minimal)
Elimination
```
79
Uptake depends on
1. Solubility of anesthetic in body tissues
2. CO
3. Alveolar to venous PP differences (A-vD)
79
As the A-vD decreases what happens?
Rate of uptake into blood decreases
| Pi should be decreased TO AVOID OVERDOSE
80
What should you always do during the overpressure technique?
Keep your hand on the vaporizer to dial concentration back down
81
Increasing alveolar ventilation will _____ the rate of rise of the Pa toward the Pi
Increase
82
Hyperventilation *hypothetically* results in a ____ rate of rise of PBr
Delayed
| D/t decreased CBF
83
Effect of Spontaneous ventilation on induction
Delivery of IA is decreased as spontaneous ventilation is decreased; protective “negative feedback” loop
84
Effect of mechanical ventilation on IAs
No decrease in ventilation as Pa approaches Pi
85
Effect of high FGF during uptake
1. Faster filling of the volume of anesthetic circuit (CO2 canister, breathing bag)
2. Greater amount of Rx/time to replace gases taken up via alveoli
86
Rubber/plastic parts of breathing circuit can take up anesthetic gases - how will this effect induction/emergence?
1. Induction: slows rate of rise of Pa
| 2. Reverse gradients will delay the rate of the fall of Pa (delayed emergence)
87
Solubilities of IAs in blood/tissues are denoted by
Ostwald Partition Coefficients
88
Ostwald partition coefficient
Distribution ratio that describes how anesthetics distribute between 2 phases (partial pressures equilibriate, NOT CONCENTRATION) at 37degreeC at atmospheric pressure.
89
Which is more soluble in blood - ISO or N2O?
ISO
(Iso has 1.5 molecules in blood for every molecule it has in alveolar gas; while N2O has 1 molecule in the blood for every 1/2 molecule in alveolar gas)
90
Determine uptake into tissues and time necessary to do so
Tissue:Blood partition coefficients
91
Time constant
Time to equilibration of PPs between blood and tissue phase
92
Required for 95% equilibration of PPs between blood/tissue phase
3 time constants
93
Pa:Brain equilibration requires _______ for IAs
5-15 minutes
94
TC of Pa:Brain equilibration
TC = 2-5 minutes
95
Changes in CO affect _____ soluble agents more
Highly
96
Which agent has a rapid rise in Pa despite CO changes?
N2O
97
A-vD
Alveolar to Venous partial pressure differences
| Reflects tissue uptake of IAs
98
A-vD is dependent on
Solubility of agent in tissues
Tissue blood flow
Arterial-tissue PP differences
99
Concentration effect is a result of _____ uptake of the ____ gas leaves the _____ gas in the alveoli in ______ concentration
Concentration effect is a result of __Rapid___ uptake of the __1st__ gas leaves the ___2nd__ gas in the alveoli in __greater____ concentration
100
If two gases are given and the second gas is O2, leftover in the alveolus, what occurs?
Hyperoxygenation
101
Does percutaneous loss affect metabolism of IAs?
No
102
Will underpressuring speed recovery?
No
103
Will equilibrium be achieved in all tissues at conclusion of surgery?
No
104
Time to recovery is longer for ____ soluble agents
More soluble agents
105
How does the anesthetic circuit affect rate of recovery?
The absorbed anesthesia will return to the inspired flow and slow the rate of decrease of Pa
106
Elimination of IAs depends on
Length of administration
| Blood:Gas solubility of agent
107
Initial decrease of anesthesia
<5 minutes
| Does not vary with duration
108
Initial phase of elimination is a function of
Alveolar ventilation
109
Major differences in elimination for IAs
During final 20%
