Efficacy of Nei-Guan (P6) Acupoint stimulation in reducing postoperative nausea and vomiting

Ofelia Loani Elvir Lazo^1*, Alicia Romero-Navarro, Paul F. White², Vincent Lee³, Sana Zubair⁴, Hillenn Cruz Eng⁵, Roya Yumul^1,6

¹Department of Anesthesiology, Cedars-Sinai Medical Center, Los Angeles, CA, USA

²White Mountain Institute, The Sea Ranch, CA, USA (a not-for-profit private foundation)

³Nova Southeastern University Dr. Kiran C. Patel College of Osteopathic medicine

⁴Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia 

⁵Department of Anesthesiology, Adena Health System, Chillicothe, OH, USA

⁶David Geffen School of Medicine-UCLA, Charles R, Drew University of Medicine and Science, Los Angeles, CA, USA

^*Corresponding Author: Ofelia Loani Elvir Lazo, Department of Anesthesiology, Cedars-Sinai Medical Center, Los Angeles, CA, USA

Received: 21 May 2025; Accepted: 04 June 2025; Published: 24 July 2025

Introduction

Postoperative nausea and vomiting (PONV) remain a significant challenge despite many recent advances in antiemetic medications. Consequently, non-pharmacological approaches like Nei-Guan P6 (pericardium point 6) acupoint stimulation have gained increased attention in clinical practice. While P6 acupressure, a traditional Chinese medicine technique involving physical pressure applied at the P6 acupoint on the medial side of the wrist rather than via needles, has shown promise for PONV prevention with minimal side effects [1]. Acupressure has been used in traditional Chinese medicine for over 3,000 years, applies the same principles as acupuncture but relies on physical touch rather than needle insertion. Studies suggest that the effects of P6 acupressure are comparable to those of P6 acupuncture, with various forms such as finger pressure, wristbands with a plastic sphere (Sea-Band), or transcutaneous electro-stimulation yielding similar outcomes [2]. P6 stimulation, alleged to influence energy flow (qi or bioenergy) via meridians, may exert its antiemetic effect by modulating neurotransmitter release (e.g., endorphins, serotonin) within the central nervous system (CNS) [3].

The proposed mechanism of action of acupoint stimulation is related to the release of β-endorphin from the hypothalamus into the cerebrospinal fluid, while modulating serotonin transmission through serotonergic and norepinephrinergic pathways. Signal transduction occurs via Aβ and Aδ afferent sensory fibers, which transmit impulses to the spinal dorsal horn. Given the antiemetic properties of β-endorphins, this neurobiological basis supports the potential efficacy of P6 stimulation [4]. Among the 365 classical acupoints, P6 is specifically targeted to alleviate nausea and vomiting by enhancing qi flow through various methods, including transcutaneous acupoint electrical stimulation (TAES) with Reliefband (Neurowave Medical, Chicago, IL), P6 acupoint injections, a combination of acupuncture and acupressure, acu-stimulation with devices such as Sea-Band (Sea-Band, Newport, RI) or Acuband (Acuband, Inc, Little Silver, NJ), and simply physical or electrical acupressure. Acupressure wristbands, available in elastic and other designs with a protruding plastic button or electrical stimulation, offer a noninvasive and cost-effective solution with minimal adverse effects [5].

PONV is a complication after surgery that affects 20% to 40% of all surgical patients, with incidence rates rising to 80% in women undergoing high-risk surgical procedures (e.g., laparoscopic surgery) [6]. The mechanism of acupressure in PONV management involves the stimulation of afferent nerve fibers, which transmit impulses to the spinal cord, triggering endorphin release and blocking signals from the chemoreceptor trigger zone (CTZ). Additionally, impulses to the periaqueductal gray area in the midbrain stimulate the release of enkephalins, which modulate serotonin and norepinephrine levels in the spinal cord. Furthermore, acustimulation promotes the secretion of β-endorphins and adrenocorticotropic hormone from the pituitary gland into the bloodstream and cerebrospinal fluid. These processes restore energy flow and help regulate upper gastrointestinal function, thereby reducing PONV symptoms when used either alone or in combination with antiemetic medications [7].

