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*Pharmacology > Prodigy- Volatile anesthetics > Flashcards

Prodigy- Volatile anesthetics Flashcards

1
Q

T/F: the exact mechanism by which inhaled anesthetics produce anesthesia has not been entirely determined.

A

True

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2
Q

What rule states that lipid solubility of the agent is directly related to it’s potency

A

Meyer-Overton

*Potency increases with lipid solubility

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3
Q

Typically, what is MAC-awake

A

about half MAC

Des- 3%
Sevo- 1%

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4
Q

T/F MAC-memory is significantly less than mac awake levels

A

true

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5
Q

The term to describe mean alveolar concentration that blocks the adrenergic response to skin incision

A

MAC BAR

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6
Q

Tank pressure reading of nitrous oxide

A

745psi

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7
Q

What is the only reliable indicator of the volume of N20 in a storage tank?

A

Cylinder weight

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8
Q

Once the pressure of nitrous oxide drops below 745psi, appoximately how many liters are left in the tank?

A

400

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9
Q

T/F nitrous oxide produces minimal skeletal muscle relaxation

A

True

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10
Q

Which inhalational anesthetic can produce deleterious effects on cell function through inactivation of vitamin B12?

A

Nitrous oxide

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11
Q

What si the most clinically significant and accurate concern with nitrous oxide?

A

It’s ability to enlarge air-filled spaces.

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12
Q

T/F Sevo metabolism does NOT result in the production of trifluroacetate

A

True - avoids risk of hepatotoxicity

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13
Q

Which anesthetic can enhance seizure activity and needs to be used with caution in patients with a history of epilepsy

A

Sevoflurane

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14
Q

Boiling point of desflurane

A

~23

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15
Q

The must pungent anesthetic

A

Desflurane

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16
Q

Which anesthetic produces the highest concentrations of carbon monoxide?

A

Desflurane

  • secondary to degradation in desiccated soda lime
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17
Q

Blod:gas partition coefficient of Xenon & It’s MAC

A

0.115

MAC 71%

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18
Q

T/F Xenon is not a trigger agent for malignant hyperthermia

A

True

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19
Q

*operating room personnel should not be exposed to more than how many parts per million of a halogenated agent?

What if nitrous oxide is used?

A

0.5ppm - INH + nitrous

2ppm - INH alone

25ppm- nitrous alone

*Nagelhout

20
Q

Where do anesthetics act to inhibit motor responses to noxious stimuli?

A

Spinal cord

21
Q

What is the most likely site of action for the amnestic effect of anesthetics?

A

Hippocampus

22
Q

*What is AD95 and how does it relate to MAC-BAR?

A

The AD95 (anesthetic dose 95) is the dose of a volatile anesthetic that is effective in preventing movement in response to surgical incision in 95% of patients and usually correlates to the approximate value of MAC-BAR

*Nagelhout

23
Q

*How does body temperature affect MAC?

A

MAC decreases as the body temperature decreases and vice versa.

*Nagelhout

24
Q

besides hypothermia and avanced age, what other physiologic factors decrease MAC?

A 
metabolic acidosis, 
alpha-2 agonists, 
hypoxia, 
hypothermia, 
hyponatremia, 
hypo-osmolality, 
pregnancy, 
acute ethanol levels, 
anemia, 
lidocaine, 
decreased catecholamine levels.
25
Q

What factors may increase the minimum alveolar concentration (MAC)?

A

Increased catecholamines, hyperthermia, hypernatremia, and a history of chronic ethanol abuse

26
Q

How does low blood solubility affect the pulmonary uptake and elimination of a volatile anesthetic?

A

The lower the blood solubility, the faster pulmonary uptake and elimination occurs.

27
Q

Which agent would have a faster onset at induction, a highly soluble anesthetic agent or a poorly soluble agent?

A

A poorly soluble agent would not be absorbed from the alveoli into the blood as quickly, therefore, its alveolar partial pressure would rise more quickly.

28
Q

How does the blood:gas coefficient affect the rate at which the alveolar concentration of a volatile anesthetic approaches the inspired concentration?

