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Anesthesia Pharm. I > Module 4 > Flashcards

Module 4 Flashcards

Inhaled Anesthetics

1
Q

When discussing inhalational agents, what is the relationship between a higher blood/gas partition coefficient and its’ lipid solubility?

A

Higher lipophilicity

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2
Q

Administered via lungs
Kinetics are the same as for any drug
Other factors may come into play

A

Inhalation agents

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3
Q

Factors determining partial pressure gradiant necessary for establishment of anesthesia: Transfer of inhaled anesthetics from Anesthetic Machine to Alveoli

A
  • Inspired partial pressure
  • Alveolar ventilation
  • Characteristics of anesthetic breathing system
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4
Q

Factors determining partial pressure gradiant necessary for establishment of anesthesia: Transfer of inhaled anesthetics from Alveoli to Arterial Blood

A
  • Blood-gas partition coefficient
  • Cardiac output
  • Alveolar-to–venous partial pressure difference
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5
Q

Factors determining partial pressure gradiant necessary for establishment of anesthesia: Transfer of inhaled anesthetic from Arterial Blood to Brain

A
  • Brain-blood partition coefficient
  • Cerebral blood flow
  • Arterial-to-venous partial pressure difference
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6
Q

When a gradient is established between your machine and the patient via the lungs, the lungs in turn…..

A

Equilibrates with the blood, which in turn will equilibrate with brain causing the desired effect

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7
Q

Most important factor in determining potency of inhalation agents

A

Blood-gas partition coefficient

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8
Q

Function of solubility of the agent in blood and is a measure of how quickly the inhalation anesthetic equilibrates between the lungs and blood and ultimately the target site in the brain

A

Blood-gas partition coefficient

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9
Q

Blood-gas partition coefficient is _________ proportional to induction rate, the higher the number the longer the induction and thus the longer the emergence

A

INVERSELY

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10
Q

In the case of inhalational agents, what is the relationship between a higher lipophilicity and agent potency?

A

Higher potency

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11
Q

With inhalational agents, the higher the blood/gas partition coefficient in the agent the _________ the solubility.

A

Higher

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12
Q

Inhalational agents with high solubility have _________ uptake/onset of anesthetic effect

A

Slower onset/uptake

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13
Q

A high blood/gas partition coefficient generally would mean a ________ MAC (Mean Alveolar Concentration).

A

Low MAC.

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14
Q

When considering the effects of inhalational agents on induction it is helpful to consider that what is happening in the lungs/alveoli is likely happening in the _________.

A

Brain

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15
Q

A mnemonic that identifies inhaled anesthetics in order of highest blood/gas partition-lipophilicity-solubility- and therefore slowest uptake.

A

“HI-SE” (H-alothane, I-soflurane, Se-voflurane) Not included are Desflurane and N20, in that order.

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16
Q

Name inhaled anesthetics in order of fastest uptake.

A

N20, Desflurane, Sevoflurane, Isoflurane, Halothane (“HI-SE” in reverse)

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17
Q

In reference to the elimination rate with inhaled anesthetic agents, the higher the plasma drug concentration the _________ the rate of elimination is.

A

Faster

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18
Q

Inhaled anesthetic agents follow what type of pharmacokinetics?

A

First-order

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19
Q

Order of recovery times from inhaled anesthetics from fastest to slowest.

A

N20-Desflurane-Sevoflurane-Isoflurane-Halothane. “HI-SE” in reverse. (inverse relationship between partition coefficient and uptake and recovery)

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20
Q

Increased cardiac output does what to the speed of induction?

A

Slows it down with all inhaled anesthetics.

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21
Q

How does hypothermia affect induction with inhaled anesthetics?

A

Slows induction.

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22
Q

How does a high minute ventilation affect inhaled anesthesia induction?

A

Makes for a faster induction

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23
Q

What is the MAC and blood:gas coefficient for N20?

A

104%, 0.47

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24
Q

What is the MAC and blood:gas coefficient for Desflurane?

A

6.6%, 0.42

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25
Q

What is the MAC and blood:gas coefficient for Sevoflurane?

