Spirometry

Question 1

What is spirometry used for?

Answer 1

To asses flow or use flow in their calculations

These tests are used in assessing the degree of airway obstruction

Question 2

What is the definition of a Forced Vital Capacity (FVC)?

Answer 2

Maximum volume of gas that can be exhaled forcefully and rapidly after a maximum inhalation

Most common spirometry test

Question 3

What is the significance of FVC?

Answer 3

FVC usually = (S)VC or within 150 mls of each other
FVC may be less than SVC in obstructive disorders
A decreased FVC is non specific

Question 4

What is the definition of FEVt?

Answer 4

Volume of gas exhaled over a given time period while performing a FVC

Question 5

What are the severity classification based on FEV1% of predicted?

Answer 5

Mild > 70 (but < 80%)
Moderate 60-69%
Moderately Severe 50-59%
Severe 35-49%
Very Severe < 35%

Question 6

What is the significance of FEVt?

Answer 6

Decreased FEVts are non specific
FEV1 reflects from from large, medium, +/- small airways (good overall assessment)
FEV1 used in screening, bronchodilator assessment, EIA assessment, exercise testing, etc.
FEV2,3,6 reflects flows from the small airways

Question 7

What does FEV1/FVC % determine?

Answer 7

Whether an obstruction exists and its severity

Normal = 75-85%

Question 8

Describe FEF 25-75%

Answer 8

Average flowrates during the middle of an FVC maneuver
Flow rate value is dependent upon FVC
Value is not dependent upon patient effort
Normal variability is +/- 40% even in healthy individuals

Question 9

Describe PEFR (PEF)

Answer 9

Maximum flow rate during a FVC
Should occur during the first 15% of a FVC
Very patient dependent
Gauges patient effort and repeatability
Values should be within 10% of each other to be acceptable

Question 10

Which flows are effort dependent?

Answer 10

From TLC-25% of FVC exhaled

Greater effort means greater flow

Question 11

Which flows are effort independent?

Answer 11

After 25% of exhaled FVC (ie at lower lung volumes)

Greater effort means NO greater flow

Question 12

Describe Backextrapolation (BEV)

Answer 12

Used to determine the start of the forced maneuver

Eliminates any volume lost due to hesitation at the start of “blast”

Question 13

What is the technique used for a F/V Loop?

Answer 13

Patient breaths to TLC and then performs a FVC, followed by a FVC
Simple lung volumes (FVC) and flows can be obtained from curve

Question 14

What is flow-volume loop interpretation based on?

Answer 14

1. Curve location (volume) with respect to RV and TLC

2. flowrates

Question 15

What does a intrapulmonary restrictive disorder look like on a F/V loop?

Answer 15

Curve shifted towards RV, therefore smaller lung volumes

Flow rates are greater than normal at the same lung volume

Question 16

What does a small airway obstruction look like on a F/V loop?

Answer 16

Flow rates in small peripheral airways very depressed

TLC is greater than predicted ie) moved to higher lung volumes

Question 17

What does asthma look like on a F/V loop?

Answer 17

Decreased flow rates in all airways

Lung volumes closer to predicted TLC but may still be within +/- 20%

Question 18

Describe what happens in a variable intrathoracic large airway obstruction

Answer 18

Airways are smaller on expirations

Decreased expiratory flows

Question 19

Describe what happens in variable extrathoracic large airway obstructions

Answer 19

Airways are narrowed on inspiration

Decreased inspiratory flows

Question 20

Describe what happens in fixed upper airway obstructions

Answer 20

Both inspiratory and expiratory flows are equally decreased compared to predicted

Question 21

What is the purpose of pre and post broncholdilator testing?

Answer 21

To determine reversibility of lung dysfunction
To determine the course of therapy
Most important value assessed is FEV1

Question 22

What is the possible order of testing?

Answer 22

1. Spiromety
2. Lung Volumes
3. Bronchodilator administration
4. Diffusion Capacity testing
5. Post Bronchodilator spirometry

Question 23

What determines the amount of response to bronchodilator?

Answer 23

Reactivity of the airways
The baseline bronchomotor tone and degree of obstruction
Site of drug absorption in relation to sure if the obstruction
Dose if drug deposited in the obstructed airway

Question 24

What is the formula for % FEV1 change?

Answer 24

% FEV1 Change = [(Post FEV1 - Pre FEV1)/Pre FEV1] x 100