Influence of Obstructive Sleep Apnea (OSA) on Rostral Fluid Shift, and the Pathophysiology on Asthma
Bibliographic record
Abstract
The presence of obstructive sleep apnea (OSA) in persons with asthma confers a heightened risk of overnight exacerbation of asthma, declined lung function, increased airway hyperresponsiveness, and greater need for asthma medications. Previous studies showed that overnight fluid shift from the legs into the neck and peripharyngeal tissues increases upper airway resistance and severity of OSA. Recent findings also indicated that in asthma, fluid shift into the thorax induced by lower body positive pressure (LBPP) while supine provokes an increase in small airway resistance. However, whether fluid redistribution links OSA with asthma remains unknown. This thesis aimed to investigate the role of fluid accumulation in the thorax in the pathophysiological link between OSA and asthma. The central hypothesis is that one mechanism by which OSA can predispose to small airway narrowing in asthma is by aggravating fluid accumulation in the thorax during sleep. We found that simulated obstructive apneas in awake participants increased thoracic fluid volume (TFV) by approximately 50 ml in both healthy and asthma groups. However, small airway narrowed only in the asthma group, indicating that increases in TFV resulting from negative intrathoracic pressure swings during simulated apneas, increase small airway narrowing in patients with asthma, but not in healthy controls (Chapter 3). We expanded this work into the overnight and clinical setting, and found that patients with asthma and co-existing OSA had a larger increase in TFV and greater small airway narrowing than asthma patients without OSA (Chapter 4). Moreover, we investigated whether asthma treatment with bronchodilators can prevent the airway narrowing that is attributable to rostral fluid shift. It was found that small airway narrowing would increase after application of LBPP, both with and without bronchodilator (Chapter 5). Finally, we developed a model of the respiratory system, to estimate elastance of the airway tissues and total respiratory system in patients with asthma in response to increase in TFV. Our modelling results showed that increases in TFV was associated with an increase in airway tissue elastance (Chapter 6). Taken together, these studies demonstrate that fluid accumulation in the thorax narrows the small airway in patients with asthma, and contributes to the pathophysiological link between OSA and asthma.
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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 | 0.000 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".