SGU SVM Term 4 Anesthesiology MT - F2019
What is the Meyer-Overton correlation for anesthetics? Correct Answer: It is based on the lipid cell
membrane as the site of action, and the chart compares the oil:gas partition coefficient and the potency
of an anesthetic drug
How do inhalant anesthetics act on excitatory and inhibitory neurotransmission? Correct Answer:
Depresses excitatory neurotransmission; enhances inhibitory neurotransmission
What affect does inhalant anesthetics have on the spinal cord? Correct Answer: Generates muscle
relaxation
What affect does inhalant anesthetics have on the CNS? Correct Answer: Hypnosis
Which gets knocked out first when using inhalant anesthetics: mobility or consciousness? Correct
Answer: Consciousness
What two factors make determine the kinetics of inhalant anesthetics? Correct Answer: Blood-gas
partition coefficient and oil-gas partition coefficient.
What is Dalton's Law of Partial Pressures? Correct Answer: Total pressure of a mixture of gases is the
sum of the partial pressures of all component gases. Ptot= P1+P2+P3+...
What is the Saturated Vapor Pressure? Correct Answer: The pressure (in mmHg) the vapor molecules
exert when liquid and vapor phases are in equilibrium (ability to evaporate)
What is the boiling point, and which inhalant anesthetic has the highest BP and which has the lowest
BP? Correct Answer: Temperature at which vapor pressure of the liquid = atmospheric pressure. N2O
has the lowest boiling point (-89C) whereas Desflurane has the highest (23.5C)
Why is a special vaporizer needed when using Desflurane as an inhalant anesthetic Correct Answer: The
boiling point is very close to room temperature
Blood:gas partition coefficient Correct Answer: Solubility of anesthetic agent in the blood, which
dictates the speed of induction, recovery and change of anesthetic depth
What does a low blood:gas coefficient mean? Correct Answer: Gases will exert a high partial pressure so
changes will be fast (anesthetic leaves blood quickly)
What does a high blood:gas coefficient mean? Correct Answer: Anesthetic stays in blood longer so
changes will be slower
Oil:gas partition coefficient Correct Answer: Correlates with the potency of an anesthetic drug - The
higher the solubility (in oil) the more potent the anesthetic (Meyer-Overton rule)
What is the relationship between oil:gas partition coefficient and minimum alveolar concentration
(MAC)? Correct Answer: They are inversely related to each other, meaning that an anesthetic with a
, high oil:gas is very potent, meaning the MAC will be low since less of the drug is needed to maintain
anesthesia
What is the Minimum Alveolar Concentration (MAC)? Correct Answer: The concentration of an
anesthetic at 1 atm that produces immobility in 50% of subjects exposed to a supramaximal noxious
stimuli (the lower the MAC, the more potent the drug is)
What is Fick's Law of Diffusion? Correct Answer: The net diffusion rate of a gas across a fluid membrane
is proportional to the difference in partial pressure, proportional to the area of the membrane, and
inversely proportional to the thickness of the membrane
What are 6 factors that affect the diffusion rate of a gas? Correct Answer: 1. Pressure difference
2. Solubility
3. Surface available for exchanges
4. Thickness of the barrier
5. Molecular weight of the gas
6. Temperature of the fluid
How does Cardiac Output (CO) effect the uptake of anesthesia? Correct Answer: The greater the CO, the
more blood is passing through the lungs carrying away anesthetic
What effect does a low CO (caused by myocardial failure, bradycardia, shock) have on Pa? Correct
Answer: Increase in the rate of rise of the Pa
What effect does a high CO (excitement, etc.) have on Pa? Correct Answer: Delays the alveolar rise in Pa
How does a patient recover from an inhalant anesthetic? Correct Answer: By reducing the partial
pressure of inhalant anesthetic in the CNS which will allow the return to consciousness
How can you speed up the recovery of a patient from anesthesia who is attached to a rebreathing
(circle) system? Correct Answer: Increase the FGF
Increase the minute volume
Empty reservoir bag in scavenging
How can you speed up the recovery of a patient from anesthesia who is attached to a non-rebreathing
system? Correct Answer: Turn the vaporizer off
Which inhalant anesthetic has the highest reduction in cardiac output and direct myocardial depression?
Correct Answer: Halothane
Which inhalant anesthetic has the least reduction in cardiac output and direct myocardial depression?
