| Cerebrovascular reactivity and dynamic autoregulation in tetraplegia. | |
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MedLine Citation:
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PMID: 20089710 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Humans with spinal cord injury have impaired cardiovascular function proportional to the level and completeness of the lesion. The effect on cerebrovascular function is unclear, especially for high-level lesions. The purpose of this study was to evaluate the integrity of dynamic cerebral autoregulation (CA) and the cerebrovascular reactivity in chronic tetraplegia (Tetra). After baseline, steady-state hypercapnia (5% CO(2)) and hypocapnia (controlled hyperventilation) were used to assess cerebrovascular reactivity in 6 men with Tetra (C5-C7 lesion) and 14 men without [able-bodied (AB)]. Middle cerebral artery blood flow velocity (MCAv), cerebral oxygenation, arterial blood pressure (BP), heart rate (HR), cardiac output (Q; model flow), partial pressure of end-tidal CO(2) (Pet(CO(2))), and plasma catecholamines were measured. Dynamic CA was assessed by transfer function analysis of spontaneous fluctuations in BP and MCAv. MCAv pulsatility index (MCAv PI) was calculated as (MCAv(systolic) - MCAv(diastolic))/MCAv(mean) and standardized by dividing by mean arterial pressure (MAP). Resting BP, total peripheral resistance, and catecholamines were lower in Tetra (P < 0.05), and standardized MCAv PI was approximately 36% higher in Tetra (P = 0.003). Resting MCAv, cerebral oxygenation, HR, and Pet(CO(2)) were similar between groups (P > 0.05). Although phase and transfer function gain relationships in dynamic CA were maintained with Tetra (P > 0.05), coherence in the very low-frequency range (0.02-0.07 Hz) was approximately 21% lower in Tetra (P = 0.006). Full (hypo- and hypercapnic) cerebrovascular reactivity to CO(2) was unchanged with Tetra (P > 0.05). During hypercapnia, standardized MCAv PI reactivity was enhanced by approximately 78% in Tetra (P = 0.016). Despite impaired cardiovascular function, chronic Tetra involves subtle changes in dynamic CA and cerebrovascular reactivity to CO(2). Changes are evident in coherence at baseline and MCAv PI during baseline and hypercapnic states in chronic Tetra, which may be indicative of cerebrovascular adaptation. |
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Authors:
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Luke C Wilson; James D Cotter; Jui-Lin Fan; Rebekah A I Lucas; Kate N Thomas; Philip N Ainslie |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-01-20 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 298 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2010 Apr |
Date Detail:
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Created Date: 2010-03-23 Completed Date: 2010-04-15 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R1035-42 Citation Subset: IM |
Affiliation:
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Department of Physiology, University of British Columbia Okanagan, Kelowna, BC V1X, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adolescent Adult Blood Flow Velocity Brain / physiology, physiopathology Catecholamines / blood Cerebrovascular Circulation / physiology* Frontal Lobe / physiopathology Homeostasis / physiology* Humans Male Middle Cerebral Artery / physiology, physiopathology Quadriplegia / blood, physiopathology* Reference Values Respiration Supine Position Tidal Volume Vascular Resistance Young Adult |
| Chemical | |
Reg. No./Substance:
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0/Catecholamines |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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