Reduction of cerebral perfusion precedes rise of intracranial pressure in rats with ischemic fulminant liver failure.

In fulminant liver failure, brain edema may progress to intracranial hypertension. However, the rise in intracranial pressure is a late event in this sequence. We investigated the relationship between cerebral perfusion and development of intracranial hypertension in a well-characterized model of fulminant liver failure, the rat subjected to hepatic devascularization (n = 11). In addition, we examined the effects of hyperglycemia on the development of brain edema because high blood glucose level can exacerbate other forms of brain edema, as seen in stroke. Intracranial pressure was continuously monitored with a cisterna magna catheter; relative changes in blood flow were continuously assessed with a Doppler flow probe on the internal carotid artery. Cerebral perfusion decreased by 62%, with the greatest reduction before the onset of increased intracranial pressure. Intracranial pressure did not change until 2 hr before death, at which time it increased exponentially. Brain water in fulminant liver failure rats was significantly increased compared with that in controls. Hyperglycemia (200 to 220 mg/dl) had no effect on time elapsed until loss of corneal reflex, percentage of brain water, maximal intracranial pressure or pattern of change in cerebral perfusion compared with euglycemia (80 to 100 mg/dl). Sham-operated animals showed no changes in measured parameters. We conclude that a linear reduction in cerebral perfusion precedes the rise of intracranial pressure in this model, a decrease that may reflect changes in brain metabolic activity at the time that brain edema develops. Carotid blood flow monitoring may be a useful noninvasive tool for the detection of cerebral events in fulminant liver failure.