Laparoscpic procedures

In laparoscopic surgery, alternative therapies targeting the P6 acupoint, including pressure, electroacupuncture (EA), TAES, and capsicum plaster, have shown varying efficacy in reducing PONV. Agarwal et al. [8] and Sadighha et al. [9] found that acupressure at the P6 point, applied 30 minutes before induction and removed 6 hours postoperatively, significantly reduced PONV and the need for rescue medication in laparoscopic cholecystectomy patients. These findings were comparable to standard antiemetic treatments [8,9]. White et al. [10] reported that using a Pressure Right device applied at the P6 acupoint, as part of a multimodal antiemetic strategy, significantly decreased the incidence of vomiting. Similarly, Harmon et al. [11] demonstrated that applying Sea-Bands immediately before induction of anesthesia reduced PONV from 42% to 19% in a placebo-controlled double-blind study. However, subsequent studies by Samad et al. [12] and Yilmaz et al. [13] found no significant benefit to acupoint stimulation, and Naik et al. [14] reported that the antiemetic drug palonosetron was more effective.

EA has shown significant benefits perioperatively. Arnberger et al. [15] and Lee et al. [16] observed reduced PONV incidence in patients receiving EA compared to a control group. Ho et al.17 found electroacupuncture to be as effective as prochlorperazine in preventing emesis, whereas TEAS was less effective. Sharma et al. [18] demonstrated that P6 acupuncture is comparable to ondansetron in preventing PONV following laparoscopic cholecystectomy. The importance of timing has been highlighted by Zárate et al. [19] Khan et al. [20] and Liu et al. [21] who demonstrated that electroacupuncture significantly reduces the incidence of PONV when applied either preoperatively or intraoperatively. The effect of timing was demonstrated after comparing patient outcomes based on the initiation point of stimulation; these studies consistently found that earlier or continuous application of electroacupuncture, beginning prior to anesthesia induction or maintained throughout surgery, was associated with greater reductions in PONV compared to delayed or no stimulation [19-21]. However, some studies [22-25] found that while TEAS reduced nausea, it did not significantly affect vomiting, and other studies reported only transient antiemetic effects [22-25]. Capsicum plaster at P6 demonstrated some efficacy by reducing nausea but not vomiting or the need for antiemetic drugs [26].

Pediatric

The effectiveness of P6 acupoint stimulation in managing PONV among pediatric patients is influenced by the procedure, timing, and targeted symptoms. Shin et al.27 found acupuncture at P6 to be cost-effective in preventing emesis after pediatric tonsillectomy compared to antiemetic therapy. Liodden et al.28-29 observed that acupuncture followed by Sea-Band acupressure reduced retching and vomiting in younger children undergoing pediatric tonsillectomy or adenoidectomy, though a placebo-controlled study by the same group also reported no significant benefit. In pediatric hernia repair, circumcision, and orchidopexy, Butkovic et al.30 noted that preoperative laser acupuncture reduced vomiting in the early postoperative period, though long-term benefits were not observed. Wang et al.31 demonstrated P6 acupuncture’s efficacy in reducing nausea and vomiting in the PACU after strabismus surgery, but later in the recovery process PONV rates remained unchanged. TEAS showed comparable efficacy to ondansetron in tonsillectomy with fewer side effects and higher parental satisfaction.32 Conversely, Schwager et al.33 found that TEAS was ineffective in reducing vomiting during circumcision or herniotomy/orchidopexy.

Acupressure results are mixed, with Pouy et al.34 finding that acupressure applied by a finger at P6 alleviated PONV after tonsillectomy. In contrast, Lewis et al.35 reported no benefit from Sea-Band wristbands in preventing PONV after strabismus surgery. Rusy et al.36 reported that while electroacupuncture reduced nausea, it did not impact vomiting or the need for antiemetics following tonsillectomy.

General surgery

P6 acupoint stimulation techniques have been investigated for their potential to reduce PONV after general surgery. For instance, Barsoum et al. [37] reported reduced nausea severity with bilateral P6 acupressure bands, though the reduction in vomiting was not statistically significant. Hofman et al. [38] and Fan et al. [39] observed reduced PONV intensity and incidence in high-risk and short-stay surgery patients, respectively, with timing playing a crucial role. A study [40] found that P6 acupressure is as effective as ondansetron and metoclopramide in preventing PONV after strabismus surgery. Electroacupuncture [41] and TEAS [42-45] significantly reduced PONV in middle ear, thyroidectomy, plastic, and laparoscopic surgeries, with improved outcomes when combined with pharmacologic antiemetic treatments [41-45]. Capsicum plaster at P6 was effective in reducing PONV severity and antiemetic use, showing comparable results to ondansetron after thyroid and middle ear surgeries [46].

