Effects of Acupuncture on Gas Analysis of the Synovial Fluid

Abstract

Although acupuncture is considered to have normalizing effects on the physical metabolism in addition to analgesic action, the precise mechanisms of its action are still uncertain, it is also widely applied to treatment of arthralgia.
In this study, effects of acupuncture on 18 patients with knee osteo-arthritis (OA) were examined using gas analysis of the synovial fluid. Acupuncture needles were inserted into the “Zusanli” (F₆ 9) and “Xuehai” (F₁ 10) of the involved side and electrical stimulation with square wave pulses at 1Hz was applied through the needles for 30min. Two ml of synovial fluid was sampled from the knee joint using a heparinized syringe before and after the acupuncture, and partial pressures of CO₂ (PCO₂) and O₂ (PO₂) as well as pH of the samples were measured immediately by a gas analyzer, ABL30 (Radiometer, Copenhagen). Base excess (BE), total CO₂ density (TCO₂) and bicarbonate density (HCO₃) were calculated from these values using the equation of Siggaard-Andersen.
After the acupuncture, a significant (p<0.05) elevation of PO₂ in synovial fluid was observed, but no significant change was observed in PCO₂, pH, BE, TCO₂, and HCO₃. A significant (p<0.05) negative correlation was seen between the elevation of PO₂ and lowering of PCO₂ (r=0.4682). These results suggest that acupuncture may increase the local blood flow around the joint and thus may stimulate the metabolism and replacement of gas in synovial fluid. From the above, it is suggested that acupuncture is useful for treating arthralgia such as osteo-arthritis.