UMEM Educational Pearls

Mechanically ventilated patients can develop a condition in which air becomes trapped within the alveoli at end-expiration; this is called auto-PEEP.

Auto-peep has several adverse effects:

  • Barotrauma from positive pressure trapped within the alveoli 
  • Increased work of breathing
  • Worsening pulmonary gas exchange
  • Hemodynamic compromise secondary to increased intra-thoraic pressure

Auto-PEEP classically occurs in intubated patients with asthma or emphysema, but it may also occur in the absence of such disease. The risk of auto-PEEP is increased in patients with:

  • Short expiration times (i.e., inadequate time for the evacuation of alveolar air at end-expiration)
  • Bronchoconstriction
  • Plugging of the bronchi (e.g., mucus or foreign body) creating a one-way valve and air-trapping

Auto-PEEP may be treated by:

  • Reducing tidal volume
  • Reducing the respiratory rate
  • Decreasing inspiratory time
  • Increasing PEEP

Patients may need to be heavily sedated to accomplish the above ventilator maneuvers.


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