taVNS During Multi-site HRV Measurement: Reliability & Agreement Study

NCT07548723 | Enrolling By Invitation

• 2 other identifiers: taVNS1BEU-ETH 2026/01-11
• Study Type: interventional
• Target: 1
• Locations: 1 country
• Sites: 1

Brief Summary

This study examines the reliability and agreement of autonomic nervous system measurements obtained from different anatomical sites during transcutaneous auricular vagus nerve stimulation (taVNS). taVNS is a non-invasive electrical stimulation delivered to the ear using a small stimulator. Healthy volunteers aged 18-40 years will participate in one laboratory session. Heart rate and heart rate variability will be recorded from the chest (reference), finger, and arm. Blood pressure and pulse will also be measured. Data will be collected in three standardized periods: T0 (5-minute resting baseline), T1 (10 minutes during taVNS), and T2 (5-minute recovery). The main goal is to determine how closely finger- and arm-based measurements match the chest reference and how consistent these measurements are across the study periods. Participation is voluntary, and participants may withdraw at any time. Expected risks are minimal and may include temporary tingling or mild discomfort at the ear and, rarely, lightheadedness. No direct medical benefit is expected, but the findings may help improve how autonomic responses are monitored during taVNS in future research.

Conditions

Autonomic Nervous System (ANS) Functioning and Mood State; Heart Rate Variability (HRV); Blood Pressure Monitoring; Transcutaneous Electric Nerve Stimulation; Photoplethysmography

Keywords

Transcutaneous auricular vagus nerve stimulation; Autonomic nervous system; Anatomical measurement sites; Heart rate variability; Measurement reliability; Method comparison; Agreement analysis

Outcome Measures

Primary Outcomes (5)

• RMSSD inter-site agreement across chest, finger, and arm recordings

  Root mean square of successive differences (RMSSD) derived from simultaneous recordings at three sites (chest as reference, finger, and arm) will be compared to determine inter-site agreement and reliability. Agreement will be evaluated using Bland-Altman analysis (bias and limits of agreement), and reliability/consistency will be quantified using intraclass correlation coefficients (ICC). Unit of Measure: ms

  During a single session: baseline (T0, 5 minutes), stimulation (T1, 10 minutes), and recovery (T2, 5 minutes).

• SDNN inter-site agreement across chest, finger, and arm recordings

  Standard deviation of normal-to-normal intervals (SDNN) derived from simultaneous recordings at three sites (chest as reference, finger, and arm) will be compared to determine inter-site agreement and reliability. Agreement will be evaluated using Bland-Altman analysis (bias and limits of agreement), and reliability/consistency will be quantified using intraclass correlation coefficients (ICC). Unit of Measure: ms

  During a single session: baseline (T0, 5 minutes), stimulation (T1, 10 minutes), and recovery (T2, 5 minutes).

• LF power inter-site agreement across chest, finger, and arm recordings

  Low-frequency (LF) power derived from simultaneous recordings at three sites (chest as reference, finger, and arm) will be compared to determine inter-site agreement and reliability. Agreement will be evaluated using Bland-Altman analysis (bias and limits of agreement), and reliability/consistency will be quantified using intraclass correlation coefficients (ICC). Unit of Measure: ms²

  During a single session: baseline (T0, 5 minutes), stimulation (T1, 10 minutes), and recovery (T2, 5 minutes).

• HF power inter-site agreement across chest, finger, and arm recordings

  High-frequency (HF) power derived from simultaneous recordings at three sites (chest as reference, finger, and arm) will be compared to determine inter-site agreement and reliability. Agreement will be evaluated using Bland-Altman analysis (bias and limits of agreement), and reliability/consistency will be quantified using intraclass correlation coefficients (ICC). Unit of Measure: ms²

  During a single session: baseline (T0, 5 minutes), stimulation (T1, 10 minutes), and recovery (T2, 5 minutes).

• LF/HF ratio inter-site agreement across chest, finger, and arm recordings

  The low-frequency to high-frequency ratio (LF/HF ratio) derived from simultaneous recordings at three sites (chest as reference, finger, and arm) will be compared to determine inter-site agreement and reliability. Agreement will be evaluated using Bland-Altman analysis (bias and limits of agreement), and reliability/consistency will be quantified using intraclass correlation coefficients (ICC). Unit of Measure: unitless

  During a single session: baseline (T0, 5 minutes), stimulation (T1, 10 minutes), and recovery (T2, 5 minutes).

Secondary Outcomes (3)

• Systolic blood pressure

  Single session: baseline (5 minutes), stimulation (10 minutes), and recovery (5 minutes)

• Diastolic blood pressure

  Single session: baseline (5 minutes), stimulation (10 minutes), and recovery (5 minutes).

