{"id":{"repo_id":"east-anglia","oai_identifier":"oai:ueaeprints.uea.ac.uk:54339"},"canonical_url":"https://search.dev.ndltd.org/etd/east-anglia/oai:ueaeprints.uea.ac.uk:54339","repository":{"repo_id":"east-anglia","name":"University of East Anglia","base_url":"https://ueaeprints.uea.ac.uk/cgi/oai2"},"display":{"title":"Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people?","abstract":"Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people? Introduction: The aim of this thesis was to investigate whether abnormalities in dynamic cerebral auto-regulation (dCA) explain the symptoms associated with orthostatic (OH) and post-prandial hypotension (PPH). Methods: Based on clinical symptoms and signs for the OH study: 4 Groups: Asymptomatic No OH (control), Symptomatic No OH, Asymptomatic OH, and Symptomatic OH. PPH study: double-blind placebo controlled cross-over study of glucose (50g) drink. 2 Groups: No PPH (control) and PPH. Baseline and head-up-tilt (HUT, for OH maximum 30 minutes study or to symptoms; PPH study maximum 60 minutes per visit). All had Transcranial Doppler ultrasound, beat-to-beat BP, ECG and CO2 monitoring. Baseline autonomic function, arterial stiffness, cardiac baroreceptor sensitivity (BRS) were calculated and dynamic cerebral auto-regulation (as the autoregulatory index ARI) assessed before and during tilt. Results: OH: n=85, mean age 73.9±7.1 years; PPH: n= 40, mean age 73.4±7.3 years Baseline: No significant differences were found between groups for cardiac BRS, arterial stiffness, cerebral blood flow velocity (CBFV) or dCA in either study. HUT both studies: falls in BP, CO2 and CBFV, increases in HR, and fall in ARI amongst symptomatic subjects prior to the end of HUT (maximum duration or symptom onset) compared to pre-HUT values. PPH study: fall in ARI with HUT irrespective of whether glucose or placebo phase. Conclusions: The development of symptoms during tilt in both studies was related to a fall in CBFV and impaired cerebral auto-regulation. Abnormalities in cerebral autoregulation may explain the symptoms of OH and PPH although these changes can only be detected during head-up-tilt.","abstract_html":"Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people? Introduction: The aim of this thesis was to investigate whether abnormalities in dynamic cerebral auto-regulation (dCA) explain the symptoms associated with orthostatic (OH) and post-prandial hypotension (PPH). Methods: Based on clinical symptoms and signs for the OH study: 4 Groups: Asymptomatic No OH (control), Symptomatic No OH, Asymptomatic OH, and Symptomatic OH. PPH study: double-blind placebo controlled cross-over study of glucose (50g) drink. 2 Groups: No PPH (control) and PPH. Baseline and head-up-tilt (HUT, for OH maximum 30 minutes study or to symptoms; PPH study maximum 60 minutes per visit). All had Transcranial Doppler ultrasound, beat-to-beat BP, ECG and CO2 monitoring. Baseline autonomic function, arterial stiffness, cardiac baroreceptor sensitivity (BRS) were calculated and dynamic cerebral auto-regulation (as the autoregulatory index ARI) assessed before and during tilt. Results: OH: n=85, mean age 73.9±7.1 years; PPH: n= 40, mean age 73.4±7.3 years Baseline: No significant differences were found between groups for cardiac BRS, arterial stiffness, cerebral blood flow velocity (CBFV) or dCA in either study. HUT both studies: falls in BP, CO2 and CBFV, increases in HR, and fall in ARI amongst symptomatic subjects prior to the end of HUT (maximum duration or symptom onset) compared to pre-HUT values. PPH study: fall in ARI with HUT irrespective of whether glucose or placebo phase. Conclusions: The development of symptoms during tilt in both studies was related to a fall in CBFV and impaired cerebral auto-regulation. Abnormalities in cerebral autoregulation may explain the symptoms of OH and PPH although these changes can only be detected during head-up-tilt.","abstract_has_math":false,"creators":["Ong, Alice"],"institution":"University of East Anglia","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-11","date_published":"2014-11","updated_at":"2026-07-24T02:12:10Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Ong, Alice"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-11"]},{"key":"dc:date.issued","label":"Date","values":["2014-11"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Norwich Medical School"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of East Anglia"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://ueaeprints.uea.ac.uk/id/eprint/54339/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://ueaeprints.uea.ac.uk/id/eprint/54339/1/2014OngACLPhD.