Enhancing Vagal Tone, Modulating Heart Rate Variability with Auricular Acupressure at Point Zero: A Randomized Controlled Trial.

Introduction: Point Zero located within the vagus nerve's auricular branch shows promise in addressing imbalances. This study aims to explore its effects on vagal activity using auricular acupressure (AA), measured through heart rate variability (HRV).

Methods: This single-blinded randomized controlled trial involved 114 healthy volunteers randomly assigned to receive AA (AA group, n = 57) or sham-AA (SA group, n = 57) at Point Zero. The 30-minute procedure comprised six stages: T1 and T2 (pre-intervention), T3 to T5 (intervention), and T6 (post-intervention). Interventions involving 30-s acupoint pressure stimulations at T3 and T5. The HRV-measured outcomes included heart rate (HR), standard deviation of R-R intervals (SDNN), root mean square of successive RR interval differences (RMSSD), natural logarithm of low-frequency power (LnLF), and natural logarithm of high-frequency power (LnHF). In addition, respiratory rate (RR) was monitored for its stability.

Results: The AA group demonstrated a significant decrease in HR and increases in SDNN, RMSSD, and LnHF from stages T3 to T6 compared with T1 (baseline), notably prominent at T3 (median changes [25th; 75th percentiles]: -2 [-5; -1], 17.85 [9.65; 31.72], 4.9 [1.08; 10.65], 0.26 [0.00; 0.62], respectively) and T5 (-3 [-6; -1], 19.45 [10.6; 32.89], 6.17 [-0.17; 16.34], 0.40 [-0.14; 0.83], respectively), while the SA group did not. LnLF showed nonsignificant alterations, and RR remained stable in both groups. Despite minor HRV fluctuations, the AA group consistently displayed significantly higher changes in SDNN and RMSSD compared with the SA group from T3 onwards. HR remained unchanged at T6, and LnHF significantly differed only at T5.

Conclusion: AA at Point Zero may promptly enhance vagal activity, evident in the modulation of HRV, notably pronounced with pressure stimulation, and can be sustained for at least 5 min. Further studies are needed to assess its long-term effectiveness and efficacy in preventing or treating patients.(Clinical Trial Registration: NCT05586698).