Interrelationship between blood pressure and regional cerebral blood flow in experimental intracranial hypertension

Abstract

✓ The interrelationship between systemic blood pressure (BP), regional cerebral blood flow (rCBF), and intracranial pressure (ICP) was investigated in two experimental models of intracranial hypertension in cats. In one group, ICP was raised by the inflation of an extradural balloon; in the other, brain swelling was produced. The effects of raised blood pressure on rCBF and ICP in the two groups differed considerably. In the “brain-swelling” group, elevated BP had no beneficial effects on rCBF. When ICP approached diastolic BP, an increase in BP was followed by a marked increase in ICP and a decrease in rCBF. Therefore, the elevated BP often observed in extreme intracranial hypertension (Cushing response) cannot be regarded as a beneficial, compensatory defense mechanism, but rather as a deleterious phenomenon.