Acute Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Cardiac Autonomic Function in People Living with HIV: A Randomized Clinical Trial
HIV; Aids; Vagus Nerve Stimulation; Autonomic Nervous System; Heart Rate
Objective: To evaluate the acute effect of transcutaneous auricular vagus nerve stimulation (taVNS) on cardiac autonomic function in people living with HIV.
Design: A single-blind, randomized, crossover clinical trial.
Setting: Human Movement Laboratory, Department of Physical Education, Federal University of Rio Grande do Norte, Natal-RN, Brazil.
Subjects: 21 men living with HIV under antiretroviral therapy.
Interventions: Two counterbalanced conditions (taVNS vs. Sham) with 48-hour intervals between applications. taVNS was applied to the left ear's cymba concha with stimulation parameters including a pulse width of 500 µs, a frequency of 10 Hz, and intensity set at the perceptual threshold. Sham (control) was applied to the same region of the left ear with stimulation parameters set at 0.
Main measures: Comparisons between heart rate (HR) measurements and heart rate variability (HRV) indices between groups (taVNS x Sham). Intra-group comparisons for HR and HRV measurements over time in relation to rest. Interactions of HR and HRV measurements between conditions (taVNS vs Sham) x time.
Results: HR and HRV measures did not differ between conditions (taVNS vs. Sham). Over time, HR decreased, and HRV indices increased in both conditions but did not show an interaction (condition x time).
Conclusion: Acute taVNS did not have an effect on HR and HRV in men living with HIV during and after stimulation cessation. It is suggested that new protocols be tested with different stimulation parameters to explore the potential for a more significant effect on HR and HRV