CRNA Boards Practice-Exam TEST MOD 010 with Revised
Correct Q & A 2023/2024 ATESTED
What is responsible for a gases vapor pressure? correct answers Temperature
From greatest to least, what are the vapor pressures of the inhaled anesthetic agents? correct answers
Nitrous Oxide - XDesflurane - 669 mmHgHalothane - 244 mmHgIsoflurane - 240 mmHgEnflurane - 172
mmHgSevoflurane - 170 mmHDenise Has Intercourse Every Sunday
What is Dalton's Law of Partial Pressures?Why do we care? correct answers The total pressure exerted
by a mixture of gases is equal to the sum of the partial pressures of each individual gas.This means you
can calculate the final percent concentration of a mixture of gas if you know the pressure of Oxygen at
sea level and the partial pressure of the other gases.
What is the partial pressure of oxygen at sea level? correct answers 14.7 PSI760 mm Hg760 torr1 atm101
kPa
If isoflurane is added to a flask of oxygen what is the percentage concentration of both isoflurane and
oxygen? correct answers Oxygen Partial Pressure = 760Isoflurane Partial Pressure = 240After adding
Isoflurane to the flask, the partial pressure of oxygen is now 520 mmHg.% Oxygen = (520/760) = 69%%
Isoflurane = (240/760) = 31%It really is just that easy.
If you add Desflurane to a flask of Oxygen, what is the percentage concentration of both Desflurane and
oxygen? correct answers Oxygen Partial Pressure = 760 mmHgDesflurane Partial Pressure = 669
mmHgAfter adding Isoflurane to the flask, the partial pressure of oxygen is now 91 mmHg% Oxygen = (91
/ 760) = 11%% Desflurane = () = 89%It really is just that easy.
What happens if a volatile agent with a higher vapor pressure is added to a vaporizer calibrated for a
lower vapor pressure? correct answers The concentration delivered will be higher than normal.Higher
Lower High - HLH
What happens if a volatile agent with a lower vapor pressure is added to a vaporizer calibrated for a
higher vapor pressure? correct answers The concentration delivered will be lower than normal.Lower
Higher Low - LHL
What is unique about the deslflurane vaporizer? correct answers It is heated to approxmiately 39
degrees celsius which creates a vapor pressure of nearly 1500 mmHg (two atmospheres).This drives"
desflurane to the gas outlet"
1 mmHg = (X) cm H2O1 atm = (X) mmHg = (X) psi = (X) kPa = (X) bar1 psi = (X) mmHg correct answers 1
mmHg = 1.36 cm H2O1 atm = 760 mmHg = 14.7 psi = 101 kPa = 1 bar1 psi = 54 mmHg
How do Bourdon gauges work?What does it mean when the Bourdon gauge on a cylinder reads zero?
correct answers They measure high (cylinder) pressure relative to atmospheric pressure.That the cylinder
pressure is equal to atmospheric pressure and there is no 'drive' to the gas.
, What is the Law of Laplace?What structures within the body does this apply to? correct answers Tension
= (Pressure) x (radius)This is try for cylinder structures, such as blood vessels and the left ventricle.It
means that as the structure expands (radius increases) the tension (force) of the structure increases as
well.
How does the Law of LaPlace help understand why aneurysms are more likely to rupture than healthy
blood vessel? correct answers Tension = (Pressure) x (Radius)So, the tension on the wall is proportional
to the radius. The larger the radius (anyeursm) more likely the vessel will rupture as the tension
increases.
How does the Law of LaPlace help understand why capillaries are more likely to withstand high pressures
than larger blood vessels? correct answers Tension = (Pressure) x (Radius)Because the radius in a
capillary is so much smaller (perhaps 1/100th of a larger vessel) it can withstand a much greater increase
in Pressure before Tension will increase.
