Lung Testing - Test Your Knowledge (Workbook)

Question 1

The volume of gas remaining in the lungs at the end-expiratory level is termed

A. residual volume
B. total lung capacity
C. expiratory reserve volume
D. functional residual capacity

Answer 1

A. residual volume

Question 2

A technologist is performing FRC measurement with the helium dilution technique. The technologist has completed one full testing session. The technologist should wait 10-15 minutes before repeating the procedure to allow for the

A. infrared analyzer to be recalibrated
B. patient to relax
C. clearance of helium from the lungs
D. proper “switch in”

Answer 2

C. clearance of helium from the lungs

Question 3

A technologist is performing FRC measurement with the nitrogen washout technique. After several minutes of testing, the technologist notices that the % N2 has failed to drop from the start of the test. The most common cause is

A. analyzer failure
B. air is leaking into the system
C. CO2 absorber was not placed correctly
D. patient fatigue

Answer 3

B. air is leaking into the system.

Question 4

All of the following can account for erroneously high measurements that are out of proportion to the patient’s clinical history when performing He dilution EXCEPT

A. analyzer failure
B. switch in occurred before end expiration
C. CO2 absorber was placed incorrectly
D. ruptured eardrum

Answer 4

C. CO2 absorber was placed incorrectly

The placement of the scrubber may affect other factors, but will not affect helium concentration.

*page C-8

High measurements (more helium is being diluted than normal) can be caused by

1. leaks
2. switch in occurred before end expiration
3. ruptured eardrum (tympanic membrane)
4. failure of analyzers

Question 5

A technologist is performing FRC measurement utilizing the body plethysmograph. At what point during testing should the technologist instruct the patient to pant?

A. end expiration
B. peak inspiration
C. total lung capacity
D. maximal expiratory level

Answer 5

A. end expiration

Question 6

Which of the following are appropriate methods for measuring FRC?

1. nitrogen washout
2. DLCO-SB
3. radiologic estimation
4. inductive plethysmograph

A. 1 and 2 only
B. 1, 2, and 3 only
C. 3 and 4 only
D. 1 and 3 only

Answer 6

D. 1 and 3 only

The ONLY 4 methods that measure FRC (all static volumes, aka anything with an RV in it) are

helium dilution
nitrogen washout
radiologic estimation
body box

Question 7

A technologist is performing FRC measurement with the nitrogen washout technique. After several minutes of testing the technologist notices on the oscilloscope that the % N2 has dropped initially, however has leveled off to a consistent level that is higher than normal. The most likely explanation is that

A. the technologist forgot to “switch in” the patient
B. air is leaking into the system
C. the patient has an obstructive disease
D. the analyzer has failed

Answer 7

C. the patient has an obstructive disease

*page C-9

The clue was that the N2 has dropped “initially” but now leveled off.

Patient’s with obstructive diesease (emphysema, as stated in the study guide) may not wash out completely, leading to the reported results in the question. The N2 dropped at the start, but was still high when leveling off.

A leak in the system is a good choice, but will be indicated by NO drop in % N2 after several minutes. There was a drop initially in this case.

Question 8

Which of the following is an appropriate calculation for FRC?

A. VC + RV
B. TLC - IC
C. VT + IRV
D. ERV - RV

Answer 8

B. TLC - IC

Inspiratory capacity is made up of IRV and VT.
If you remove those from TLC, you are left with ERV + RV, which are the volumes that make up the FRC.

Question 9

The measured V-TG from body plethysmography is determined to be higher than the FRC measured from helium dilution and nitrogen washout. The most common pathology that can yield these results is

A. diffusion defect
B. pulmonary fibrosis
C. emphysema
D. muscular dystrophy

Answer 9

C. emphysema

Emphysema is associated with air trapping, and a body box test will be able to measure the trapped air.

Another way of looking at this is to compare the given choices. There is only one obstructive disease (CBABE) listed. If you recall, the body box is the best method for calculating trapped (obstructed) air.

Question 10

A technologist has an order to perform bronchial provocation testing with methacholine. The technologist performed the initial baseline spirometry and measured the FEV1 of 3.2L. The technologist should continue administration of methacholine until the FEV1 drops to a value of

A. 2.56
B. 2.49
C. 1.28
D. 0.64

Answer 10

A. 2.56

You continue the methacholine challenge until a 20% decrease is FEV1 is reached.

