To add or not to add? An empirical study on droperidol and intravenous patient-controlled analgesia.

Background: Droperidol is commonly added to intravenous patient-controlled analgesia (IVPCA) regimens as an antiemetic agent. Although some studies have demonstrated its safety and efficacy, it is not clear whether adding droperidol to IVPCA infusate without an extra loading dose can effectively reduce the incidence and severity of postoperative nausea and vomiting (PONV) in real-life clinical settings.

Methods: Patients receiving IVPCA in this retrospective survey were classified into two groups based on their IVPCA regimens. The droperidol group used morphine 1mg/mL with droperidol 50 μg/mL, and the non-droperidol group was given morphine 1 mg/mL alone. The incidence and severity of PONV were compared between the two groups during the 3-day course of IVPCA treatment using logistic regression and ordinal logistic regression. Propensity score methodology was applied to adjust for potential confounders.

Results: Among the 186 patients enrolled, 94 patients received IVPCA with droperidol, and 92 patients received a pure morphine solution. There was no significant difference in patient attributes between the two groups. On the 1st postoperative day, there was no significant difference in incidence or severity of PONV between the two groups. From the 2nd day onward, the patients in the droperidol group had significantly fewer and less severe episodes of PONV (relative risk 0.34 and 0.31, respectively). The overall effects of droperidol on PONV and its severity during the whole IVPCA course were also statistically significant, whether or not adjustment for propensity score was made. However, although a statistically significant decrease in nausea was observed in the droperidol group after the 1st day, no significant difference in the incidence of vomiting between the two groups was noted during the study.

Conclusion: A loading dose should be considered on the 1st postoperative day. Our study suggests just how beneficial droperidol can be to IVPCA users in practical clinical settings, showing that droperidol can reduce with some significance the amount and severity of nausea suffered by patients postoperatively, even if the frequency of patient vomiting remains unchanged.