The Comparison of Multiple Chemosensitivity Tests in Healthy Adults
Bibliographic record
Abstract
Chemoreceptor activity and sensitivity have been shown to be elevated in clinical conditions such as heart failure, hypertension and chronic obstructive pulmonary disease, with heightened chemosensitivity being predictive of mortality in heart failure. Various protocols have been used in these studies to evaluate chemosensitivity, and the purpose of our project was to examine the relationship between three of these chemoreceptor tests: 1) the transient hypoxic ventilatory drive test, 2) the single‐breath (SB) CO 2 test, 3) the CO 2 rebreathe test. It was hypothesized that the transient hypoxia test and the SB CO 2 test would be correlated as both likely stimulate the carotid chemoreceptors and that they would be unrelated to the rebreathe test, as this test likely stimulates the central chemoreceptors. Ten healthy individuals (5 males, 5 females, mean age 27±10 yrs) were recruited. The SB CO 2 test and the CO 2 rebreathe test were performed first, with the order randomized within subjects. For the SB CO 2 test, subjects were given a single breath of 13% CO 2 , 10 times at 2 min intervals. The hypercapnic ventilatory response was calculated by plotting the change in ventilation relative to the change in P ET CO 2 during the 20s following the SB of CO 2 . For the CO 2 rebreathe protocol, subjects rebreathed 50% O 2 , 7% CO 2 and 43% N 2 from a 5L Douglas bag until P ET CO 2 reached 55mmHg, or until subjects requested termination of the test. The ventilatory response to the CO 2 rebreathe was calculated by plotting the change in ventilation relative to the change in P ET CO 2 . The transient hypoxia trial was conducted, where subjects were given 2–8 breaths of pure N 2 . The number of breaths was randomized and repeated 10–14 times. The slope of the regression line between the change in ventilation and the change in SpO 2 represented the hypoxic ventilatory response. The average hypoxic ventilatory response was 0.56±0.09 L/min/% SpO 2 . The mean SB CO 2 response was 0.37±0.07 L/min/mmHg and the mean rebreathe response was 1.81±0.94 L/min/mmHg. There was no significant correlation between the transient hypoxia test and SB CO 2 test (r = 0.13, p = 0.72), no significant correlation between the SB CO 2 test and the CO 2 rebreathe test (r = 0.09, p = 0.81), and no significant correlation between the CO 2 rebreathe test and the transient hypoxia test (r = 0.07, p = 0.85). Our results suggest that the transient hypoxic ventilatory drive test, the single‐breath CO 2 test, and the CO 2 rebreathe test are unrelated to each other in healthy humans. Our results support earlier suggestions that these tests may evaluate independent components of chemosensitivity.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".