Correct Answer: Desflurane
Which inhalant anesthetic generates the least amount of peripheral vasodilation? Correct Answer:
Halothane
Which inhalant anesthetic causes the most respiratory depression? Correct Answer: Isoflurane
What is the Meyer-Overton correlation for anesthetics? Correct Answer: It is based on the lipid cell
membrane as the site of action, and the chart compares the oil:gas partition coefficient and the potency
of an anesthetic drug
How do inhalant anesthetics act on excitatory and inhibitory neurotransmission? Correct Answer:
Depresses excitatory neurotransmission; enhances inhibitory neurotransmission
What affect does inhalant anesthetics have on the spinal cord? Correct Answer: Generates muscle
relaxation
What affect does inhalant anesthetics have on the CNS? Correct Answer: Hypnosis
Which gets knocked out first when using inhalant anesthetics: mobility or consciousness? Correct
Answer: Consciousness
What two factors make determine the kinetics of inhalant anesthetics? Correct Answer: Blood-gas
partition coefficient and oil-gas partition coefficient.
What is Dalton's Law of Partial Pressures? Correct Answer: Total pressure of a mixture of gases is the
sum of the partial pressures of all component gases. Ptot= P1+P2+P3+...
What is the Saturated Vapor Pressure? Correct Answer: The pressure (in mmHg) the vapor molecules
exert when liquid and vapor phases are in equilibrium (ability to evaporate)
What is the boiling point, and which inhalant anesthetic has the highest BP and which has the lowest
BP? Correct Answer: Temperature at which vapor pressure of the liquid = atmospheric pressure. N2O
has the lowest boiling point (-89C) whereas Desflurane has the highest (23.5C)
Why is a special vaporizer needed when using Desflurane as an inhalant anesthetic Correct Answer: The
boiling point is very close to room temperature
Blood:gas partition coefficient Correct Answer: Solubility of anesthetic agent in the blood, which
dictates the speed of induction, recovery and change of anesthetic depth
What does a low blood:gas coefficient mean? Correct Answer: Gases will exert a high partial pressure so
changes will be fast (anesthetic leaves blood quickly)
What does a high blood:gas coefficient mean? Correct Answer: Anesthetic stays in blood longer so
changes will be slower
Oil:gas partition coefficient Correct Answer: Correlates with the potency of an anesthetic drug - The
higher the solubility (in oil) the more potent the anesthetic (Meyer-Overton rule)
What is the relationship between oil:gas partition coefficient and minimum alveolar concentration
(MAC)? Correct Answer: They are inversely related to each other, meaning that an anesthetic with a
, high oil:gas is very potent, meaning the MAC will be low since less of the drug is needed to maintain
anesthesia
What is the Minimum Alveolar Concentration (MAC)? Correct Answer: The concentration of an
anesthetic at 1 atm that produces immobility in 50% of subjects exposed to a supramaximal noxious
stimuli (the lower the MAC, the more potent the drug is)
What is Fick's Law of Diffusion? Correct Answer: The net diffusion rate of a gas across a fluid membrane
is proportional to the difference in partial pressure, proportional to the area of the membrane, and
inversely proportional to the thickness of the membrane
What are 6 factors that affect the diffusion rate of a gas? Correct Answer: 1. Pressure difference
2. Solubility
3. Surface available for exchanges
4. Thickness of the barrier
5. Molecular weight of the gas
6. Temperature of the fluid
How does Cardiac Output (CO) effect the uptake of anesthesia? Correct Answer: The greater the CO, the
more blood is passing through the lungs carrying away anesthetic
What effect does a low CO (caused by myocardial failure, bradycardia, shock) have on Pa? Correct
Answer: Increase in the rate of rise of the Pa
What effect does a high CO (excitement, etc.) have on Pa? Correct Answer: Delays the alveolar rise in Pa
How does a patient recover from an inhalant anesthetic? Correct Answer: By reducing the partial
pressure of inhalant anesthetic in the CNS which will allow the return to consciousness
How can you speed up the recovery of a patient from anesthesia who is attached to a rebreathing
(circle) system? Correct Answer: Increase the FGF
Increase the minute volume
Empty reservoir bag in scavenging
How can you speed up the recovery of a patient from anesthesia who is attached to a non-rebreathing
system? Correct Answer: Turn the vaporizer off
Which inhalant anesthetic has the highest reduction in cardiac output and direct myocardial depression?
Correct Answer: Halothane
Which inhalant anesthetic has the least reduction in cardiac output and direct myocardial depression?
Correct Answer: Desflurane
Which inhalant anesthetic generates the least amount of peripheral vasodilation? Correct Answer:
Halothane
Which inhalant anesthetic causes the most respiratory depression? Correct Answer: Isoflurane
