Inhalation 2 Flashcards
(137 cards)
1
Q
Mechanism of action : Meyer-Overton Theory (Critical Volume Hypothesis
A
States that there is a correlation between lipid
solubility on inhaled anesthetics and MAC
2
Q
Meyer-Overton Theory (Critical Volume
Hypothesis ANESTHESIA occur when
A
Anesthesia occurs when a sufficient number of
molecules dissolve in lipid cell membranes which changes the shape of the membrane
3
Q
Meyer-Overton Theory: Expansion of cell membranes by dissolved
A
anesthetic could distort channels necessary for ion
flux, and a subsequent effect on the development
of action potentials necessary for synaptic
transmission to occur.
4
Q
Mechanism of action (Protein
Receptor Hypothesis)
A
Evidence for protein receptors in the central nervous system as a site and mechanism of action of inhaled anesthetics is suggested by the steep dose response curve (MAC) of inhaled anesthetics (crucial degree of
receptor occupancy)
5
Q
Another theory About GABA
A
Volatile anesthetics and injected anesthetics may activate GABAA channels (preventing the release of neurotransmitters) and inhibit glutamate channels.
6
Q
Volatile anesthetics are
A
Halogenated methyl ethyl ETHER derivaties.
7
Q
Volatile anesthetics that is not an ETHER? what is it?
A
Halothane, halogenated alkane derivative
8
Q
In which gas is fluorine the only halogen present
A
Desflurane
9
Q
Blood solubility of Desflurane , and VP and metabolism
A
low, high vapor pressure ; low metabolism
10
Q
What contributes to the RAPID onset of PA and recovery from NO, Des and Sevo
A
LOW BLOOD/GAS solubility
11
Q
EEG, as the dose of anesthetic approaches ___MAC, the frequency on the EEG_______
A
1 ; Decreases
12
Q
Administration of concentrations of ______MAC produce dose depended increases in
A
0.6; CBF
13
Q
CBF effects of Volatile from HIGHEST to LOWEST
HEIDS
A
Halothane–> ENFLURANE–> ISOFLURANE –> DESFLURANE–> SEVO
14
Q
Does NO increase CBF?
A
Yes
15
Q
Do inhaled anesthetics alter the RESPONSIVENESS of the CEREBRAL CIRCULATION to changes in PaO2?
A
No
16
Q
The greater decrease in CMRO2 requirements in produced by
A
ISOFLURANE
17
Q
Inhaled that alters the GLOBAL CEREBRAL OXYGEN supply-demand balance
A
ISOFLURANE
18
Q
May have cerebral protecting EFFECT
A
ISOFLURANE
19
Q
Inhaled anesthetics and ICP
A
increases ICP parallels the CBF
20
Q
What patients are most vulnerable in increase in ICP?
A
Patients with space-occupying intracranial lesions.
21
Q
CSF production is increased by which inhaled anesthetic?
A
ENFLURANE
22
Q
Conscious memory is suppressed by
A
Volatile anesthetics
23
Q
Conscious memory suppressed by _____MAC Isoflurane
A
0.45
24
Q
Conscious memory suppressed by _____MAC NO
A
0.60
25
Conscious memory concentrations are similar to
MAC awake
26
NitrousO effect on BP
No effect or A MODEST INCREASE in BP
27
Volatile anesthetics and BP
Produce dose dependent and similar DECREASES in BLOOD PRESSURE
28
The decrease in BP of Halothane and enflurane is PRINCIPALLY due to
Decreases in myocardial contractility
29
The decrease in BP of DIS (Des, ISO, SEVO) is PRINCIPALLY due to
Decreases in SVR
30
Agent associated with junctional rhythm
Halothane
31
Agent associated with Suppression of sinus node activity
Halothane
32
HR does not change despite decrease in BP with those 2 agents
Halothane and Sevoflurane
33
Because HR does not change despite decrease in BP with halothane and sevo what does it indicate
Depression of carotid sinus reflex response by the volatile anesthetic
34
Depression of carotid sinus reflex 2 agents
Sevo and halothane
35
HR change OCCUR and tend to INCREASE with the decrease in BP with those 2 agents
Isoflurane and Desflurane
36
Preservation of carotid sinus reflex response by the volatile anesthetics (2)
Isoflurane and Desflurane.
37
Increase in HR of iso and des are ______. Occur at low dose for _____and at high doses for ______
dose-dependent; Iso; Des
38
2 agents produces dose dependent decrease in CO
Halothane , enflurane
39
Not associated with decreases in CO ,despite decrease in BP
SID (sevoflurane, Isoflurane, and Desflurane)
40
Modestly increase CO
Nitrous
41
Agent with mild sympathomimetic effect
Nitrous
42
Possible explanation of why SID doesn't affect myocardial contractility?
