Effect of Fast Ascent, Acclimatization and Re-Exposure To 5050 m On Cerebral Autoregulation in Unacclimatized Lowlanders. A Prospective Cohort Study.
Bibliographic record
Abstract
Abstract ABSTRACT Cerebral autoregulation (CA) is impaired during acute high-altitude (HA) exposure and effects of acclimatization and re-exposure on CA are unknown. In 18 healthy lowlanders (11 women), we hypothesized that the cerebral autoregulation index (ARI) assessed by the percentage change in middle cerebral artery peak blood flow velocity (Δ%MCAv)/percentage change in mean arterial blood pressure (Δ%MAP) induced by a sit-to-stand maneuver, is i) reduced on Day1 at 5050m compared to 520m, ii) is improved after 6 days at 5050m, and iii) is less impaired during re-exposure to 5050m after 7 days at 520m compared to Cycle1. Participants spent 4-8h/day at 5050m and slept at 2900m similar to real-life working shifts. High/low ARI indicate impaired/intact CA, respectively. With the sit-to-stand at 520m, mean(95%CI) in ΔMAP and ΔMCAv were -26%(-41 to -10) and -13%(-19 to -7); mean±SE in ARI was 0.58±0.63Δ%/Δ%, respectively. On Day1 at 5050m, ARI worsened compared to 520m (3.29±0.70Δ%/Δ%), but improved with acclimatization (1.44±0.65Δ%/Δ%, P<0.05 for both). ARI was less affected during re-exposure to 5050m (1.22±0.70Δ%/Δ%, P<0.05 acute altitude-induced change between sojourns). This study showed that CA i) is impaired during acute HA exposure, ii) improves with acclimatization and iii) is ameliorated during re-exposure to HA a week later.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".