Mechanisms of orthopnea in patients with advanced COPD
Bibliographic record
Abstract
Background: Many patients with COPD report unpleasant respiratory sensation at rest, further amplified by adoption of supine position (orthopnea). The source of this sensation remains poorly understood. Methods: 16 symptomatic patients with advanced COPD and 16 age- and gender-matched healthy controls (CTRL) underwent pulmonary function tests and detailed sensory-mechanical measurements with diaphragm electromyography (EMGdi) and respiratory pressures in sitting and supine positions. Results: Patients (age:66±7years, BMI:25±6 Kg/m2, smoking history:52±25 pack-year, FEV1:40±18 %predicted) had lower inspiratory capacity (IC) by 44% and greater intensity of breathing difficulty (Borg scale) compared with CTRL (p<0.01). In supine (vs. sitting): CTRL expanded IC (by 0.33L) with a drop in ventilation mainly due to reduced breathing frequency (all p<0.05). In contrast, patients’ IC remained fixed and ventilation and breathing frequency, which were significantly higher (p<0.05) than CTRL, remained stable while supine. In COPD, (vs CTRL) supine position shift was associated with greater rise in both unpleasant respiratory sensation, inspiratory neural drive (EMGdi/EMGdi, max) and tidal trans-diaphragmatic pressure as % of maximum (p<0.05) [Figure]. Conclusion: In COPD, acute orthopnea while supine coincided with an abrupt increase in amplitude of diaphragm activation and force generation in the setting of a low fixed inspiratory capacity.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".