A

1.8%, 0.65

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26
Q

What is the MAC and blood:gas coefficient for Enflurane?

A

1.63%, 1.8

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27
Q

What is the MAC and blood:gas coefficient for Isoflurane?

A

1.17%, 1.4

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28
Q

What is the MAC and blood:gas coefficient for Halothane?

A

0.75%, 2.3

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29
Q

Factors which slow elimination of inhalational anesthetic agents

A
  • High tissues solubility
  • Longer anesthetic times
  • Low gas flows
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30
Q

What causes diffusion hypoxia after an anesthetic case?

A

N2O elimination is so rapid that alveolar O2 and CO2 concentration is diluted.

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31
Q

How do you prevent diffusion hypoxia after an anesthetic case?

A

Administer 100% oxygen for 5-10 minutes after discontinuing N2O. Can be done through face mask or nasal cannula.

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32
Q

True/False High fresh gas flows will increase elimination of inhalational anesthetic agents.

A

True

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33
Q

What CNS effects are decreased with inhaled anesthetics?

A
  • Mental function and awareness
  • Cerebral metabolic oxygen requirements
  • Seizure Threshold (specifically Enflurane)
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34
Q

What CNS effects are increased with inhaled anesthetics?

A
  • Cerebral blood flow
  • Intracranial pressure
  • Cerebrospinal fluid production (can be increased or not changed)
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35
Q

Other CNS effects caused by inhaled anesthetics.

A
  • Electroencephalogram (EEG)
  • Evoked potentials (Don’t want agents too high during a neuro case)
  • Cerebral protection
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36
Q

The concentration of an agent at 1 atmosphere of pressure that prevents skeletal muscle movement in response to supramaximal painful stimulus in 50% of patients.

A

Mean Alveolar Concentration (MAC)

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37
Q

What are the physiological factors that can alter MAC levels?

A
  • Hyperthermia
  • True Redheads
  • Catecholamines
  • Increased cardiac ouput
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38
Q

Flow delivered (FD) of volatile agents is dependent on what two factors?

A
  • Type of vaporizer

- Flowmeter settings

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39
Q

Inspired gas concentration (FI) is dependent on what three factors?

A
  • Fresh gas flow rate (vaporizer, flowmeter)
  • Breathing circuit volume
  • Absorption by machine or breathing circuit
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40
Q

Alveolar concentration (FA) is dependent on what two factors?

A
  • Uptake

- Second gas effect (theoretically)

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41
Q

Uptake is determined by what five factors?

A
  • Pulmonary circulation (whisking away)
  • Minute volume
  • Inspired anesthetic concentration
  • Volume delivered
  • Cardiac output
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42
Q

How is the minute volume determined?

A

RR x TV (Respiratory Rate x Tidal Volume)

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43
Q

How is cardiac output determined?

A

PR X SV (Pule Rate x Stroke Volume)

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44
Q

What concept is assumed to be explained by the reaching equilibrium between the alveoli-arterial circulation-and target tissue in the CNS

A

The mechanism of action of inhalational anesthetics

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45
Q

A higher delivery of flow (FD), leads to a higher inspired concentration of gas (FI), leads to an increased rate of rise in alveolar concentration (FA), ultimately leading to??

A
  • Faster induction

- Faster induction/recovery

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46
Q

Why can alveolar concentration (FA) never approach inspired concentration (FI) (FA/FI<1.0)?

A
  • Uptake, pulmonary circulation (“whisking away effect”)
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47
Q

Three factors that affect anesthetic uptake?

A
  • Solubility in blood
  • Alveolar blood flow
  • Partial pressure difference between alveolar gas and venous blood
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48
Q

Alveolar partial pressure determines partial pressure of anesthetic in the blood and ultimately…

A

Partial pressure of anesthetic in the brain/CNS, creates clinical effect.

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49
Q

Anesthetic gases need to pas through what three pressure gradient to enact their clinical effect?

A

Alveoli-Blood-Brain

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50
Q

What attribute of volatile agents determines their solubility?

A

Blood/gas partition coefficient

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51
Q

Because they are less readily taken up by blood, insoluble agents have ______ inductions?

