Effects of decreased cerebral perfusion pressure on cerebral hemodynamics, brain cell membrane function and energy metabolism during the early phase of experimental Escherichia coli meningitis in the newborn piglet

In this study, we tested the hypothesis that decreased cerebral perfusion pressure (CPP) induces cerebral ischemia and worsen brain damage in neonatal bacterial meningitis, Meningitis was induced by intracisternal injection of 10(9) colony forming units of Escherichia coli in 21 newborn piglets. Although GPP decreased significantly at 8 hr after bacterial inoculation, deduced hemoglobin (HbD), measured as an index of changes in cerebral blood flow by near infrared spectroscopy, did not decrease significantly. in correlation analyses, CPP showed significant positive correlation with brain ATP and inverse correlation with brain lactate levels, CPP also correlated positively with HbD and oxidized cytochrome aa(3) (Cyt aa(3)) by near infrared spectroscopy. However, CPP did not show significant correlation with cerebral cortical cell membrane Na+, K+-ATPase activity, nor with levels of lipid peroxidation products. In summary, decreased CPP observed in this study failed to induce cerebral ischemia and further brain injury, indicating that cerebrovascular autoregulation is intact during the early phase of experimental neonatal bacterial meningitis.