Inhaled Anesthetics Flashcards
(217 cards)
1
Q
Function of the Respiratory System
A
- Gas exchange
- Acid-base balance
- Phonation
- Pulmonary defense
- Metabolism
2
Q
• Upper Airway Function
A
Humidification and filtration of inspired air.
3
Q
Tracheobronchial tree function
A
conduct gas flow to and from the alveoli
4
Q
alveoli generations present secondary to dichotomous division
A
23
5
Q
How many alveoli are present for gas exchange?
A
300 million
6
Q
Gas exchange begins at generations
A
17-19
7
Q
Largest alveoli are found where?
A
Apex
8
Q
Function of the THIN side of alvoli?
A
gas exchange
9
Q
Function of the thick side of alveoli?
A
Structural support
10
Q
Supplies circulation to the tracheobronchial tree to the level of the respiratory bronchioles
A
Bronchial circulation
11
Q
bronchial circulation arrives from the aorta via which vessels
A
2 left arteries & 1 right artery
12
Q
receives output from the right heart and pulmonary arteries
A
pulmonary circulation
13
Q
takes part in perfusion tissues taking part in gas exchange
A
Pulmonary circulation
14
Q
perfusion of tissues that TAKE PART in pulmonary exchange
A
Pulmonary circulation
15
Q
passes through pulmonary capillaries, O2 is taken up, and CO2 eliminated
A
Deoxygenated
16
Q
blood returned to the left side of the heart via the pulmonary veins is said to be
A
oxygenated
17
Q
Combination of what elements decreased flammability?
A
Carbon together with fluorine
18
Q
Halothane produced what negative side effects when introduced in the 1950’s?
A
Hepatitis and dysthymias
19
Q
Halothane is a dysrhymogenic worsened by which drug?
A
Epinephrine
20
Q
Halothane brand name
A
Fluothane
21
Q
Enflurane brand namE
A
Ethrane
22
Q
Isoflurane brand name
A
Forane
23
Q
Desflurane brand name
A
Suprane
24
Q
Sevoflurane brand name
A
Ultane
25
all agents are volatile anesthetics except
Nitrous oxide
26
Most beneficial features of IA
speed of onset, gaseous state, route of administration.
27
Features of IA contributing to rapid diffusion.
unionization & low molecular weight
28
How drugs affect the body
pharmacodynamics
29
how the body affects drugs
pharmacokinetics
30
Pharmacokinetic features unique to IA
uptake, redistribution, biotransformation, excretion
31
absorption equates to what for IA
uptake
32
metabolism equates to what for IA
biotransformation
33
distribution equates to what for IA
redistribution
34
elimination equates to what for IA
excretion
35
propels IA across barriers to action sites in the CNS
partial pressure gradients
36
tissue group first reach by blood/anesthetic
VRG
37
VRG includes which organs
brain, kidney, heart, liver
38
second tissue group reached by anesthetic/blood mixture
muscle, skin
39
last tissue group reached by anesthetic/blood mixture
fat, connective tissue
40
VRG AKA tissue of ____ effect
desired
41
muscle and skin AKA the tissue of ____ effect
undesired
42
fat and connective tissue is known as the site of ___.
accumulation
43
At what point does the saturation of fat tissue play a role in emergence?
>4 hour anesthetic time
44
VRG % body mass
10%
45
Muscle % body mass
50%
46
fat % body mass
20%
47
VRG % cardiac output
75%
48
Muscle % cardiac output
19%
49
Fat % cardiac output
6%
50
VRG perfusion
55-500 (ml/min/100g)
51
muscle perfusion
3 (ml/min/100g)
52
fat perfusion
1 (ml/min/100g)
53
goal of anesthesia
establish specific concentrations of anesthetics in the CNS.
