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Flashcards in 11 Spirometry Deck (13)
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1

Why should spirometry be done sitting down even though FVC standing > FVC seated?

Don't want patient to faint

High intrathoracic pressure- reduced CO and reduced cerebral blood flow

2

From this graph, how do we work out Inspiratory Capacity and Functional Residual Capacity?

3

What can forced flow measurements show us?

  • Response to treatment
  • Change with age/growth
  • Progression of disease

4

What are each of the following : FVC, FEV1 and PEF?

Functional vital capacity

Maximum volume of air that can be inhaled following a maximum exhalation

FEV1 (Forced Expiratory Volume)

Volume exhaled in first second

PEF (Peak Expiratory Flow)

Maximal speed of airflow as patient exhales (can use FLOWMETER)

5

Why is FEV1 useful?

Most reproducible parameter

Useful for diagnosing and managing patients with obstructive pulmonary diseases eg COPD or Asthma

6

Explain why the volume time graph for an obstructive pulmonary disease would give the following trace? What would be the expected FEV1/FVC ratio for this type of disease?

  • FVC not markedly reduced
  • Narrowing of airways
    • So FEV1 reduced 

FEV1/FVC ratio <70% compared to expected (from Nomogram)

7

How would you expect the volume time graph to appear in a restrictive pulmonary disease? What would you expect the FEV1/FVC ratio to be?

  • FVC markedly reduced- lungs can't expand properly
  • Fraction of air expelled in 1 second is normal but total FEV1 is reduced

Low FVC

Low FEV1

But FEV1/FVC ratio >70%

8

Where on this flow volume loop is there air coming out of the smaller airways? Indicate the Total lung capacity and the vital capacity

9

What does the scalloping of the graph on the right indicate?

10

What pathology may be causing each of these flow volume loops?

11

For reference: Flow volume loops with restrictive and obstructive pulmonary diseases.

12

When carrying out spirometry, how many recording should you aim for?

3

More than 3= fatigue will begin to affect results

13

What lung function test can be used to measure:

  • Residual volume
  • Dead space
  • Diffusion capacity

 

  • Residual volume: helium dilution test
  • Dead space: nitrogen washout method
  • Diffusion capacity: Carbon monoxide transfer factor (TLCO)