Acupuncture therapy on postoperative nausea and vomiting in abdominal operation: A Bayesian network meta-analysis

Postoperative nausea and vomiting, known as PONV, represent one of the most frequent complications in the postoperative period. Studies show that approximately 30% of patients experience these unpleasant symptoms, reaching 80% in high-risk cases. Although not life-threatening, these symptoms can lead to serious complications such as dehydration, electrolyte imbalance, and even esophageal rupture. Traditional medications, including antiemetics such as 5-HT3 receptor antagonists and corticosteroids, reduce only 20-25% of PONV risk when used individually, and even drug combinations do not exceed 60% efficacy.

In addition, these drugs have side effects such as drowsiness, headache, and cardiac changes, which has motivated researchers to seek safer alternative therapies, such as acupuncture.

The researchers conducted a network meta-analysis, a type of scientific study that allows simultaneous comparison of multiple treatments even when they have not been directly tested against one another. The main objective was to assess which form of acupuncture would be most effective in preventing nausea and vomiting in patients undergoing abdominal surgery. To this end, they searched five scientific databases, analyzing studies published through June 2019. Twenty randomized clinical trials involving 2,862 patients undergoing abdominal surgery under general anesthesia were included.

The studies evaluated different acupuncture techniques, including acupressure, electroacupuncture, transcutaneous electrical stimulation (TENS), acupoint injection, and capsaicin application. The quality of the studies was rigorously assessed using specific tools to identify possible methodological biases.

The results clearly demonstrated that acupuncture therapies were superior to placebo and usual care in preventing PONV. Compared with placebo, transcutaneous electrical stimulation significantly reduced the risk of nausea by 58%, vomiting by 47%, and the need for rescue medication by 39%. Capsaicin application proved even more effective, reducing the risk of nausea by an impressive 84% and vomiting by 77%. In the comparative analysis among all techniques, acupoint injection emerged as the most promising, showing the highest probability of being the best treatment for both nausea and vomiting individually.

The study also revealed that nausea seems to be more easily controlled than vomiting, suggesting that different neurological mechanisms may be involved. The most-used acupuncture points were PC-6 (located on the wrist) and ST-36 (located on the leg), which according to traditional Chinese medicine are specific for gastrointestinal problems.

For patients and health professionals, these results offer solid evidence that acupuncture can be a safe and effective alternative to traditional medications for PONV prevention. This is particularly relevant for patients who have contraindications to conventional antiemetics or who prefer to avoid their side effects. For physicians and nurses, the study suggests that techniques such as acupressure and transcutaneous electrical stimulation can be easily incorporated into perioperative care protocols. The possibility of combining acupuncture with conventional medications also appears promising, potentially providing superior protection with lower drug doses.

In addition, non-invasive techniques such as acupressure can be taught to patients themselves, allowing self-application when necessary.

However, the study has some important limitations that should be considered. First, the analysis focused only on the first 24 hours after surgery, not distinguishing between early and late nausea and vomiting, which limited more detailed analyses. Second, there is considerable variation among studies in terms of treatment duration, specific technique used, and selection of acupuncture points, making it difficult to determine the optimal protocol. Third, some types of acupuncture, especially acupoint injection, were evaluated in few studies, limiting the reliability of those findings.

Finally, methodological differences among studies may have influenced the results. Despite these limitations, this research represents a comprehensive and systematic analysis of the available evidence on acupuncture for PONV, offering valuable guidance for clinical practice and highlighting the need for high-quality future studies to confirm the most promising findings and establish standardized treatment protocols.