Pulmonary Function Test

Question 1

How do you conduct a CO diffusion test?

Answer 1

Question 2

What are the 3 categories of lung diseases we should be familiar with?

Answer 2

Question 3

What values on spirometry would be altered in a person with obstructive airway disease?

Answer 3

Increased RV and TLC

Decreased FEV1/FRC ratio

Question 4

What are all the labels on this diagram?

Answer 4

1) Total lung capacity (TLC)
2) Functional residual capacity (FRC)
3) Expiratory reserve volume (ERV)
4) Inspiratory reserve volume (IRV)
5) Forced vital capacity (FVC)
6) Residual volume (RV)
7) Inspiratory capacity (IC)
8) Tidal volume (Vt)
9) Vital capacity (VC)

Question 5

Why is the inhalation flow negative in this graph?

Answer 5

The spirometer measures air taken away from the device as negative (sucking air in during inhalation) and flow that is given back to the device as positive (blowing air out during expiration)

Question 6

Forced Vital capacity = […] + […]

Answer 6

IRV + ERV

Question 7

Where is the FEV1 and FVC on this graph?

Question 8

What is the peak expiratory flow rate?

Answer 8

Rate of change of volume / rate of change of time

Question 9

Answer 9

Question 10

What is FEV1?

What is FVC?

Answer 10

• FEV1 is forced expiratory volume, or the VOLUME of air that a person can force out of their lungs during 1 second
• FVC is forced vital capacity, or the total amount of air that the person can force out of their lungs

Question 11

What causes an increased diffusion capacity result for CO test?

Answer 11

Question 12

What is coving?

Answer 12

Question 13

What does this spirometry report tell you?

Answer 13

Decreased FVC

Decreased FEV1

Decreased FEV1/FVC –> COPD

Increased TLC –> COPD

Increased RV –> COPD

Question 14

What values on spirometry would you expect if a person has restrictive airway disease?

Answer 14

All volumes of air decreased

FEV1/FVC is normal to increased

Question 15

Why would you order a PFT?

Answer 15

• Diagnose symptomatic disease (dyspnea, cough, hypoxemia that is unexplained)
• Screen for early asymptomatic disease
• Prognosis of known disease
• Monitor response to treatment

Question 16

What could cause a decreased diffusion capacity for CO?

Answer 16

Question 17

If the diffusion capacity of CO is decreased on spirometry, what does that indicate?

Answer 17

Obstructive disease –> a problem occuring at the level of the respiratory membrane that impairs the ability of CO to diffuse from the blood into the alveoli (fibrosis, surface area, etc.)

Question 18

• What does the FEV1 / FVC ratio tell you clinically?
• What is a normal value for this ratio?
• What does a reduced ratio indicate?
• What does an increased ratio indicate

Answer 18

• This ratio is a measure of airway resistance, since the FEV is the volume of air that can be forced out in 1 second and the FVC is the total volume of air that can be forced out overall.
• A normal value for this ratio is around 0.8
• Asthma and emphysema can reduce the FEV1, resulting in a reduction of the overall ratio so ratio < 0.8 may indicate obstructive disease (difficulty getting air out thus decreased FEV1)
• Restrictive lung diseases like fibrosis cause increased restriction of the airways leading to decreased FVC. This will result in an increase in the ratio and thus can indicate restrictive airway disease (difficulty getting air in, thus decreased FVC)

Question 19

What values on spirometry would you expect if a person had mixed obstructive and restrictive disease?

Answer 19

FEV1/FVC decreased

TLC decreased