Point injection as an alternative acupuncture technique--an exploratory study of responses in healthy subjects

Point injection as a therapeutic technique is well documented, but its physiological effects have not been formally compared with traditional acupuncture. One aim of this study was to compare the effects of the two techniques at one acupuncture point, as a step towards understanding the mode of action of point injection and validating its clinical use. A second aim was to explore whether repeated point injection at the same site might provide a way of increasing the dose of stimulation, in the hope of identifying a dose response curve which could be an alternative strategy to placebo control in demonstrating the biological effects of acupuncture.

Sixty nine healthy subjects (age range 18-56 years, mean 29.9; 48 females) completed the study, which employed a counterbalanced experimental design with two stimulation sessions of LI4 approximately one week apart. One half of the participants received point injection first, and the other half received traditional acupuncture first. Baseline physiological data were recorded, then measurements were made before, during and after stimulation; each subject also reported needle sensation (de qi). The measures were heart rate, derived pressure rate product and mean arterial pressure.

Although stronger sensations of de qi were reported with point injection, no significant differences were found for mean heart rate (HR), pressure rate product (PRP) and mean arterial pressure (MAP) before and after stimulation by the two techniques. No subject gender or age bias was encountered and previous exposure to acupuncture had no effect on outcome. Power spectral analysis of heart rate variability (HRV) made on data from a small subset (n=10) of this cohort also showed no significant differences in autonomic response.

Point injection and traditional acupuncture seem to provoke similar physiological responses, although the greater needle sensation seen with point injection might indicate it could have more powerful clinical effects. Further studies of repeated point injection are necessary to indicate whether this technique may provide a method of increased strength of point stimulation, as an alternative to traditional needling in acupuncture research.