Intrapulmonary percussive ventilation (IPV) works by injecting short, rapid inspiratory pulses into the airway opening and relies on what for exhalation?

• A. Chest wall elastic recoil.
• B. External chest compressor.
• C. Active inhalation from the patient.
• D. Positive end-expiratory pressure.

Answer: (A)

Intrapulmonary percussive ventilation delivers rapid, small inspiratory pulses into the airway, but exhalation is not actively driven by the device. After each pulse, air exits passively as the chest wall and lungs return to their resting state. This reliance on the natural elastic recoil of the chest wall to drive exhalation is the key mechanism. External chest compression would actively push air out, and active inhalation by the patient would not fit the device’s passive exhalation design. Positive end-expiratory pressure affects the pressure at end of exhalation, not how exhalation is generated.