Efficacy and adverse effects of prophylactic antiemetics during patient-controlled analgesia therapy: A quantitative systematic review

Nausea and vomiting are frequent adverse effects of patient-controlled anal gesia (PCA) with opioids. To identify the optimal prophylactic antiemetic i ntervention in this setting, we performed a systematic search for randomize d trials (MEDLINE, EMBASE, Cochrane Library, reference lists, hand-searchin g, no language restriction) published up to May 1998 that compared prophyla ctic antiemetic interventions with placebo or no treatment in the postopera tive PCA-setting with opioids. Fourteen placebo-controlled trials (1117 pat ients) with different regimens of droperidol, ondansetron, hyoscine TTS, tr opisetron, metoclopramide, propofol, and promethazine were analyzed. One PC A was with tramadol, all others were with morphine. At 24 h, the cumulative incidence of nausea and vomiting without antiemetics was approximately 50% . Droperidol 0.017-0.17 mg/mg of morphine (0.5-11 mg/d droperidol) was stat istically significantly more effective than placebo without evidence of dos e-responsiveness; the number needed to treat to prevent nausea compared wit h placebo was 2.7 (95% confidence interval 1.8-5.2), and that to prevent vo miting was 3.1 (2.3-4.8). Compared with placebo, the incidence of minor adv erse effects with droperidol was increased with doses >4 mg/d. Implications : Of 100 patients treated with droperidol added in a patient-controlled ana lgesia pump with morphine, 30 who would have vomited or been nauseated had they not received droperidol will not suffer these effects. There is no evi dence of dose-responsiveness for efficacy with droperidol, but the risk of adverse effects is dose-dependent. There is a lack of evidence for other an tiemetics.