An incentive spirometer is used to prevent postoperative atelectasis. The device indicates a deep breath by what mechanism?

• A. The piston rises with each deep inhalation
• B. The device emits a beep on inhalation
• C. The device shows a green light when full
• D. The device requires manual calibration

Answer: (A)

Incentive spirometry uses visual feedback to promote a deep, slow breath that expands the lungs and prevents postoperative atelectasis. The device has a piston that rises inside the chamber as you inhale. You aim to lift the piston by taking a smooth, sustained deep breath and hold briefly to maximize lung inflation. This rising piston provides immediate feedback on how deeply you’re inhaling, helping recruit and keep open the alveoli. Other cues like beeps, color indicators, or manual calibration aren’t how this device signals inspiratory depth, which is why the rising piston is the correct mechanism.