54
Partial pressure in the CNS equates to what other compartments?
blood and alveoli
55
Sevo Vapor pressure
157
56
Des vapor pressure
669
57
Iso vapor pressure
238
58
Enflurane vapor pressure
172
59
Halothane vapor pressure
243
60
Sevo B/G coefficient
0.65
61
Des BG coefficient
0.42
62
Iso BG coefficient
1.46
63
Enflurane BG coefficient
1.9
64
Halothane BG coefficient
2.5
65
Nitrous oxide BG coefficient
0.46
66
Nitrous oxide vapor pressure
38,770
66
Nitrous oxide vapor pressure
38,770
67
Sevo MAC
1.8%
68
Des MAC
6.6%
69
Iso MAC
1.17%
70
Enflurane MAC
1.63%
71
Halothane MAC
0.75%
72
Nitrous oxide MAC
104%
73
IA that are unstable in MOIST CO2 absorber?
Sevo & Halothane
74
vapor pressure
pressure exerted by a vapor in a closed container when at equilibrium with its liquid and gas phase.
75
vapor pressure increases as ____ increases.
temperature
76
boiling point
temp at which a liquid's vapor exceeds atmospheric pressure in an open container.
77
1 atmosphere = _____ mmHg
760
78
Partial pressure
fractional amount of pressure a single gas exerts within a gas mixture.
79
Dalton's law of partial pressures
the total gas pressure in a container is equal to the sum of the partial pressures exerted by each individual gas.
80
solubility
the tendency of a gas to equilibrate with a solution, determines concentration.
81
Gases are more soluble in liquid when temperature ____.
decreases
82
uptake looks at the concentration of
alvolar / inspired
83
Fi (fraction inspired) represents
concentration of anesthetic leaving the circuit
84
factors increasing Fi
increased FGF, increased Fd (delivered) from FGO, decrease volume of breathing system (dead space)
85
factors that decreasing Fi
decreased FGF, increased volume of breathing system (dead space), absorption by anesthesia machine parts, CO2 absorbent decomposition.
86
Faster Fa relative to Fi results in
faster induction
87
Factors that speed induction of insoluble agents
increased MV, decreased FRC
88
What happens to anesthetic uptake as CO increases
minimal effect on insoluble agents. soluble agents however will take longer to achieve adequate alveolar concentration, thus slowing induction.
89
What happens to anesthetics with deceased CO
decreased CO results in an increased concentration of anesthetic in the alveoli which could lead to overdose and subsequent lower CO/myocardial depression.
90
What determines clinical effect of anesthetics?
concentration of anesthetics in the CNS and brain tissue.
91
Factors affecting anesthetic uptake
blood solubility, alveolar blood flow, partial pressure gradient between alveolar and venous blood
92
agents are taken by blood less readily, results in higher alveolar concentration
insoluble
93
relative solubilities of anesthetics
partition coefficients
94
higher partition coefficients results in _____ uptake.
greater
95
which factors have a greater impact on changing concentrations of soluble agents
MV and CO
96
How much of a role does metabolism play in delaying induction
little
97
overpressurization
delivering a higher partial pressure of anesthetic than the desired alveolar concentration of that agent to achieve a quicker desired effect.
98
Concentration effect
Increasing the inspired concentration of an IA
99
N2O has the greatest concentrating effect at what concentration?
50%-70%
100
Augmented gas inflow
high partial pressure of N2O causes the quick influx of N2O into the blood, this causes an increase in the concentration of agent within the alveoli.
101
second gas effect
N2O augments the effects of a VA due to its higher partial pressure
102
Concentration/second gas effect is less augmented with ____ agents.
soluble
103
increasing MV for insoluble agents has what effect
minimal changes
104
What is the rate limiting step during hyperventilation and increased alveolar concentration.
Spontaneous ventilation. This will eventually provide a negative feedback loop, decreasing alveolar concentration and effects.
105
right to left VQ mismatch leads to
dilution and slowed induction
106
Left to right VQ mismatch lead to
may (but likely wont) speed induction
107
washout
alveolar concentration v. expired concentration at time zero.
108
all IA have the same rate of elimination until __%
50%
109
emergence doesnt occur until ____% of anesthetics have been eliminated.
