Elevated End-Tidal Pco2 During Long-Duration Spaceflight
Bibliographic record
Abstract
BACKGROUND: Elevated ambient Pco2 in the International Space Station (ISS) has been cited as a potential contributor to the vision impairment intracranial pressure syndrome (VIIP), a significant health risk for astronauts during long-duration space missions. The elevation in ambient Pco2 is rather modest and normal respiratory compensation could minimize the impact on arterial Pco2.METHODS: In nine male astronauts, breaths measured prior to a rebreathing maneuver were examined to assess inspired and end-tidal Pco2 during upright seated preflight and in-flight conditions.RESULTS: Inspired Pco2 increased from preflight baseline (0.6 ± 0.1 mmHg) to in flight (3.8 ± 0.4 mmHg). End-tidal Pco2 also increased from preflight baseline (36.0 ± 3.2 mmHg) to in flight (42.1 ± 3.7 mmHg). The difference between end-tidal Pco2 comparing in flight to preflight (6.1 ± 1.6 mmHg) was greater than the difference between inspired Pco2 comparing preflight to in flight (3.3 ± 0.5 mmHg).DISCUSSION: The greater increase in end-tidal vs. inspired Pco2 might reflect alveolar hypoventilation due to differences in ventilatory control with spaceflight. These data suggest that further studies should focus on arterial Pco2 and acid-base balance to determine if CO2 dilates cerebral and retinal vessels and might contribute to the incidence of VIIP in astronauts.Hughson RL, Yee NJ, Greaves DK. Elevated end-tidal Pco2 during long-duration spaceflight. Aerosp Med Hum Perform. 2016; 87(10):894–897.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".