[Postoperative analgesia with tramadol and metamizol. Continual infusion versus patient controlled analgesia].

OBJECTIVE: The study compares the i.v. analgesia of tramadol and dipyrone delivered either as continuous infusion or as patient controlled analgesia (PCA).

METHODS: After approval by the local ethics committee and informed consent 203 patients recovering from abdominal surgery were randomly assigned to pain treatment either by PCA or continuous intravenous infusion. Both groups received the same analgesic drug combination of tramadol (20 mg/ml) and dipyrone (200 mg/ml). The PCA bolus was set to 1 ml, the continuous infusion varied between 0-8 ml/h according to individual needs. Demographic and surgery related data were compared between the treatment groups, as well as pain scores, analgesic consumption and response rates over a 48 hour study period.A patient was assessed as non responder when rescue medication was necessary during the study period or the patient rated analgesia as insufficient during the final interview.

RESULTS: In total,data of 191 patients (infusion-group: 94, PCA-group: 97) could be analyzed. Tramadol consumption was higher in the infusion group compared to the PCA-group (48 hours: 1009.4+/-494.4 vs. 813.0+/-585.3 mg;p<0.001) with no difference in pain scores. In the infusion group, significantly more interventions were necessary to adjust the infusion rate to individual needs (min-max: 1-15 vs. 0-2). The number of non responders amounted to 30 (31.9%) and 18 (18.6%;p=0.03) in the infusion and PCA group, respectively.

CONCLUSIONS: PCA with tramadol and dipyrone can be considered an alternative for postoperative pain management and provided a more individualized treatment approach with lower analgesic consumption and more responders compared to a continuous infusion.