A
  • Faster

- Alveolar concentration builds

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52
Q

What is the relative solubility of anesthetic agents in air, blood, and tissues?

A

Blood/gas partition coefficient

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53
Q

The higher the blood/gas partition coefficient the greater the _______ by pulmonary circulation.

A

Uptake

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54
Q

What inhaled anesthetics produce similar and dose-dependent decreases in mean arterial pressure when administered to healthy human volunteers?

A

Halothane, isoflurane, desflurane, and sevoflurane

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55
Q

In contrast with volatile anesthetics, nitrous oxide produces what changes to systemic blood pressure?

A

Either no change or modest increases in systemic blood pressure

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56
Q

What three specific inhaled agents cause decrease in systemic blood pressure due to a decrease in systemic vascular resistance?

A

isoflurane, desflurane, and sevoflurane

57
Q

The decrease in blood pressure produced by halothane is due to?

A

A consequence of decreases in myocardial contractility and cardiac output.

58
Q

What effect does Isoflurane, desflurane, and sevoflurane have on the HR?

A

Increases Heart Rate.

59
Q

What inhaled agent causes decrease in cardiac output?

A

Halothane

60
Q

What type of effect do all volatile anesthetic cause to patient’s left ventricular stroke volume?

A

The calculated left ventricular stroke volume was similarly decreased by 15% to 30% for all the volatile anesthetics

61
Q

Which inhaled agents increase CVP?

A

Halothane, isoflurane, and desflurane increase right atrial pressure (central venous pressure)

62
Q

Which volatile anesthetics decrease blood pressure principally by decreasing systemic vascular resistance?

A

Isoflurane, desflurane, and sevoflurane

63
Q

Which volatile anesthetic decreases systemic blood pressure by decreasing CO?

A

Halothane

64
Q

Does Nitrous oxide have any effect in systemic vascular resistance?

A

Nitrous oxide does not change systemic vascular resistance.

65
Q

Which agent decreases the dose of epinephrine necessary to evoke ventricular cardiac dysrhythmias?

A

Alkane derivative Halothane

66
Q

Effect on coronary blood flow caused by Volatile anesthetics?

A

Volatile anesthetics induce coronary vasodilation

67
Q

Peripheral vasodilation produced by isoflurane, desflurane and sevoflurane is undesirable in patients with?

A

Aortic Stenosis

68
Q

Brief exposure to a volatile anesthetic (isoflurane, sevoflurane, desflurane) can activate KATP channels resulting in?

A

Cardioprotection (anesthetic preconditioning) against subsequent prolonged ischemia and myocardial reperfusion injury.

69
Q

How do inhaled anesthetics affect the frequency of breathing?

A

Inhaled anesthetics, except for isoflurane, produce dose-dependent increases in the frequency of breathing.
(Isoflurane doesn’t increase frequency at a concentration of >1 MAC).

70
Q

How do Volatile anesthetics affect ventilatory response to CO2?

A

Volatile anesthetics produce dose-dependent depression of ventilation characterized by decreases in the ventilatory response to carbon dioxide and increases in the PaCO2.

71
Q

How is the ventilatory response to hypoxemia affected by inhaled anesthetics?

A

All inhaled anesthetics, including nitrous oxide, profoundly depress the ventilatory response to hypoxemia.

72
Q

Risk factors for developing bronchospasm during anesthesia?

A

Young age (<10 years), perioperative respiratory infection, endotracheal intubation, and the presence of COPD.

73
Q

Isoflurane and sevoflurane produce bronchodilation in patients with?

A

COPD

74
Q

Vasoconstrictor on the hepatic circulation?

A

Halothane

75
Q

Hepatic blood flow and hepatic artery blood flow is maintained while portal vein blood flow is increased by using which agents?

A

Sevoflurane, isoflurane and desflurane.

76
Q

How do inhaled anesthetics affect intrinsic clearance by hepatic metabolism of drugs such as propranolol?

A

Intrinsic clearance by hepatic metabolism of drugs such as propranolol is decreased by 54% to 68% by inhaled anesthetics

77
Q

How do volatile anesthetics affect hepatotoxicity?

