Systemic Determinants of Exercise Intolerance in Patients With Fibrotic Interstitial Lung Disease and Severely Impaired D <sub>LCO</sub>
Bibliographic record
Abstract
BACKGROUND: The precise mechanisms driving poor exercise tolerance in patients with fibrotic interstitial lung diseases (fibrotic ILDs) showing a severe impairment in single-breath lung diffusing capacity for carbon monoxide (D LCO < 40% predicted) are not fully understood. Rather than only reflecting impaired O 2 transfer, a severely impaired D LCO may signal deranged integrative physiologic adjustments to exercise that jointly increase the burden of exertional symptoms in fibrotic ILD. METHODS: Sixty-seven subjects (46 with idiopathic pulmonary fibrosis, 24 showing D LCO < 40%) and 22 controls underwent pulmonary function tests and an incremental cardiopulmonary exercise test with serial measurements of operating lung volumes and 0–10 Borg dyspnea and leg discomfort scores. RESULTS: Subjects from the D LCO < 40% group showed lower spirometric values, more severe restriction, and lower alveolar volume and transfer coefficient compared to controls and participants with less impaired D LCO ( P < .05). Peak work rate was ∼45% (vs controls) and ∼20% (vs D LCO > 40%) lower in the former group, being associated with lower (and flatter) O 2 pulse, an earlier lactate (anaerobic) threshold, heightened submaximal ventilation, and lower S pO 2 . Moreover, critically high inspiratory constrains were reached at lower exercise intensities in the D LCO < 40% group ( P < .05). In association with the greatest leg discomfort scores, they reported the highest dyspnea scores at a given work rate. Between-group differences lessened or disappeared when dyspnea intensity was related to indexes of increased demand-capacity imbalance, that is, decreasing submaximal, dynamic ventilatory reserve, and inspiratory reserve volume/total lung capacity ( P > .05). CONCLUSIONS: A severely reduced D LCO in fibrotic ILD signals multiple interconnected derangements (cardiovascular impairment, an early shift to anaerobic metabolism, excess ventilation, inspiratory constraints, and hypoxemia) that ultimately lead to limiting respiratory (dyspnea) and peripheral (leg discomfort) symptoms. D LCO < 40%, therefore, might help in clinical decision-making to indicate the patient with fibrotic ILD who might derive particular benefit from pharmacologic and non-pharmacologic interventions aimed at lessening these systemic abnormalities.
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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 | 0.002 |
| 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 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".