Lung Testing B

Question 1

Nitrogen washout: A method to measure ___.

Answer 1

FRC

Functional Residual Capacity

Question 2

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 ___.

Answer 2

7 minutes
Less than 1%.
N2%
FRC

Question 3

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).

Answer 3

3 minutes

Longer (than 7 minutes)

Question 4

Nitrogen washout: when should “switch in” occur?

Answer 4

At the end of normal expiration.

Question 5

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

Answer 5

FRC, RV, and TLC.

Question 6

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

Answer 6

Rapid nitrogen analyzer.

Question 7

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

Answer 7

CO2 reabsorber.

Question 8

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

Answer 8

Air leaking into the system.

Amount of nitrogen in room air: 79%

Question 9

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

Answer 9

50psi

Question 10

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

Answer 10

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.

Question 11

Body Plethysmography: The VTG is usually equal to ___.

Answer 11

FRC

Question 12

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

Answer 12

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

Question 13

What is the technique for doing a typical body plesthysmography?

Answer 13

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)

Question 14

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

Answer 14

Boyle’s law

Question 15

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

Answer 15

Mouth pressure

Question 16

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

Answer 16

Volume change

Question 17

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

Answer 17

Mouth pressure transducer line was not connected.

Question 18

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

Answer 18

Helium dilution and nitrogen washout

Question 19

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

Answer 19

45

Question 20

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

Answer 20

Restrictive

Question 21

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

Answer 21

PA and lateral

Radiologic estimates are similar in accuracy to body plethysmography measurements.

Question 22

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

Answer 22

TLC, RV, and FRC.

Question 23

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

Answer 23

Radiological estimation of TLC

Question 24

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

Answer 24

Falsely low.