• Heart rate during transcutaneous auricular vagus nerve stimulation

  Single session: baseline (5 minutes), stimulation (10 minutes), and recovery (5 minutes).

Study Arms (1)

Transcutaneous Auricular Vagus Nerve Stimulation - Single Session

EXPERIMENTAL

All participants receive a single session of transcutaneous auricular vagus nerve stimulation (taVNS). Autonomic measures are recorded simultaneously from chest (reference), finger, and arm during baseline (T0, 5 min), stimulation (T1, 10 min), and recovery (T2, 5 min). Blood pressure and pulse are also measured during the session. No separate arms or randomization are used.

Device: Transcutaneous auricular vagus nerve stimulation

Interventions

Transcutaneous auricular vagus nerve stimulation DEVICE

Transcutaneous auricular vagus nerve stimulation will be delivered to the cymba conchae region of the auricle using an external stimulator. Stimulation will be set to 25 Hz with a pulse width of 200-300 microseconds. Current intensity will be individually adjusted to a clearly perceptible but non-painful level (typically 0.5-5 mA). Stimulation will be applied for 10 minutes.

Transcutaneous Auricular Vagus Nerve Stimulation - Single Session

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18 to 40 years.
• Healthy volunteers without known chronic disease or acute illness at the time of participation.
• Able and willing to comply with study procedures and instructions.
• Provided written informed consent.

You may not qualify if:

• Any cardiovascular disease, arrhythmia, hypertension, or similar condition. Any neurological disorder (e.g., diabetes mellitus, peripheral neuropathy, epilepsy).
• Any diagnosed psychiatric disorder.
• Pregnancy or suspected pregnancy.
• Ear conditions that prevent stimulation (infection, open wound, pain/tenderness) or the presence of a piercing at/near the stimulation site.
• Vigorous exercise within 24 hours prior to the measurement.
• Caffeine intake, smoking, or alcohol consumption within 4-6 hours prior to the measurement.
• Marked intolerance or hypersensitivity to the devices or the procedure.
• Inability to follow instructions during measurements or refusal to complete the session.

Sponsors & Collaborators

• SEFA HAKTAN HATIK: lead

Study Sites (1)

Güzelyurt Neighborhood, Mustafa Bozkurt Street, No: 9, Türkeli, Sinop, Türkiye

Sinop, 57900, Turkey (Türkiye)

Location

Related Publications (6)

• Coste A, Millour G, Hausswirth C. A Comparative Study Between ECG- and PPG-Based Heart Rate Sensors for Heart Rate Variability Measurements: Influence of Body Position, Duration, Sex, and Age. Sensors (Basel). 2025 Sep 15;25(18):5745. doi: 10.3390/s25185745.

  PMID: 41012985 BACKGROUND

• Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Circulation. 1996 Mar 1;93(5):1043-65. No abstract available.

  PMID: 8598068 BACKGROUND

• Koo TK, Li MY. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. J Chiropr Med. 2016 Jun;15(2):155-63. doi: 10.1016/j.jcm.2016.02.012. Epub 2016 Mar 31.

  PMID: 27330520 BACKGROUND

• Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater reliability. Psychol Bull. 1979 Mar;86(2):420-8. doi: 10.1037//0033-2909.86.2.420.

  PMID: 18839484 BACKGROUND

• Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986 Feb 8;1(8476):307-10.

  PMID: 2868172 BACKGROUND

• Wang Y, Li SY, Wang D, Wu MZ, He JK, Zhang JL, Zhao B, Hou LW, Wang JY, Wang L, Wang YF, Zhang Y, Zhang ZX, Rong PJ. Transcutaneous Auricular Vagus Nerve Stimulation: From Concept to Application. Neurosci Bull. 2021 Jun;37(6):853-862. doi: 10.1007/s12264-020-00619-y. Epub 2020 Dec 23.

  PMID: 33355897 BACKGROUND

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Masking Details: No masking was implemented; this is an open-label, single-session methodological study without sham stimulation.
• Purpose: OTHER
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Assistant Professor

Model Details: Single-group, within-subject design. All participants complete one standardized session consisting of baseline (T0), stimulation (T1), and recovery (T2). Autonomic measures are recorded simultaneously from multiple anatomical sites (chest as reference, finger, and arm) to assess inter-site reliability and agreement; no separate study arms or randomization are used.

Study Record Dates

• First Submitted: February 22, 2026
• First Posted: April 23, 2026
• Study Start: March 20, 2023
• Primary Completion: April 20, 2026
• Study Completion: May 5, 2026
• Last Updated: April 23, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)