3.30 - Spirometry Bronchodilator Responsiveness Testing

Question 1

What does a full pulmonary function (PF) test typically include?

Answer 1

• Spirometry (pre-bronchodilator)
• Lung volumes
• Bronchodilator administration
• Diffusion capacity testing
• Spirometry (post-bronchodilator)

These components assess various aspects of lung function.

Question 2

Why is spirometry performed both before and after bronchodilator administration?

Answer 2

To compare pre- and post-bronchodilator results and assess airway responsiveness or reversibility.

This helps determine the effectiveness of bronchodilators.

Question 3

Why are bronchodilators given during PFTs?

Answer 3

To assess airway responsiveness or reversibility—whether airway obstruction improves after medication.

This is crucial for diagnosing conditions like asthma.

Question 4

Which bronchodilator category is typically used for testing responsiveness?

Answer 4

SABA (Short-Acting Beta-Agonists) — e.g., Ventolin (Salbutamol) — because it acts quickly and effectively.

SABA is preferred for its rapid onset of action.

Question 5

What is the typical Ventolin dosage and delivery method during testing?

Answer 5

• 400 µg (4 doses of 100 µg)
• Given via MDI with a spacer to ensure proper lung deposition.

This method enhances the effectiveness of the medication.

Question 6

Why is Ventolin given before diffusion testing?

Answer 6

It takes 5–15 minutes to act, and diffusion testing (~10 min) allows time for the bronchodilator to take effect before post-spirometry.

Timing is essential for accurate assessment.

Question 7

Does every patient show improvement after bronchodilator administration? Why or why not?

Answer 7

No — only patients with active bronchoconstriction will respond. Those without significant smooth-muscle tightening won’t show measurable improvement.

This highlights the variability in patient responses.

Question 8

What condition is most commonly characterized by bronchoconstriction and shows bronchodilator responsiveness?

Answer 8

Asthma.

Asthma is a key condition where bronchodilator response is a diagnostic criterion.

Question 9

What physiological changes occur when bronchodilation happens?

Answer 9

• Airway smooth muscle relaxes → ↓ airway resistance
• Leads to improved flows and less air trapping
• Improved FVC, FEV₁, and/or PEF

These changes indicate enhanced lung function.

Question 10

According to the 2021 ATS/ERS update, how is responsiveness determined?

Answer 10

Responsiveness is present if:
* FEV₁ increases by >10% post-bronchodilator relative to predicted FEV₁ and/or
* FVC increases by >10% post-bronchodilator relative to predicted FVC

These criteria help in evaluating the effectiveness of bronchodilator therapy.

Question 11

What is the formula for calculating bronchodilator responsiveness?

Answer 11

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