A questionable association of stroke volume and arterial pulse pressure under gravitational stress
Bibliographic record
Abstract
Arterial pulse pressure (PP) has been shown to be correlated strongly with stroke volume (SV) when humans are subjected to a gravitational stress. The purpose of this investigation was to assess the PP and SV response to progressive lower body negative pressure (LBNP) using individual responses rather than the mean response per stage of LBNP as reported previously. Sixteen healthy men and women (Age(SD) = 24.4(3.0)) were assessed during a 12 min baseline collection, during four 12‐minute stages of progressive LBNP at −15, −30, −45 and −60 mm Hg, and during 12 min of recovery. Hemodynamic measures were compared from baseline throughout −60 mm Hg. Systolic blood pressure (105 ± 7.8 to 103± 8.3 mm Hg) and mean arterial pressure were not statistically different (81 ± 5.6 to 83 ± 5.9 mm Hg); however, there was a significant difference for diastolic blood pressure (69 ± 5.3 to 72 ± 5.8 mm Hg), PP (37 ± 5.7 to 31 ± 7.0), SV (80 ± 17.0 to 26.6 ± 10.0) and heart rate (63 ± 8.3 to 86 ± 14.2). Typical group analysis revealed a strong positive relationship between LBNP and SV (r 2 = 0.99), LBNP and PP (r 2 = 0.96), and SV and PP (r 2 = 0.97). When comparing the individual slopes there was a more modest relationship (r 2 = 0.53). Our results show high individual variability in response to LBNP and the need to consider individual PP and SV responsiveness. Natural Sciences and Research Council of Canada, Canadian Institutes of Health Research, Michael Smith Foundation
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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 | 0.001 | 0.003 |
| 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) | 0.001 | 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".