Impaired Consciousness and CSF MetabolismSummary. A total of 156 tests of acid-base balance (pI-I) and respiratory gases and a total of 79 estimations of lactate and pyruvate in blood and CSF were performed in 107 patients with a variety of neurological diseases.Our subjects fell into 3 groups; 1. normal subjects, 2. sick patients with normal perception, 3. patients with impaired eonsiousness. Uncompensated metabolic (lactate) acidosis was found to be most pronounced in the patients in group 3. Cheeks in 19 patients with viral meningoeneephalitis revealed a significant correlation between the level of consciousness and the pit and the lactate and HCO3-levels in the CSF.The values we found to be critical for the metabolic parameters are cited as they allow an assessment of the prognosis and must be recognized as important indicators of a potentially fatal condition.