Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting: Cochrane systematic review
Assessed as up to date: 2014/12/31
Postoperative nausea and vomiting (PONV) are common complications following surgery and anaesthesia. Antiemetic drugs are only partially effective in preventing PONV. An alternative approach is to stimulate the PC6 acupoint on the wrist. This is an update of a Cochrane review first published in 2004, updated in 2009 and now in 2015.Objectives
To determine the effectiveness and safety of PC6 acupoint stimulation with or without antiemetic drug versus sham or antiemetic drug for the prevention of PONV in people undergoing surgery.Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 12, 2014), MEDLINE (January 2008 to December 2014), EMBASE (January 2008 to December 2014), ISI Web of Science (January 2008 to December 2014), World Health Organization Clinical Trials Registry, ClinicalTrials.gov, and reference lists of articles to identify additional studies. We applied no language restrictions.Selection criteria
All randomized trials of techniques that stimulated the PC6 acupoint compared with sham treatment or drug therapy, or combined PC6 acupoint and drug therapy compared to drug therapy, for the prevention of PONV. Interventions used in these trials included acupuncture, electro-acupuncture, transcutaneous electrical acupoint stimulation, transcutaneous nerve stimulation, laser stimulation, capsicum plaster, acu-stimulation device, and acupressure in people undergoing surgery. Primary outcomes were the incidences of nausea and vomiting after surgery. Secondary outcomes were the need for rescue antiemetic therapy and adverse effects.Data collection and analysis
Two review authors independently extracted the data and assessed the risk of bias domains for each trial. We used a random-effects model and reported risk ratio (RR) with associated 95% confidence interval (95% CI). We used trial sequential analyses to help provide information on when we had reached firm evidence in cumulative meta-analyses of the primary outcomes, based on a 30% risk ratio reduction in PONV.Main results
We included 59 trials involving 7667 participants. We rated two trials at low risk of bias in all domains (selection, attrition, reporting, blinding and other). We rated 25 trials at high risk in one or more risk-of-bias domains. Compared with sham treatment, PC6 acupoint stimulation significantly reduced the incidence of nausea (RR 0.68, 95% CI 0.60 to 0.77; 40 trials, 4742 participants), vomiting (RR 0.60, 95% CI 0.51 to 0.71; 45 trials, 5147 participants) and the need for rescue antiemetics (RR 0.64, 95% CI 0.55 to 0.73; 39 trials, 4622 participants). As heterogeneity among trials was substantial and there were study limitations, we rated the quality of evidence as low. Using trial sequential analysis, the required information size and boundary for benefit were reached for both primary outcomes.
PC6 acupoint stimulation was compared with six different types of antiemetic drugs (metoclopramide, cyclizine, prochlorperazine, droperidol. ondansetron and dexamethasone). There was no difference between PC6 acupoint stimulation and antiemetic drugs in the incidence of nausea (RR 0.91, 95% CI 0.75 to 1.10; 14 trials, 1332 participants), vomiting (RR 0.93, 95% CI 0.74 to 1.17; 19 trials, 1708 participants), or the need for rescue antiemetics (RR 0.87, 95% CI 0.65 to 1.16; 9 trials, 895 participants). We rated the quality of evidence as moderate, due to the study limitations. Using trial sequential analyses, the futility boundary was crossed before the required information size was surpassed for both primary outcomes.
Compared to antiemetic drugs, the combination of PC6 acupoint stimulation and antiemetic therapy reduced the incidence of vomiting (RR 0.56, 95% CI 0.35 to 0.91; 9 trials, 687 participants) but not nausea (RR 0.79, 95% CI 0.55 to 1.13; 8 trials, 642 participants). We rated the quality of evidence as very low, due to substantial heterogeneity among trials, study limitations and imprecision. Using trial sequential analysis, none of the boundaries for benefit, harm or futility were crossed for PONV. The need for rescue antiemetic was lower in the combination PC6 acupoint stimulation and antiemetic group than the antiemetic group (RR 0.61, 95% CI 0.44 to 0.86; 5 trials, 419 participants).