What is the Law of LaPlace when applied to spheres?How is this applied to physiology?Why do we care?
correct answers Tension = (Pressure)(Radius) / 2This is applied to normal alveoli which have surfactant
and those that do not (ARDS).We care, because this law is what explains that smaller alveoli with
surfactant do not empty into larger alveoli. Furthermore, why smaller alveoli without surfacant do
empty into larger alveoli
Explain how the Law of LaPlace applies to ARDS alveoli. correct answers Tension is independent of radius
for all spheres where there is a liquid / air interface (alveoli without surfactant).T = PR / 2 → P =
2T/RAs the radius decreases, the pressure increases because tension is constant.If a small alveoli and
large alveoli were connected (as they are in the lung), the higher pressure in the small alveoli will push
gas into the lower presssure larger alveoli.This is what causes alveolar collapse in ARDS.
Explain how the Law of LaPlace applies to normal, surfactant full, alveoli? correct answers Tension is
directly proportional to radius in surfacant full alveoli.T= PR / 2 → P = 2T / RAs the radius decreases,
the tension decreases proportionally - this maintained equal pressure.Therefore, there is no pressure
gradient between a smaller and larger alveoli, and this is why small alveoli do not empty into large
alveoli in a healthy lung.
What is the definition of Laminar Flow?What law defines this? correct answers Hagen-Poiseuille's
LawFlow = (π)(radius4)(ΔP) / (8)(n)(L)'Flow is equal to pi times radius to the fourth power times
the pressure gradient over viscosity times length.Flow is directly proportional to the fourth power of the
radius.
What happens to laminar flow if you double the radius of the given tube? correct answers Flow would
increase 16 timesFlow is directly proportional to the fourth power of the radius.Flow = 2x2x2x2 = 16
What happens to laminar flow if you triple the radius of a given tube? correct answers Flow would
increase 81 timesFlow is directly proportional to the fourth power of the radius.Flow = 3x3x3x3 = 81
What is the relationship between Laminar Flow and the Pressure Gradient? correct answers Laminar
Flow is directly proportional to the hydrostatic pressure gradient.
Correct Q & A 2023/2024 ATESTED
What is responsible for a gases vapor pressure? correct answers Temperature
From greatest to least, what are the vapor pressures of the inhaled anesthetic agents? correct answers
Nitrous Oxide - XDesflurane - 669 mmHgHalothane - 244 mmHgIsoflurane - 240 mmHgEnflurane - 172
mmHgSevoflurane - 170 mmHDenise Has Intercourse Every Sunday
What is Dalton's Law of Partial Pressures?Why do we care? correct answers The total pressure exerted
by a mixture of gases is equal to the sum of the partial pressures of each individual gas.This means you
can calculate the final percent concentration of a mixture of gas if you know the pressure of Oxygen at
sea level and the partial pressure of the other gases.
What is the partial pressure of oxygen at sea level? correct answers 14.7 PSI760 mm Hg760 torr1 atm101
kPa
If isoflurane is added to a flask of oxygen what is the percentage concentration of both isoflurane and
oxygen? correct answers Oxygen Partial Pressure = 760Isoflurane Partial Pressure = 240After adding
Isoflurane to the flask, the partial pressure of oxygen is now 520 mmHg.% Oxygen = (520/760) = 69%%
Isoflurane = (240/760) = 31%It really is just that easy.
If you add Desflurane to a flask of Oxygen, what is the percentage concentration of both Desflurane and
oxygen? correct answers Oxygen Partial Pressure = 760 mmHgDesflurane Partial Pressure = 669
mmHgAfter adding Isoflurane to the flask, the partial pressure of oxygen is now 91 mmHg% Oxygen = (91
/ 760) = 11%% Desflurane = () = 89%It really is just that easy.
