Inhalation 2 Flashcards

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

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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

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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.

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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)

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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.

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6
Q

Volatile anesthetics are

A

Halogenated methyl ethyl ETHER derivaties.

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7
Q

Volatile anesthetics that is not an ETHER? what is it?

A

Halothane, halogenated alkane derivative

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8
Q

In which gas is fluorine the only halogen present

A

Desflurane

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9
Q

Blood solubility of Desflurane , and VP and metabolism

A

low, high vapor pressure ; low metabolism

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10
Q

What contributes to the RAPID onset of PA and recovery from NO, Des and Sevo

A

LOW BLOOD/GAS solubility

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11
Q

EEG, as the dose of anesthetic approaches ___MAC, the frequency on the EEG_______

A

1 ; Decreases

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12
Q

Administration of concentrations of ______MAC produce dose depended increases in

A

0.6; CBF

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13
Q

CBF effects of Volatile from HIGHEST to LOWEST

HEIDS

A

Halothane–> ENFLURANE–> ISOFLURANE –> DESFLURANE–> SEVO

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14
Q

Does NO increase CBF?

A

Yes

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15
Q

Do inhaled anesthetics alter the RESPONSIVENESS of the CEREBRAL CIRCULATION to changes in PaO2?

A

No

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16
Q

The greater decrease in CMRO2 requirements in produced by

A

ISOFLURANE

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17
Q

Inhaled that alters the GLOBAL CEREBRAL OXYGEN supply-demand balance

A

ISOFLURANE

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18
Q

May have cerebral protecting EFFECT

A

ISOFLURANE

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19
Q

Inhaled anesthetics and ICP

A

increases ICP parallels the CBF

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20
Q

What patients are most vulnerable in increase in ICP?

A

Patients with space-occupying intracranial lesions.

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21
Q

CSF production is increased by which inhaled anesthetic?

A

ENFLURANE

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22
Q

Conscious memory is suppressed by

A

Volatile anesthetics

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23
Q

Conscious memory suppressed by _____MAC Isoflurane

A

0.45

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24
Q

Conscious memory suppressed by _____MAC NO

A

0.60

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25
Q

Conscious memory concentrations are similar to

A

MAC awake

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26
Q

NitrousO effect on BP

A

No effect or A MODEST INCREASE in BP

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27
Q

Volatile anesthetics and BP

A

Produce dose dependent and similar DECREASES in BLOOD PRESSURE

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28
Q

The decrease in BP of Halothane and enflurane is PRINCIPALLY due to

A

Decreases in myocardial contractility

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29
Q

The decrease in BP of DIS (Des, ISO, SEVO) is PRINCIPALLY due to

A

Decreases in SVR

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30
Q

Agent associated with junctional rhythm

A

Halothane

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31
Q

Agent associated with Suppression of sinus node activity

A

Halothane

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32
Q

HR does not change despite decrease in BP with those 2 agents

A

Halothane and Sevoflurane

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33
Q

Because HR does not change despite decrease in BP with halothane and sevo what does it indicate

A

Depression of carotid sinus reflex response by the volatile anesthetic

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34
Q

Depression of carotid sinus reflex 2 agents

A

Sevo and halothane

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35
Q

HR change OCCUR and tend to INCREASE with the decrease in BP with those 2 agents

A

Isoflurane and Desflurane

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36
Q

Preservation of carotid sinus reflex response by the volatile anesthetics (2)

A

Isoflurane and Desflurane.

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37
Q

Increase in HR of iso and des are ______. Occur at low dose for _____and at high doses for ______

A

dose-dependent; Iso; Des

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38
Q

2 agents produces dose dependent decrease in CO

A

Halothane , enflurane

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39
Q

Not associated with decreases in CO ,despite decrease in BP

A

SID (sevoflurane, Isoflurane, and Desflurane)

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40
Q

Modestly increase CO

A

Nitrous

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41
Q

Agent with mild sympathomimetic effect

A

Nitrous

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42
Q

Possible explanation of why SID doesn’t affect myocardial contractility?

A

Those agents are more potent

Readily depress brain, spare the heart

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43
Q

Inhaled anesthetics on RAP

A

Dose-dependent INCREASE

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44
Q

RAP increase with N2O most likely reflects increase

A

PVR

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45
Q

Which agents produce does dependent decreases in SVR

A

SID (Sevoflurane, Isoflurane, Desflurane)

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46
Q

What can offset the magnitude of the decrease in SVR

A

Substitution of Nitrous with part of the case.

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47
Q

Volatiles on PVR

A

Little or no predictable effect

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48
Q

PVR: Nitrous oxide may produce ? what patients are at higher risk?

