Short-Time Effects of Laser Needle Stimulation on the Peripheral Microcirculation Assessed by Laser Doppler Spectroscopy and Near-Infrared Spectroscopy

Abstract

The aim of the present study was to evaluate immediate effects of a standardized laser needle stimulation over a defined acupuncture point on the microvascular blood flow and muscle oxygenation in the human forearm. Recently, it has been shown that laser stimulation improves tissue perfusion. This is relevant since adequate blood supply is an important factor in the treatment of pain syndromes. The study was designed as a randomized, double-blinded, placebo-controlled trial. Thirty-three healthy non-smoking males were randomly assigned to a control group (n = 15) with no laser irradiation and to an intervention group (n = 18) for which laser needle irradiation was performed on the right forearm at acupuncture point Pe6. Non-invasive blood flow measurements (laser Doppler spectroscopy [LDS]) were performed before, during, and after intervention. Additionally, the dynamic changes in muscle oxygenation of the m. flexor carpi ulnaris were investigated using near-infrared spectroscopy (NIRS). Repeated measures MANOVA demonstrated a statistically significant interaction between time and group (p = 0.034, effect size = 0.39), indicating that peripheral blood flow was influenced by laser needle application. In contrast, tissue oxygenation was not affected by the experimental treatment. It has been demonstrated that laser needle stimulation may improve peripheral microcirculation under standardized conditions, whereas tissue oxygenation remained unchanged. Further research is required to determine the influence of various parameter settings and irradiation treatments on the peripheral microcirculation. Moreover, different acupuncture points should be investigated in order to appraise the clinical effectiveness of laserneedle stimulation.