Cerebral blood flow and cerebral metabolism in acute increase of intracranial pressure.

Abstract

The effects of a stepwise acute increase of intracranial cerebrospinal fluid pressure on cerebral blood flow, cerebral arteriovenous differences of oxygen and glucose and on the output of lactate were studied in anaesthetized normoventilated normoxic dogs. Intracranial hypertension was produced by infusing mock-CSF into the cisterna magna. Mean arterial blood pressure was kept at a constant level throughout the experimental investigations. At a cerebral perfusion pressure of about 70 mm Hg, CBF and the cerebral metabolic rates of oxygen and glucose were not significantly changed. However, further reduction in the cerebral perfusion pressure to below 40 mm Hg, was accompanied by a statistically significant decrease of CBF and a deterioration of the oxidative metabolism. Glucose uptake was particularly disturbed by raised intracranial pressure. Increased cerebral output of lactate and low CMRO2 indicated raised glycolysis. But (V-A)lactate was also increased at a relatively moderate reduction of the cerebral perfusion pressure, when autoregulation was still effective and CMRO2 unchanged. The data are discussed in context with similar experimental results recently published by other investigators.