A

increases in PVR ; Patients with HTN

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49
Q

Volatile anesthetics and EPI

A

Decrease the dose of epi necessary to cause Ventricular cardiac dysrhythmias. Greatest with ALKANE (halothane) least with DIES (ether)

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50
Q

Which is the MORE POTENT CORONARY ARTERY VASODILATOR?

A

Isoflurane

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51
Q

What can ISOFLURANE-induced Coronary artery vasodilation cause______/ what is the phenomenon known as ?

A

redistribution of coronary blood flow from diseased areas of myocardium to AREAS with normally responsive coronary arteries. Known as CORONARY STEAL SYNDROME

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52
Q

Why is spontaneous breathing better with inhaled anesthetics?

A

because of the impact of accumulation of CO2 and better venous return with spontaneous breathing

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53
Q

What are the preexisting disease and drug therapy affecting the circulatory effects of inhaled anesthetics

A

Diseased cardiac muscle
Aortic stenosis
Prior drug therapy

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54
Q

Mechanism of circulatory effects from inhaled anesthetics?

Myocardial and sympathetic outflow

A

Myocardial depression

Inhibition of CNS sympathetic outflow

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55
Q

Mechanism of circulatory effects from inhaled anesthetics?

Peripheral ganglion and carotid sinus reflex

A

Peripheral autonomic ganglion blockade

Attenuated carotid sinus reflex activity

56
Q

Mechanism of circulatory effects from inhaled anesthetics?cAMP and Calcium

A

Decrease formation of cAMP

Decrease influx of Calcium

57
Q

A rapid increase in the MAC of desflurane increases

A

SNS activity, catecholamine release , HR and BP

58
Q

How does the rapid increase in anesthetic concentration leads to sympathetic activity?

A

it stimulates medullary centers via IRRITATION of receptors in the airway , resulting in increase sympathetic activity

59
Q

When and What do you administer before an INCREASE In anesthetic concentration to blunt evidence of CV stimulation? FEC

A

Fentanyl, Esmolol, clonidine; 5 minutes before

60
Q

The most useful drug to BLUNT the CV response when increase concentration is

A

FENTANYL (blocks increase in HR and BP, min CV and LITTLE POST ANESTHETIC SEDATION)

61
Q

Inhaled anesthetics on RR (frequency)

A

Dose dependent INCREASES

62
Q

Inhaled anesthetics on TV

A

Dose dependent DECREASES

63
Q

Minute ventilation and inhaled anesthetics

A

Decrease MV and increase PaCO2

64
Q

Inhaled anesthetics on ventilatory response to CO2

A

Dose-dependent DEPRESSION of ventilation characterized by: Decreases in ventilatory response to CO2 and increases PaCO2

65
Q

More PROFOUND DEPRESSION of ventilation

A

ISOFLURANE

66
Q

Substitution of which agent for portion of the anesthetic may result in less depression of ventilation

A

Nitrous

67
Q

This agent does not increase PaCO2

A

Nitrous

68
Q

What MAC does not alter ventilatory response to CO2?

A

subanesthetic concentraiton (0.1MAC)

69
Q

Anesthetic-induced depression most likely reflect direct depressant effects of these drugs on the

A

MEDULLARY VENTILATORY CENTER

70
Q

Management of depression is most often managed by

A

Institution of mechanical ventilation

71
Q

All ANESTHETICS do this

A

PROFOUNDLY DEPRESS the ventilatory response to ARTERIAL HYPOXEMIA that is normally mediated by the carotid bodies.

72
Q

Inhaled anesthetics on AIRWAY Resistance

A

Volatiles produces dose-dependent decreases in airway resistance

73
Q

Airway irritant agent

A

Desflurane

74
Q

Desflurane on airway

A

COUGHING and LARYNGOSPASM when given to unmedicated patients for inhalation induction

75
Q

Hepatic BLOOD flow tend to decrease with VA

A

isoflurane and desflurane

76
Q

Hepatic blood flow and volatile anesthetics

A

Decreases hepatic blood flow

Inhibition of drug-metabolizing enzymes

77
Q

Not significant on liver with VA

A

changes in liver function tests

78
Q

Volatiles anesthetics may interfere with the clearance of 2 drugs? why?

A

Propanolol

Lidocaine

79
Q

What is the most likely cause of hepatic dysfunction with volatile anesthetics?

A

Inadequate hepatocyte oxygenation

80
Q

Halothane hepatitis

A

reactive oxidative TriFluoroAcetyl halide metabolite which acetylate the liver proteins, change them from self to nonself (neoantigens)
Antibodies developed in 70%

81
Q

Mild hepatic dysfunction with those agents

A

Enflurane and Isoflurane (because of hepatic oxygen demand and delivery mismatch)

82
Q

This agent is unlikely to result in formation of neoantigens?