80%-90%
110
Factors slowing elimination
high tissue solubility, longer anesthetic times (>4 hours), low FGF
111
diffusion hypoxia
rapid elimination of O2 and CO2 when N2O is discontinued.
112
treatment for diffusion hypoxia
100% oxygen for 5-10min after discontinuation of N20.
113
characteristics of an ideal anesthetic
quick onset/recovery, easy to administer, clear indication of anesthetic depth, inexpensive, wide safety margin, minimal effects on organs
114
Most metabolized IA
Halothane, second is Sevo
115
Most physically stable VA
Iso
116
VA not used for mask induction
Des & Iso
117
VA with risk of coronary steal
Iso
118
VA with lowest BF solubility, quick recovery
Des
119
MOST pungent VA
Des
120
requires a heated/pressurized vaporizer
Des
121
may see an increase in BP and HR if opioids not provided with this VA
Des
122
high or rapid increases in concentration of this VA may cause myocardial ischemia.
Des
123
VA with least airway irritation and most bronchodilation
Sevo
124
Agents producing carbon monoxide (most to least)
Des, Iso, Sevo
125
risk of fire due to exothermic reaction
Sevo
126
Compound A
nephrotoxic in rats
127
Produces compound A
Sevo
128
May explode
N2O
129
analgesic effects
Nitrous oxide, Xenon
130
IA not metabolized by the body
N2o
131
not a trigger for MH
N2O & Xenon
132
risk of PONV
N2o
133
inactivates b12
N2O
134
absorbs into gas containing spaces
N2O
135
May cause myocardial ischemia in hypovolemic patients or those with CAD.
N2O
136
Sympathetic stimulation. Depresses the myocardium but stimulates catecholamine release
N2O
137
chemically inert
Xenon
138
Xenon MAC
71%
139
disadvantage of Xenon
high cost & scarcity
140
MAC
Concentration of IA at 1atm preventing skeletal muscle movement with surgical stimulation in 50% of patients.
141
how do MAC and potency correlate
Increased MAC = low potency
142
Immobility with MAC occurs primarily in the
spinal cord
143
MAC Bar
MAC X 1.5
144
MAC Awake
Follows commands
| MAC X 0.5
145
MAC Memory
Associated with amnesia in 50% of patients
146
MAC is _____ but the effects may not be the same
additive
147
MAC was established with what age group
33-55 year olds
148
MAC decreases by ____% after ___ years of age.
6% after 40 years of age
149
MAC is highest at what age?
6 months
150
Factors that reduce MAC
hypothermia, sedatives, other anesthetics, hypoxemia, hyponatremia, anemia, hypotension, pregnancy, lithium, alpha2 agonist, opioids.
151
Factors increase MAC
Young age, hyperthermia, hypernatremia, CNS stimulants, red hair in females, chronic alcohol abuse, hyperthyroidism
152
factors that do not affect MAC
duration of anesthesia, gender, hypo/hypercapnia, metabolic alkalosis, hypertension, hyper/hypokalemia
153
VA cause isoelectric EEG at clinical doses
des, iso, sevo
154
VA isoelectric EEG changes may revert to continuous despite no changes do dose.
Des
155
Sevo at MAC __to ___ combined with ________ can decrease CBF and trigger EEG abnormalities and increase ______.
1.5-2, hyperventilation, heart rate
156
Iso, Des, Sevo have minimal changes to CBF at ___ MAC.
Less than 1
157
All VA increase CBF , which VA increases CBF the most
Halothane
158
Uncoupling
increase in CBF despite decrease in CMRO2
159
Sevo preserves autoregulation up to ____ MAC.
1
160
which agent preserves autoregulation best at 1.5 MAC
Sevo
161
Physiological process can diminish/prevent elevated ICP
hyperventilation/hypocapnia
162
At ____MAC will des, iso, and sevo increase CBF.
1
163
Which agent increases ICP the most
Des
164
Which VA may lessen the risk of increased ICP, why?
Sevo. Decreased pungency/airway irritation lessens coughing/bucking.
165
VA increases PO2 and maintain PO2 better than thiopental during cerebral artery occlusion surgery.
