[Changes in epidural pulse pressure in brain edema following experimental focal ischemia]

It is well known that epidural pulse pressure (PP) increases with rising intracranial pressure (ICP). However, PP at the same ICP is not always identical in various intracranial pathologies. Many authors have investigated PP at increased states of ICP, but few studies related to brain edema have been done. This study was carried out in order to clarify the changes of PP in brain edema following focal ischemia. ICP and PP were measured in two groups of anesthetized dogs; 1) increased volume of CSF by cisternal saline injection (control, n = 5), 2) brain edema caused by focal ischemia (edema, n = 11). Ischemia was induced by electro-coagulation of the right anterior cerebral artery and by clipping the right middle cerebral artery and right internal carotid artery transorbitaly. The brain was recirculated for 6 hours after 2 hours of ischemia. The ischemic areas were identified by Evans blue, triphenyl tetrazolium chloride (TTC) or histological examination. Water content of the brain was measured by the wet-dry weight method. The canine focal ischemic model showed consistent ischemic damage in the caudate nucleus and produced brain edema successfully. PP increased linearly with rising ICP to 35 mmHg, and PP in the edema group was significantly smaller than that in the control group at the same ICP value. The slopes of the regression equation of ICP and PP were significantly different between the edema and control group (edema: 0.061 +/- 0.030, control: 0.107 +/- 0.015, mean +/- SD, p less than 0.01). These results suggest that PP is easily affected by ischemic brain edema.(ABSTRACT TRUNCATED AT 250 WORDS)