Effect of five nights of normobaric hypoxia on cardiovascular responses to acute isocapnic hypoxia in humans: relationship to ventilatory chemosensitivity
Bibliographic record
Abstract
The aim of this study was to elucidate (1) the cardiovascular responses to acute isocapnic hypoxia stimuli following five nights of normobaric poikilocapnic hypoxia, and (2) whether the changes in the cardiovascular responses to hypoxia are correlated to the change in acute hypoxic ventilatory (AHVR) chemosensitivity. Twelve male subjects [26.6 +/- 4.1 (SD) years] slept 8-9 h day(-1) overnight for five consecutive days at a simulated altitude of 4300 m (FiO2 = approximately 13.8%). Using the technique of dynamic end-tidal forcing, the AHVR was assessed twice, prior to and immediately after the hypoxic exposure. During each AHVR test, mean arterial blood pressure (MAP) and heart rate (HR) were measured continuously using finger photoplethysmography and an ECG monitor, respectively. Immediately following the exposure, AHVR and MAP sensitivities were increased by 1.80 +/- 1.30 l min(-1) %(-1) (p < 0.01) and 0.69 +/- 0.40 mmHg %(-1) (p < 0.05), respectively, and there were significant correlations between the increases in the AHVR and MAP sensitivities (r = 0.67; p < 0.05). In summary, following five nights of normobaric hypoxia, there is an enhanced MAP response to hypoxic stimuli. The relationship between the enhanced AHVR and MAP sensitivity raises the possibility of a common pathway in the regulation of peripheral chemosensitivity and MAP responses during periods of isocapnic hypoxia.
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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) | 0.001 | 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".