(auto-PEEP) (aw'tō-pos'i-tiv-end-eks-pīr'ă-tōr-ē presh'ŭr) The difference between expiratory alveolar pressure and end expiratory pressure at the airway opening: the pressure is associated with the trapped gas when dynamic hyperinflation occurs in the lungs. Synonym(s): intrinsic PEEP, occult PEEP.