What COPD ventilation strategy helps avoid dynamic hyperinflation?

• A. Using higher tidal volumes.
• B. Longer expiratory time with lower tidal volume and permissive hypercapnia.
• C. Shortening expiratory time.
• D. Keeping PEEP at zero.

Answer: (B)

Dynamic hyperinflation happens when expiration is cut short, so air trapping occurs between breaths. The most effective strategy to prevent this is to give smaller breaths and allow more time for exhalation, ensuring the lungs can empty before the next inhalation begins. Lower tidal volumes reduce the amount of air that can be trapped, and a longer expiratory phase lets expiratory flow complete without rushing to the next breath. Permissive hypercapnia accepts higher CO2 levels within safe limits to avoid increasing ventilatory pressures that could worsen air trapping.

Higher tidal volumes would push more air into the lungs and worsen hyperinflation. Shortening the expiratory time would leave even less opportunity for complete exhalation, increasing air trapping. Keeping PEEP at zero doesn’t address the underlying problem of incomplete emptying and not addressing auto-PEEP, so it’s not the best approach.