Vascular Effects of Auricular Acupuncture Evaluated via Two Digital Volume Pulse Measurements

Stimulation of some auricular acupoints produces changes in the radial pulse (Nogier, 1989), and electric stimulation of the auricular acupoint stomach can modify the radial artery pulse wave (Ikezono et al., 2003). Measurement of light transmission through the finger pulp during the cardiac cycle (photoplethysmography) provides a digital volume pulse (DVP). Changes in the contour of the DVP associated with aging, vascular disease, and drugs have been described (Dillon & Hertzman, 1941; Morikawa, 1967). The contour of the DVP is mainly influenced by the systemic vasculature (Nichols, 2005). A previous study has shown that the acute effects of manual acupuncture at the acupoint 6 of pericardium channel (PC6) on vascular pathophysiology in healthy and hypertensive subjects (Rivas-Vilchis et al, 2007), and non-smokers versus smokers (Rivas-Vilchis et al., 2008) can be detected by changes in the indices obtained from the second derivative of the DVP. Two indices derived from the DVP have been proposed. RIDVP as an index of pressure wave reflection and SIDVP as an estimate of pulse wave velocity (PWV) in the aorta and large arteries, i.e., an index of large artery stiffness (Chowienczyk et al., 1999; Millasseau et al., 2002; Millasseau et al., 2003). The purpose of the present study was to assess the acute differential vascular effects of auricular acupoints located in the right and left ear using two DVP indices.