Jugular and Portal Vein Volume, Middle Cerebral Vein Velocity, and Intracranial Pressure in Dry Immersion
Bibliographic record
Abstract
BACKGROUND: The objective was to determine if short term exposure to dry immersion (DI) results in a cephalic fluid shift similar to what has been observed with spaceflight. METHODS: Data were collected from 10 individuals at rest and during the first 2 h of dry immersion. Jugular vein (JV), portal vein (PV), and thyroid volume were measured using 3D echography. Middle cerebral vein velocity (MCVv) was determined using transcranial Doppler ultrasound. The cochlear response to audio stimulation was used to derive an estimate of intracranial pressure (dICP). RESULTS: After 2 h of DI, there was a significant increase (mean ± SD) in JV (2.21 ± 1.10 mL), PV (1.05 ± 0.48 mL), and thyroid (0.428 ± 0.313 mL) volume. MCVv was also significantly increased with DI (3.90 ± 5.03 cm · s-1). There was no change in dICP with DI in part due to large individual variability. The range of dICP changes appeared to be related to MCVv, with participants with the largest increase in MCVv also showing increased dICP. DISCUSSION: The results suggest that DI induces a significant cephalic fluid shift similar to what is observed with spaceflight. The increased thyroid volume suggests that cerebral tissue may also be subjected to similar fluid filtration, with implications for changes in intracranial pressure. However, despite all participants having an increase in JV and thyroid volume, only half showed an increase in dICP, suggesting that increased venous pooling alone is not sufficient to cause increased intracranial pressure.Arbeille P, Avan P, Treffel L, Zuj K, Normand H, Denise P. Jugular and portal vein volume, middle cerebral vein velocity, and intracranial pressure in dry immersion. Aerosp Med Hum Perform. 2017; 88(5):457-462.
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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".