Abstract: AIM: To study the effect of tramadol on restlessness in recovery period of general anesthesia and its dose-response and time-effect relationship. METHODS: 138 adult patients (ASA Ⅰ-Ⅲ) following abdominal surgery with isoflurane-balanced anesthesia were divided into 5 groups (a double-blind randomized study); control-group (n =34), T1 and T2 group (tramadol given 1 and 2 mg·kg ^-1, respectively, at the thirtieth minute before the end of operation, n =26), and T3 and T4 group (tramadol 1 and 2 mg·kg ^-1, respectively, at the end of operation, n =26).Some indices were observed including the changes of respiration and circulation, the conscious state with Robertson' s conscious scores and pain with Prince-Henry score, and the incidence and degree of adverse reaction. RESULTS: In comparison with control-group, the respiration and circulation were steady (P <0.05) in T1 and T2, with lower Prince-Henry score (P <0.01) and light restlessness, but that were not difference in T3 and T4.The time of extubation was not difference between each other, but consciousness level in the groups administered tramadol were lower than that in control group, and the lowest level existed at the end of operation in groups administered tramadol. CONCLUSION: Intravenous tramadol 1~2mg·kg ^-1 can effectively inhibit restlessness in recovery period of general anesthesia, but its effect is related to the time administered tramadol.

Key words: pharmacodynamics, intravenous-inhalation anesthesia, recovery period, tramadol, complication, dose-response relationship, time-effective relationship