ITE Qns help

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cockblockandrun

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Hey guys-

I've been doing some old ITE qns off the ABA site and got stumped on some questions. If someone can help explain a few of these, that would be awesome.

1. An enflurane vaporizer is filled with halothane and the vaporizer dial is set at 1%. Which of the following will occur?
a. less than 1% halothane will be delivered
b. more than 1% halothane will be delivered
c. thymol preparation will prevent vaporization
d. The vaporizer bypass will not open
e. The vaporizer will be damaged

2. Two opened oxygen cylinders, one full and one empty, are attached to the anesthesia machine. The check valve to the empty cylinder fails. This is expected to result in:
a. activation of the fail-safe device
b. cessation of oxygen flow to the anesthesia circuit
c. filling of the empty cylinder with a mixture of all gases supplied to the anesthesia machine
d. increase in the temperature of the empty cylinder
e. interruption of gas delivery from the central oxygen supply

3. Which of the following is the most important function of temperature compensation in anesthestic vaporizers?
a. compensation for changes in the specific heat of the anesthestic during vaporization
b. delivery of diluent gas at a constant temperature regardless of flow rate
c. increase of bypass flow when the vaporizer is cooled by high fresh gas flow
d. maintenance of constant anesthestic vapor output over a range of vaporizer temperatures
e. maintenance of constant vapor concentrations at low flow rates

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Hey guys-

I've been doing some old ITE qns off the ABA site and got stumped on some questions. If someone can help explain a few of these, that would be awesome.

1. An enflurane vaporizer is filled with halothane and the vaporizer dial is set at 1%. Which of the following will occur?
a. less than 1% halothane will be delivered
b. more than 1% halothane will be delivered
c. thymol preparation will prevent vaporization
d. The vaporizer bypass will not open
e. The vaporizer will be damaged

2. Two opened oxygen cylinders, one full and one empty, are attached to the anesthesia machine. The check valve to the empty cylinder fails. This is expected to result in:
a. activation of the fail-safe device
b. cessation of oxygen flow to the anesthesia circuit
c. filling of the empty cylinder with a mixture of all gases supplied to the anesthesia machine
d. increase in the temperature of the empty cylinder
e. interruption of gas delivery from the central oxygen supply

3. Which of the following is the most important function of temperature compensation in anesthestic vaporizers?
a. compensation for changes in the specific heat of the anesthestic during vaporization
b. delivery of diluent gas at a constant temperature regardless of flow rate
c. increase of bypass flow when the vaporizer is cooled by high fresh gas flow
d. maintenance of constant anesthestic vapor output over a range of vaporizer temperatures
e. maintenance of constant vapor concentrations at low flow rates

I think 3 is D not sure about the other 2
 
#1- I would hope they have removed Q's regarding two agents that are no longer used, though I guess there may be a similar question on more modern volatiles.

#2- Should be choice D, which I suspect would be a result of gas from the full O2 canister equilibrating with the empty cylinder. There is a good diagram in brash, p 559 in the 5th ed.
 
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Hey guys-

I've been doing some old ITE qns off the ABA site and got stumped on some questions. If someone can help explain a few of these, that would be awesome.

1. An enflurane vaporizer is filled with halothane and the vaporizer dial is set at 1%. Which of the following will occur?
a. less than 1% halothane will be delivered
b. more than 1% halothane will be delivered
c. thymol preparation will prevent vaporization
d. The vaporizer bypass will not open
e. The vaporizer will be damaged

2. Two opened oxygen cylinders, one full and one empty, are attached to the anesthesia machine. The check valve to the empty cylinder fails. This is expected to result in:
a. activation of the fail-safe device
b. cessation of oxygen flow to the anesthesia circuit
c. filling of the empty cylinder with a mixture of all gases supplied to the anesthesia machine
d. increase in the temperature of the empty cylinder
e. interruption of gas delivery from the central oxygen supply

3. Which of the following is the most important function of temperature compensation in anesthestic vaporizers?
a. compensation for changes in the specific heat of the anesthestic during vaporization
b. delivery of diluent gas at a constant temperature regardless of flow rate
c. increase of bypass flow when the vaporizer is cooled by high fresh gas flow
d. maintenance of constant anesthestic vapor output over a range of vaporizer temperatures
e. maintenance of constant vapor concentrations at low flow rates

1. B. halothane has HIGHER vapor pressure than enflurane, so for a given flow, more is vaporized (volume) in the vaporizing chamber. They can easily change this question to Iso and Sevo since they respectively have similar vapor pressures to Hal and En.

2. C.

3. D.

I've seen nearly identical questions in the new Hall, which may be helpful for your studying. Good luck
 
I'm interested in seeing the answer to #2.

