Lung Testing B Flashcards

1
Q

Nitrogen washout: A method to measure ___.

A

FRC

Functional Residual Capacity

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2
Q

In nitrogen washout, the patient breathes 100% oxygen for up to ___ minutes or until the N2% is less than ___ to “wash out” the nitrogen from the lungs. Exhaled gases are collected in a spirometer or bag and the final ___ is used to calculate the ___.

A

7 minutes
Less than 1%.
N2%
FRC

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3
Q

Nitrogen washout: a patient with normal lungs should wash out in ___ minutes or less. A patient with obstructive lung disease will take (shorter or longer).

A

3 minutes

Longer (than 7 minutes)

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4
Q

Nitrogen washout: when should “switch in” occur?

A

At the end of normal expiration.

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5
Q

Nitrogen washout: There are three lung values that are calculated. What are they?

A

FRC, RV, and TLC.

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6
Q

Nitrogen washout: breath by breath analysis is possible with a/an ___.

A

Rapid nitrogen analyzer.

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7
Q

Nitrogen washout: a ___ is not required in nitrogen washout because no rebreathing occurs.

A

CO2 reabsorber.

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8
Q

Nitrogen washout: If %N2 does not drop after several minutes, what should you suspect?
How much N2 is in the atmosphere?

A

Air leaking into the system.

Amount of nitrogen in room air: 79%

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9
Q

Nitrogen washout: If the O2 tank is less than ___, you should replace it.

A

50psi

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10
Q

Body Plethysmography: What is the definition of Thoracic Gas Volume (VTG)?

A

Volume of gas contained in the thorax measured at end expiration. Includes measurement of air trapped in thorax which is not in communication with airways.

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11
Q

Body Plethysmography: The VTG is usually equal to ___.

A

FRC

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12
Q

Body Plethysmography: How is the RV/TLC ratio calculated?

A

Divide residual volume by total lung capacity then multiply by 100.

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13
Q

What is the technique for doing a typical body plesthysmography?

A
  1. Patient breathes normally for several minutes.
  2. At end expiration, shutter closes and patient “pants”. No airflow is occurring.
  3. Mouth pressure approximates alveolar pressure when there is no airflow. (Pmouth = Palveolar)
  4. A second pressure transducer measures pressure in the box, which is equal to the volume of gas in the thorax. (Pbox = V tg)
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14
Q

Body Plethysmography: What law is used to calculate thoracic gas volume?

A

Boyle’s law

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15
Q

Body Plethysmography: On the oscilloscope, the vertical axis represents ___.

A

Mouth pressure

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16
Q

Body Plethysmography: On the oscilloscope, the horizontal axis represents ___.

A

Volume change

17
Q

Body Plethysmography: If the volume changed during the procedure but the pressure didn’t, what should you suspect?

A

Mouth pressure transducer line was not connected.

18
Q

In patients with emphysema, the FRC measurements will be higher than the FRC measured by ___ or ___.

A

Helium dilution and nitrogen washout

19
Q

Body Plethysmography: The angle of the pressure volume loop should should be ___ degrees.

A

45

20
Q

Body Plethysmography: A flattened pressure-volume curve displaced downward indicates ___.

A

Restrictive

21
Q

Radiological estimation of TLC: CXR is taken from two views. What are they?

A

PA and lateral

Radiologic estimates are similar in accuracy to body plethysmography measurements.

22
Q

In patients with obstructive lung disease, radiologic measurements will result in higher ___, ___, and ___ when compared to Body Plethysmography.

A

TLC, RV, and FRC.

23
Q

If a patient is unable to do lung testing, ___ is a good alternative.

A

Radiological estimation of TLC

24
Q

When doing radiological estimation of TLC, diseases such as pneumonia, atelectasis, and tumors will result in falsely (high/low) measurements.

A

Falsely low.