Systematic reviews and meta-analyses further support the efficacy of P6-based therapies [47-49] Stoicea et al. [4] and Cheong et al. [48] reported significant reductions in early PONV symptoms and enhanced recovery, while Lee et al. [49] confirmed effectiveness in reducing nausea, vomiting, and rescue antiemetic needs, comparable to antiemetic drugs. However, some studies found no significant benefit in some surgical procedures, such as Agarwal et al. [50] who observed no effect in patients undergoing endoscopic urological procedures, and Ferrara-Love et al. [51] in patients undergoing orthopedic and general procedures during the early postoperative period.

Neurosurgery

P6 acupoint stimulation in neurosurgical patients undergoing craniotomy, yielded mixed results. Acupressure using Sea-Bands at P6 did not significantly reduce PONV in randomized controlled trials [52-54]. In contrast, TEAS at P6 demonstrated greater efficacy. Xu et al. found a significant reduction in the 24-hour cumulative PONV incidence in infratentorial craniotomy patients when TEAS was used in combination with antiemetic drugs, though rescue antiemetic use remained similar [55]. Wang et al. observed a reduced PONV prevalence with TEAS at the right P6 acupoint combined with ondansetron in supratentorial craniotomy patients [56]. Additionally, Tu et al. reported that TEAS reduced vomiting during the initial 2-6 hour postoperative period and provided pain relief in the 6-24 hour period, highlighting its broader benefits [57].

Cardiovascular

The effectiveness of P6 acupoint stimulation in cardiac surgery and related conditions remains uncertain. Klein et al [58] found that bilateral acupressure wristbands at P6 did not significantly reduce PONV incidence or affect pain scores, analgesic use, or antiemetic needs in a randomized, double-blind trial involving 152 adults undergoing cardiac surgery. A subgroup analysis suggested a possible, though statistically insignificant, benefit in female patients [58].

Dental

The effectiveness of P6 acupoint therapies in dental procedures varies. Somri et al. [59] demonstrated that bilateral P6 acupuncture combined with ondansetron significantly reduced postoperative emetic episodes after discharge in pediatric dental patients under general anesthesia, though it provided no significant benefit in the immediate post-anesthesia care unit (PACU). Zotelli et al. [60] reported that unilateral P6 acupuncture significantly reduced nausea during maxillary impression-taking, as measured by the Gagging Severity Index/Gagging Prevention Index (GSI/GPI), compared to a sham group. The gag reflex and nausea & vomiting are closely linked through shared neural pathways and physiological mechanisms, although they are distinct responses. Another study by Eachempati et al. yielded inconclusive results on acupuncture's effectiveness in managing the gag reflex during dental treatment [61].

Breast surgery

P6-targeted therapies show varying effectiveness in managing PONV following breast surgery. Gan et al. [62] demonstrated that bilateral electro-acupoint stimulation significantly reduced nausea at two hours post-surgery, with trends toward reduced vomiting and pain after major breast procedures. Said et al. [63] reported that Sea-Band acupressure significantly reduced chemotherapy-induced nausea, vomiting episodes, and antiemetic use in breast cancer patients. TEAS also showed promise, with Zhang et al. [64] reporting improved recovery times and reduced postoperative pain in ambulatory breast surgery. Kim et al. [65] also found significantly reduced nausea but not vomiting after minor breast procedures. However, acupuncture results were inconsistent. Streitberger et al. [66] found no significant reduction in overall PONV incidence or rescue antiemetic use, though vomiting was decreased. Fujii Y. [67] noted acupuncture's enhanced effectiveness when combined with pharmacological treatments such as anti-serotonin drugs and dexamethasone.

