Regional cerebral blood flow responses to rapid reductions in blood pressure after high level spinal cord injury: the effect of alpha1‐agonist (1068.8)
Bibliographic record
Abstract
Spinal cord injury (SCI) above the T6 level frequently results in orthostatic intolerance, but how cerebral blood flow (CBF) responds to an orthostatic challenge in SCI is poorly understood. It is also unclear how alpha 1 agonists, meant to improve orthostatic tolerance, influence the CBF response. This study examined: 1) the acute regional CBF velocity (CBFv) response to acute blood pressure (BP) reductions secondary to orthostatic stress in SCI, compared to able‐bodied controls (AB), and 2) the effect of Midodrine (alpha1‐agonist) on orthostatic tolerance and CBFv regulation in SCI. Ten individuals with SCI >T6, and 10 age‐and sex‐matched controls had beat‐by‐beat BP, as well as middle and posterior cerebral artery blood velocity (MCAv, PCAv) recorded during a progressive tilt‐test to quantify the acute CBF response and orthostatic tolerance. Dynamic CBFv‐BP relationships were evaluated from the first 60s after tilt. The SCI group was tested again after administration of an alpha 1 ‐agonist (10 mg midodrine) in order to elevate BP. The acute (i.e., 0‐30s after tilt) MCAv and PCAv responses were similar in SCI and AB. In contrast, Midodrine led to improved PCAv responses 30‐60 s (10±3 vs. 4±2 %decline; p <0.05) after tilt, and a 59% improvement in orthostatic tolerance ( p <0.01). The vertebrobasilar region may be particularly susceptible to hypoperfusion in SCI, leading to increased orthostatic intolerance. Grant Funding Source : Supported by HSFC, NSERC, MSFHR & CNF
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".