Significance of cerebrospinal fluid bicarbonate ions in the management of patients with cerebral injury

Acid-base balance and arterial and CSF lactate levels following human head injury

✓ Sequential arterial and cerebrospinal fluid (CSF) lactate, pH, pCO2, HCO3−, and pO2 levels were determined for 4 days in 17 patients immediately following uncomplicated head injury. Lactate was initially markedly elevated in both fluids and decreased by the third day after injury. There was mild arterial metabolic acidosis and respiratory alkalosis on admission; the alkalosis continued. Arterial pO2 was below normal at all times. The CSF showed a normal pO2, and metabolic acidosis related to lactate accumulation. Blood and CSF pCO2 and HCO3− levels equilibrated well, probably because of the time factor; CSF and arterial pO2 levels were not significantly related. The clinical implications of CSF lacticacidosis after head injury are discussed.