A

DESFLURANE

83
Q

Volatile anesthetics and renal effects

A

Decreases RBF, GFR and UO (2nd to decrease BP and CO)

84
Q

Fluoride Induced Nephrotoxicity signs include

PHI HIS

A
PHI HI
Polyuria
Hypernatremia
Increase serum Creatinine
Hyperosmolarity
Inability to concentrate urine
85
Q

Inorganic Fluoride metabolite is

A

Nephrotoxic

86
Q

Sevoflurane induced Nephrotoxicity Metabolized to

A

Inorganic fluoride

No effect with SEVO in patients WITHOUT PRE-EXISTING RENAL DISEASE.

87
Q

Sevo reacts with

A

CO2 absorbents (soda lime and baralyme)

88
Q

Sevo degradation of

A

Compound A is associated with nephrotoxicity

89
Q

What is required to prevent compound A?

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
Q

% metabolism of Nitrous

A

0.004%

91
Q

Nitrous undergoes

A

reductive metabolism to nitrogen in GI tract

92
Q

Halothane metabolism

A

15-20% with metabolites

93
Q

Enflurane metabolism is ___%

A

3% to inorganic and organic fluoride

94
Q

Desflurane metabolism is _____

A

0.02%–> TFA, CO2 and H2O

95
Q

Sevoflurane metabolism is

A

5%

96
Q

Sevo Degraded by CO2 absorber to

A

potentially toxic compounds–> Vinyl halide

97
Q

Volatile anesthetics enhance effects of NMB (EDSI)

A

Enflurance, Desflurane, Sevoflurane, Isoflurane

98
Q

Most potent trigger for Malignant Hyperthermia

A

Volatile anesthetics

99
Q

Weak trigger of MH

A

Nitrous

100
Q

MAC of Sevo

A

1.8

101
Q

MAC of Des

A

6.6

102
Q

MAC of Iso

A

1.17

103
Q

MAC of Enflurane

A

1.63

104
Q

MAC of nitrous

A

104

105
Q

BP of Sevo

A

58.5

106
Q

BP of Des

A

22.8

107
Q

BP of Iso

A

48.5

108
Q

BP of Enflu

A

56.5

109
Q

Weak anesthetic

A

Nitrous

110
Q

B/G partition coefficient of Nitrous vs NITROGEN

A

34 times greater than that of NITROGEn

111
Q

Nitrous and nitrogen difference B/G meaning

A

nitrous leaves the blood to enter air filled cavity 34 times more rapidly than nitrogen can leave to enter blood

112
Q

NItrous results in (volume and pressure)

A

Increase volume or pressure of an airl filled cavity

113
Q

Nitrous increase air in noncompliant wall

A

middle ear , cerebral ventricles

114
Q

Nitrous increase air in Compliant wall

A

Pneumo, Intestinal gas, air bubbles

115
Q

Nitrous and pneumothorax

A

Can DOUBLE the VOLUME OF A PNEUMOTHORAX in 10 minutes

116
Q

Nitrous oxide check this often

A

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
Q

Diffusion Hypoxia occurs how? and which agents

A

Nitrous oxide, when discontinued abruptly leading to a reversal of partial pressure gradients. -
Nitrous leaves blood to enter alveoli

118
Q

In diffusion hypoxia the initial high volume of nitrous

A

from blood to alveoli dilutes the PaO2 and decrease PaO2

119
Q

In diffusion hypoxia there is also dilution of ____which can lead to what?

A

PaCO2 which can also decrease the stimulus to breathe

120
Q

When does outpouring with nitrous occur?

A

during the first 1-5 minutes of nitrous is turned off

121
Q

How can you prevent diffusion hypoxia

A

100% O2 for several minutes at the end of the case.

122
Q

VA: NOT good for neuro or kidney cases

A

Enflurance

123
Q

Ether means

A

oxygen between 2 carbons

124
Q

VA:Fluoride presents problem

A

Enflurane

125
Q

if CO =30 torr _____Is associated with seizure with high MAC concentration

A

Enflurane ; 2 MAC increase EEG assocaited with seizures.

126
Q

VA decrease ICP

A

Isoflurane

127
Q

Good for NEURO CASES VA

A

Isoflurane

128
Q

VERY pungent VA

A

Desflurane

129
Q

Requires specialied vaporizer

A

DESfLurane

130
Q

Took isoflurane and replaces a CHLORIDE with a fluoride (FULLY FLUORINATED)

A

DESFLURANE

131
Q

Very expensive

A

Desflurane

132
Q

Decreases CO and BP more than ISO

A

Desflurane

133
Q

Non irritating to AIRWAYS

A

Sevoflurane

134
Q

No preservatives but LESS STABLE

A

Sevoflurane

135
Q

Associated with Compound A

A

Sevoflurane

136
Q

All volatiles on CBF?

A

INcrease

137
Q

All volatiles on CMRO2

A

Decrease