80% of 3.2 is 2.56

Question 11

The senior pulmonary function technologist has an order to perform Mannitol challenge testing. While perorming an initial assessment prior to the test, the patient informs the technologist that they have had a viral infection for the past two weeks. The technologist should

A. contact the referring physician
B. refuse to administer the test
C. proceed with testing
D. delay the test for another two weeks

Answer 11

D. delay the test for another two weeks.

*page C-17

Patient’s with viral infections should have testing delayed by 3 weeks

Question 12

The normal value for airways resistance is

A. 1.5-2.5
B. 0.6-2.4
C. 0.42-1.67
D. 42.4-34.5

Answer 12

B. 0.6-2.4

*page C-18

Narrator recommends remembering the range as 1-2. Note choice B was the only option that included all values between 1-2.

Question 13

During testing with a body box, the point at which an S-shaped curve appears on the oscilloscope plots

A. flow against box pressure
B. mouth pressure against box pressure
C. box pressure against flow
D. flow against mouth pressure.

Answer 13

A. flow against box pressure.

*page C-18

“patient pants gently at a rate of 2 bpm with the shutter open allowing measurements to be made at FRC. This maneuver creates an S shaped curve on the oscilloscope (screen) that plots flow (volume) against box pressure.”

Question 14

Which of the following measurements is considered a more appropriate method for determining small airways disease?

A. Raw
B. Clt
C. Gaw
D. CL

Answer 14

C. G-aw

*page C-22

Associate Airway Conductance (G-aw) with being better for measuring small airway disease than R-aw

Question 15

The measurement that is derived from the slope of a pressure-volume curve over the segment from FRC to FRC + 0.5L is

A. Raw
B. Clt
C. Gaw
D. Cl

Answer 15

D. Cl

*page C-22, verbatim note is page C-23 last line.

“C” denotes compliance

Clt = lungs and thorax
Cl = lungs only
Ct = thorax only

Important: Associate Cl, Clt, and Ct with the esophageal balloon technique.

Question 16

Lung compliance can increase in patients with

A. pulmonary fibrosis
B. emphysema
C. atelectasis
D. pneumonia

Answer 16

B. emphysema

The only obstructive choice given. COPD patients have over compliant lungs and emphysema is associated with COPD.

If you have to guess, try CBABE. in many practice questions, the correct disease process is usually the one that is unlike the others.

Question 17

The technologist measured the patient’s maximum inspiratory pressure and reported a value of + 40 cm H2O. The most likely explanation for this result is

A. the patient exhaled during the maneuver
B. this is an appropriate value for MIP
C. the stopcock was left in the open position
D. the patient was not wearing nose clips

Answer 17

A. the patient exhaled during the maneuver

Normal MIP is -60 cm H20 (a NEGATIVE value)

Normal MEP is 80-100 (a POSITIVE value)

The patient’s measured value is positive, meaning he exhaled during the maneuver

Question 18

A patient with a history of heavy smoking has a CO Hb of 9% and a DLCO of 11. If the observed value were adjusted for the elevated CO level, the corrected DLCO would be

A. lower
B. higher
C. same
D. unable to determine without the Hb concentration

Answer 18

B. higher

A couple of ways to answer this…

1. Normal DLCO is 25. IMPORTANT!

If the measured DLCO is 11, you know the corrected amount should be higher.

2. Know the 3 factors that affect the DLCO (page C-27) which are:
   Hb and Hct levels
   Alveolar PCO2
   CO Hb

Increased CO Hb will decrease DLCO because of backpressure. 1% increase CO Hb will decrease DLCO by 1%.

If backpressure is preventing the diffusion of CO, you know the corrected amount should be higher.

Question 19

Before transporting a patient to the pulmonary function lab for a single breath diffusing capacity (DLCO-SB), the technologist reviews the patient’s chart. The technologist notes that the physician has written an order for the head of the patient’s bed to be in the flat position at all times. If the technologist performs the test with the patient in this position, what effect would the bed position have on the results?

A. lower than expected DLCO value
B. no effect on the results
C. higher than expected DLCO value
D. increases the washout value

Answer 19

C. higher than expected DLCO value

*page C-27 “body position”

“lying down will increase the DLCO because of increased capillary blood flow.”

Question 20

During a DLCO-SB procedure, the technologist records the results of three different trials

Trial 1 25ml/CO/min/mmHg
Trial 2 24ml/CO/min/mmHg
Trial 3 18ml/CO/min/mmHg

The technologist should

A. discard all three maneuvers and begin again
B. accept all three maneuvers and record the results
C. accept Trial 3 only and continue testing
D. accept Trial 1 and 2 and record the results

Answer 20

D. accept Trial 1 and 2 and record the results