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.