Independent changes in cerebrospinal fluid and in blood pH and lactate concentrations in children with purulent meningitis

In order to evaluate the relationship of the hydrogen and lactate concentrations in cerebrospinal fluid (CSF) with those in the blood, three groups of children were studied: Group I, (n=20) with purulent meningitis (PM); Group II, (n=20) with metabolic acidosis and Group III, (n=17) with suspicion of septicemia but no metabolic acidosis. In all infants a CSF sample was obtained for cytochemical analysis, culture as well as pH and lactate determinations; the latter two were also measured in a blood sample obtained simultaneously. In group I, the CSF [H+] and [lactate] were higher than in the blood (p less than 0.001 and less than 0.01 respectively) and no significant correlation was observed between the CSF and blood values. In group II, no such differences existed in [H+] and [lactate] between both compartments and again no correlation was disclosed between CSF and blood values. In group III only the [H+] was higher in CSF than in blood (p less than 0.01) and a significant correlation was observed between both compartments (r = 0.486, p less than 0.05). The existence of differences in group I among the CSF and blood [H+] and [lactate], along with the lack of correlation between CSF and blood [H+] or [lactate], could suggest that such compartmental changes are independent from each other. However, the variations were quite large and thus, the biological significance of this observation could be questioned.