A

Postoperative liver dysfunction has been associated with most volatile anesthetics, with halothane receiving the most attention.

78
Q

Risk factors commonly associated with halothane hepatitis?

A

Include female gender, middle age, obesity, and multiple exposures to halothane

79
Q

Clinical manifestations of halothane hepatitis?

A

Eosinophilia, fever, rash, arthralgia, and prior exposure to halothane

80
Q

What factors slow elimination of inhalational anesthetic agents?

A

Exhalation
Bio-transformation
Transcutaneous loss

81
Q

Recovery from anesthesia depends on

A

Lowering the anesthetic concentration in the brain

82
Q

True or False

Factors that increase induction also increase recovery

A

True

83
Q

In regards to concentration:

Effects of uptake can be lessened by

A

Increasing the inspired concentration

Stoelting ch 4, pg 104 5ed

84
Q

In regards to concentration:

A higher inspired concentration results in

A

A disproportionately concentration higher alveolar concentration

85
Q

Does Higher FD and thus higher FI increase or decrease the rate of rise of FA

A

Increases

86
Q

True or False

The higher the FI, the more rapidly the FA approaches the FI.

A

True

Stoelting ch 4, pg 104 5ed

87
Q

True or False

The higher FI provides anesthetic molecule input to offset uptake and thus speeds the rate at which the FA increases

A

True

Stoelting ch 4, pg 104 5ed.

88
Q

What is Alveolar blood flow essentially equal to?

A

Cardiac Output

89
Q

Perfusion but no ventilation

A

Shunting

90
Q

Ventilation but no perfusion

A

Dead Space

91
Q

As CO increases, how is anesthetic uptake, alveolar pressure, and induction affected?

A

Anesthetic uptake Increases, the rise in alveolar pressure slows, and induction is prolonged

92
Q

Patients with a low cardiac output are at risk for?

A

Overdosage with more soluble agents

93
Q

The transfer of anesthetic agent from blood to tissues is determined by:

A
  • Tissue solubility of anesthetic agent
  • Tissue blood flow – brain will perfuse and uptake more than the bone
  • Partial pressure difference between arterial blood and tissue – facilitate from blood to tissue
94
Q

Alveolar (gas) to venous (blood) partial pressure differences depend on what gradient?

A

Tissue uptake

95
Q

Due to what effect can higher than anticipated levels of volatile anesthestic do to CO?

A

Lower CO due to its myocardial depressant effect

96
Q

Name the four tissues groups based on their solubility and blood flow

A

Vessel-rich group
Muscle group
Fat group
Vessel-poor group

97
Q

Which organs make up the vessel-rich group.

A

Brain, heart, liver, kidneys, and endocrine organs

98
Q

Which organs make up the muscle group.

A

Skin and muscle

99
Q

what makes up the fat group.

A

adipose tissue

100
Q

Which organs make up the Vessel-poor group.

A

Bone, ligaments, teeth, hair, and cartilage.

101
Q

How can lowering of alveolar partial pressure by uptake can be countered?

A

Lowering of alveolar partial pressure by uptake can be countered by increasing alveolar ventilation

102
Q

When will the effect of increasing ventilation be most obvious?

A

The effect of increasing ventilation will be most obvious in raising the FA/FI ratio for soluble anesthetics

103
Q

How does increasing ventilation affect insoluble agents?

A

For insoluble agents, increasing ventilation has minimal effect (consider the FA/FI ratio…)

104
Q

How does hyperventilation affect FA?

A

Hyperventilation increases the rate of rise of FA

105
Q

How does hypoventilation affect FA?

A

Hypoventilation decreases the rate of rise of FA

106
Q

Which Bronchus is more vertical, shorter, and wider? Left or right?

A

Right

107
Q

What replaces cartilage as you move down the trachea into the bronchial tubes?

A

Smooth muscle [ think asthma]

108
Q

What is the function of the tracheobronchial tree?

A

Conduct gas flow to and from the alveoli

109
Q

Where does the tracheobronchial tree start and end?

A

It starts in the trachea and ends in the alveoli sacs

110
Q

What I’d the function of the upper airway?

