Frequency-Dependent Effects of Auricular Vagus Nerve Stimulation on Autonomic and Cardiovascular Parameters

Acute Effects of Different Frequencies of Auricular Vagus Nerve Stimulation on HRV, Blood Pressure, and Respiratory Rate: A Sham-Controlled, Randomized, Crossover Dose-Response Study

This randomized, sham-controlled, crossover study investigates the acute autonomic effects of transcutaneous cervical vagus nerve stimulation (tcVNS) applied at five different frequencies (0 Hz/sham, 10 Hz, 25 Hz, 50 Hz, 100 Hz) in healthy adults. The primary objective is to determine how stimulation frequency modulates heart rate variability (HRV), blood pressure, and respiratory rate. The study aims to establish a frequency-specific dose-response model using validated physiological measurements.

Transcutaneous cervical vagus nerve stimulation (tcVNS) is a non-invasive neuromodulation technique capable of activating afferent vagal pathways projecting to autonomic brainstem nuclei. Although previous studies demonstrate tcVNS-related modulation of autonomic functions, the frequency-response relationship remains insufficiently explored.

This crossover trial randomizes participants to receive five stimulation conditions (sham, 10 Hz, 25 Hz, 50 Hz, 100 Hz) in counterbalanced order. HRV (Polar H10), blood pressure (Omron), and respiratory rate (Kinovea-based thoracoabdominal video tracking) are collected pre- and post-stimulation. Washout between sessions is ≥48 hours.

The study provides one of the first systematic evaluations of frequency-dependent tcVNS effects in healthy adults.

Inclusion Criteria:

• 18-30 years
• Healthy (self-reported)
• No cardiovascular, neurological, metabolic or psychiatric disorders
• No regular medication affecting autonomic function
• Non-smoker
• BMI 18-29.9

Exclusion Criteria:

• Pregnancy
• Cardiac arrhythmia
• Hypertension or hypotension
• Chronic respiratory disorders
• Active infection
• Metal implants in cervical area
• Epilepsy
• Syncope history
• Prior vagus stimulation experience