Intracranial pressure changes following aneurysm rupture. Part 2: associated cerebrospinal fluid lactacidosis.

Lactate concentrations and pH were measured serially in the cerebrospinal fluid (CSF) of 52 patients with ruptured intracranial aneurysms. Measurements were made during continuous monitoring of the intraventricular pressure (IVP) in the first 12 days after the initial subarachnoid hemorrhage. A total of 226 samples of CSF were analyzed. The clinical condition of the patients was graded according to the Hunt and Hess system. The degree of cerebral arterial spasm was measured on angiograms taken on admission and again approximately 7 days later. Results showed that the lactate concentrations in hemorrhagic and xanthochromic CSF were significantly higher than in clear CSF, indicating lactate production from shed blood cells. However, regardless of the degree of blood admixture to CSF, lactate increased with deteriorating clinical condition. Patients with a moderately increased IVP (20 to 40 mm Hg) had lactate levels of about 3 mmol/liter. A rising IVP or the development of severe spasm was accompanied by a persistent elevation or an increase in lactate. These results suggest that increased CSF concentrations of lactate reflected an increased production of lactate by partially ischemic cerebral tissue. A CSF lactate value above 3.5 mmol/liter was associated with a poor prognosis.