Difference in Steady‐state Chemoreflex Drive Between Groups With and Without a Patent Foramen Ovale
Bibliographic record
Abstract
Ventilatory acclimatization is a hallmark physiological response to high altitude. In ~30% of the population, a shunt located between the right and left atrium called patent foramen ovale (PFO) is present. People with a PFO have a reduced degree of ventilatory acclimatization which may contribute to their increased risk for high altitude illnesses. Recently, the development of a steady‐state chemoreflex drive (SS‐CD) index has provided a novel approach to assessing the overall ventilatory drive at altitude. Using data from a previous high‐altitude expedition (AltitudeOmics), the SS‐CD index (SS‐CD = Minute ventilation (V E ), / (arterial partial pressure of carbon dioxide (PaCO 2 ) / arterial oxygen saturation (SaO 2 )) was utilized to quantify differences in the degree of ventilatory acclimatization between groups with a PFO, (PFO+) and without a PFO, (PFO‐). We aimed to test two hypotheses: 1) PFO‐ subjects would have a higher SS‐CD than PFO+ subjects 2) PFO+ subjects would have no significant change in their SS‐CD from ALT1 to ALT16. Twenty‐one participants (n=11 PFO+, n=10 PFO‐) participated in a high‐altitude study during which they spent 16 days at 5260 meters in Bolivia. V E , PaCO 2 , and SaO 2 data were collected at sea level (SL), day 1 at 5260m (ALT1), and day 16 at 5260m (ALT16). V E was obtained using a pneumotach. PaCO 2 and SaO 2 were obtained from a radial artery catheter. A mixed‐model 2 way repeat measure ANOVA was performed for statistical analysis with Tukey's multiple comparisons test. There was a main effect of time on the SS‐CD (p<0.0001), but no significant difference between PFO+ and PFO‐ subjects (p=0.2). Within PFO+ and PFO‐ subject groups the SS‐CD significantly increased from SL to ALT16 (PFO+ : 33.5 ± 5.9 vs 80.9 ± 47.8, p=0.0006; PFO‐ : 37.7 ± 10.3 vs 103.1 ± 44.2, p<0.0001) and from ALT1 and ALT16 (PFO+ : 43.16 ± 9.2 vs 80.9 ± 47.8, p=0.0077; PFO‐ : 52.08 ± 14.3 vs 103.1 ± 44.2, p=0.0052). Using the SS‐CD to quantify chemoreceptor drive between groups, our findings suggest the overall chemoreflex drive from ALT1 to ALT16 in both groups reflects significant changes in ventilation. Additionally, PFO+ subjects exhibit no differences in their overall chemoreflex response to altitude from PFO‐ subjects, despite significant differences in a more classical index of drive (i.e., change in VE/change in SaO 2 ). Future research should aim to investigate this inconsistency in chemoreflex responses in PFO+ and PFO‐ subjects at altitude.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".