Ventricular fluid lactate, pyruvate, bicarbonate and ph in unconscious brain-injured patients subjected to controlled ventilation.

In 35 unconscious patients suffering from traumatic brain injury and subjected to controlled hyperventilation within 12 hours of the acute trauma, we measured continuously the intraventricular pressure (IVP), ventricular fluid lactate, pyruvate, L/P ratio, pH and bicarbonate during the first 4 posttraumatic days, and related the findings to the clinical course. In patients in whom the follow-up study did not reveal severe mental impairment or dementia, the ventricular fluid lactate never exceeded 4 mmol/litre. In this group, the IVP level never exceeded 40 mmHg/hour, and the mean pressure/day never exceeded 20 mmHg. In half of the patients in whom dementia, vegetative survival or death occurred, ventricular fluid lactate exceeded 4 mmol/litre; the IVP level/hour exceeded 40 mmHg in two of 23 patients, and the mean pressure/day exceeded 20 mmHg in nine of 23 patients. The prognostic value of pyruvate was of less importance, although a significant increase in patients with a poor outcome was seen. No prognostic conclusions could be drawn from ventricular fluid, L/P ratio, pH and bicarbonate.