We used positron emission tomography to examine retrospectively the effects of blood pressure on regional cerebral blood flow and oxygen metabolism in seven normotensive and eight hypertensive patients with a history of transient neurologic deficits. In the hypertensive patients, a decrease in regional cerebral blood flow was closely related to blood pressure; these changes were most pronounced...

The key to surviving hypoxia is to protect the brain from energy depletion. The epaulette shark (Hemiscyllium ocellatum) is an elasmobranch able to resist energy depletion and to survive hypoxia. Using epi-illumination microscopy in vivo to observe cerebral blood flow velocity on the brain surface, we show that cerebral blood flow in the epaulette shark is unaffected by 2 h of severe hypoxia (0...

Cerebral blood flow and cerebral oxygen consumption are not altered in patients with uncomplicated hypertension (1). Scheinberg observed that in a mixed group of patients who had congestive heart failure, the cerebral blood flow was depressed (2). This suggests altered cerebral hemodynamics either as a primary abnormality or as a result of disturbances in the cerebral circulatory dynamics secon...

PURPOSE To determine the value of the acetazolamide challenge test with stable xenon-enhanced CT (Xe CT) for making therapeutic decisions in patients with chronic cerebrovascular disease. METHODS We compared the Xe CT-measured acetazolamide response with various measures obtained by positron emission tomography. We performed both a positron emission tomographic scan and a Xe CT study in 11 pa...

We studied the effects of removal of the superior cervical sympathetic ganglion on cerebral blood flow and vascular reactivity to adrenergic agonists and antagonists in 11 unanesthetized goats. Cerebral blood flow was measured by an electromagnetic flow transducer previously implanted on the internal maxillary artery. Ganglionectomy produced an increase of 66 ± 8.26% (SEM) in cerebral blood flo...

1. Six unanaesthetized goats were used to evaluate the effect of liver failure on the hypoxic responsiveness of cerebral blood flow. The animals breathed air and several different hypoxic gas mixtures enriched with sufficient CO2 to maintain an isocapnic state. The cerebral metabolic rate for O2 (CMRo2) was also measured in four of these goats. 2. In baseline studies there was a linear relation...

BACKGROUND Reduction of cerebral blood flow plays a crucial role in causing posttraumatic cerebral ischemia. However, the methodologic adequacy of studies from which currently used cerebral blood flow thresholds in traumatic brain injury have been derived has not been evaluated. OBJECTIVE To systematically evaluate the evidence available on cerebral blood flow thresholds and its methodologic ...

BACKGROUND AND PURPOSE This study sought to determine the degree of agreement between asymmetries of neuropsychological functioning and nine methods of quantifying asymmetries of regional cerebral blood flow. METHODS The regional cerebral blood flow methods combined three markers of cerebral blood flow asymmetry (percent hemispheric difference, maximum percent probe-pair asymmetry, and number...

To study the effect of non-hypotensive hemorrhage on cerebral blood flow in normo- and hypertensive states, chloralose anesthetized cats were subjected to graded blood loss (5 ml/kg) every 30 min. Cerebral blood flow was measured using radiolabelled microspheres or H2 clearance. Hypertension was produced by infusion of phenylephrine to a diastolic blood pressure of 100 mm Hg. Control animals su...