Deck 3: Diffusing Capacity Tests

Question 1

If the He and CO analyzers used for a DLCOsb test are linear with respect to each other,the fractional concentration of CO at the beginning of the breath hold (F_ACO₀)is equal to:

A) F_AHe
B) F_AHe/F_IHe
C) F_ICO
D) logn F_IHe

Answer 1

A

Question 2

An adult male subject has the following measurements made: What DLCO value should be reported?

A) 9.1 ml CO/min /mm Hg STPD
B) 10.6 ml CO/min/mm Hg STPD
C) 12.6 ml CO/min/mm Hg STPD
D) 13.3 ml CO/min/mm Hg STPD

Answer 2

D

Question 3

The following DLCO data (reported in ml CO/min/mm Hg)are obtained from a subject: What should the technologist do next?

A) Report the mean of all three trials.
B) Perform another maneuver.
C) Report the mean of the second and third trials.
D) Report the third trial only.

Answer 3

C

Question 4

Differences in the calculation of the DLCOsb because of the timing of the breath-hold period may be minimized by:

A) Having the subject breath hold at 80% VC
B) Measuring breath-hold time from the midpoint of inspiration
C) Having the subject inspire and expire rapidly
D) Limiting breath-hold time to less than 8 seconds

Question 5

Diffusing capacity is reduced in emphysema because of which of the following?

A) Loss of alveolar surface area
B) Engorgement of pulmonary capillaries
C) Dynamic airway compression
D) Elevated pulmonary arterial pressure

Question 6

In which of the following situations would the DLCO be artificially increased?

A) The measurement is performed at 1500 m above sea level.
B) The subject smoked 1 hour before the test.
C) The measurement is made with the subject in the standing position.
D) The subject has had his or her right lung removed.

Question 7

A subject has her DLCOsb measured as 10.1 ml CO/min/mm Hg (STPD);her diffusing capacity measured by the DLCOrb is 9.1 ml CO/min/mm Hg (STPD).These findings are consistent with:

A) Normal lung function
B) Normal difference in a subject with restriction
C) An improperly calibrated He analyzer
D) The inability to breath hold near TLC

Question 8

A subject has a DLCOsb of 10.2 ml CO/min/mm Hg (STPD),which is 51% of her predicted value.Her D_L/V_A ratio is 4.1.Which of the following diagnoses is most consistent with these values?

A) Pulmonary emphysema
B) Pulmonary resection
C) Cystic fibrosis
D) COHb of 5.5%

Question 9

The membrane diffusion coefficient (resistance to diffusion by the alveolo-capillary membrane)is estimated by:

A) The DLCOss method
B) Dividing the DLCO by the PaO₂
C) Performing the DLCOsb at two different levels of PAO₂
D) Subtracting F_ACO_T1 from F_ACO_T2 obtained from the DLCOrb

Question 10

Which of the following determines the fractional concentration of CO after 10 seconds of breath holding (F_ACO_T)?

A) (F_AHe/F_IHe) $\times$ F_ICO
B) Volume inspired divided by F_AHe/F_IHe
C) Estimation of the ratio F_ICO/F_AHe
D) Measurement of CO from an alveolar sample

Question 11

Why is CO an ideal gas for measuring diffusing capacity of the lungs?

A) It is taken up by Hb in a manner similar to O₂.
B) It is always present in capillary blood at 0.3%.
C) It is quickly converted to CO₂ in the lungs.
D) It does not react with He or other tracer gases.

Question 12

Which of the following DLCO methods is deemed to provide the most accurate measurement of diffusion?

A) DLCOrb
B) Membrane diffusing capacity
C) DLCOsb
D) DLCOib

Question 13

Which of the following is an advantage of continuous analysis of expired gas during a DLCOsb test?

A) Instrument dead space is eliminated.
B) Exhaled gas concentrations can be visually inspected.
C) CO back pressure is reduced.
D) Breath-hold times longer than 12 seconds are acceptable.

Question 14

A subject has a DLCOsb of 8.3 ml CO/min/mm Hg STPD,which is 38% of his predicted value.His calculated D_L/V_A ratio is 1.1.These values are most consistent with which of the following?

A) Pulmonary emphysema
B) Pulmonary resection
C) Pulmonary fibrosis
D) Pulmonary edema

Question 15

A Valsalva maneuver during the DLCOsb:

A) Is required to properly perform the breath hold
B) May cause the D_L/V_A to appear artificially elevated
C) May cause the DLCOsb to appear artificially reduced
D) Helps keep breath-hold time between 8 and 12 seconds

Question 16

The Jones method of timing the breath hold for DLCOsb measures the interval from _____ of alveolar sampling.

