[A comparison of a tramadol/metamizole infusion with the combination tramadol infusion plus ibuprofen suppositories for postoperative pain management following hysterectomy].

Postoperative pain management is still a grossly neglected field. In most cases, antipyretic analgesics alone are insufficient during the early postoperative period. Powerful narcotics are often avoided or underdosed because they are associated with the risk of respiratory depression. Some authors recommend combined infusion of tramadol and metamizole, which is assumed to provide sufficient pain relief without the risk of respiratory depression. However, this regimen has not yet been investigated in a study that meets currently accepted scientific standards. METHODS. Sixty patients who underwent vaginal hysterectomy were included in a randomised, prospective double-blind study. Thirty women received two placebo suppositories immediately after induction of anaesthesia and a postoperative infusion of tramadol and metamizole (400 mg tramadol plus 5 g [= 10 ml] metamizole in 500 ml electrolyte solution). The 30 women of the control group received two ibuprofen suppositories (585.2 mg) preoperatively and a post-operative tramadol infusion (400 mg tramadol plus 10 ml placebo [NaCl 0.9%] in 500 mg electrolyte solution). The patients of both groups received 125 ml of the appropriate infusion solution as a loading dose over 10 min (corresponding to 1.25 mg metamizole and 100 mg tramadol in the metamizole/tramadol group or 100 mg tramadol in the ibuprofen/tramadol group) 10 min after awakening. The remaining solution was administered at an infusion rate of 12.5-25 ml/h (corresponding to 125-250 mg metamizole and 10-20 mg tramadol/h or 10-20 mg tramadol/h). On request or when complaining of stronger pain, the patients received an additional bolus infusion of 125 ml over 10 min. In case of insufficient pain reduction despite repeated infusion of 125-ml boli or consumption of the entire infusion solution, the patients discontinued the study and received demand-adapted intravenous titration of piritramide. Postoperative pain was evaluated on the visual analogue scale (VAS) and the 101-point numerical rating scale immediately before the start of the infusion. Pain evaluation was repeated 20, 30, 40, 60, 100, 120, and 240 min after awakening accompanied by registration of heart rate, respiratory rate, systolic and diastolic blood pressure, and side effects. RESULTS. About 60% of the entire infusion solution was administered within 60 min in both groups. Significant postoperative pain reduction in both groups and on both the 101-point scale and the VAS was observed only at 100, 120, and 240 min after awakening. In the tramadol/metamizole group, nausea occurred in 7 cases and vomiting in 1. Nine patients in this group additionally required intravenous piritramide because of insufficient pain relief. In the tramadol/ibuprofen group, 8 patients complained about nausea and 4 patients vomited. Six patients additionally received intravenous piritramide because of insufficient pain reduction. CONCLUSIONS. Satisfactory pain reduction occurred rather late despite high doses of both the tramadol/metamizole and the tramadol/ibuprofen. Both analgesic combination must be regarded as insufficient after inhalational anaesthesia because of the very slow onset of action and the high failure rate.