Segment analysis among all end-expiratory conditions partitioned the lung into 10 segments of equal mass along the (A) dorsal-ventral axis and (B) the caudal-cephalad axis. The cluster frequencies of reinflation (red), limited response (black), and deflation (blue) are displayed at the level of each segment. The far right column shows the spatial orientation of the 10 equal mass segments that were used in the compartment analysis of cluster distribution. In (A), the top five segments correspond to the ventral compartment, and the bottom five segments are the dorsal compartment. In (B), segments that contain a pixel adjacent to the diaphragm are considered to be in the diaphragmatic compartment. The dorsal and caudal bins were shaded with red color. PEEP, positive end-expiratory pressure.