Does breathing pattern affect cerebrovascular reactivity?
Bibliographic record
Abstract
NEW FINDINGS: What is the central question of this study? Is cerebrovascular reactivity affected by isocapnic changes in breathing pattern? What is the main finding and its importance? Cerebrovascular reactivity does not change with isocapnic variations in tidal volume and frequency. ABSTRACT: Deviations of arterial carbon dioxide tension from resting values affect cerebral blood vessel tone and thereby cerebral blood flow. Arterial carbon dioxide tension also affects central respiratory chemoreceptors, adjusting respiratory drive. This coincidence raises the question: does respiratory drive also affect the cerebral blood flow response to carbon dioxide? A change in cerebral blood flow for a given change in the arterial carbon dioxide tension is defined as cerebrovascular reactivity (CVR). Two studies have reached conflicting conclusions on this question, using voluntary control of breathing as a disturbing factor during measurements of CVR. Here, we address some of the methodological limitations of both studies by using sequential gas delivery and targeted control of carbon dioxide and oxygen to enable a separation of the effects of carbon dioxide on CVR from breathing vigour. We confirm that there is no detectable superimposed effect of breathing efforts on CVR.
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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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".