Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting: a network meta-analysis

RATIONALE: Postoperative nausea and vomiting (PONV) are common complications following surgery and anaesthesia. Antiemetic drugs are only partially effective in preventing PONV. Stimulating the PC6 acupoint(s) on the wrist offers an alternative approach, but the effectiveness of the various common techniques is unclear. OBJECTIVES: To update and compare the effects and safety of PC6 acupoint stimulation with or without antiemetic drug(s) versus sham or antiemetic drug(s) for preventing postoperative nausea (PON) and postoperative vomiting (POV) in people undergoing surgery, and to identify the most effective techniques using network meta-analyses (NMAs). SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, ISI Web of Science, CINAHL, WHO Global Index Medicus, major trial registries, and reference lists of articles for studies up to 6 June 2025, with no language restrictions. ELIGIBILITY CRITERIA: receptor antagonists, corticosteroids, and antihistamines. The sham group included sham PC6 interventions and/or placebo saline antiemetic interventions. OUTCOMES: Critical outcomes: incidence of PON and POV. Important outcomes: need for rescue antiemetic therapy when prophylaxis failed and adverse events (side effects). RISK OF BIAS: We assessed the risk of bias in the included studies using RoB 1. SYNTHESIS METHODS: We performed frequentist NMAs using random-effects models to report risk ratios (RRs) with 95% confidence intervals (95% CIs). We compared the relative effects (with sham as reference) of six broad classes of PC6 acupoint stimulation techniques and their combined use with antiemetic drugs on the outcomes. We summarised the safety data narratively due to heterogeneous reporting of adverse events (side effects). We assessed the certainty of evidence of the NMA treatment effect on outcomes according to the CINeMA and GRADE approaches. INCLUDED STUDIES: This update included 77 trials, conducted between 1986 and 2022, involving 9847 participants. The majority were adults across several countries (USA, South Korea, India, China, Turkey, and Iran). There were 58 (33.9%) sham groups, 16 (9.4%) invasive PC6 acupoint stimulation groups, 50 (29.3%) noninvasive PC6 acupoint stimulation groups, 32 (18.7%) antiemetic(s) groups, 4 (2.3%) combined invasive PC6 acupoint stimulation and antiemetic(s) groups, 10 (5.8%) combined noninvasive PC6 acupoint stimulation and antiemetic(s) groups, and one (0.6%) combined invasive and noninvasive PC6 acupoint stimulation group for the NMAs. The high risk of bias was primarily due to selective reporting. SYNTHESIS OF RESULTS: Postoperative nausea The evidence from the NMA (63 studies; 7534 participants) suggests that the combined invasive PC6 and antiemetics technique probably results in a larger reduction in PON than sham (RR 0.21, 95% CI 0.10 to 0.45; moderate confidence from indirect evidence only). The evidence also suggests that invasive PC6, noninvasive PC6, and antiemetic(s) may reduce PON, compared to sham (invasive PC6: RR 0.49, 95% CI 0.38 to 0.64, low confidence; noninvasive PC6: RR 0.67, 95% CI 0.58 to 0.76, low confidence; antiemetic(s): RR 0.73, 95% CI 0.59 to 0.91, very low confidence). The combined use of noninvasive PC6 and antiemetic(s) may reduce PON, compared to sham, based on indirect evidence (RR 0.65, 95% CI 0.45 to 0.96; low confidence). Postoperative vomiting The evidence from the NMA (75 studies; 8627 participants) suggests that the combined invasive PC6 and antiemetics technique may result in a moderate reduction in POV, compared to sham (RR 0.37, 95% CI 0.18 to 0.76; low confidence from indirect evidence only). The evidence also suggests that invasive PC6, noninvasive PC6, antiemetic(s), and combined noninvasive PC6 and antiemetic(s) may reduce POV, compared to sham (invasive PC6: RR 0.47, 95% CI 0.34 to 0.64, low confidence; noninvasive PC6: RR 0.58, 95% CI 0.49 to 0.70, low confidence; antiemetic(s): RR 0.62, 95% CI 0.47 to 0.81, very low confidence; combined noninvasive PC6 and antiemetic(s): RR 0.52, 95% CI 0.33 to 0.83, very low confidence). The combined use of noninvasive PC6 and invasive PC6 may result in little to no difference in POV, compared to sham, based on direct evidence (RR 1.02, 95% CI 0.43 to 2.44; low confidence). Need for rescue antiemetic drug(s) The evidence from the NMA (55 studies; 6614 participants) suggests that combined use of noninvasive PC6 and antiemetic(s) probably reduces the need for rescue antiemetic drug(s) when prophylactic techniques fail, compared to sham (RR 0.44, 95% CI 0.28 to 0.70; moderate confidence from indirect evidence). Antiemetic(s), noninvasive PC6, and invasive PC6 may reduce the need for rescue antiemetics, compared to sham (antiemetic(s): RR 0.56, 95% CI 0.40 to 0.80, very low confidence; noninvasive PC6: RR 0.60, 95% CI 0.51 to 0.70, low confidence; invasive PC6: RR 0.61, 95% CI 0.44 to 0.84, low confidence). The combined use of invasive PC6 and antiemetic(s) (RR 0.31, 95% CI 0.04 to 2.49; low confidence from indirect evidence only) and the combined use of noninvasive PC6 and invasive PC6 may result in little or no difference in the need for rescue antiemetic drug(s), compared to sham (RR 1.41, 95% CI 0.64 to 3.09; low confidence from direct evidence only). Adverse events (side effects) None of the included studies reported serious or long-term complications. Thirty-nine studies, involving 5334 participants, reported minor side effects that go away (e.g. skin irritation, redness, and swelling) with PC6 acupoint stimulation, but the evidence is very uncertain. Publication bias was not apparent in the NMA funnel plots. AUTHORS' CONCLUSIONS: NMAs suggest that both invasive and noninvasive PC6 acupoint stimulation combined with antiemetics may reduce PON and POV, compared to sham, and likely lower rescue antiemetic use. PC6 acupoint stimulation may cause minor side effects, but the evidence is very uncertain. FUNDING: This updated Cochrane review was partially funded by the Cochrane Complementary Medicine Field Bursary 2020 from the National Center for Complementary and Alternative Medicine, National Institutes of Health (Grant Number R24 AT001293). REGISTRATION: Protocol (2001): doi.org/10.1002/14651858.CD003281 Original review (2004): doi.org/10.1002/14651858.CD003281.pub2 Update review (2009): doi.org/10.1002/14651858.CD003281.pub3 Update review (2015): doi.org/10.1002/14651858.CD003281.pub4.