Reduction of postoperative nausea and vomiting with the combination of morphine and droperidol in patient-controlled analgesia

Purpose: To determine whether low doses of droperidol mixed with morphine in patient-controlled analgesia (PCA) would extend the duration of prophylaxis against postoperative nausea and vomiting. Methods: Healthy women having elective open-abdominal gynaecological surgery consented to this double-blind, placebo-controlled study. Subjects were randomized to receive placebo, or 1 mg droperidol before induction followed by droperidol 0.0 (bolus group), 0.02 (0.02 group), or 0.04 (0.04 group) mg . mg(-1) of PCA morphine. Study endpoints included severity of nausea, episodes of vomiting and rescue antiemetic doses, pain, and sedation and were assessed at 1, 2, 4, 8, 12, 16, 20 and 24 hr postoperatively. Results: Seventy-one subjects completed the study. The groups were similar in age, weight, surgical time, pain scores, and morphine used. The 0.04 group had lower mean visual analogue scale scores for nausea (P < 0.05 vs all other groups). The incidence of vomiting was lower in all treatment groups (P < 0.05 for all groups vs placebo). The 0.04 group had lower rescue antiemetic requirements than the bolus group (P < 0.03). Mean sedation scores were low in all groups but were increased with PCA droperidol (P < 0.02). Conclusion: Droperidol 1 mg before induction of anaesthesia reduces postoperative vomiting. The addition of droperidol 0.04 mg . mg(-1) of PCA morphine further reduces (i) severity of nausea and (ii) rescue antiemetic requirements postoperatively. No clinically significant side-effects were attributed to this regimen.