Transdermal scopolamine for prevention of postoperative nausea and vomiting. No clinically relevant result in spite of reduced postoperative vomiting in general surgical and gynecologic patients

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In a prospective double-blind trial, transdermal scopolamine (TS) was compared to placebo (P) in the prevention of postoperative nausea and vomiting (PONV) within a 48-h interval. After stratification for gender and surgical procedure, patients were randomly chosen to receive either TS or placebo. Of 304 surgical and gynaecological patients included in this study, the data of 263 patients were evaluated (48 thyroidectomies, 15 open, and 36 laparoscopic cholecystectomies, 41 open, and 36 laparoscopic hernia repairs, 37 hysterectomies, and 50 gynaecological laparoscopies). The two groups were comparable with regard to biometrical data and duration of anaesthesia and surgery. Although anaesthesia was not standardized, there was no difference in anaesthesia techniques, drug dosage or perioperative management. Patients were evaluated once preoperatively and 2, 6, 10, 24, and 48 h postoperatively using a 100-mm visual analogue scale (VAS) for "nausea", "pain", "dry mouth", "sedation", and "blurred vision". Episodes of vomiting or retching and the need for additional antimetics (0.03 mg.kg-1 metoclopramide i.v., followed by 1 mg.kg-1 dimenhydrinat i.v., if necessary) were recorded. TS significantly reduced the incidence of postoperative vomiting within the first 48 h postoperatively [TS: 47 patients (36.2%) with 125 cumulative episodes vs P: 70 patients (52.6%) with 209 cumulative episodes]. Analysing the five observation intervals seperately, this difference could only be demonstrated 0-2 h and 6-10 h postoperatively. In patients suffering from emetic sequelae, TS did not reduce the frequency of vomiting significantly (mean frequency: TS: 2.7 vs P: 3.0). TS also had no significant effect on the requirement of additional antiemetics [TS:. 81 times in 46 (35.7%) patients vs P: 116 times in 58 (44.3%) patients]. Nausea as rated by the VAS was not significantly different between the two groups at any time during the postoperative observation. No relevant side-effects occurred, although there was a trend toward higher ratings of "dry mouth" in the TS group, reaching statistical significance 10 h after operation. The routine administration of TS for gynaecological and surgical patients cannot be recommended because of the lack of effect on postoperative nausea and only marginal benefit concerning postoperative vomiting.