Near-infrared monitoring reveals that acupuncture produces reversible local blood-flow changes, offering an objective way to assess needle stimulation.
Researchers developed hollow near-infrared spectroscopy probes that could measure tissue blood signals around an acupuncture point while a needle was inserted. They applied acupuncture at the Xuehai point in healthy volunteers and continuously monitored oxygenated haemoglobin, deoxygenated haemoglobin, and total blood volume before, during, and after needle stimulation.
Needle stimulation consistently increased deoxygenated haemoglobin and local blood volume, with signals returning to baseline after needle removal. These changes suggest local vessel widening and increased oxygen use, while an observed fainting episode showed a distinct pattern of increased deoxygenated haemoglobin alongside reduced oxygenated haemoglobin.
