Pulmonary Function Tests

Question 1

FVC

Answer 1

Forced Vital Capacity

Total volume of gas exhaled from maximum inspiration to maximum expiration

TLC - RV

Question 2

FEV1

Answer 2

The volume of gas that is exhaled in the first second, from total lung capacity

Question 3

FEV1/FVC

Answer 3

Normalizes the volume of gas expelled in the first second in relation to lung volume

Normal is 0.7 - 0.8

Reduced ratio < 0.7 is diagnostic of obstructive lung disease

Question 4

PFTs in Restrictive Lung Disease

Answer 4

Reduced lung volumes

TLR or FRC < 80% of expected

Question 5

Hyperinflation

Answer 5

TLC or FRC > 120% of predicted

Question 6

DLCO

Answer 6

Measures diffusing capacity

Increased DLCO > 120% caused by polycythemia, interstitial hemorrhage

Decreased DLCO < 80% caused by emphysema, pulmonary vascular disease, interstitial lung disease, anemia, pneumonia

Question 7

DLCO/VA

Answer 7

Normalizes the measurement of gas exchange for lung volume

Decreased DLCO but normal DLCO/VA may indicate chest wall abnormality, lung wall resection, etc.

Question 8

PiMax

Answer 8

Maximum inspiratory pressure generated when the patient inspires forcefully against an occluded airway

Question 9

PeMax

Answer 9

Maximum expiratory pressure generated when the patient expires forcefully against an occluded airway

Question 10

TV

Answer 10

Tidal Volume

The amount of air moved during a normal inspiration

Question 11

IRV

Answer 11

Inspiratory Reserve Volume

The volume of air that a subject can inhale above what they would normally inhale during a tidal breath, requiring maximum effort of respiratory muscles

Question 12

ERV

Answer 12

Expiratory Reserve Volume

The volume of gas from the end of a tidal breath that can be expelled by the subject; requires maximum effort of respiratory muscles

Question 13

RV

Answer 13

Residual Volume

The volume of air retained in the lung even after maximal exhalation

This is a calculated number

Question 14

FRC

Answer 14

Functional Residual Capacity

The volume of gas in the lung at the end of a normal exhalation; this is the point at which the respiratory system is in equilibrium with the desire of the lung to recoil equally opposed by the desire of the chest wall to expand

RV + ERV

Question 15

Inspiratory Capacity

Answer 15

The amount of air that can be inhaled from FRC

TV + IRV

Question 16

Bronchodilator testing in asthma

Answer 16

Asthma is diagnosed on spirometry by an obstructive pattern that improves with the administration of a bronchodilator

Improvement is defined as > 12% in FEV1 or FVC AND > 200 mL increase in FEV1 or FVC

Question 17

Methacholine challenge

Answer 17

Patient inhales progressively higher concentrations of nebulized methacholine, stimulating bronchoconstriction; asthmatics require lower concentrations to reduce airflow by 20% (PC20)

Question 18

Exercise-induced bronchoprovocation

Answer 18

Patient performs spirometry before the test, then exercise on a treadmill breathing cold air; spirometry is performed post exercise to assess whether there was a > 20% decrease in FEV1