Analysis of CO
            <sub>2</sub>
            Vasomotor Reactivity and Vessel Diameter Changes by Simultaneous Venous and Arterial Doppler Recordings

Valdueza, José M.; Draganski, Bogdan; Hoffmann, Olaf; Dirnagl, Ulrich; Einhäupl, Karl M.

doi:10.1161/01.str.30.1.81

Cited by 79 publications

(63 citation statements)

References 37 publications

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“…12,13 Therefore, the bulk of evidence suggests that changes in cerebrovascular resistance caused by changes in arterial CO 2 occur downstream from the MCA M1 segment. 16,24 In contrast, Valdueza et al 25 reported a dilation of the MCA with hypercapnia in conscious humans. This observation was made by comparing the change in MCA inflow velocity with the contralateral sphenoparietal sinus outflow velocity.…”

Section: Discussionmentioning

confidence: 94%

“…However, it is not known whether differential drainage from other cerebral vascular beds and/or whether venous sinus volumes remained constant in their study. 25 There is controversy regarding sympathetic vasoconstrictor effects on cerebral vasculature. Sympathetic innervation of cerebral arteries has been found to be greatest in the basal arteries (ie, MCA and anterior cerebral artery).…”

Section: Discussionmentioning

confidence: 99%

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MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

Serrador

Picot

Rutt

et al. 2000

Stroke

647

508

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Background and Purpose-The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood flow (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (P ET CO 2 ) on MCA diameter and CFV. Methods-Twelve subjects participated in a CO 2 manipulation protocol and/or an LBNP protocol. In the CO 2 manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO 2 (hypercapnia), or they hyperventilated to Ϸ25 mm Hg P ET CO 2 (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of Ϫ20 and Ϫ40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols. Results-Compared with normocapnia, hypercapnia produced increases in both P ET CO 2 (from 36Ϯ3 to 40Ϯ4 mm Hg, PϽ0.05) and CFV (from 63Ϯ4 to 80Ϯ6 cm/s, PϽ0.001) but did not change MCA diameters (from 2.9Ϯ0.3 to 2.8Ϯ0.3 mm). Hypocapnia produced decreases in both P ET CO 2 (24Ϯ2 mm Hg, PϽ0.005) and CFV (43Ϯ7 cm/s, PϽ0.001) compared with normocapnia, with no change in MCA diameters (from 2.9Ϯ0.3 to 2.9Ϯ0.4 mm). During Ϫ40 mm Hg LBNP, P ET CO 2 was not changed, but CFV (55Ϯ4 cm/s) was reduced from baseline (58Ϯ4 cm/s, PϽ0.05), with no change in MCA diameter. Conclusions-Under the conditions of this study, changes in MCA diameter were not detected. Therefore, we conclude that relative changes in CFV were representative of changes in CBF during the physiological stimuli of moderate LBNP or changes in P ET CO 2 .

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

Serrador

Picot

Rutt

et al. 2000

Stroke

647

508

View full text Add to dashboard Cite

show abstract

“…Valdueza et al 14 showed, in 16 healthy subjects, with transcranial Doppler, an increase of 9.5 Ϯ 7.0% in the diameter of the MCA during CO 2 -induced hypercapnia. Conflicting results were observed in the study of Schreiber et al, 13 in which no changes in MCA diameters contralateral to a carotid artery occlusion were found in 8 patients after administration of acetazolamide.…”

Section: Discussionmentioning

confidence: 98%

“…However, these studies have primarily focused on the proximal cerebral arteries. [12][13][14][15] Recent advances in MRA have enabled noninvasive visualization of cerebral arteries with increased detail. With 3T MRA, it is possible to directly and reliably measure changes in the diameter of intracranial vessels.…”

mentioning

confidence: 99%

Vasodilatory Capacity of the Cerebral Vasculature in Patients with Carotid Artery Stenosis

Bokkers

Wessels²,

Worp³

et al. 2011

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: Impairment of the cerebral autoregulation is an important predictor of TIA and stroke in patients with an ICA stenosis. The autoregulative status can be assessed directly by measuring the vasodilatory capacity of the cerebral arteries. The aim of our study was to investigate the vasodilatory capacity of the proximal and distal cerebral vasculature in patients with an ICA stenosis and healthy control subjects by combining MRA with an acetazolamide provocation challenge.

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“…30 Nevertheless, other investigations could show that illness and interventions as orthostasis, migraine attacks, CO 2 -rebreathing, or vasoactive medicine could change the MCA diameters by 5% to 12%. [31][32][33][34] Reports of cerebrovascular CO 2 -R of CBF and V MCA in humans give inconsistent results. Additionally, comparisons between cerebrovascular CO 2 -R of CBF and V MCA in humans under general anesthesia are very rare.…”

Section: Discussionmentioning

confidence: 99%

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Grüne

Kazmaier

Stolker

et al. 2015

J Cereb Blood Flow Metab

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In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO 2 -induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO 2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean V MCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r = 0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP.

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Analysis of CO ₂ Vasomotor Reactivity and Vessel Diameter Changes by Simultaneous Venous and Arterial Doppler Recordings

Abstract: Background and Purpose-The use of flow velocity changes in the middle cerebral artery (MCA) measured by Doppler techniques as an index of corresponding cerebral blood flow (CBF) changes is based on the assumption that the insonated arterial diameter remains stable.

Cited by 79 publications

References 37 publications

MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

Vasodilatory Capacity of the Cerebral Vasculature in Patients with Carotid Artery Stenosis

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

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Analysis of CO 2 Vasomotor Reactivity and Vessel Diameter Changes by Simultaneous Venous and Arterial Doppler Recordings

Abstract: Background and Purpose-The use of flow velocity changes in the middle cerebral artery (MCA) measured by Doppler techniques as an index of corresponding cerebral blood flow (CBF) changes is based on the assumption that the insonated arterial diameter remains stable.

Cited by 79 publications

References 37 publications

MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

MRI Measures of Middle Cerebral Artery Diameter in Conscious Humans During Simulated Orthostasis

Vasodilatory Capacity of the Cerebral Vasculature in Patients with Carotid Artery Stenosis

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

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Analysis of CO ₂ Vasomotor Reactivity and Vessel Diameter Changes by Simultaneous Venous and Arterial Doppler Recordings