Spirometry

Question 1

When using a spirometer, what is the best practice method?

Answer 1

Measure FVC seated - althrough FVC standing is a better measure, high intrathoracic pressure can cause fainting

Nose clip is prefereable but not essential

Question 2

On a spirometry trace, what is associated with an upwards and a downwards deflection?

Answer 2

• Upwards = Inspiration
• Downwards = Expiration

Question 3

On the trace, identify:

• Tidal Volume
• Inspiratory Reserve Volume
• Expiratory Reserve Volume
• Residual volume
• Vital Capacity
• Total Lung Capacity
• Function Reserve Volume

Answer 3

Question 4

How do you calculate inspiratory capacity?

Answer 4

Tidal Volume + Inspiratory reserve volume

Question 5

How do you calculate functional residual capacity?

Answer 5

Expiratory reserve volume + Residual Volume

Question 6

What is FVC?

Answer 6

Forced Vital Capacity

i.e the max amount of air that the patient can forcible exhale after taking a maximal inhalation

Question 7

What is FEV₁ ?

Answer 7

Volume air exhaled in the first second

Question 8

What is PEF?

Answer 8

Peak Expiratory Flow

i.e. Maximal speed of airflow as the patient exhales (the slope)

Question 9

What is the most useful flow parameter to use when diagnosing and monitoring patients with obstructive pulmonary disease?

Answer 9

FEV₁

Question 10

What is the typical volume-time graph pattern you will see in obstructive lung disease (asthma and COPD) compared to a healthy individual?

Answer 10

• FEV₁ markedly reduced as narrowed airways reduce speed air is breathed out
• FVC is nearly normal
• FEV₁/ FVC ratio is <70%

Question 11

What is the typical volume-time graph pattern you will see in restrictive lung disease (lung fibrosis) compared to a healthy individual?

Answer 11

• FVC markedly reduced as stiff lungs cannot adequately expand
• FEV₁ normal (ish)
• FEV₁ / FVC ratio is > 70%

Question 12

Identify the key features of the Flow Volume Loop

Answer 12

Question 13

What characteristic feature would you see on a flow volume loop in a patient with obstructive lung disease (e.g asthma)

Explain what causes this shape change

Answer 13

Scalloping on expiration

• Flow is not constant throughout expiration due to narrowing of small airways

Question 14

In which condition would you expect to see a flow volume loop that looks like this?

Answer 14

COPD

Question 15

In which type of condition would you expect to see a flow volume loop that looks like this?

Answer 15

Restrictive lung disease

Question 16

In which condition would you expect to see a flow volume loop that looks like this?

Answer 16

Vocal cord dysfunction

Question 17

In which condition would you expect to see a flow volume loop that looks like this?

Answer 17

Fixed upper airway obstruction e.g tracheal stenosis