Pulmonary function testing in bronchiectasis typically shows which finding?

• A. Decreased expiratory flow rates
• B. Increased DLCO with normal FEV1
• C. Normal flows
• D. Isolated restrictive pattern

Answer: (A)

Bronchiectasis creates chronic narrowing and distortion of the airways due to mucus plugging and inflammation, which makes exhalation more difficult. On pulmonary function testing this shows an obstructive pattern with decreased expiratory flow. You’d see lower FEV1 and reduced mid‑expiratory flows (FEF25‑75), along with a reduced FEV1/FVC ratio. The idea is that the airways resist expiration more, so the flow rates drop.

Other patterns don’t fit as well. A normal flow pattern wouldn’t reflect the airway obstruction from bronchiectasis, and an isolated restrictive pattern points to reduced lung volumes from interstitial or chest‑wall disease rather than airway obstruction. An increased DLCO with normal FEV1 isn’t typical for bronchiectasis, where the defining feature is decreased expiratory flow due to obstructed airways.