Cerebrospinal Fluid Lactic Acidosis in Bacterial Meningitis

Abstract

The concentration of lactate, PCO2, HCO3-, Na, K, Cl and the pH of cerebrospinal fluid (CSF) and arterial blood were measured simultaneously in 104 samples obtained from 17 patients with bacterial meningitis. These values were compared with those of 12 control subjects, including patients with pituitary adenoma or individuals with non-neurological disease. Initially, patients with bacterial meningitis had significant CSF lactic acidosis, arterial respiratory alkalosis, low CSF HCO3-, low CSF and arterial Na and Cl, and high CSF K in comparison to the control group. CSF PCO2 did not differ significantly between the two groups. Subsequently, following successful treatment of meningitis, these parameters gradually normalized. The most significant correlations were found between CSF pH and CSF HCO3-, between arterial blood pH and CSF lactate, and between arterial blood PCO2 and CSF HCO3-. There was no significant relationship between electrolyte changes and the acid-base balance. In conclusion, brain metabolic changes in patients with bacterial meningitis were similar to those observed in other neuropathological states, such as head trauma and cerebrovascular disease. Assessment of lactate concentration and acid-base balance in both arterial blood and CSF was useful in differentiating bacterial meningitis from aseptic meningitis and proved to be a good indicator of intracranial microchemical status in cases of bacterial meningitis.