Which of the following methods is used to minimize air trapping in mechanically ventilated patients?

• A. Increasing inspiratory flow
• B. Decreasing expiratory time
• C. Increasing inspiratory time
• D. Reducing tidal volume

Answer: (A)

Air trapping happens when expiration isn’t complete before the next breath starts, leaving extra air in the lungs (auto-PEEP). The key is giving the lungs enough time to exhale within each cycle. Increasing inspiratory flow makes the inhalation phase shorter, which in turn leaves more time for expiration. With more time to exhale, the lungs can empty more fully before the next breath, reducing trapped air.

If you lengthen the inspiratory phase or reduce expiratory time, expiration becomes even more incomplete and air trapping worsens. Reducing tidal volume lowers the amount of air but doesn’t directly create more expiration time, so it’s less effective for this issue.