Effects of inhaled bronchodilators on dynamic lung mechanics during exercise in COPD: protocol for a randomised, placebo-controlled crossover trial
Bibliographic record
Abstract
Background Activity-related dyspnoea in moderate–severe COPD is centrally related to heightened wasted ventilation in the physiological dead space colliding with constraints to tidal expansion due to acute-on-chronic gas trapping. Both phenomena are ultimately related to small airway dysfunction. However, it remains unknown whether the positive effects of pharmacological deflation on exertional dyspnoea in COPD can be ascribed to improved small airway conductance, enhancing ventilation–perfusion matching and neuromechanical coupling. Main hypotheses We postulate that inhaled bronchodilators will enhance small airway function at rest and during exercise, improving gas exchange efficiency, lung mechanics and exertional dyspnoea in hyperinflated patients with COPD. Methods A double-blind, placebo-controlled study involving 25 symptomatic patients (modified Medical Research Council score ≥2) showing functional residual capacity >120% pred and/or >upper limit of normal will receive nebulised salbutamol sulphate (2.5 mg) plus ipratropium bromide (0.5 mg) or normal saline. On different days, patients will undergo a constant-load test at 75% peak to symptom limitation. Single- and multiple-breath N 2 washout and impulse oscillometry (IOS) will assess resting small airway function. Key exercise measurements will include 1) alveolar and physiological dead space by volumetric capnography, 2) operating lung volumes, 3) oesophageal catheter-based respiratory manometry and inspiratory neural drive via diaphragm electromyography, 4) exercise IOS, and 5) exertional dyspnoea (0–10 Borg scale). Implications Confirmation of the study's hypotheses will shed new light on the mechanisms of dyspnoea improvement after inhaled bronchodilators in patients with COPD. Moreover, it will provide a novel integrative platform for assessing the effects of therapeutic approaches targeting their small airways.
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | no category Domain: not available · Genre: Protocol About the Canadian research system: no · About a Canadian topic: no | Randomized trial | low |
| gpt | no category Domain: not available · Genre: Protocol About the Canadian research system: no · About a Canadian topic: no | Randomized trial | high |
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 | 0.012 | 0.014 |
| Meta-epidemiology (narrow) | 0.007 | 0.003 |
| Meta-epidemiology (broad) | 0.015 | 0.004 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.008 | 0.007 |
| Insufficient payload (model declined to judge) | 0.061 | 0.013 |
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, unvalidatedLabeled directly by 2 models reading the full record.
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".