Autonomic Nervous System Modulation During Accidental Syncope Induced by Heat and Orthostatic Stress
Bibliographic record
Abstract
BACKGROUND: Heart rate variability (HRV) indices (LF, HF, LF/HF, RMSSD, and pNN50) under combined heat and orthostatic stress leading up to and during accidental syncope (EXP group: one man, two women; age: 23.7 +/- 2.9 yr) were compared with data collected from subjects who did not experience syncope (CON group: one man, two women; age: 22.3 +/- 1.5 yr). METHODS: Minute averages of HRV indices were collected during 5 min at baseline (Base), 5 min leading up to syncope (PRE), and 5 min during syncope (Syncope) (i.e., 2 min leading up to, 1 min during, and 2 min post-syncope). Data were individually analyzed as 1-min means during Syncope as well as 5-min means during Base, PRE, and Syncope. RESULTS: Between-group results revealed that LF and LF/HF were significantly higher and HF was significantly lower in EXP compared to CON subjects at minutes 1, 2, and 3 during Syncope. Further, RMSSD (CON: 161.1 +/- 37.0 ms; EXP: 17.5 +/- 13.3 ms) and pNN50 (CON: 26.4 +/- 36.3%; EXP: 1.3 +/- 1.2%) were significantly lower in EXP compared to CON subjects at minute 3 during Syncope. During Syncope, 5-min averages of LF (CON: 46.1 +/- 13.9 nu; EXP: 77.5 +/- 6.6 nu) and LF/HF (CON: 1.0 0.5; EXP: 3.8 +/- 1.7) were significantly higher, and HF (CON: 53.9 +/- 13.9 nu; EXP: 22.5 +/ 1 6.6 nu) was significantly lower in EXP subjects compared to CON. DISCUSSION: Our findings show that autonomic nervous system modulation leading up to and during accidental syncope induced by heat and orthostatic stress is characterized by an exaggerated suppression of parasympathetic and elevation of sympathetic activity. Thus, elevated LF and LF/HF, and lower HF, RMSSD, and pNN50 may represent risk factors for accidental syncope.
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How this classification was reachedexpand
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) | 0.000 | 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) | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".