The effect of isovolemic hemodilution with dextran 40 on local cerebral blood flow was measured in eight cats by means of the hydrogen clearance technique. Under normotension the decrease of hematocrit from 35% to 25% causes a sudden increase of up to 30% in local cerebral blood flow. After lowering the mean arterial blood pressure from 140 to 80 mm Hg, hemodilution did not alter cerebral blood...

In diabetic patients, vascular disease and autonomic dysfunction might compromise cerebral autoregulation and contribute to orthostatic intolerance. The aim of our study was to determine whether impaired cerebral autoregulation contributes to orthostatic intolerance during lower body negative pressure in diabetic patients. Thirteen patients with early-stage type 2 diabetes were studied. We cont...

PURPOSE To determine the utility of [15O]H2O positron emission tomography (PET) for the quantitative determination of cerebral blood flow in patients undergoing balloon test occlusion of the internal carotid artery. METHODS Twenty-two [15O]H2O PET cerebral blood flow studies were completed on 20 patients for whom temporary or permanent occlusion of the internal carotid artery was being consid...

This study was performed to determine whether sympathetic stimulation reduces or redistributes cerebral blood flow. Total and regional cerebral blood flows were measured with the use of microspheres. Left stellate and superior cervical ganglia were stimulated electrically in anesthetized dogs. Sympathetic stimulation did not alter blood flow to ipsilateral cerebrum, cerebellum, or brainstem. Re...

Introduction: Partial liquid ventilation may benefit the lung disease in preterm neonates but intratracheal instillation of perfluorocarbon increases cerebral blood flow and may cause brain injury. We aimed to determine if the effects of perfluorocarbon administration on cerebral blood flow vary by dose-volume, rate of administration, endotracheal tube portal of entry, or closely targeting PaCO...

Regional cerebral blood flow decreases during chronic hyperglycemia, a condition frequently associated with elevated hematocrit. To test the hypothesis that an elevated hematocrit is responsible for the reduced regional cerebral blood flow during chronic hyperglycemia, I used isovolemic hemodilution to normalize the hematocrit in seven normoglycemic and seven streptozotocin-treated (hyperglycem...

Daily estimations of hemispheral cerebral blood flow using the xenon-133 inhalation technique was made in 116 patients during the first three weeks after subarachnoid haemorrhage. The patients' cerebral perfusion on average remained less than the normal perfusion expected for their age (based on a single estimation of cerebral blood flow in 67 volunteers). On each separate day after subarachnoi...