Prodigy- Volatile anesthetics

Question 1

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

Answer 1

True

Question 2

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

Answer 2

Meyer-Overton

*Potency increases with lipid solubility

Question 3

Typically, what is MAC-awake

Answer 3

about half MAC

Des- 3%
Sevo- 1%

Question 4

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

Answer 4

true

Question 5

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

Answer 5

MAC BAR

Question 6

Tank pressure reading of nitrous oxide

Answer 6

745psi

Question 7

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

Answer 7

Cylinder weight

Question 8

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

Answer 8

400

Question 9

T/F nitrous oxide produces minimal skeletal muscle relaxation

Answer 9

True

Question 10

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

Answer 10

Nitrous oxide

Question 11

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

Answer 11

It’s ability to enlarge air-filled spaces.

Question 12

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

Answer 12

True - avoids risk of hepatotoxicity

Question 13

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

Answer 13

Sevoflurane

Question 14

Boiling point of desflurane

Answer 14

~23

Question 15

The must pungent anesthetic

Answer 15

Desflurane

Question 16

Which anesthetic produces the highest concentrations of carbon monoxide?

Answer 16

Desflurane

• secondary to degradation in desiccated soda lime

Question 17

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

Answer 17

0.115

MAC 71%

Question 18

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

Answer 18

True

Question 19

*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?

Answer 19

0.5ppm - INH + nitrous

2ppm - INH alone

25ppm- nitrous alone

*Nagelhout

Question 20

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

Answer 20

Spinal cord

Question 21

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

Answer 21

Hippocampus

Question 22

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

Answer 22

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

Question 23

*How does body temperature affect MAC?

Answer 23

MAC decreases as the body temperature decreases and vice versa.

*Nagelhout

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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.

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

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

Answer 30

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

Question 31

What is the second gas effect?

Answer 31

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.

Question 32

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

Answer 32

phase I oxidation in the liver.

Question 33

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

Answer 33

True

Question 34

T/F - all volatile anesthetics reduce hepatic blood flow

Answer 34

True

Question 35

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

Answer 35

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

Question 36

Which volatile anesthetic decreases CMRO2 the most?

Answer 36

Isoflurane

Question 37

Which inhalational agent increases CMRO2?

Answer 37

Nitrous

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

Isoflurane Oil: Gas Iso - 100 Sevo - 50 Des- 20 Nitrous- 1.4

Question 41

How can desflurane affect the heart rate in high concentrations?

Answer 41

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.

Question 42

*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?

Answer 42

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

Question 43

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

Answer 43

Sevo

Question 44

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

Answer 44

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.

Question 45

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

Answer 45

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

Question 46

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

Answer 46

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.