A

They are inversely proportional.

The higher the blood:gas solubility coefficient, the slower the rate at which FA approaches FI.

29
Q

How do changes in cardiac output affect the rate at which the alveolar concentration of a volatile anesthetic approaches the inspired concentration?

A

They are inversely proportional.

As cardiac output increases, the rate at which FA approaches FI decreases and vice versa.

30
Q

What is the most important factor in the rate of rise of FA/FI?

A

The rate of uptake of anesthetic from the alveoli into the bloodstream

31
Q

What is the second gas effect?

A

The combined administration of a potent inhaled anesthetic with nitrous oxide can increase the alveolar concentration of the volatile anesthetic as the nitrous exits the alveoli and enters the bloodstream more rapidly.

32
Q

*What is the primary way in which all volatile anesthetics are metabolized?

A

phase I oxidation in the liver.

33
Q

T/F: The volatile anesthetics all prolong the QT interval.

A

True

34
Q

T/F - all volatile anesthetics reduce hepatic blood flow

A

True

35
Q

*At what MAC level would you expect to first see burst suppression on the EEG with inhalation agents?

A

Burst suppression on the EEG usually occurs between 1.5 and 2.0 MAC with desflurane and around 2.0 MAC with isoflurane and sevoflurane.

*Nagelhout

36
Q

Which volatile anesthetic decreases CMRO2 the most?

A

Isoflurane

37
Q

Which inhalational agent increases CMRO2?

A

Nitrous

38
Q

*What are the oil:gas partition coefficients for isoflurane, des, sevo, and nitrous

A

Iso - 100
Sevo - 50
Des- 20
Nitrous- 1.4

*Nagelhout

39
Q

What are the moleclar weights of n20, iso, des, and sevo?

A

N20- 44g
Des- 168
Iso- 184
Sevo- 200g

40
Q

Between desflurane, isoflurane, sevoflurane, and nitrous oxide, which inhaled anesthetic is the most potent?

What is this determined by?

A

Isoflurane

Oil: Gas

Iso - 100
Sevo - 50
Des- 20
Nitrous- 1.4

41
Q

How can desflurane affect the heart rate in high concentrations?

A

Desflurane produces a small increase in sympathetic activity. When the concentration of desflurane is increased rapidly, catecholamine release is more pronounced and can result in increases in heart rate and blood pressure.

42
Q

*Comparing desflurane, sevoflurane, nitrous oxide and isoflurane, an increase in cardiac output would slow the onset of which inhalation anesthetic the most?

What determines this?

A

Isoflurane.

The effect is greatest in agents with a high blood:gas partition coefficient.

Iso- 1.43
Sevo- 0.69
Nitrous- 0.47
Des- 0.42

43
Q

Which inhalational agent has no adverse effects on cerebral physiology at normal C02 and blood pressure?

A

Sevo

44
Q

Isoflurane has been demonstrated to cause coronary steal in some cases. What is meant by this?

A

Isoflurane dilates coronary arteries. Diseased vessels with fixed, stenotic lesions, however cannot dilate as effectively as normal vessels. As the normal vessels dilate, blood is shunted towards the normal areas of the heart and away from the areas supplied by the already diseased vessels. This can result in worsening of ischemia.

Desflurane and sevoflurane do not cause this effect.

45
Q

Why is desflurane not used for inhalation inductions in pediatric patients?

A

desflurane acts as a respiratory irritant in concentrations above 6% and can result in breath-holding, coughing, and laryngospasm during induction.

46
Q

*What is methionine synthetase and how does nitrous oxide affect it?

A

Methionine synthetase is a cobalamin-dependent enzyme necessary for nerve myelination, homocysteine degradation, and DNA synthesis.

Nitrous oxide oxidizes the cobalt atom found on vitamin B12 (cobalamin) which can inhibit the formation of methionine synthetase.

This would exert little effect on normal, healthy patients, but may warrant consideration of the use of nitrous oxide in patients with severe B12 deficiency.

*Pharmacology (25 decks)

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