Effect of droperidol addition to fentanyl-based intravenous patient-controlled analgesia on postoperative nausea and vomiting: a single-center retrospective cohort study

To the editor,

Droperidol addition to morphine-based intravenous patient-controlled analgesia (ivPCA) decreased postoperative nausea and vomiting (PONV) in some studies [1,2,3,4]; however, the effect of droperidol addition to fentanyl-based ivPCA on PONV is unclear. The antiemetic effect of droperidol addition and its optimal dose may be different between morphine-based and fentanyl-based ivPCA, because fentanyl-based ivPCA, unlike morphine-based ivPCA, is often accompanied by baseline infusion. The only study which showed an association between droperidol addition to fentanyl-based ivPCA and decreased PONV did not include patients undergoing body cavity surgeries [5]. Because surgery type has been suggested to affect PONV risk [6], the antiemetic effect of droperidol addition to ivPCA might differ among surgery type. Therefore, we investigated the effect of droperidol addition to fentanyl-based ivPCA on the development of PONV in patients who underwent gynecologic laparoscopic surgery.

This single-center, retrospective study was approved by the ethics committee of Kyoto University Hospital (approval number R1272-3; January 23, 2020). Patients who underwent laparoscopic gynecological surgery (adnexal surgery and/or hysterectomy) under general anesthesia at Kyoto University Hospital between 2012 and 2018 and who received fentanyl-based ivPCA were included. The exposure of interest was droperidol addition to fentanyl-based ivPCA. We used a disposable patient-controlled anesthesia (PCA) device which delivers 1 ml bolus with a lockout interval of 10 min, combined with a baseline infusion of 1 ml/h. The primary outcome measure was the incidence of PONV, defined as the occurrence of at least one episode of nausea or vomiting during the 2-day postoperative period. We conducted a multivariable logistic regression analysis to assess the independent relationship between droperidol addition to ivPCA and PONV. We selected six potentially confounding variables (age, smoking history, duration of surgery, anesthetic method, intraoperative antiemetic use, and the concentration of fentanyl to be filled into the PCA device) based on clinical relevance and the available literature [6,7,8,9]. Two-sided P < 0.05 was considered to be statistically significant.

Among 588 study participants, droperidol was added to ivPCA in 350 patients (60%; Table 1). The median concentration of droperidol to be filled into ivPCA was 50 μg/mL (range 20–167 μg/mL). PONV occurred in 56% and 76% of patients with or without droperidol via ivPCA, respectively (P < 0.001). Multivariable logistic regression analysis revealed that droperidol addition to fentanyl-based ivPCA was independently associated with decreased PONV (adjusted odds ratio 0.383, 95% confidence interval 0.260–0.563, P < 0.001; Table 2). The extrapyramidal symptoms were present in 0.9% of the patients who received droperidol via ivPCA.

Table 1 Patient characteristics and operative variables according to droperidol use

Table 2 Multivariable logistic regression analysis assessing independent association between addition of droperidol to ivPCA and PONV

Our study included patients who underwent laparoscopic gynecological surgery, which was not included in the previous study [5] and still showed a significant association between droperidol administration via ivPCA and a reduction in PONV incidence. Based on the results of our study, the extrapyramidal symptoms are considered a rare problem in the patients who received droperidol via ivPCA. In conclusion, droperidol addition to fentanyl-based ivPCA may reduce PONV in patients who underwent laparoscopic gynecological surgery.