Which ventilator setting should NOT be employed on a patient who is Auto-PEEPing?

• A. PEEP
• B. APRV
• C. Volume assist control
• D. CMV

Answer: (C)

Auto-PEEP (intrinsic PEEP) comes from air trapping when exhalation isn’t complete before the next breath starts. The main goal in this situation is to give the lungs enough time to exhale and to avoid increasing the time air stays in the lungs or raising the overall pressure.

Delivering a fixed tidal volume with a set inspiratory time (volume-targeted assist-control) tends to push air in with a relatively rigid cycle, which can shorten the available expiratory time or raise mean airway pressure. That combination makes it easier for air to remain trapped and increases end-expiratory lung volume, worsening auto-PEEP. So, this mode is not appropriate for a patient with auto-PEEP.

Other approaches aim to prolong expiratory time and reduce air trapping: using PEEP cautiously to aid triggering elsewhere in the ventilator strategy, employing modes like APRV that allow long expiratory phases, or choosing CMV with adjustable expiratory timing to optimize exhalation.