Fig. 3.  A represents mean (SD) static lung compliance at baseline and over the course of the protocol in the absence of antibiotic therapy in normocapnia (n = 10) and hypercapnic acidosis (HCA; n = 10). *  P < 0.05 indicates significant within group change from baseline.  B represents a stereologic assessment of the extent of histologic injury in established  Escherichia coli pneumonia in the absence of antibiotic therapy.  P = NS indicates that the overall comparison between HCA and normocapnia was not significantly different.