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| ID | Type | Description | Link |
|---|---|---|---|
| 19CER24 | Other Identifier | Research Ethics Committee of the University of the Balearic Islands (UIB) |
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| Name | Class |
|---|---|
| Health Research Institute of the Balearic Islands (IdISBa, Spain) | UNKNOWN |
| University of the Balearic Islands - Institute for Health Sciences Research (UNICS) | UNKNOWN |
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This study investigates the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on autonomic cardiovascular regulation during exercise and recovery in individuals with chronic spinal cord injury (SCI). Participants undergo two experimental conditions (active taVNS and sham stimulation) in a randomized crossover design while performing a standardized exercise protocol.
Heart rate variability (HRV) is used as a non-invasive biomarker to assess autonomic nervous system dynamics across different phases (baseline, exercise, and recovery). The aim is to characterize physiological responses to neuromodulation and explore whether taVNS modulates autonomic adaptability in this population.
This is a mechanistic physiological study designed to improve the understanding of autonomic regulation in SCI and to explore potential biomarkers of response to neuromodulation.
Spinal cord injury (SCI) is associated with significant impairments in autonomic nervous system function, particularly affecting cardiovascular regulation. These alterations reduce physiological adaptability to internal and external stressors and may contribute to increased cardiovascular risk.
Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that has been proposed as a potential tool to influence autonomic function. However, its effects on dynamic autonomic regulation during physiological stress, such as exercise, remain insufficiently characterized in individuals with SCI.
The present study is a randomized, controlled, crossover experimental protocol designed to investigate the acute effects of taVNS on autonomic cardiovascular dynamics during a structured exercise and recovery paradigm. Participants with chronic SCI are exposed to two conditions: active taVNS and sham stimulation, applied in a randomized order.
Each experimental session includes three phases: baseline (rest), exercise (submaximal effort), and recovery. Continuous electrocardiographic recordings are obtained to derive heart rate variability (HRV) metrics. Both linear (time and frequency domain) and non-linear analyses are performed to characterize autonomic regulation and system dynamics.
The primary objective is to evaluate whether taVNS modulates autonomic responsiveness and adaptability across different physiological states. Secondary objectives include the exploration of HRV-derived biomarkers that may reflect autonomic complexity and the identification of response patterns to neuromodulation.
This study is not designed to evaluate clinical efficacy or therapeutic outcomes but to provide mechanistic insight into autonomic regulation and neuromodulation effects in SCI. The results may contribute to the development of personalized approaches in neurorehabilitation and autonomic monitoring.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Active taVNS | Experimental | Transcutaneous auricular vagus nerve stimulation applied during the experimental protocol. |
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| Sham Stimulation | Sham Comparator | Sham stimulation applied under identical experimental conditions without effective vagus nerve activation. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Transcutaneous Auricular Vagus Nerve Stimulation | Device | Non-invasive electrical stimulation applied to the auricular branch of the vagus nerve using transcutaneous electrodes during the experimental protocol. |
| Measure | Description | Time Frame |
|---|---|---|
| DFA α2 | Detrended fluctuation analysis (α2) derived from RR intervals to assess long-term fractal scaling properties of heart rate variability. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. The value reported at each specific time point represents the calculation for the preceding 5-minute window to characterize autonomic regulation across the session. | Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes. |
| Measure | Description | Time Frame |
|---|---|---|
| RMSSD (ms) | Root mean square of successive differences (RMSSD) of RR intervals to assess short-term heart rate variability and parasympathetic activity. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. The value reported at each time point represents the calculation for the preceding 5-minute window.. | Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes. |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of the Balearic Islands | Palma de Mallorca | Balearic Islands | 07122 | Spain |
Individual participant data (IPD) will not be shared due to privacy and ethical considerations. Aggregated data may be available upon reasonable request.
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| ID | Term |
|---|---|
| D013119 | Spinal Cord Injuries |
| D000092122 | Bronchiolitis Obliterans Syndrome |
| ID | Term |
|---|---|
| D013118 | Spinal Cord Diseases |
| D002493 | Central Nervous System Diseases |
| D009422 | Nervous System Diseases |
| D020196 | Trauma, Nervous System |
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Randomized, controlled, crossover experimental study with two conditions (active taVNS and sham). Each participant undergoes both conditions during standardized exercise and recovery phases.
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Participants are blinded to the stimulation condition (active taVNS vs sham), while investigators are aware of the assigned condition.
| Sham Stimulation | Device | Sham stimulation delivered with identical device setup but without effective activation of the vagus nerve. |
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| HF power (ms²) | High-frequency (HF) power (0.15-0.40 Hz) derived from RR intervals to assess parasympathetic modulation. Spectral analysis is performed using standard frequency-domain methods. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point. | Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes. |
| LF power (ms²) | Low-frequency (LF) power (0.04-0.15 Hz) derived from RR intervals to assess combined autonomic modulation. Frequency-domain analysis is performed after preprocessing of RR interval data. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point. | Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes. |
| SD1 (ms) | SD1 derived from the Poincaré plot of RR intervals, representing short-term beat-to-beat variability. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point. | Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes. |
| D014947 | Wounds and Injuries |
| D000092124 | Organizing Pneumonia |
| D001989 | Bronchiolitis Obliterans |
| D001988 | Bronchiolitis |
| D001991 | Bronchitis |
| D001982 | Bronchial Diseases |
| D012140 | Respiratory Tract Diseases |
| D008173 | Lung Diseases, Obstructive |
| D008171 | Lung Diseases |
| D006086 | Graft vs Host Disease |
| D007154 | Immune System Diseases |