Experiments in volunteers confirm that electroacupuncture applying electrical current to acupuncture needles has pain-reducing effects, reports a study in the September issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS), according to a statement released by the organization.

Shu-Ming Wang, MD, and colleagues of Yale School of Medicine, said in the statement that the results also lend new insights into how long treatments should be for greatest effectiveness. The researchers concluded that the optimal duration for asynchronous electroacupuncture stimulation is 30 minutes, said Wang in the statement.

In the technique of asynchronous electroacupuncture, a small electrical current is applied to needles inserted into acupuncture points, alternating between low- and high-frequency stimulation. Electroacupuncture is thought to provide pain-relieving benefits beyond those of traditional acupuncture—however, it has been unclear how long electrical stimulation should be applied to achieve the best pain response, according to the statement.

In the study, volunteers underwent needle placement at acupuncture sites in the lower leg. Cold was then applied, and the temperature at which the cold sensation turned into pain was compared for different durations of electroacupuncture up to 40 minutes.

Volunteers receiving electroacupuncture applied for 30 minutes experienced the least pain, compared to those receiving 20 or 40 minutes of electroacupuncture (or no electroacupuncture at all), says the statement. Subjects receiving electroacupuncture for 30 minutes were able to tolerate significantly colder temperatures before sensing pain. The reduced pain response lasted for at least an hour after the end of electroacupuncture, says the statement.

Acupuncture techniques, including electroacupuncture, have become widely used in clinical pain management. However, more research is needed to confirm the effectiveness of electroacupuncture and the best ways to take advantage of its analgesic effects, says the statement.

The new results suggest that 30 minutes is the optimal time for application of electroacupuncture: 20 minutes is not long enough, and 40 minutes is too long. Further study will be needed to explain why this is so, says the statement. Wang and colleagues point out that that the 30-minute duration is the same as in previous studies of other electrical nerve stimulation techniques, such as transcutaneous electrical nerve stimulation (TENS). The similarities suggest that the various types of nerve stimulation for pain control "may share a similar underlying mechanism," the researchers concludde.

IARS is a nonpolitical, not-for-profit medical society that  funds ongoing anesthesia-related research and projects.

[Source: IARS]