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With Comments from Russell H. Greenfield, MD
Acupuncture for PONV
Source: Gan TJ, et al. A randomized controlled comparison of electro-acupoint stimulation or ondansetron versus placebo for the prevention of postoperative nausea and vomiting. Anesth Analg 2004;99:1070-1075.
Goal: To determine whether electro-acupoint stimulation (EAS) is an effective alternative to ondansetron (OND) for postoperative nausea and vomiting (PONV) prophylaxis.
Design: Prospective, randomized, sham-controlled study.
Subjects: Seventy-seven patients having major breast surgery under general anesthesia (75 included in analysis).
Methods: Subjects were randomized to one of three groups: active EAS at acupoint P6 using pads (no needles), single dose OND 4 mg IV, or sham acupoint control (pads placed but no EAS). Those not receiving OND IV were given an equivalent volume of saline. EAS was applied 30-60 minutes before induction of anesthesia, and was continued throughout the procedure until the electrodes were removed just prior to waking the patient. Measurements included incidence of nausea and vomiting, use of rescue anti-emetics, postoperative pain, and patient satisfaction. Assessments were made at 0, 30, 60, 90, 120 minutes and at 24 hours (the latter by phone follow-up).
Results: Both EAS and OND use resulted in significantly more procedures not complicated by nausea or vomiting at all, as well as less need for rescue anti-emetics, than the sham control. Subjects who received EAS had a lesser incidence and severity of nausea, and less pain, than patients in the OND and control groups. Patients in the active treatment groups were more satisfied with the management of their PONV than those in the control group.
Conclusion: Both OND and EAS reduce PONV, but EAS appears to be slightly more effective than OND, and has the added benefit of an analgesic effect. Thus, EAS is a viable alternative to the use of OND.
Study strengths: Degree of blinding (a different postop nurse was even used for data collection); enrolled consecutive patients (no selection bias).
Study weaknesses: Complete blinding not possible while subjects were awake.
Of note: Subjects receiving OND fared significantly better than those in the control group, but less well compared to the EAS group; all subjects were told the electrical stimulation unit produces an electrical current they may or may not feel, and the screen of the unit was covered by tape to also blind clinicians and researchers; all patients received fentanyl and midazolam as premedication and the intraoperative anesthetic regimen was standardized; no difference between groups was identified with respect to adverse events or length of stay; a reusable acupoint stimulation unit with disposable electrodes costs about $200, while each administration of OND runs approximately $16; subjects who had previously experienced acupuncture were excluded from the trial, which was performed at Duke University Medical Center.
We knew that: PONV are the most common reasons for low patient satisfaction in the postoperative period; OND use is associated with headache, abdominal pain, and elevated liver function tests; acupuncture effects may be blocked by naloxone; low-frequency EAS (2-4 Hz) causes release of endorphins, while high-frequency stimulation (50-200 Hz) involves release of enkephalins; a 30% placebo response rate exists when assessing efficacy of anti-emetics; studies in which EAS is offered following induction of anesthesia show less effect on PONV.
Clinical import: Patient satisfaction surveys hold significant sway, as do cost-containment measures, so both practitioners and administrators are likely to be intrigued by the results of this trial. Although a number of papers have compared acupuncture to placebo for PONV, most showing benefits with acupuncture, many suffer from significant methodologic flaws. This well-done study, however, comparing EAS to a well-accepted pharmaceutical agent, creates a persuasive argument that members of the surgical team learn how to perform EAS.
What to do with this article: Make copies to hand out to your peers.