Cesarean section

P6 acupoint stimulation demonstrates mixed results in cesarean sections. Direkvand-Moghadam et al. [68] and Harmon et al. [69] reported acupressure effects comparable to intravenous metoclopramide when applied before spinal anesthesia and maintained for 6 hours. El-Deeb et al. [70] found that electrical acupoint stimulation at P6 effectively reduced nausea and vomiting during surgery and the early postoperative period. Ahn et al. [71] highlighted Korean hand acupressure, including P6, as beneficial in reducing opioid-induced emetic symptoms and pain. Similarly, Wani et al. [72] found it more effective than ondansetron in managing drug-induced nausea and vomiting during cesarean sections. However, TEAS yielded inconclusive results, as Habib et al. [73] reported no significant reduction in PONV after preoperative TEAS. Other studies [74-77] found limited or no significant benefits of P6 acupressure or acupuncture; however, some improvements in the management of emetic symptoms were noted in patients with a history of PONV and following epidural morphine [74-77].

Gynecological surgery

P6 acupoint interventions exhibit varying effectiveness in reducing PONV after gynecological surgical procedures. Acupressure studies, such as those by Alkaissi et al.78 and Turgut et al. [79] reported significant reductions in PONV and antiemetic use, particularly with bilateral Sea-Bands or wristbands worn during and after surgery. Reliefbands also reduced nausea severity and antiemetic needs when used perioperatively [80-82]. However, some studies [83,84] found no significant reduction in emetic symptoms after hysterectomy surgery.

Acupuncture has shown promise, with Albooghobeish et al. [85] reporting superior efficacy over metoclopramide for nausea reduction after laparoscopy. Dundee et al. [86,87] also observed significant reductions in PONV after minor gynecological surgeries. While preoperative electroacupuncture improved recovery and reduced pain, its effects on PONV were inconsistent [88]. Conversely, some studies reported no significant benefits of acupuncture or electroacupuncture after hysterectomy procedures [89,90].

TEAS has demonstrated beneficial effects in managing PONV by reducing vomiting and antiemetic use [91-93]. Oh and Kim [94] identified greater efficacy of TENS-based relief bands compared to simple acupressure wristbands. El-Bandrawy et al. [95] reported TEAS to be superior to acupressure and standard antiemetics in hysterectomy patients. Additionally, simple subcutaneous injections with glucose or droperidol at the P6 acupoint significantly reduced nausea and vomiting, performing comparably or better than antiemetic drugs alone [96,97].

Pregnancy

Studies of P6 acupoint therapy for pregnancy-related nausea and vomiting have yielded mixed results. Habek et al. [98] reported a 90% success rate with acupuncture compared to 64% with acupressure, while Shin et al. [99] found acupressure significantly reduced nausea and vomiting. Norheim et al. [100] and Werntoft et al. [101] also observed a notable decrease in the duration of emetic symptoms and sustained relief with acupressure wristbands compared to placebo.  

Jamigorn et al. [102] reported comparable efficacy between P6 acupressure and vitamin B6 for the relief of nausea and vomiting in early pregnancy.  However, Saberi et al. [103] found ginger to be more effective for mild-to-moderate pregnancy-related nausea. Conversely, reviews by Matthews et al. [104,105] and Boelig et al. [106] indicated insufficient evidence to support acupuncture's superiority over placebo. Heazell et al. [107] reported no significant impact of P6 acupressure on unexpected hospitalizations, and Sinha et al. [108] found acupressure wristbands ineffective in reducing labor-induced nausea and vomiting.

Oncological surgery

Research on P6 acupressure for PONV in oncological surgery patients suggests limited benefits compared to standard antiemetic drug therapy. Hsiung et al. [109] found that while acupressure at P6 and ST36 acupoints reduced postoperative pain and accelerated gastrointestinal recovery in gastric cancer patients undergoing subtotal gastrectomy, it did not significantly decrease the incidence of PONV. These findings suggest that although acupressure can facilitate postoperative recovery, its beneficial role in PONV management remains inconclusive in this surgical population.

