Spirometry

Question 1

What does spirometry measure?

Answer 1

Timed inhaled and exhaled lung volumes, mainly FEV1, FVC, and the FEV1/FVC ratio.

Question 2

What is FEV1?

Answer 2

The volume of air forcibly exhaled in the first second after maximal inhalation.

Question 3

What is FVC?

Answer 3

The total volume of air forcibly exhaled after a full inspiration.

Question 4

What is the normal FEV1/FVC ratio?

Answer 4

> 0.7 (70%).

Question 5

What spirometry pattern defines obstructive lung disease?

Answer 5

Reduced FEV1, normal or reduced FVC, and FEV1/FVC ratio < 0.7.

Question 6

What spirometry pattern defines restrictive lung disease?

Answer 6

Reduced FEV1 and FVC, but normal or high FEV1/FVC ratio (>0.7).

Question 7

Give three intrathoracic causes of obstruction.

Answer 7

Asthma, COPD, bronchiectasis.

Question 8

Give two extrathoracic causes of obstructive spirometry.

Answer 8

Tracheal stenosis, large airway tumour or foreign body.

Question 9

Give three pulmonary causes of restrictive spirometry.

Answer 9

Idiopathic pulmonary fibrosis, sarcoidosis, asbestosis.

Question 10

Give three extrapulmonary causes of restrictive spirometry.

Answer 10

Neuromuscular disease (e.g. MND), obesity, kyphoscoliosis.

Question 11

What does bronchodilator reversibility testing assess?

Answer 11

Whether spirometric values improve after giving a short-acting bronchodilator.

Question 12

What is a positive bronchodilator response?

Answer 12

Significant improvement in FEV1 or FVC after bronchodilator (suggests asthma).

Question 13

What does reduced FEV1 with preserved FVC suggest?

Answer 13

Obstructive pattern.

Question 14

What does reduced FEV1 and FVC but normal ratio suggest?

Answer 14

Restrictive pattern.

Question 15

Why must spirometry values be given as % predicted?

Answer 15

Because normal values depend on age, sex, and height.

Question 16

When is spirometry used in asthma?

Answer 16

Diagnosis, bronchodilator reversibility, and assessing severity.

Question 17

When is spirometry used in COPD?

Answer 17

Diagnosis, staging of severity, and monitoring progression.

Question 18

Why can FVC be normal in obstructive disease?

Answer 18

Because obstruction mainly reduces early airflow (FEV1) more than total volume.

Question 19

Why are both FEV1 and FVC reduced in restrictive disease?

Answer 19

Because lung expansion is limited, reducing all lung volumes.