175 TRANSLATING NEW TECHNOLOGY INTO CLINICAL PRACTICE: SHOULD A DIRECT MEASURE OF CEREBRAL PERFUSION BE USED IN SYNCOPE AND FALLS ASSESSMENT?
Bibliographic record
Abstract
Background Orthostatic hypotension (OH) when combined with symptoms on standing and a positive history of falls or syncope is thought to indicate risk of impaired cerebral perfusion. However age and cognitive impairment are known to reduce the perception of orthostatic symptoms and recall of syncopal and falls events, potentially affecting the validity of this approach. Here we examine if OH combined with self-reported orthostatic symptoms and a positive syncope or falls history is a marker of cerebral hypoperfusion. Methods 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. All participants underwent an active stand (AS). Orthostatic symptoms were quantified using an 8-point orthostatic symptoms scale. Beat-to-beat blood pressure (mmHg) was recorded throughout 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. Results 9.3% reported a positive falls history, with 6.4% having sustained OH at up to 3 minutes after standing. 51.3% reported one or more orthostatic symptoms. 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 decrease in relative [OxHb] (B = -1.88.; P = 0.017). Conclusion Combining OH and self reported symptoms and a falls/syncope history did not strengthen these associations. Postural symptoms are an unreliable marker of cerebral perfusion in older adults, while orthostatic BP changes are a better, yet still limited surrogate marker of cerebral hypoperfusion. A direct measure of cerebral perfusion should be considered to assess cerebral hypoperfusion and will likely play an emerging role in syncope and falls risk.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.026 | 0.099 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".