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people? Introduction: The aim of this thesis was to investigate whether abnormalities in dynamic cerebral auto-regulation (dCA) explain the symptoms associated with orthostatic (OH) and post-prandial hypotension (PPH). Methods: Based on clinical symptoms and signs for the OH study: 4 Groups: Asymptomatic No OH (control), Symptomatic No OH, Asymptomatic OH, and Symptomatic OH. PPH study: double-blind placebo controlled cross-over study of glucose (50g) drink. 2 Groups: No PPH (control) and PPH. Baseline and head-up-tilt (HUT, for OH maximum 30 minutes study or to symptoms; PPH study maximum 60 minutes per visit). All had Transcranial Doppler ultrasound, beat-to-beat BP, ECG and CO2 monitoring. Baseline autonomic function, arterial stiffness, cardiac baroreceptor sensitivity (BRS) were calculated and dynamic cerebral auto-regulation (as the autoregulatory index ARI) assessed before and during tilt. Results: OH: n=85, mean age 73.9±7.1 years; PPH: n= 40, mean age 73.4±7.3 years Baseline: No significant differences were found between groups for cardiac BRS, arterial stiffness, cerebral blood flow velocity (CBFV) or dCA in either study. HUT both studies: falls in BP, CO2 and CBFV, increases in HR, and fall in ARI amongst symptomatic subjects prior to the end of HUT (maximum duration or symptom onset) compared to pre-HUT values. PPH study: fall in ARI with HUT irrespective of whether glucose or placebo phase. Conclusions: The development of symptoms during tilt in both studies was related to a fall in CBFV and impaired cerebral auto-regulation. Abnormalities in cerebral autoregulation may explain the symptoms of OH and PPH although these changes can only be detected during head-up-tilt."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people?"]}]}],"canonical_facts":{"dc:creator":["Ong, Alice"],"dc:date":["2014-11"],"dc:date.issued":["2014-11"],"dc:description.abstract":["Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people? Introduction: The aim of this thesis was to investigate whether abnormalities in dynamic cerebral auto-regulation (dCA) explain the symptoms associated with orthostatic (OH) and post-prandial hypotension (PPH). Methods: Based on clinical symptoms and signs for the OH study: 4 Groups: Asymptomatic No OH (control), Symptomatic No OH, Asymptomatic OH, and Symptomatic OH. PPH study: double-blind placebo controlled cross-over study of glucose (50g) drink. 2 Groups: No PPH (control) and PPH. Baseline and head-up-tilt (HUT, for OH maximum 30 minutes study or to symptoms; PPH study maximum 60 minutes per visit). All had Transcranial Doppler ultrasound, beat-to-beat BP, ECG and CO2 monitoring. Baseline autonomic function, arterial stiffness, cardiac baroreceptor sensitivity (BRS) were calculated and dynamic cerebral auto-regulation (as the autoregulatory index ARI) assessed before and during tilt. Results: OH: n=85, mean age 73.9±7.1 years; PPH: n= 40, mean age 73.4±7.3 years Baseline: No significant differences were found between groups for cardiac BRS, arterial stiffness, cerebral blood flow velocity (CBFV) or dCA in either study. HUT both studies: falls in BP, CO2 and CBFV, increases in HR, and fall in ARI amongst symptomatic subjects prior to the end of HUT (maximum duration or symptom onset) compared to pre-HUT values. PPH study: fall in ARI with HUT irrespective of whether glucose or placebo phase. Conclusions: The development of symptoms during tilt in both studies was related to a fall in CBFV and impaired cerebral auto-regulation. Abnormalities in cerebral autoregulation may explain the symptoms of OH and PPH although these changes can only be detected during head-up-tilt."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://ueaeprints.uea.ac.uk/id/eprint/54339/1/2014OngACLPhD.pdf"],"dc:language":["en"],"dc:publisher.department":["Norwich Medical School"],"dc:publisher.institution":["University of East Anglia"],"dc:relation.isreferencedby":["https://ueaeprints.uea.ac.uk/id/eprint/54339/"],"dc:title":["Do abnormalities in dynamic cerebral auto-regulation underlie the pathophysiological processes behind syncope in older people?"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T02:12:10Z"}