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).

The results also lend new insights into how long treatments should be for greatest effectiveness. "We conclude that the optimal duration for asynchronous electroacupuncture stimulation is 30 minutes," write Dr. Shu-Ming Wang and colleagues of Yale School of Medicine.

Electricity Applied to Acupuncture Raises Pain Thresholds

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.

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). Subjects receiving electroacupuncture for 30 minutes were able to tolerate significantly colder temperatures before sensing pain. Furthermore, the reduced pain response lasted for at least an hour after the end of electroacupuncture.

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.

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. However, Dr. 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 conclude.

About the IARS

The International Anesthesia Research Society is a nonpolitical, not-for-profit medical society founded in 1922 to encourage, stimulate, and fund ongoing anesthesia-related research and projects that will enhance and advance the anesthesiology specialty. The IARS has a worldwide membership of 15,000 physicians, physician residents, and others with doctoral degrees, as well as health professionals in anesthesia-related practice. In addition to publishing the monthly scientific journal Anesthesia & Analgesia, the IARS sponsors an annual clinical and scientific meeting, funds anesthesia-related research, and sponsors the SAFEKIDS research initiative in conjunction with the FDA.

Source: International Anesthesia Research Society