Orthostatic hypotension, but not orthostatic symptoms, is a marker of cerebral hypoperfusion in older adults

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCB153

Poster Communications: Orthostatic hypotension, but not orthostatic symptoms, is a marker of cerebral hypoperfusion in older adults

L. Fitzgibbon2, C. Finucane1, I. Brar2, R. Hughson2

1. Medical Physics and Bioengineering, Mercers Institute for Successful Ageing, St James's Hospital, Dublin, Ireland. 2. Schlegel-Waterloo Research Institute for Ageing, Waterloo, Ontario, Canada.

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Falls affect one in three older adults annually with orthostatic hypotension (OH) and its variants significant and treatable risk factors particularly for unexplained and injurious falls. OH when combined with self-reported orthostatic symptoms and a positive falls or syncope is considered a clinical marker of impaired cerebral autoregulation. Age and cognitive impairment reduce the perception of such symptoms and recall of such events, affecting the validity of this approach. Here we examine if self-reported orthostatic symptoms in combination with OH variants is a marker of cerebral hypoperfusion. A self-selected sample of N=80 older adults (age 87(6.1) years;73.5% female) were recruited from a nursing home population living in Ontario, Canada. The protocol was approved by the local ethics committee. All participants underwent a supine-stand transition (AS). Orthostatic symptoms were quantified using an 8-point orthostatic symptoms scale. Beat-to-beat blood pressure (mmHg) was recorded using a calibrated volume clamp method, while near-infra red spectroscopy (NIRS) measured relative changes in regional cerebral tissue oxygen saturation (tSO2 – %), oxyhemoglobin (OxHb – µmol/l) and deoxyhemoglobin (Hb – µmol/l) concentration. 9.3% reported a positive falls history, 24.4% had OH 40 seconds after standing with 6.4% having sustained OH at up to 3 minutes after standing. 51.3% reported one or more orthostatic symptoms. 41.3% reported a feeling of unsteadiness during standing, 16.3% a feeling of light-headedness/dizziness. After adjusted multivariate analyses (SPSS, V22) orthostatic symptoms were not associated with relative changes in tSO2, [OxHb] or [Hb], while the presence of OH at 40 seconds after standing was associated with a decrease in tSO2 (B =-4.562; P=0.011) and percent [OxHb] (B=-1.88.; P=0.017). Combining OH and symptoms did not strengthen these associations. OH accounting for 20% of model variance. Current medical practice combines peripheral measurements of BP during AS stand, and orthostatic symptoms to identify those at risk of cerebral hypoperfusion. Our results suggest that postural symptoms are an inadequate surrogate marker of cerebral perfusion in older adults which maybe related to a broader range of cognitive and/or sensory mechanisms, while orthostatic BP changes are a better, yet still limited surrogate marker of cerebral perfusion. A direct measure of cerebral perfusion should be considered to assess cerebral hypoperfusion in older adults and will likely play an emerging role in identifying future syncope and falls risk.



Where applicable, experiments conform with Society ethical requirements.

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