Fig. 3. From top  to bottom,  tracings of gastric pressure (P^ga), tidal volume (V^T), airflow (V), esophageal pressure (P^es) and airway pressure (P^aw) obtained in a representative patient during ventilation at positive end-expiratory pressure (PEEP) 0 and PEEP 10. Intrinsic PEEP (PEEPi), airway pressure during the phase of ventilator triggering (P^0.1t), and work of breathing (WOB) were maximal at PEEP 0. Note the marked inspiratory P^esswings and the presence of abdominal muscle recruitment during expiration at PEEP 0.