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 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 | 0.001 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".