Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting

Abstract

Background: 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.

Conflict of interest statement

Anna Lee has no conflicts relating to this review. Simon KC Chan has no conflicts relating to this review. Lawrence TY Fan has no conflicts relating to this review.

Figures

1

Study flow diagram.

2

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.

3

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

4

Contour‐enhanced funnel plot of comparison: PC6 acupoint stimulation versus sham for nausea. Contour lines are at 1%, 5% and 10% levels of statistical significance.

5

Trial sequential analysis of 40 trials comparing PC6 acupoint stimulation versus sham (despite risk of bias) for postoperative nausea, with control event proportion of 46.8%, diversity of 71%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

6

Contour‐enhanced funnel plot of comparison: PC6 acupoint stimulation versus sham for vomiting. Contour lines are at 1%, 5% and 10% levels of statistical significance.

7

Trial sequential analysis of 45 trials comparing PC6 acupoint versus sham (despite risk of bias) for postoperative vomiting, with control event proportion of 32.9%, diversity of 74%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

8

Contour‐enhanced funnel plot of comparison: PC6 acupoint stimulation versus antiemetic for nausea. Contour lines are at 1%, 5% and 10% levels of statistical significance.

9

Trial sequential analysis of 14 trials of PC6 acupoint stimulation versus antiemetic (despite risk of bias) for postoperative nausea, with control event proportion of 25.0%, diversity of 40%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

10

Contour‐enhanced funnel plot of comparison: PC6 acupoint stimulation versus antiemetic for vomiting. Contour lines are at 1%, 5% and 10% levels of statistical significance.

11

Trial sequential analysis of 19 trials comparing PC6 acupoint stimulation versus antiemetic (despite risk of bias) for postoperative vomiting, with control event proportion of 14.7%, diversity of 0%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

12

Trial sequential analysis of 8 trials comparing PC6 acupoint and antiemetic versus antiemetic (despite risk of bias) for postoperative nausea, with control event proportion of 47.5%, diversity of 79%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

13

Trial sequential analysis of 9 trials comparing PC6 acupoint stimulation and antiemetic versus antiemetic (despite risk of bias) for postoperative vomiting, with control event proportion of 32.9%, diversity of 68%, α of 5%, power of 80%, and relative risk reduction of 30% (Apfel 2007).

1.1. Analysis

Comparison 1 Acupoint PC6 stimulation versus sham, Outcome 1 Nausea.

1.2. Analysis

Comparison 1 Acupoint PC6 stimulation versus sham, Outcome 2 Vomiting.

1.3. Analysis

Comparison 1 Acupoint PC6 stimulation versus sham, Outcome 3 Rescue antiemetics.

2.1. Analysis

Comparison 2 Acupoint PC6 stimulation versus antiemetic drug, Outcome 1 Nausea.

2.2. Analysis

Comparison 2 Acupoint PC6 stimulation versus antiemetic drug, Outcome 2 Vomiting.

2.3. Analysis

Comparison 2 Acupoint PC6 stimulation versus antiemetic drug, Outcome 3 Rescue antiemetic.

3.1. Analysis

Comparison 3 Acupoint PC6 stimulation and antiemetic combination vs antiemetic, Outcome 1 Nausea.

3.2. Analysis

Comparison 3 Acupoint PC6 stimulation and antiemetic combination vs antiemetic, Outcome 2 Vomiting.

3.3. Analysis

Comparison 3 Acupoint PC6 stimulation and antiemetic combination vs antiemetic, Outcome 3 Rescue antiemetic.