Miscellaneous non-surgical related nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV)

P6 acupoint interventions, including acupuncture and acupressure, have demonstrated varying effectiveness in managing nausea and vomiting across diverse conditions like CINV. Despite advancements in antiemetic therapies, chemotherapy-induced nausea and vomiting (CINV) remains a significant challenge, with nausea significantly affecting patients' quality of life. Studies report significant benefits of P6 acupressure in reducing CINV. For example, Taspinar et al. [110] and Genç et al. [111] found that acupressure significantly reduced nausea, vomiting, and anxiety in gynecologic and breast cancer patients, with sustained improvements post-chemotherapy. Suh et al. [112] also reported enhanced efficacy when acupressure was combined with counseling for delayed CINV in breast cancer patients. Acupressure bands have also shown benefits in radiation therapy and leukemia, reporting reduced nausea and vomiting compared to standard antiemetics [113,114]. However, some studies [115,116] reported no significant differences in nausea, vomiting, or quality of life between active and sham acupressure bands in breast cancer patients. Additionally, studies in pediatric oncology and radiotherapy patients showed no advantage of P6 acupoint stimulation over placebo [117,118].

Complementing these findings, acupuncture has also demonstrated effectiveness, particularly in delaying CINV. Rithirangsriroj et al. [119] found P6 acupuncture to be more effective than ondansetron in preventing delayed emesis in gynecologic cancer patients. Li et al. [120] further confirmed reductions in nausea and vomiting severity, along with improved nutritional status, with acupuncture over sham treatments. Capodice et al. [121] and Wang et al. [122] highlighted acupuncture's safety and efficacy as a complementary treatment for chemotherapy-related emetic symptoms.

Others

Zhang et al. [123] reported that combining acupuncture with standard care significantly reduced nausea scores and improved patient satisfaction in an emergency department. Similarly, Chang et al. [124] found that acupuncture combined with relaxation therapy effectively alleviated nausea in human immunodeficiency virus (HIV) patients undergoing highly active antiretroviral therapy (HAART). Acupressure using Sea-Bands has also shown benefits in reducing nausea in patients with acute vertigo [125]. The application of Sea-Bands at the onset of an acute migraine attack was observed to significantly reduce nausea intensity in patients [126]. These findings are not surprising, as acupressure needs to be used prophylactically.

The efficacy of P6 acupoint stimulation for postoperative nausea and vomiting (PONV), and nausea and vomiting secondary to other therapies or diseases is shown in table 1.

Table 1: Clinical studies characteristics on the efficacy of P6 acupoint stimulation for postoperative nausea and vomiting (PONV), and nausea and vomiting secondary to other therapies or diseases.

Alternative acupoint for preventing nausea and vomiting: auricular acupoint stimulation

Shin et al. [127] found that auricular acupressure significantly reduced nausea and retching in 50 colorectal cancer patients receiving chemotherapy after surgery. The experimental group showed significantly lower nausea (p = 0.011) and retching (p = 0.014) compared to the control group, with significant interaction effects between time and group on the total Index of Nausea, Vomiting, and Retching (INVR) score (F = 8.23, p < 0.001).127 Eghbali et al.128 found that auricular acupressure significantly (p = 0.001) reduced chemotherapy-induced nausea and vomiting in 48 breast cancer patients. The comparison was made between standard medications and auricular acupressure for five days versus standard medications.

Conclusion

Stimulation of the P6 acupoint (Nei-Guan) can be an effective non-pharmacologic alternative for managing nausea and vomiting in various clinical settings, including postoperative care, pregnancy-related symptoms, and chemotherapy-induced nausea. Despite the advancements in antiemetic drug therapies, none have proven universally effective and are often accompanied by other adverse effects. In contrast, P6 stimulation via various methods such as acupressure, electroacupuncture, transcutaneous acupoint electrical stimulation (TAES), and even capsicum plaster offers a noninvasive, cost-effective, and well-tolerated approach to preventing emetic symptoms. However, the evidence remains mixed and sometimes contradictory when it comes to treating active emetic symptoms. The variability in outcomes may be attributable to differences in the type of procedure, the timing and method of P6 stimulation, as well as patient-specific factors. Overall, P6 acupoint stimulation is a very well-tolerated and cost-effective therapeutic approach to managing emetic symptoms; further standardized research is needed to better define the situations where it is most efficacious and to establish optimal treatment protocols. Stimulation of other acupoints (e.g., auricular acupoint stimulation) may also be effective alternatives to P6 acupoint stimulation for managing emetic symptoms.

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