Comparison of intravenous patient-controlled analgesia with tramadol versus morphine after microvascular breast reconstruction

Tramadol is a weak centrally acting analgesic and it might provide efficaci ous postoperative pain relief with minimal sedative effects in the use of i ntravenous patient-controlled analgesia (PCA). Sixty women scheduled to und ergo microvascular breast reconstruction under standard general anaesthesia were enrolled in a study on the performance of patient-controlled analgesi a with tramadol or morphine with special emphasis on drug- and technique-re lated side-effects. Seven patients were re-operated within the same day, le aving 25 patients in the tramadol group and 28 in the morphine group for co mparison. When postoperative pain occurred, loading doses of either 10 mg t ramadol or 1 mg morphine intravenous increments were administered in a doub le-blind fashion until the pain control was judged to be satisfactory by th e patient. After that the patients received tramadol or morphine by a PCA a pparatus (lockout 5 min, tramadol 450 mu g kg(-1), morphine 45 mu g kg(-1) bolus). In addition, all patients received 500 mg paracetamol rectally, thr ee times a day. The potency ratio of tramadol to morphine was found to be b etween 8.5:1 (loading) and 11:1 (PCA). There was neither a significant diff erence between the groups in the overall satisfaction of the analgesic medi cation nor in the visual analogue and verbal rate scales for pain. Women in the tramadol group had more nausea and vomiting during the administration of loading doses (P < 0.05) and more patients in the tramadol group (7) tha n in the morphine group (3) (NS) wanted to discontinue the PCA therapy befo re the end of the study due to nausea. Sedation or blurred vision prevented the performance of the psychomotor tests in 22 and 32% of the tramadol and morphine patients, respectively. The remaining patients performed similarl y in the Digit Symbol Substitution Test. In women receiving intravenous PCA for analgesia after microvascular breast reconstruction tramadol and morph ine provided comparable postoperative analgesia with similar sedative effec ts. However, tramadol was associated with a disturbingly high incidence of nausea and vomiting.