Those agents are more potent
| Readily depress brain, spare the heart
43
Inhaled anesthetics on RAP
Dose-dependent INCREASE
44
RAP increase with N2O most likely reflects increase
PVR
45
Which agents produce does dependent decreases in SVR
SID (Sevoflurane, Isoflurane, Desflurane)
46
What can offset the magnitude of the decrease in SVR
Substitution of Nitrous with part of the case.
47
Volatiles on PVR
Little or no predictable effect
48
PVR: Nitrous oxide may produce ? what patients are at higher risk?
increases in PVR ; Patients with HTN
49
Volatile anesthetics and EPI
Decrease the dose of epi necessary to cause Ventricular cardiac dysrhythmias. Greatest with ALKANE (halothane) least with DIES (ether)
50
Which is the MORE POTENT CORONARY ARTERY VASODILATOR?
Isoflurane
51
What can ISOFLURANE-induced Coronary artery vasodilation cause______/ what is the phenomenon known as ?
redistribution of coronary blood flow from diseased areas of myocardium to AREAS with normally responsive coronary arteries. Known as CORONARY STEAL SYNDROME
52
Why is spontaneous breathing better with inhaled anesthetics?
because of the impact of accumulation of CO2 and better venous return with spontaneous breathing
53
What are the preexisting disease and drug therapy affecting the circulatory effects of inhaled anesthetics
Diseased cardiac muscle
Aortic stenosis
Prior drug therapy
54
Mechanism of circulatory effects from inhaled anesthetics?
| Myocardial and sympathetic outflow
Myocardial depression
| Inhibition of CNS sympathetic outflow
55
Mechanism of circulatory effects from inhaled anesthetics?
| Peripheral ganglion and carotid sinus reflex
Peripheral autonomic ganglion blockade
| Attenuated carotid sinus reflex activity
56
Mechanism of circulatory effects from inhaled anesthetics?cAMP and Calcium
Decrease formation of cAMP
| Decrease influx of Calcium
57
A rapid increase in the MAC of desflurane increases
SNS activity, catecholamine release , HR and BP
58
How does the rapid increase in anesthetic concentration leads to sympathetic activity?
it stimulates medullary centers via IRRITATION of receptors in the airway , resulting in increase sympathetic activity
59
When and What do you administer before an INCREASE In anesthetic concentration to blunt evidence of CV stimulation? FEC
Fentanyl, Esmolol, clonidine; 5 minutes before
60
The most useful drug to BLUNT the CV response when increase concentration is
FENTANYL (blocks increase in HR and BP, min CV and LITTLE POST ANESTHETIC SEDATION)
61
Inhaled anesthetics on RR (frequency)
Dose dependent INCREASES
62
Inhaled anesthetics on TV
Dose dependent DECREASES
63
Minute ventilation and inhaled anesthetics
Decrease MV and increase PaCO2
64
Inhaled anesthetics on ventilatory response to CO2
Dose-dependent DEPRESSION of ventilation characterized by: Decreases in ventilatory response to CO2 and increases PaCO2
65
More PROFOUND DEPRESSION of ventilation
ISOFLURANE
66
Substitution of which agent for portion of the anesthetic may result in less depression of ventilation
Nitrous
67
This agent does not increase PaCO2
Nitrous
68
What MAC does not alter ventilatory response to CO2?
subanesthetic concentraiton (0.1MAC)
69
Anesthetic-induced depression most likely reflect direct depressant effects of these drugs on the
MEDULLARY VENTILATORY CENTER
70
Management of depression is most often managed by
Institution of mechanical ventilation
71
All ANESTHETICS do this
PROFOUNDLY DEPRESS the ventilatory response to ARTERIAL HYPOXEMIA that is normally mediated by the carotid bodies.
72
Inhaled anesthetics on AIRWAY Resistance
Volatiles produces dose-dependent decreases in airway resistance
73
Airway irritant agent
Desflurane
74
Desflurane on airway
COUGHING and LARYNGOSPASM when given to unmedicated patients for inhalation induction
75
Hepatic BLOOD flow tend to decrease with VA
isoflurane and desflurane
76
Hepatic blood flow and volatile anesthetics
Decreases hepatic blood flow
| Inhibition of drug-metabolizing enzymes
77
Not significant on liver with VA
changes in liver function tests
78
Volatiles anesthetics may interfere with the clearance of 2 drugs? why?
Propanolol
| Lidocaine
79
What is the most likely cause of hepatic dysfunction with volatile anesthetics?