What happens if a volatile agent with a higher vapor pressure is added to a vaporizer calibrated for a
lower vapor pressure? correct answers The concentration delivered will be higher than normal.Higher
Lower High - HLH
What happens if a volatile agent with a lower vapor pressure is added to a vaporizer calibrated for a
higher vapor pressure? correct answers The concentration delivered will be lower than normal.Lower
Higher Low - LHL
What is unique about the deslflurane vaporizer? correct answers It is heated to approxmiately 39
degrees celsius which creates a vapor pressure of nearly 1500 mmHg (two atmospheres).This drives"
desflurane to the gas outlet"
1 mmHg = (X) cm H2O1 atm = (X) mmHg = (X) psi = (X) kPa = (X) bar1 psi = (X) mmHg correct answers 1
mmHg = 1.36 cm H2O1 atm = 760 mmHg = 14.7 psi = 101 kPa = 1 bar1 psi = 54 mmHg
How do Bourdon gauges work?What does it mean when the Bourdon gauge on a cylinder reads zero?
correct answers They measure high (cylinder) pressure relative to atmospheric pressure.That the cylinder
pressure is equal to atmospheric pressure and there is no 'drive' to the gas.
, What is the Law of Laplace?What structures within the body does this apply to? correct answers Tension
= (Pressure) x (radius)This is try for cylinder structures, such as blood vessels and the left ventricle.It
means that as the structure expands (radius increases) the tension (force) of the structure increases as
well.
How does the Law of LaPlace help understand why aneurysms are more likely to rupture than healthy
blood vessel? correct answers Tension = (Pressure) x (Radius)So, the tension on the wall is proportional
to the radius. The larger the radius (anyeursm) more likely the vessel will rupture as the tension
increases.
How does the Law of LaPlace help understand why capillaries are more likely to withstand high pressures
than larger blood vessels? correct answers Tension = (Pressure) x (Radius)Because the radius in a
capillary is so much smaller (perhaps 1/100th of a larger vessel) it can withstand a much greater increase
in Pressure before Tension will increase.
What is the Law of LaPlace when applied to spheres?How is this applied to physiology?Why do we care?
correct answers Tension = (Pressure)(Radius) / 2This is applied to normal alveoli which have surfactant
and those that do not (ARDS).We care, because this law is what explains that smaller alveoli with
surfactant do not empty into larger alveoli. Furthermore, why smaller alveoli without surfacant do
empty into larger alveoli
Explain how the Law of LaPlace applies to ARDS alveoli. correct answers Tension is independent of radius
for all spheres where there is a liquid / air interface (alveoli without surfactant).T = PR / 2 → P =
2T/RAs the radius decreases, the pressure increases because tension is constant.If a small alveoli and
large alveoli were connected (as they are in the lung), the higher pressure in the small alveoli will push
gas into the lower presssure larger alveoli.This is what causes alveolar collapse in ARDS.
Explain how the Law of LaPlace applies to normal, surfactant full, alveoli? correct answers Tension is
directly proportional to radius in surfacant full alveoli.T= PR / 2 → P = 2T / RAs the radius decreases,
the tension decreases proportionally - this maintained equal pressure.Therefore, there is no pressure
gradient between a smaller and larger alveoli, and this is why small alveoli do not empty into large
alveoli in a healthy lung.
What is the definition of Laminar Flow?What law defines this? correct answers Hagen-Poiseuille's
LawFlow = (π)(radius4)(ΔP) / (8)(n)(L)'Flow is equal to pi times radius to the fourth power times
the pressure gradient over viscosity times length.Flow is directly proportional to the fourth power of the
radius.
What happens to laminar flow if you double the radius of the given tube? correct answers Flow would
increase 16 timesFlow is directly proportional to the fourth power of the radius.Flow = 2x2x2x2 = 16
What happens to laminar flow if you triple the radius of a given tube? correct answers Flow would
increase 81 timesFlow is directly proportional to the fourth power of the radius.Flow = 3x3x3x3 = 81
What is the relationship between Laminar Flow and the Pressure Gradient? correct answers Laminar
Flow is directly proportional to the hydrostatic pressure gradient.
