Figure 36-23 Auto-positive end-expiratory pressure (auto-PEEP). Severe airway obstruction may result in high alveolar gas pressure at end expiration, which can exert the same effect on hemodynamics as externally applied PEEP. This is not usually detectable unless the expiratory port of the ventilator circuit is occluded. Auto-PEEP may then be read directly from the airway pressure monitor. (Adapted from Pepe PE, Marini JJ: Occult positive end-expiratory pressure in mechanically ventilated patients with airflow obstruction: The auto-PEEP effect. Am Rev Respir Dis 126:166, 1982.)