A) Beginning of inspiration to beginning
B) 0.3 units of inspiratory time to the middle
C) 0.5 units of inspiratory time to the middle
D) Beginning of breath hold to the end

Question 17

All of the following gases may be used as a tracer gas when performing the DLCO test except:

A) Methane
B) Neon
C) Carbon dioxide
D) Helium

Question 18

A nonsmoking subject performs two DLCOsb maneuvers,and the following results are obtained: Test 1 24.3 ml CO/min/mm Hg
Test 2 18.7 ml CO/min/mm Hg
Which of the following is appropriate?

A) Reporting the largest value as the DLCO
B) Reporting the average of the two values
C) Performing an additional maneuver
D) Correcting the value from Test 2 for COHb

Question 19

Which of the following DLCO methods is best suited to measuring diffusing capacity during exercise?

A) DLCOsb
B) DLCO membrane
C) DLCOrb
D) Membrane conductance

Question 20

The pressure gradient for the diffusion of CO in the lung is:

A) Equivalent to the partial pressure of inspired CO
B) The difference between inspired and expired CO
C) Equal to the alveolar minus capillary partial pressure of CO
D) Equal to the alveolar-arterial O₂ gradient

Question 21

The following data are obtained from a 19-year-old female subject complaining of shortness of breath: Which of the following interpretations is most consistent with the data?

A) Mixed pattern
B) Obstruction
C) Restriction
D) Fixed obstruction

Question 22

The following data are obtained from a 25-year-old male with an FVC of 6.50 L and an FEV₁ of 3.46 L: What should the technologist do next?

A) Report the mean of the two trials.
B) Perform another trial because the values are not repeatable.
C) Perform another maneuver because the IVC is too low.
D) Report the first trial only.

Question 23

The following data are obtained from an 80-year-old male subject complaining of shortness of breath: Which of the following interpretations is most consistent with the data?

A) Emphysema
B) Bronchitis
C) Pulmonary fibrosis
D) Asthma

Question 24

A subject performs the following two DLCO maneuvers: What should the technologist do next?

A) Data are not acceptable;perform another maneuver.
B) Data are repeatable;report the mean of two results.
C) Data are repeatable;report the largest value from maneuver #2.
D) Data are acceptable and repeatable;report the mean of the two results.

Question 25

In a healthy subject,what are the ATS-ERS recommended washout volume and sample volumes?

A) Washout volume 0.75-1.0 L and sample volume 0.5-1.0 L
B) Washout volume 1.0 L and sample volume 0.25 L
C) Washout volume 0.5 L and sample volume 0.25 L
D) Washout volume 1.0-1.5 L and sample volume 0.5-1.5 L

Question 26

Which of the following methods does the ATS-ERS recommend to calculate breath-hold time?

A) Epidemiology Standardization Project (ESP)method
B) Jones method
C) Ogilvie method
D) Three-equation method

Question 27

Compared with oxygen,how much more readily does carbon monoxide combine with hemoglobin?

A) 210 times
B) 150 times
C) 175 times
D) 240 times

Question 28

Which of the following statements is correct regarding DLCO adjustments?

A) Anemia will cause the DLCO values to be higher.
B) Altitude will lower DLCO.
C) Smoking will falsely increase DLCO.
D) Polycythemia will increase the DLCO.

Question 29

What does the abbreviation DM represent?

A) Diffusion membrane
B) Diffusion mean
C) Membrane conductance
D) Membrane resistance

Question 30

The following data are obtained from a subject complaining of shortness of breath: Which of the following statements would be most correct regarding the data?

A) The data are consistent with obstructive lung disease.
B) The data are consistent with normal lung function.
C) Isolated reduction in DLCO is consistent with pulmonary vascular disease.
D) DLCO data should be questioned because the V_A is significantly larger than the TLC.

Question 31

According to the 2005 ATS-ERS guidelines for diffusing capacity,what is the recommended breath-hold time?

A) 9-11 seconds
B) 8-12 seconds
C) 10 seconds $\pm$ 1 second
D) 10 seconds

Question 32

In what units is DLCO/V_A reported?

A) ATPS
B) STPD
C) BTPS
D) None of the above

Question 33

The following data are obtained from a 40-year-old male with an FVC of 4.70 L and an FEV₁ of 3.46 L: What should the technologist do next?

A) Report the mean of the two trials.
B) Perform another maneuver because the DLCO/V_A is unbelievable.
C) Perform another maneuver because the IVC is too low.
D) Perform another maneuver because the V_A is not repeatable.