BACKGROUND. The effect of vasoconstrictors on intracerebral hemodynamics in anesthetized @entity1 is controversial. The influence of @entity2647 and @entity1063 on the cerebral circulation was investigated in @entity5161 - or @entity1875 -anesthetized @entity1 using transcranial Doppler ultrasonography. METHODS: Forty @entity1 were randomly assigned to have vasoconstrictor tests with @entity1063 or @entity2647 during either @entity5161 or @entity1875 anesthesia. Blood flow velocities were simultaneously measured in the middle cerebral artery and ipsilateral extracranial internal carotid artery. Baseline recordings were done during stable anesthesia in a supine position (test 0). A second series of measurements were performed after @entity1063 or @entity2647 had increased mean arterial blood pressure by about 20% ( @entity5482 ). With maintained @entity1063 or @entity2647 infusion, a final series of results were obtained after the increased mean arterial blood pressure was counteracted by a slightly head-up @entity1 position (test 2). RESULTS: Both vasoconstrictors significantly increased mean flow velocities in the middle cerebral artery ( @entity1063 : 43 +/- 11 cm/s to 49 +/- 11 cm/s; @entity2647 : 43 +/- 8 cm/s to 48 +/- 9 cm/s; +/- SD) and internal carotid artery ( @entity1063 : 27 +/- 7 cm/s to 31 +/- 8 cm/s; @entity2647 : 27 +/- 9 cm/s to 31 +/- 10 cm/s) in the @entity5161 -but not in the @entity1875 -anesthetized @entity1 . In the head-up position, only small and insignificant flow velocity changes were observed in both cerebral arteries independent of the vasoconstrictor or background anesthetic. CONCLUSIONS: The results of the present study indicate that @entity1063 and @entity2647 do not directly affect intracranial hemodynamics in anesthetized @entity1 , but rather that hemodynamic changes observed with vasoconstrictors reflect the effect of the background anesthetic agents on cerebral pressure autoregulation.

The impact of systemic vasoconstrictors on the cerebral circulation of anesthetized XXXX .

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity5482 :: ('10942', 'Gene') :: ['test 1'] @entity2647 :: ('MESH:D010656', 'Chemical') :: ['phenylephrine'] @entity1875 :: ('MESH:D015742', 'Chemical') :: ['propofol'] @entity5161 :: ('MESH:D007530', 'Chemical') :: ['isoflurane'] @entity1063 :: ('MESH:D009638', 'Chemical') :: ['norepinephrine']
@entity1 :: (9606,Species) :: ['patients']
