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Brian's Practice Course > Lung Testing - Flash Cards > Flashcards

Lung Testing - Flash Cards

1
Q

Describe the helium dilution technique.

  1. Helium concentration used is usually ___%
  2. The helium is mixed with ___ ___.
  3. The patient rebreathes the mixture for ___ minutes.
  4. “Switch in” begins at this part of the breath.
  5. Because the patient rebreathes the mixture, you’ll need a ___
A
  1. 10% concentration
  2. room air
  3. 7 minutes
  4. end expiration
  5. CO2 scrubber
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2
Q

How do you know when to end a helium dilution test?

A

The end of the test occurs when the helium concentration changes by less than 0.02% over 30 seconds.

Look for 2-3 similar readings on the exam.

*page C-7

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3
Q

Helium Dilution:

  1. If the helium starts to rise, this is a good indication of what?
  2. Why does the helium concentration rise?
A
  1. That there is no leak in the system
  2. The concentration may rise because you are consuming gas (the O2) in a closed system. This lowers the baseline volume of gas in the system, causing the ratio of helium to other gases to increase.
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4
Q

When troubleshooting the body box, erroneously high FRC measurements (out of proportion to clinical history or other values) may be the result of

1.
2.
3.
4.

A
  1. leaks
  2. ruptured eardrum
  3. switch in happened before end-expiration
  4. analyzer failure
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5
Q

Gas Cylinder Troubleshooting:

If the cylinder pressure is low, what should you do?

Is 50 psi a low pressure?

Full tanks are normally ___ psi.

A

replace the cylinder

yes.

2200 psi

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6
Q

Describe the nitrogen washout technique.

Patient rebreathes ___% oxygen for up to ___ minutes, or until the N2 is < ___%.

A

100% oxygen
7 minutes
< 1%

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7
Q

What part of the breath should switch in occur for a nitrogen washout test?

A

end expiration

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8
Q

Is nitrogen washout an “open” system?
Does rebreathing occur in the test?
Do you need a CO2 scrubber?

A

Yes it is an open system.
No rebreathing occurs in an open system
Since no rebreathing occurs, you do not need a CO2 scrubber.

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9
Q

Which method is the “most accurate” test for measuring static volumes?

What is its FRC equivalent measurement called?

A

The body box (body plethysmograph)

Thoracic Gas Volume, V-tg.

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10
Q

If a V-tg is larger than the FRC value on another type of test, what caused the difference?

A

Trapped air. The body box will measure all trapped gases

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11
Q

Body box troubleshooting: Choose either mouth or box for each of the blanks

  1. The vertical signal on a body box reading is produced by the ___, which measures pressure.
  2. The horizontal signal on a body box reading is produced by the ___, which measures volume.
A
  1. Mouth (associate with vertical signal and pressure)

2. Box (associate with horizontal signal and volume)

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12
Q

Name the 4 tests that can be used to measure static lung volumes (aka, any volume including RV)

1.
2.
3.
4.

A
  1. helium dilution
  2. nitrogen washout
  3. radiologic estimation
  4. body plethysmograph
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13
Q

A positive methacholine challenge test occurs when there is a ___% decrease in the ___.

A

20% decrease in the FEV1

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14
Q
  1. How long should you hold a SABA before a methacholine challenge test?
  2. How long should you hold a LABA before a methacholine challenge test?
  3. Do beta blockers affect the test results?
A
  1. SABA 8 hours
  2. LABA 48 hours
  3. Yes.
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15
Q

A 15% decrease in FEV1 is considered a positive test for which two methods?

A

Exercise testing and Mannitol challenge.

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16
Q

What would you do before a maximal inhalation to get the best MIP?

A

Maximal exhalation. You should blow out until you are at RV before inhaling.

17
Q

What would you do before a maximal exhalation to get the best MEP?

A

Maximal inhalation. You should inhale to TLC before exhaling.

18
Q

True or false:

The results on the DLCO are reported in STPD and not BTPS.

A

True

19
Q

Fill in the blank:

  1. When values are corrected from ATPS to BTPS they ___

2. When values are corrected from BTPS to ATPS they ___

A
  1. Increase

2. Decrease

20
Q

DLCO: Increase or decrease?

If PACO2 increases, DLCO will ___.

A

Decrease.

If PACO2 increases, DLCO decreases.

This happens because with higher PACO2, there is less PAO2. Less PAO2 means Less room for CO.

21
Q

A patient should not smoke for ___ hours before a DLCO test.

A

48 hours

22
Q

Increase or Decrease?

Lower lung values and thickened membranes associated with restrictive disease will ___ DLCO

A

Decrease

23
Q

___ is the only obstructive disease that will produce a low DLCO. This is due to a loss of surface area and VQ mismatch.

A

Emphysema.

Note: If you are choosing between 2 obstructive diseases as answers look at the DLCO results if provided to determine if the answer is emphysema. If the DLCO is low, the answer is emphysema.

24
Q

True or False?

  1. A leak will increase DLCO because air will be introduced into the sample and lower the CO concentration, making it apper as though more CO has diffused into the body.
  2. If more CO diffuses into the body, the DLCO is increased.
A
  1. True. A leak will increase DLCO
  2. True. Higher diffusion = higher DLCO
    * page C-28
25
Q

You have to take two different diffusion studies at two different levels of oxygen to get this value.

A

Membrane Diffusion Coefficient/Factor

26
Q

Yes or No:

During exercise testing, the patient complains of dyspnea after exercising. Should you proceed with testing by having the patient perform and FVC?

A

Yes. This is the point of exercise testing. To find the cardiac/ventilatory limitation to work.

27
Q

Typical airway resistance value in cm H2O/L/sec?

A

1-2

28
Q

Typical airway resistance (total) in percent, of upper airway, trachea, bronchi, and small airways combined?

___%

A

80%

29
Q

Esophageal Balloon:

What is the amount of air added to the balloon?

A

0.5 ml

30
Q

Esophageal Balloon:

What is the optimum placement of the tip of the balloon when measured from the nose?

___cm

A

50 cm

page C-23

31
Q

Not so important: (just look at them, don’t worry if you miss these)

  1. Normal static lung compliance?
  2. Normal coefficient of retraction?
  3. Normal maximum static recoil pressure range?
A
  1. 0.2
  2. 4-8
  3. 25-35
32
Q

What is a typical MIP?

A

-60

33
Q

What is a typical MEP?

A

80-100

34
Q

What is a typical DLCO?

A

25

35
Q

This is always asked on the exam

When performing a DLCO-SB (single breath) the inspired volume must be ___% of the SVC.

A

85%

36
Q

The ONLY test reported in STPD is ____?

A

DLCO

37
Q

What is the gas mixture in a DLCO-SB study?

___% CO
___% He
___% O2
and the rest is ___.

A

0.3% CO
10% He
21% O2
and the rest is N2

38
Q

How much CO is given in a DLCO-SB study?

A

0.3% CO

Brian's Practice Course (32 decks)

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