The effects of patent foramen ovale (PFO) on pulmonary gas exchange during incremental exercise
Bibliographic record
Abstract
The prevalence of a probe‐patent foramen ovale (PFO) reported in autopsy studies vary between 20 and 35%. We hypothesized that individuals with a PFO (PFO+) would have greater pulmonary gas exchange inefficiency during exercise than subjects without a PFO (PFO−) because a PFO could act as a right‐to‐left shunt. PFO+ (n=8) and PFO− (n=8) performed two incremental cycle ergometer exercise tests to max, separated by one hour, while breathing either room air or hypoxic gas ( FIO 2 =0.12). Using saline contrast echocardiography, both PFO− and PFO+ demonstrated significant intrapulmonary shunt (bubbles appearing in the left atrium (LA) after 5 heart beats) during both exercise conditions. However, at rest and during both exercise conditions in PFO+, contrast bubbles were also observed traveling through the foramen ovale as small, intermittent boluses entering directly into the LA within 3 heart beats. These findings suggest, qualitatively, a very small intracardiac shunt at rest and during exercise in PFO+. Consequently, the alveolar‐to‐arterial oxygen difference was not significantly different between PFO+ and PFO− at either peak normoxic (24.2 ± 7.8 vs. 17.5 ± 10.8 mm Hg, p= 0.18) or hypoxic (22.7 ± 2.9 vs. 20.2 ± 4.9 mm Hg, p= 0.25) exercise. We conclude that a PFO does not further exacerbate pulmonary gas exchange inefficiency occurring during exercise in healthy humans. Support: HL‐15469 & T32 HL07654; AHA 0550176Z.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 | 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) | 0.000 | 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 teacher head, 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".