Development Of A Cold Pressor Test Protocol To Evaluate Cardiac Autonomic Function
Bibliographic record
Abstract
PURPOSE This study tested the reliability and reproducibility of a cold pressor test protocol for the evaluation of cardiac autonomic function. Secondary goals were to investigate the effects of gender and posture on cardiac autonomic function. METHODS Twenty-four normotensive men (n = 12) and women (n = 12) completed 3 trials of the study protocol that included heart rate, blood pressure and ventilatory data collection during 3 postures (left lateral lying, standing and seated for 15 minutes each) and during the cold pressor test (hand immersed in 5°Celsius water for 6 minutes). Spectral analysis of heart rate variability and spontaneous baroreflex sensitivity were used to identify variables indicative of of cardiac autonomic function. RESULTS Betwen trials 1 and 2, there were no significant differences in variables indicative of cardiac autonomic function during the cold pressor test and postural changes. Significant correlations were observed in all heart rate variability and spontaneous baroreflex sensitivity variables, except for low frequency power in the lying posture and during the cold pressor test. Bland-Altman plots constructed for heart rate variability and spontaneous baroreflex variables in trials 1 versus 2 revealed no significant systematic biases. Heart rate and blood pressure were significantly higher and total power, high frequency power, and low frequency power were significantly lower during the cold pressor test compared to the seated posture. The sympathetic nervous system (SNS) indicator increased significantly from a baseline value of 0.45±0.06 to 0.82±0.2 during the cold pressor test. Significant changes were also observed in the parasympathetic nervous system (PNS) indicator, which decreased from a baseline value of 0.87±0.10 to 0.45±0.30 in response to the cold pressor test. In comparison to the left lateral lying posture, both genders showed a significant increase in the SNS indicator and decreases in the R-R interval and spontaneous baroreflex slope when standing. The only significant gender difference was in the PNS indicator during the left lateral lying posture, with women having a higher value than men (0.50±0.05 vs. 0.29±0.04). CONCLUSIONS Findings support the hypothesis that the cold pressor test is a reliable and reproducible method for testing cardiac autonomic function. Cardiac autonomic function exhibits gender and postural differences in humans. Supported by The Physicians' Services Incorporated Foundation (Canada), the Garfield Kelly Cardiovascular Research and Development Fund, and Advisory Research Committee (Queen's University)
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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 | 0.008 | 0.012 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".