As I can tell, the check valve prevents cross-filling of cylinders. Just downstream to the check valve is a pressure gauge and then a pressure regulator, the separator between the high-pressure and intermediate-pressure circuit. That regulator maintains a pressure of 50-55 psig within the gas machine. So, you have two cylinders allowed to maintain 2200 psig separated from a machine running 45-50 psig. The 2200 psig cylinder will fill the empty cylinder long before any N2O is allowed in there.

Miller: "This check valve serves several functions. First, it minimizes transfer of gas from a cylinder at high pressure to one with lower pressure."

Plus, it's difficult for me to imagine a scenario where someone might design a machine that allows an O2 cylinder to be filled with N2O after the failure of a single valve.

I'm standing by D, until someone can describe to me why an empty cylinder does not experience a raise in temp once filled with millions of bouncing molecules.
 
Hey guys-

I've been doing some old ITE qns off the ABA site and got stumped on some questions. If someone can help explain a few of these, that would be awesome.

1. An enflurane vaporizer is filled with halothane and the vaporizer dial is set at 1%. Which of the following will occur?
a. less than 1% halothane will be delivered
b. more than 1% halothane will be delivered
c. thymol preparation will prevent vaporization
d. The vaporizer bypass will not open
e. The vaporizer will be damaged

2. Two opened oxygen cylinders, one full and one empty, are attached to the anesthesia machine. The check valve to the empty cylinder fails. This is expected to result in:
a. activation of the fail-safe device
b. cessation of oxygen flow to the anesthesia circuit
c. filling of the empty cylinder with a mixture of all gases supplied to the anesthesia machine
d. increase in the temperature of the empty cylinder
e. interruption of gas delivery from the central oxygen supply

3. Which of the following is the most important function of temperature compensation in anesthestic vaporizers?
a. compensation for changes in the specific heat of the anesthestic during vaporization
b. delivery of diluent gas at a constant temperature regardless of flow rate
c. increase of bypass flow when the vaporizer is cooled by high fresh gas flow
d. maintenance of constant anesthestic vapor output over a range of vaporizer temperatures
e. maintenance of constant vapor concentrations at low flow rates


These questions are right out of Hall.
 
I'm standing by D, until someone can describe to me why an empty cylinder does not experience a raise in temp once filled with millions of bouncing molecules.

Wouldn't that assume that the cylinder is being filled retrograde?

I vote for C.
 
Wouldn't that assume that the cylinder is being filled retrograde?

I vote for C.


The cylinder should be filled by the other O2 cylinder, which is more like a parallel phenomenon, because they both exist upstream from the pressure regulator.

I couldn't find that exact question in either version of Hall. The most similar question is

Which of the following valves prevents transfilling between compressed-gas cylinders? A. Fail-safe valve
B. Pop-off valve
C. Pressure-sensor shutoff valve
D. Adjustable pressure-limiting valve
E. Check valve

Answer: E


We could all figure this out if someone just posted the answer....ahem....
 
I'm interested in seeing the answer to #2.

As I can tell, the check valve prevents cross-filling of cylinders. Just downstream to the check valve is a pressure gauge and then a pressure regulator, the separator between the high-pressure and intermediate-pressure circuit. That regulator maintains a pressure of 50-55 psig within the gas machine. So, you have two cylinders allowed to maintain 2200 psig separated from a machine running 45-50 psig. The 2200 psig cylinder will fill the empty cylinder long before any N2O is allowed in there.

Miller: "This check valve serves several functions. First, it minimizes transfer of gas from a cylinder at high pressure to one with lower pressure."

Plus, it's difficult for me to imagine a scenario where someone might design a machine that allows an O2 cylinder to be filled with N2O after the failure of a single valve.

I'm standing by D, until someone can describe to me why an empty cylinder does not experience a raise in temp once filled with millions of bouncing molecules.

You're right on all counts. Before the cylinder O2 can get to the common O2 system there's a pressure regulator that would prevent backflow into the cylinders, so I don't believe that wall O2 can backfill an empty cylinder even if the other cylinders are empty/missing/closed. So in this question the empty O2 cylinder would be (half) filled by the full O2 cylinder, raising its temperature for the reason you stated.

C is wrong because nitrous would need multiple simultaneous failures to get into an O2 cylinder because you'd need failures all the way back from the common gas outlet ... back through the O2 flowmeter, back through the 2nd stage O2 pressure regulator, back through the cylinder pressure regulator, and back through the O2 cylinder's check valve. (Or broken failsafe valve, broken cylinder pressure regulator, broken cylinder check valve.) And even then, the ~50 psi N20 wall (& regulated N2O cylinder) gas would somehow have to overcome the ~50 psi O2 wall (& regulated O2 cylinder) pressure.

D is correct according to the ABA key (#34 book B 1995).
 
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