Expiratory muscle pressure and breathing mechanics in chronic obstructive pulmonary disease
Bibliographic record
Abstract
Expiratory muscle recruitment is common in stable chronic obstructive pulmonary disease (COPD) patients. Due to airway obstruction, there is little reason to believe that active expiration in COPD would be mechanically effective in lowering operating lung volume. The physiological significance of expiratory muscle recruitment in COPD, therefore, remains unknown. The purpose of this study was to assess, in COPD patients breathing at rest, the effect of expiratory muscle contraction on force generating ability of the diaphragm. The force generating ability of the diaphragm was evaluated from its pressure swing (Pdi) for a given diaphragm electrical activity (Edi), where Edi was normalized as % of its maximal value (Pdi/Edi/Edi,max). Phasic expiratory muscle contraction was measured as the total expiratory rise in gastric pressure (Pga,exp.rise). Nineteen seated patients with moderate to severe COPD, participated in the study and 10 exhibited phasic rise in Pga during expiration with a mean Pga,exp.rise of 1.91+/-0.89 cmH2O. The patients were thus divided into passive expiration (PE) and active expiration (AE) groups. There was no significant difference in various lung function and breathing pattern parameters between the two groups. Pdi/Edi/Edi,max was 0.63+/-0.07 and 0.54+/-0.07 cmH2O/% in PE and AE groups, respectively, and was not significantly different between each other. Compared with PE group, AE group not only recruited expiratory muscles, but also preferentially recruited inspiratory rib cage muscles and derecruited the diaphragm. The results do not support a significant improvement of the force-generating ability of the diaphragm by phasic contraction of expiratory muscles at rest in chronic obstructive pulmonary disease patients.
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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 | 0.001 | 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".