Inadequate hepatocyte oxygenation
80
Halothane hepatitis
reactive oxidative TriFluoroAcetyl halide metabolite which acetylate the liver proteins, change them from self to nonself (neoantigens)
Antibodies developed in 70%
81
Mild hepatic dysfunction with those agents
Enflurane and Isoflurane (because of hepatic oxygen demand and delivery mismatch)
82
This agent is unlikely to result in formation of neoantigens?
DESFLURANE
83
Volatile anesthetics and renal effects
Decreases RBF, GFR and UO (2nd to decrease BP and CO)
84
Fluoride Induced Nephrotoxicity signs include
| PHI HIS
```
PHI HI
Polyuria
Hypernatremia
Increase serum Creatinine
Hyperosmolarity
Inability to concentrate urine
```
85
Inorganic Fluoride metabolite is
Nephrotoxic
86
Sevoflurane induced Nephrotoxicity Metabolized to
Inorganic fluoride
| No effect with SEVO in patients WITHOUT PRE-EXISTING RENAL DISEASE.
87
Sevo reacts with
CO2 absorbents (soda lime and baralyme)
88
Sevo degradation of
Compound A is associated with nephrotoxicity
89
What is required to prevent compound A?
At least 2L/min fresh flow rate should be use with sevoflurane to minimize the accumulation of compound A in the breathing circuit.
90
% metabolism of Nitrous
0.004%
91
Nitrous undergoes
reductive metabolism to nitrogen in GI tract
92
Halothane metabolism
15-20% with metabolites
93
Enflurane metabolism is ___%
3% to inorganic and organic fluoride
94
Desflurane metabolism is _____
0.02%--> TFA, CO2 and H2O
95
Sevoflurane metabolism is
5%
96
Sevo Degraded by CO2 absorber to
potentially toxic compounds--> Vinyl halide
97
Volatile anesthetics enhance effects of NMB (EDSI)
Enflurance, Desflurane, Sevoflurane, Isoflurane
98
Most potent trigger for Malignant Hyperthermia
Volatile anesthetics
99
Weak trigger of MH
Nitrous
100
MAC of Sevo
1.8
101
MAC of Des
6.6
102
MAC of Iso
1.17
103
MAC of Enflurane
1.63
104
MAC of nitrous
104
105
BP of Sevo
58.5
106
BP of Des
22.8
107
BP of Iso
48.5
108
BP of Enflu
56.5
109
Weak anesthetic
Nitrous
110
B/G partition coefficient of Nitrous vs NITROGEN
34 times greater than that of NITROGEn
111
Nitrous and nitrogen difference B/G meaning
nitrous leaves the blood to enter air filled cavity 34 times more rapidly than nitrogen can leave to enter blood
112
NItrous results in (volume and pressure)
Increase volume or pressure of an airl filled cavity
113
Nitrous increase air in noncompliant wall
middle ear , cerebral ventricles
114
Nitrous increase air in Compliant wall
Pneumo, Intestinal gas, air bubbles
115
Nitrous and pneumothorax
Can DOUBLE the VOLUME OF A PNEUMOTHORAX in 10 minutes
116
Nitrous oxide check this often
pressure cuff - ETT cuff pressure to prevent ischemia to tracheal mucosa which can lead to swelling,necrosis and narrowing of airway during long surgeries.
117
Diffusion Hypoxia occurs how? and which agents
Nitrous oxide, when discontinued abruptly leading to a reversal of partial pressure gradients. -
Nitrous leaves blood to enter alveoli
118
In diffusion hypoxia the initial high volume of nitrous
from blood to alveoli dilutes the PaO2 and decrease PaO2
119
In diffusion hypoxia there is also dilution of ____which can lead to what?
PaCO2 which can also decrease the stimulus to breathe
120
When does outpouring with nitrous occur?
during the first 1-5 minutes of nitrous is turned off
121
How can you prevent diffusion hypoxia
100% O2 for several minutes at the end of the case.
122
VA: NOT good for neuro or kidney cases
Enflurance
123
Ether means
oxygen between 2 carbons
124
VA:Fluoride presents problem
Enflurane
125
if CO =30 torr _____Is associated with seizure with high MAC concentration
Enflurane ; 2 MAC increase EEG assocaited with seizures.
126
VA decrease ICP
Isoflurane
127
Good for NEURO CASES VA
Isoflurane
128
VERY pungent VA
Desflurane
129
Requires specialied vaporizer
DESfLurane
130
Took isoflurane and replaces a CHLORIDE with a fluoride (FULLY FLUORINATED)
DESFLURANE
131
Very expensive
Desflurane
132
Decreases CO and BP more than ISO
Desflurane
133
Non irritating to AIRWAYS
Sevoflurane
134
No preservatives but LESS STABLE
Sevoflurane
135
Associated with Compound A
Sevoflurane
136
All volatiles on CBF?
INcrease
137
All volatiles on CMRO2
Decrease
