Impact of High Altitude on Dyspnea at Rest
Bibliographic record
Abstract
Abstract RATIONALE: In lowlanders who ascend rapidly to high altitude, dyspnea is a symptom often found in cases of acute mountain sickness (AMS) and is constant in cases of acute pulmonary oedema (HAPE). However, the existence of dyspnea in healthy persons without other sign of AMS or HAPE at high altitude has not been studied. The aim of this study was to assess the prevalence, characteristics and physiological changes associated with dyspnea in healthy lowlanders after a rapid ascent to high altitude. METHODS: Twenty-six healthy participants (half female and male, aged 26 [24-35]: normal STAI-anxiety score) completed the multimensional dyspnea profile (MDP) at baseline (Calgary, Alberta, Canada, 1,048 meters above sea level) and after an ascent to 3650 meters (La Paz, Bolivia). Concurrent measures of breathing pattern variables and room air arterial blood gases were performed. RESULTS After 24 hours at high altitude, all participants reported dyspnea during room air resting breathing, with a MDP-A1 score (breathing discomfort) of 2 [2-4] in La Paz (LP) vs 0 [0-0] in Calgary (Cal) (p<0.0001), and an aggregated sensory descriptors score (SQ) of 8 [5-12.5] vs 0 [0-2] in Cal (p <0.0001).There was no statistically significant difference between Cal and LP regarding the effort, tightness, and concentration sensory qualifiers, but such a difference was present regarding air hunger (2 [0-3] in ELP vs 0 [0-0] in Cal, p=0.007) and regarding breathing a lot (3 [2-5] in LP vs 0 [0-0] in Cal, p=0.002). We observed statistically significant changes in PaO2 (87 [81-94] mmHg in Cal vs. 55 [50-58] mmHg in LP, p<0.0001) and PaCO2 (35 [32-38] mmHg in Cal vs. 31 [29-33] mmHg in LP, p<0,0001). There was no change in minute ventilation (9.3 [8-11] litre/minute in Cal vs. 9.5 [8-11] litre/minute in LP, p=0.21), respiratory rate (12 [10-15] breaths/minute in Cal vs. 13 [9-16]breath/minute in LP, (p=0.56). CONCLUSIONS Healthy humans who rapidly ascend to high altitude consistently experience dyspnea at rest, mainly of the “air hunger” and the “breathing a lot” types. This dyspnea could be explained by the absence of any change in minute ventilation, despite the existence of significant hypoxemia and hypocapnia. The pathophysiological impact of this initial finding remains to be assessed.
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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 | 0.000 | 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".