Metoclopramide decreases emesis but increases sedation in tramadol patient-controlled analgesia

To evaluate the clinical benefits and disadvantages of adding metoclopramide to tramadol for patient-controlled analgesia (PCA).Forty adult patients, undergoing elective arthroplasties, were recruited into this prospective, randomized, double-blind study. During general anesthesia all patients received 2.5 mg x kg(-1) of tramadol as a loading dose at the beginning of wound closure. In the postanesthesia care unit (PACU) patients were randomly allocated to receive PCA containing either 20 mg tramadol + 1 mg metoclopramide per millilitre (n = 20, Group T+M) or tramadol 20 mg per millilitre (n = 20, Group T). The PCA setup was 1 mL/bolus with a lockout interval of five minutes. A blinded investigator assessed the vital signs, visual analogue scale, and severity of postoperative nausea and/or vomiting in the PACU. The PCA demand and delivery, overall satisfaction rate and adverse effects were recorded in the PACU and on postoperative days one and two.Nausea/vomiting scores were more severe (1.7 +/- 1.0 vs 0.2 +/- 0.5, 2.3 +/- 1.2 vs 0.6 +/- 0.6, 1.9 +/- 0.9 vs 0.2 +/- 0.5, at 12 hr, 18 hr, 24 hr, respectively, P0.05) and more frequent (7/20 vs 1/20, 5/20 vs 0/20 for nausea and vomiting respectively, P0.05) on postoperative day one in Group T compared to Group T+M. However, the incidence of sedation was higher in Group T+M (7/20 vs 1/20, P0.05).The incidence and severity of nausea/vomiting decreased if metoclopramide was added to tramadol for PCA. An increased incidence of sedation was noticed with this drug combination.