The side effects associated with PC6 acupoint stimulation were minor, transient and self-limiting (e.g. skin irritation, blistering, redness and pain) in 14 trials. Publication bias was not apparent in the contour-enhanced funnel plots.Authors' conclusions
There is low-quality evidence supporting the use of PC6 acupoint stimulation over sham. Compared to the last update in 2009, no further sham comparison trials are needed. We found that there is moderate-quality evidence showing no difference between PC6 acupoint stimulation and antiemetic drugs to prevent PONV. Further PC6 acupoint stimulation versus antiemetic trials are futile in showing a significant difference, which is a new finding in this update. There is inconclusive evidence supporting the use of a combined strategy of PC6 acupoint stimulation and antiemetic drug over drug prophylaxis, and further high-quality trials are needed.
Lee Anna, Chan Simon KC, Fan Lawrence TY
Wrist PC6 acupuncture point stimulation to prevent nausea and vomiting after surgery
Does a review of the evidence support the use of wrist PC6 acupuncture point stimulation (PC6 acupoint) as effective in reducing nausea and vomiting after surgery (PONV), compared to sham (dummy acupoint stimulation) or antiemetics (drugs that relieve nausea and vomiting) in people undergoing surgery? This review updates the evidence published in 2009, and is current to December 2014.
Nausea and vomiting are two of the most common complications (up to 80%) after anaesthesia and surgery. Antiemetics are only partially effective and may cause adverse effects, like sedation and headache. Stimulating a PC6 acupoint, an alternative method, has been reported to reduce PONV with few serious side effects.
We found 59 relevant studies, conducted between 1986 and 2015, involving 7667 participants undergoing elective surgery. Seven of the trials were conducted in 727 children. The PC6 acupoint stimulation varied from invasive techniques, such as traditional acupuncture needles, to noninvasive techniques, such as acupressure wristbands. PC6 acupoint stimulation was compared with six different types of antiemetic drugs (metoclopramide, cyclizine, prochlorperazine, droperidol. ondansetron and dexamethasone).
Key findings and quality of evidence
Effects of PC6 acupoint stimulation versus sham on PONV
We found a moderate-size effect in children and adults, although there were concerns about study limitations and unexplained variation in the effects. Further studies with sham comparisons are not necessary to confirm this beneficial effect.
Effects of PC6 acupoint stimulation versus antiemetic on PONV
We found no difference in the incidence of PONV. We rated the quality of this evidence as moderate, due to study limitations. Further studies are unlikely to show a difference.
Effects of combining PC6 acupoint stimulation and antiemetic versus antiemetic on PONV
We found a moderate-size effect on postoperative vomiting but not on postoperative nausea. However, there were concerns about study limitations, unexplained variation in effects between studies, and an insufficient number of studies. Further high-quality research on combinations of PC6 acupoint stimulation and antiemetics are needed to reduce uncertainties about this effect on PONV.
Overall, the side effects related to PC6 acupoint stimulation were minor, transient and self-limiting (e.g. skin irritation, blistering, redness and pain) in 14 studies.
To prevent PONV, the effect of PC6 acupoint stimulation is comparable to antiemetics.
Implications for practice
Given that adverse effects associated with PC6 acupoint stimulation are minor and transient, the number needed to treat for an additional beneficial (NNTB) outcome (Additonal Estimated NNTB for preventing PONV (PC6 acupoint stimulation versus sham)) suggests that P6 acupoint stimulation is worthwhile when the baseline risk of PONV is high (i.e. above 60% as defined by Gan 2014). For example, the NNTB (95% CI) is 5 (4 to 7) for nausea and 4 (3 to 6) for vomiting at baseline risk of 60%. PC6 acupoint stimulation may be considered as an alternative to antiemetics in people in whom exposure is undesirable, for example, pregnant or breast-feeding women, and those with contraindications to antiemetics (Streitberger 2011). We do not have sufficient evidence to determine the effects of multimodal PC6 acupoint stimulation and antiemetic on the prevention of PONV.
Implications for research
The results of the trial sequential analyses suggest that no further PC6 acupoint stimulation versus sham trials are needed, and that further PC6 acupoint stimulation versus antiemetic trials would be futile in showing a significant difference. There is a need for high-quality trials to examine whether combinations of PC acupoint stimulation and antiemetic interventions (that is, multimodal prophylaxis) works better than each component alone and whether they interact. An ongoing trial (Lv 2013) may provide more insight into the comparative effectiveness of combining ondansetron and acupuncture against ondansetron and transcutaneous electrical nerve stimulation of PC6 acupoint. More importantly, future trials should include more clinically relevant outcomes, such as quality of recovery, to draw meaningful conclusions.Get full text at The Cochrane Library
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