Spirometry

Question 1

What is spirometry?

Answer 1

A basic lung function test measuring inspired and expired air volumes, flow, and time

Question 2

Why is spirometry useful?

Answer 2

It is objective, non‑invasive, sensitive to early lung changes, reproducible, and can be performed almost anywhere with portable devices

Question 3

What are the main purposes of spirometry?

Answer 3

• Detect lung disease
• Quantify impairment
• Monitor occupational/environmental exposure effects
• Assess medication effects

Question 4

What is FEV₁?

Answer 4

Forced Expiratory Volume in 1 second — the volume exhaled in the first second of a forced breath

Question 5

What is FVC?

Answer 5

Forced Vital Capacity — the maximum air exhaled as fast as possible after full inspiration

Question 6

What is VC?

Answer 6

Vital Capacity — maximum air exhaled at a steady rate after full inspiration

Question 7

What is the FEV₁/FVC ratio?

Answer 7

The proportion of FVC exhaled in the first second; used to detect obstruction

Question 8

What is PEF?

Answer 8

Peak Expiratory Flow — the fastest flow achieved during forced expiration

Question 9

What is FEF?

Answer 9

Forced Expiratory Flow — mid‑expiratory flow rates at 25%, 50%, and 75% of FVC

Question 10

What is IVC?

Answer 10

Inspiratory Vital Capacity — maximum air inhaled after full expiration

Question 11

How is spirometer calibration checked?

Answer 11

Using a 3‑L syringe (±3% tolerance) or a 1‑L syringe pumped repeatedly to check linearity

Question 12

Do all spirometers require calibration?

Answer 12

No — some portable ultrasound devices do not

Question 13

What is a biological control?

Answer 13

Weekly testing using a healthy staff member to ensure consistent readings

Question 14

What patient details must be recorded before spirometry?

Answer 14

Identity, height, weight, age, sex, race

Question 15

What can be used if height cannot be measured?

Answer 15

Arm span

Question 16

What activities should patients avoid before spirometry?

Answer 16

• Alcohol: 4 hours
• Large meal: 2 hours
• Vigorous exercise: 30 minutes
• Smoking: >1 hour
• Record medication use

Question 17

What are bronchodilator withholding times for reversibility testing?

Answer 17

• SABA (Short‑Acting β‑Agonist): 6 hours
• LABA (Long‑Acting β‑Agonist): 24 hours
• Tiotropium (LAMA): 48 hours

Question 18

When should spirometry be postponed?

Answer 18

• Haemoptysis of unknown cause
• Pneumothorax
• Recent MI or pulmonary embolism
• Thoracic/abdominal/cerebral aneurysm
• Recent eye surgery
• Acute nausea/vomiting
• Recent thoracic/abdominal surgery

Question 19

What is the correct posture for spirometry?

Answer 19

• Sit upright
• Feet flat, legs uncrossed
• Loosen tight clothing
• Dentures usually left in
• Use chair with arms (risk of light‑headedness)

Question 20

What is the basic technique for FEV₁ and FVC?

Answer 20

Deep breath in → blow out hard and fast until no air remains

Question 21

What is required for VC?

Answer 21

Deep breath in → slow, steady exhalation until empty; nose clips essential

Question 22

What is the IVC manoeuvre?

Answer 22

Deep, fast inhalation after full expiration

Question 23

Why is encouragement important?

Answer 23

It improves effort and ensures complete exhalation

Question 24

How many acceptable manoeuvres are required?

Answer 24

At least three

Question 25

What defines an acceptable manoeuvre?

Answer 25

* Explosive start (back‑extrapolated volume <150 mL) * Maximal inspiration and expiration * No cough in first second * No leaks or glottic closure * Exhalation ≥6 seconds with <50 mL in last 2 seconds

Question 26

What are reproducibility criteria?

Answer 26

Best two FEV₁ and FVC values within 150 mL or 5% (100 mL if FVC <1 L)

Question 27

What is the maximum number of attempts?

Answer 27

Usually eight

Question 28

What is reversibility testing used for?

Answer 28

Diagnosing asthma

Question 29

What bronchodilator doses are used?

Answer 29

* Salbutamol: 4 × 100 μg via spacer → retest after 15 min * Ipratropium: 4 × 40 μg → retest after 30 min

Question 30

What factors determine predicted spirometry values?

Answer 30

Age, height, sex, race

Question 31

What is the lower limit of normal for FEV₁% predicted?

Answer 31

80% predicted

Question 32

What characterises obstruction?

Answer 32

* ↓ FEV₁ * Normal or ↓ FVC * ↓ FEV₁/FVC ratio * Concave flow‑volume loop

Question 33

What diseases show obstruction?

Answer 33

Asthma, COPD, bronchiectasis

Question 34

What characterises restriction?

Answer 34

* ↓ FVC * Normal or ↑ FEV₁/FVC ratio * Normal‑shaped loop * Possibly high PEF

Question 35

What conditions cause restriction?

Answer 35

Pulmonary fibrosis, pleural disease, chest wall deformity, neuromuscular disease, obesity, pneumonectomy

Question 36

What is the hallmark spirometry finding in obstruction?

Answer 36

Reduced FEV₁/FVC ratio

Question 37

What is the hallmark spirometry finding in restriction?

Answer 37

Reduced FVC with normal/high FEV₁/FVC

Question 38

Why must there be ≥30 seconds between manoeuvres?

Answer 38

Forced expiration can cause bronchoconstriction