Acupuncture for Prevention of Postoperative Nausea and Vomiting (PONV)

Postoperative nausea and vomiting (PONV) is encountered in 20-30% of patients undergoing surgery. PONV is a costly medical condition in financial and emotional aspects by causing serious complications like elongation of hospital stay, postoperative bleeding, aspiration pneumonia and electrolyte imbalances. In high risk individuals and operations, it can be encountered in up to 80% of patients. The risk factors for PONV development in adults are female gender, previous PONV and/or motion sickness, non-smoking and younger age. Additionally, it has been reported that some surgery types, especially, laparoscopic cholecystectomy and gynecologic surgeries along with the anesthetic agent, the duration of anesthesia and postoperative opioid use also have direct effects on PONV development.

According to the 4th consensus guidelines for the management of PONV updated in 2020, in patients with one or more risk factors, a multimodal prophylaxis using a combination of at least 2 of the following methods; 5-HT3 receptor antagonists, corticosteroids, anti-histaminics, dopamine antagonists, propofol anesthesia, NK-1 receptor antagonists, anti-cholinergics and acupuncture.

Following the declaration of acupuncture as an effective treatment option for PONV in 1999 NIH Consensus Conference, studies about this topic gained speed and many high quality randomized controlled clinic studies were performed. In one of the most comprehensive reviews published in 2015, it is stated that stimulation of P6 acupuncture point remarkably reduce the risk of PONV development, significantly decrease the amount of postoperative anti-emetic requirement, provide similar PONV prophylaxis with different pharmacoprophylactic agents (metoclopramide, cyclizine, prochlorperazine, droperidol, ondansetron and dexamethasone) and have similar post-operative anti-emetic requirement with pharmacologic agents. In the same Cochrane analysis, it is clearly stated that studies enrolling groups of sham acupuncture for P6 are redundant and would not go any further than duplicating the available well-established information. In this aspect, the proposed study design is comparison between treatment groups.

PONV has a multifactorial ethology. It has been postulated that it occurs as a result of activation of emetic center in the brain stem by stimulation of various peripheral receptors as well as central receptors including the chemoreceptor trigger zone in the postrema region. Following activation, the response of emetic center for anti-emetic agents is rather weak and consequently this complicates PONV treatment. Acupuncture is a kind of periphery sensory stimulus and has modulatory effects on the emetic center in the brain stem via neuronal pathways. This neural modulation is thought to be the result of communication between cerebellum and insula. As a result of these mechanisms of action, performing acupuncture before the induction of anesthesia provides more effective PONV prophylaxis.

Pharmacologic anti-emetic agents increase treatment costs as well as bear some adverse effects. The clinical condition created by PONV and increasing dissatisfaction due to the adverse effects of the pharmacologic agents urge both patients and clinicians pursuing non-pharmacologic modalities with proven efficiency, like acupuncture.

Therefore, it is essential to develop a standard, simple, effective prophylaxis protocol with high patient compliance and without ad verse effects, especially in patients with high risk for PONV. In the literature various different technique and materials were used for acupuncture stimulation. Unfortunately, a standard is not present for the metal of the needle, the length of the needle, the depth of immersion, the technique of stimulation and in most of the studies these features are not specified at all. Meanwhile, although P6 is the most studied point for PONV, there are encouraging evidence that some other points, like ST36 or LI4, might be incorporated into the PONV protocol. ST36 have potential effects in balancing gastrointestinal motility by modulating gastric motility via vagovagal and sympathetic reflex arches. Moreover, P6 in combination with ST36 has been successful in treatment of hiccups, recently.