Overnight Shift From Obstructive to Central Apneas in Patients With Heart Failure
Bibliographic record
Abstract
BACKGROUND: Obstructive (OSA) and central sleep apnea (CSA) can coexist in patients with congestive heart failure (CHF). However, the reason why OSA events occur at one time and CSA events at another has not been determined. We hypothesized that a change in PCO(2) would be associated with an alteration in apnea type: a decrease in PCO(2) should lead to CSA. METHODS AND RESULTS: To test this hypothesis, we evaluated minute ventilation (V(I)), transcutaneous PCO(2) (PtcCO(2)), circulation time, and periodic breathing cycle length during overnight polysomnography in 12 patients with CHF and coexisting OSA and CSA. V(I) was significantly greater (mean+/-SEM, 9.4+/-1.3 versus 8.0+/-0.9 L/min; P:<0.05) and PtcCO(2) was lower (39.4+/-1.0 versus 41.9+/-1.1 mm Hg, P:<0.01) during episodes of CSA than of OSA. These changes were associated with significant lengthening of circulation time (23.6+/-3.7 versus 21.1+/-3.6 seconds, P:<0.01) and periodic breathing cycle length (53.7+/-3.5 versus 49.6+/-2.9 seconds, P:<0.01). In addition, the proportion of obstructive events decreased (from 68.5+/-11.4% to 22.5+/-7.2%, P:<0.001) and of CSA events increased (from 31.5+/-11.4% to 77.5+/-7.2%, P:<0.001) from the first to the last quarter of the night in association with a significant decrease in PtcCO(2) (from 42.6+/-0.9 to 40.8+/-0.9 mm Hg, P:<0.01). CONCLUSIONS: In patients with CHF, the shift from OSA to CSA is associated with a reduction in PCO(2). This appears to be related to an overnight deterioration in cardiac function as suggested by the concurrent lengthening of circulation time. Therefore, in CHF patients, alterations in cardiac function may influence apnea type.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".