Pattern of regional gas flow (analysis of global, ventral, middle and dorsal region-of-interest) in n = 7 pigs during pressure controlled ventilation with different ventilator settings. PEEP = positive end-expiratory pressure. VT = tidal volume. Black arrow: significant group difference. Grey crossed arrow: no significant group difference. a (left, top). Peak inspiratory flow (PIF). b (left, bottom). Late inspiratory flow (LIF). c (right, top). Peak expiratory flow (PEF). d (right, bottom). Late expiratory flow (LEF).