Intracranial optic nerve blood flow was measured by the radiolabeled microsphere technique in 30 adult sheep under light barbiturate anesthesia. Regional blood-flow rates were determined under basal conditions. The responses of regional blood flow to alterations in PaCO2 and to changes in arterial blood pressure were also measured. Under basal conditions blood flow was comparable to that found ...

Increased intracranial pressure was induced in anaesthetized dogs by application of liquid nitrogen to the dura mater. Intracranial pressure and cerebral blood flow were measured, together with arterial blood pressure and arterial and cerebral venous blood gases.Carbon dioxide was administered intermittently to test the responsiveness of the cerebral circulation, and hyperbaric oxygen was deliv...

The Effect of Carbon Dioxide Inhalation on Cerebral Blood Flow: A Two-Hour Duration Study in Dogs With Microspheres • Dogs breathed one of four gas mixtures (5% CO2-95% O2, 5% CO2-95% air, 10% CO2-90% O2, and 10% CO2-90% air) for as long as two hours. Regional cerebral blood flow as well as flow in nasal, otic, pituitary and skin tissue were measured by means of 15 ± 5 // radioactively labeled ...

Central nervous system oxygen toxicity, which occurs during diving and hyperbaric oxygen treatment, can lead to very dangerous situations, and it is of great importance to explore its mechanisms. We have speculated that cerebral blood flow plays a pivotal role in its occurrence. Except for acting as an anticonvulsant in clinical applications, acetazolamide is also a vasodilator used in both cli...

Cerebral blood flow was determined by an N2O method in 7 normal men at sea level and after 6 to 12 hr and 3 to 5 days at 3810 m altitude. An infrared N2O analyzer was used both to measure end-tidal PN2O SO that it could be kept constant for 15 min and to determine blood N2O, for which a simple gas extraction method was devised. In addition, acute changes in cerebral blood flow were estimated fr...

Cerebral perfusion pressure was reduced by graded constricting of both carotid arteries in the anesthetized dogs, of which vertebral arteries were ligated bilaterally. Cerebral blood flow and cerebral metabolic rate of oxygen remained unchanged until cerebral perfusion pressure was lowered to about 50 mm.Hg, indicating that cerebral autoregulation was preserved normally in these animals. Despit...

We measured the cerebral blood flow (CBF) of 16 patients by the xenon-133 intracarotid method before and after the intramuscular injection of ergotamine tartrate. The regional and hemispheric CBF was unaltered, even in 3 migraneurs in who ergotamine relieved the headache. Ergotamine tartrate in therapeutic doses has no effect on the cerebral circulation.

Hyperventilation and Cerebral Blood Flow • Hypocapnic-hyperventilation has a profound, but probably temporary, effect on CBF, producing approximately a 2% decline in CBF for each 1 torr decline in Pcov Th' effect appears to be mediated through changes in perivascular pH of the cerebral resistance vessels acting directly on the vessel wall. At low PC0;( the vasoconstrictor effect of short-term h...

Little is known about the effects of hyperoxia on the cerebral circulation of human infants. Using duplex Doppler we measured the changes in cerebral blood flow velocity in a group of full term (n = 15) and premature infants (n = 17, median gestational age 31 weeks) in response to a transient threefold increase in oxygen tension. Measurements of blood gas tensions as well as blood pressure and ...

The effect of arterial hypertension on cerebral blood flow was studied by the intracarotid 133Xe clearance method in baboons. The arterial blood pressure was raised in gradual steps with angiotensin. Baboons with renal hypertension of 8-12 weeks duration were studied along with normotensive baboons. In initially normotensive baboons, cerebral blood flow remained constant until the mean arterial...