Distributions of hyperaerated (hyper), normally aerated (normal), poorly aerated (poorly) and nonaerated (non) compartments at end-expiration during pressure support ventilation (PSV), biphasic positive pressure ventilation + spontaneous breaths (BIPAP+SB
), controlled (BIPAP+SB
) and spontaneous (BIPAP+SB
) breath cycles. Calculations were performed for different lung zones from ventral to dorsal (1 = ventral, 2 = mid-ventral, 3 = mid-dorsal, and 4 = dorsal) at lungs apex, hilum, and base using dynamic computed tomography. The contributions of BIPAP+SBspont and BIPAP+SBcontrolled to BIPAP+SBmean were weighted by their respective rates (weighted mean). Bars and vertical lines represent means and standard deviations, respectively. * P < 0.05 vs. PSV; † P < 0.05 vs. BIPAP+SBcontrolled.