Des
166
postoperative cognitive dysfunction
impairment to the mental processes of perception, memory, and information processing.
167
POCD is associated with increased _____ & _____ in the first year following surgery.
Morbidity and Mortality
168
all IA are associated with POCD, which the most
Iso
169
N2O is associated with POCD and _____ and high doses interfere with many _________ functions.
delirium , cognitive
170
all agents at _____ MAC and N20 at ______% can increase EEG frequencies.
>1MAC, 30%-70%
171
VA MAC of 1-2 ____frequencies and ______ amplitude of EEG.
decrease, increase
172
MAC >2 leads to _______ _______
burst suppression
173
What may be some other causes of EEG changes during administration of anesthesia?
hypoxia, hypercarbia, hypothermia
174
EVP monitoring results in an _____ in amplitude and ______ in latency.
decrease, increase
175
_____ EPs are sensitive while _____ EPs are more resistent
visual, brainstem
176
VA should be avoided in which evoked potential monitoring
MEPs
177
Sudden MAC increase of ____ can result in sudden EP monitoring changes.
>0.5 MAC
178
N2O has what effect on CBF and CMRO2
increases
179
Addition of N2O to 1MAC of Iso has what effect on CMRO2 and CBF.
No change in CMRO2 but increases CBF
180
N2O _______ ICP, this can be decreased by ______.
increases, hypocapnia
181
Avoidance of which IA in cases with likelihood of elevated ICP.
N2O
182
What intervention can negate the increase in CMRO2 and CBF seen with N2O?
Barbs and narcotics
183
VA ____ blood pressure.
decrease
184
VA _______SVR.
Decrease
185
VA _____CO.
minimal to none
186
Sevo MAC of ___ does not change HR.
1
187
VA result in 5-10% increase in baseline HR.
des and iso
188
transient increase in HR during rapid increase in concentration of which VAs? Which the most?
des and iso . Des the most.
189
transient increases in HR seen with des and iso can be minimized by administering which agents?
alpha 2 agonists and opioids
190
N2O increases _____ _____ ______ activity and _____ ______ in concentrations of 40% and higher.
sympathetic nervous system, vascular resistance
191
N2O + VA = ____ SVR and BP than VA alone.
higher
192
CO is _________ to brain, muscle, skin with IA administration.
increased.
193
CO is ______ to the liver, kidney, and gut with IA admin.
decreased
194
VA decrease HR by
decrease SA node discharge, decrease conduction in His-Purkinje/vascular conduction pathways.
195
VA _______ QT intervals. Which agent the most?
prolong, des the most
196
preconditioning protection of myocardium occurs at Sevo MAC dose of ___ and full efficacy at MAC of ___.
1 , 1.5
197
drugs that can abolish preconditioning of myocardium
Sulfonylureas (Glipizide)
198
all IA _____ TV and _____ RR
decrease , increase
199
which agent no longer increases RR above 1 MAC
ISO
200
IA cause ____ in FRC
Decrease
201
IA cause what changes in the diaphragm
none
202
IA cause _______ in intercostal muscle strength.
decrease
203
all IA cause ______ response to increased CO2
decreased
204
______ drives ventilation
PaCO2
205
Apneic threshold
CO2 threshold where respiratory drive stops. 4-5mmHg below resting Pa CO2 in a SV patient.
206
IA ______ ventilatory response to hypoxia.
decrease
207
IA best for chronic respiratory pt
Des and Sevo
208
all VA relax airway smooth muscle, which is best?
Sevo
209
IA _____ ciliary movement and _____mucus
impair, change
210
mechanical vent ____ ciliary movement, _____ airways, and _____ mucus.
impairs, dries, thickens
211
VA effect on PVR
none
212
N2O can _____ PVR.
increase
213
VA metabolized to Trifluroacetatic acid (TFA)
Des & Iso
214
VA _______ effects of NMBs.
Increase
215
Neuromuscular relaxation with VA is the most at ____MAC.
>1 MAC.
216
IA does not affect skeletal muscle relaxation
N2O
