Differential images (D) and the regional lung opening maps (O) during low-flow inflation. Differential images show the impedance differences of lung region pixels between the EIT scans acquired at time points highlighted on the total relative impedance curve (left top) with red open circles and the EIT scan at the beginning of the inflation maneuver highlighted by a red asterisk. At the corresponding time points, open lung regions are shown in white in the regional lung opening maps. The highlighted time points from left to right are: the beginning of the low-flow inflation, 85%, 50%, 0% of the recruitable lung regions, and the end of inflation. Color bars indicate the magnitude of relative impedance values in each pixel.