Oxygen saturation determined from deep muscle, not thenar tissue, is an early indicator of central hypovolemia in humans
Why this work is in the frame
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Bibliographic record
Abstract
OBJECTIVE: To compare the responses of noninvasively measured tissue oxygen saturation (StO2) and calculated muscle oxygen tension (PmO2) to standard hemodynamic variables for early detection of imminent hemodynamic instability during progressive central hypovolemia in humans. DESIGN: Prospective study. SETTING: Research laboratory. SUBJECTS: Sixteen healthy human volunteers. INTERVENTIONS: Progressive lower body negative pressure (LBNP) to onset of cardiovascular collapse. MEASUREMENTS AND MAIN RESULTS: Noninvasive measurements of blood pressures, heart rate, and stroke volume were obtained during progressive LBNP with simultaneous assessments of StO2, PmO2, and muscle oxygen saturation (SmO2). Forearm SmO2 and PmO2 were determined with a novel near infrared spectroscopic measurement device (UMMS) and compared with thenar StO2 measured by a commercial device (HT). All values were normalized to the duration of LBNP exposure required for cardiovascular collapse in each subject (i.e., LBNP maximum). Stroke volume was significantly decreased at 25% of LBNP maximum, whereas blood pressure was a late indicator of imminent cardiovascular collapse. PmO2 (UMMS) was significantly decreased at 50% of maximum LBNP while SmO2 (UMMS) decreased at 75% of maximum LBNP. Thenar StO2 (HT) showed no statistical change throughout the entire LBNP protocol. CONCLUSIONS: Spectroscopic assessment of forearm muscle PO2 and SmO2 provides noninvasive and continuous measures that are early indicators of impending cardiovascular collapse resulting from progressive reductions in central blood volume.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 it