Analyzing the effect of moxibustion treatment using the maximum instantaneous frequency of photoplethysmogram signals based on Hilbert–Huang transforms

Moxibustion is a treatment in traditional Chinese medicine that can promote human health. In order to study the effect of moxibustion on cardiovascular function, photoplethysmogram signals were obtained from acupoints at st 36 (zusanli), sp 6 (sanyinjiao), and li 11 (quchi) during moxibustion. The test data were collected from six volunteers of average weight for 6 days of treatment. The effect of moxibustion treatment was determined by comparing amplitude–frequency characteristics of the instantaneous frequency in the power spectrum after Hilbert–Huang transformation of the pulse signal before and after treatment. It was found that after moxibustion, the maximum energy frequency of the photoplethysmogram would increase, but the amplitude would decrease. The results show that moxibustion therapy has the dual benefit of the infrared effect and acupoint stimulation, which can improve cardiovascular health and has a positive effect on metabolism.