Rapid Response of autonomic nervous system to acupuncture in subjects under stress

Introduction: During functional magnetic resonance imaging (fMRI) investigating effects of acupuncture, numerous subjects reported immediate reduction in anxiety upon needle insertion. We hypothesised that the autonomic nervous system (ANS) reacted more rapidly to acupoint stimulation than previously reported. We investigated whether valid results could be obtained from 220 seconds of pulse recording. Furthermore, we looked for evidence that ANS responses differed depending on acupoints stimulated. Methods: 40 subjects participated in each of two sessions of acupuncture using LI4 Hegu, SP6 Sanyinjiao, PC6 Neiguan or ST36 Zusanli. A sterile hypodermic needle (Terumo, 0 0.50 x 16 mm) was inserted into the selected point. After a 10-minute washout period, 0.5 mL of normal saline was injected into the point at 30-second intervals for 5 doses, a total dose of 2.5 mL in 150 seconds. Continuous pulse recording was commenced 70 seconds before the first injection and continued for 220 seconds until the end of the injections. Calculated spectral power of the recordings was compared between the pre-stimulation and stimulation phases. Results: Paired-samples t-tests showed significant increases in low frequency....