The static pressure-volume curve for 2 consecutive breaths indicates the presence of which of the following?

• A. Bronchospasm
• B. Airway collapse
• C. Overdistension of the lung
• D. Normal compliance

Answer: (A)

The main idea is that comparing static pressure–volume plots from two consecutive breaths can reveal breath-to-breath changes in airway caliber. Bronchospasm narrows the small airways and makes them highly variable in resistance from breath to breath. Because the static PV curve reflects compliance with no flow, this variability shows up as a mismatch or shift between the curves for successive breaths—the pressure required to reach a given volume differs from one breath to the next. That breath-to-breath variability points to an obstructive process like bronchospasm, rather than a fixed, unchanging property of the lung.

Airway collapse tends to affect expiration more, often showing dynamic airway closure and auto-PEEP patterns rather than a simple breath-to-breath shift on the static curve. Overdistension would alter the curve shape in a more consistent way tied to increased volume and compliance changes, not typically producing two different static curves for consecutive breaths. Normal compliance would yield overlapping, nearly identical curves on successive breaths.