A

Humidify and filter inspired air

111
Q

What generation does gas exchange begin in?

A

Generation 17-19

112
Q

What is the alveoli surface area in the lungs?

A

Approx 750 square ft

300 million alveoli

113
Q

Which inhaled anesthetic is a halogenated methyl ethyl ether with intermediate solubility in blood, high potency, and is an isomer of enflurane?

A

Isoflurane

114
Q

Which inhaled anesthetic has a MAC of 1.17?

A

Isoflurane

115
Q

Which inhaled anesthetic is a fluorinated methyl ethyl ether with a pungent odor?

A

Desflurane

116
Q

Desflurane has ____ blood gas solubility, _______ induction and ________ recovery.

A

Low; prompt; rapid

117
Q

What type of vaporizer does desflurane require?

A

A heated and pressurized one (Injector type- Tech 6).

118
Q

What is the MAC of desflurane?

A

6.6

119
Q

Which inhaled anesthetic is a fluorinated methyl isopropyl ether with minimal, non-pungent odor?

A

Sevoflurane

120
Q

Which inhaled anesthetic produces compound A, bronchodilation, and the least amount of airway irritation?

A

Sevoflurane

121
Q

What is sevoflurane’s MAC?

A

1.8

122
Q

Which inhaled anesthetic is non-pungent, odorless, nonexplosive, and a chemically inert gas?

A

Xenon

123
Q

Xenon is ______ __________, meaning the MAC levels differ depending on whether the patient is male or female.

A

Gender dependent; female MAC= 63, Male= 70s.

124
Q

What are the advantages and disadvantages of xenon?

A

Advantages: Does NOT trigger malignant hyperthermia in susceptible swine, quick emergence, potent hypnotic and analgesic, no hemodynamic suppression (no decrease in HR or MAP)
Disadvantages: cost, availability, FDA guidelines for approval take a long time.

125
Q

What are some characteristics of nitrous oxide?

A

Low molecular weight, Odorless, Nonflammable (but supports combustion)

126
Q

What are possible adverse effects of nitrous oxide administration?

A

High-volume absorption in gas-containing spaces, Increase risk of PONV (especially if opioids are used), Ability to inactivate vitamin B12

127
Q

In which types of patient cases should nitrous oxide NOT be used?

A

Closed eye injury cases and ear cases

128
Q

What is the MAC of nitrous oxide?

A

104

129
Q

Characteristics of halothane

A

Halogenated alkane derivative, sweet, nonpungent odor, and intermediate solubility in blood, high potency

130
Q

How does enflurane affect the seizure threshold?

A

Decreases the threshold for seizures

131
Q

Enflurane usage should be avoided in patients with a history of ______ and/or _______

A

Renal failure / seizures

132
Q

Characteristics of enflurane

A

Halogenated methyl ethyl ether, intermediate solubility in blood (high potency), decreases the threshold for seizures and inorganic fluoride ions —> nephrotoxic

133
Q

Inhaled Anesthetics

Functions of the Respiratory system?

A
  • Gas Exchange
  • Acid-base balance
  • Phonation
  • Pulmonary defence
  • Metabolism
134
Q

The most commonly administered anesthetics depend on the lungs for (___) and (____)

A

The most commonly administered anesthetics depend on the lungs for (UPTAKE) and (DISTRIBUTION)

135
Q

anesthetic gases enter the Lung and alveoli then pass through what

A

Through the alveolar membrane into the blood, to the left side of the heart, and distributed to the tissue of the body

136
Q

How do you children a very young age respond to the PharmaKinetics of inhaled anesthetics

A

They have an increase requirement of the drug

137
Q

What is the order that the tissues are perfused for when anesthetics gas mixtures when they are administered

A

the brain, vital organs, muscles, skin, fat, and then connective tissues

138
Q

What is the goal for inhaled anesthetics

A

To achieve brain concentration of inhaled anesthetic agents that promote amnesia and analgesia

139
Q

What can influence PharmaKinetics of volatile anesthetics

A

Aging

Anesthesia Pharm. I (4 decks)

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