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Non-pharmacological techniques prevent postoperative nausea and vomiting


The P6 acupuncture point lies about four centimetres up the arm from the wrist creases. Stimulation of this point is claimed to reduces nausea and vomiting effectively. A systematic review [1] comes to the conclusion that stimulation of the P6 point is indeed effective in preventing postoperative nausea and vomiting in adults, but not in children.

Search


There was an extensive search for randomised trials, including electronic databases and a specialist acupuncture database. To be included trials had to have a non-pharmacological technique that stimulated the P6 point to prevent postoperative nausea and vomiting. Trials that treated established nausea and vomiting were not addressed. There were 19 randomised studies with 1679 patients, of whom 739 were given P6 stimulation. Four studies were in children.

Outcomes


The outcomes were nausea, vomiting or nausea and vomiting. These were examined early (0-6 hours) and late (0-48 hours) after surgery. Adults and children were treated separately.

Results


Sham acupressure or no treatment were the predominant controls. Active treatments were manual rotation of needles, electrical stimulation of needles, semipermanent needles, transcutaneous electrical stimulation and acupressure. All activated the P6 acupuncture point.

For adults, P6 acupuncture point stimulation halved the incidence of early postoperative nausea and vomiting with numbers needed to treat of about 5 (Table, Figure). Five patients would require acupuncture point stimulation to prevent postoperative nausea and vomiting in one of them. One trial with 200 patients looked at nausea and/or vomiting over six hours, and this too had an NNT of about 5.

Table: Main results from meta-analysis of P6 acupuncture point stimulation compared with sham acupuncture for the prevention of postoperative nausea and vomiting

  Number of Incidence with  
Patients Patients without Time Patients Studies P6 stimulation (%) Placebo (%) NNT (95%CI)
Adults Nausea Early 421 7 17 38 4.8 (3.4 to 8.1)
  Vomiting Early 610 9 15 33 5.5 (4.0 to 8.8)
  Nausea Late 187 3 13 40 3.6 (2.5 to 6.5)
  Vomiting Late 290 4 18 27 no benefit
Children Vomiting Late 189 3 52 48 no benefit

Figure: Incidence of PONV symptoms with P6 stimulation and control


For adults, the incidence of late nausea was reduced by P6 acupressure stimulation, with an NNT of about 4. Though there was a reduction in the incidence of late vomiting by about 10%, this did not achieve statistical significance.

For children the only useful data was for the prevention of late vomiting. Here P6 acupuncture point stimulation was without effect. There was no evidence for early effects of P6 stimulation for children in two trials.

Comment


P6 acupuncture point stimulation was effective in preventing postoperative nausea and vomiting in adults though not in children. Bandolier has made one small change in the review, judging one study which had 0-8 hour outcomes as closer to early outcomes (0-6 hours) than late outcomes (0-24 hours). It made no significant change to the results. The interesting point is that the estimate of efficacy, with NNTs of about 5, is within the borders of a size of a clinical effect judged to be worthwhile. It is also interesting that in the same setting we have the evidence of efficacy favouring an alternative therapy over a much-used pharmacological therapy, metoclopramide at a dose of 10 mg.

Reference:

  1. A Lee, ML Done. The use of nonpharmacological techniques to prevent postoperative nausea and vomiting: a meta-analysis. Anesthesia and Analgesia 1999 88: 1362-9.
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