Objective To compare the suppressive effects of tramadol and low-dose ketamine on postoperative hyperalgesia af- ter remifentanil-based anaesthesia.Methods Atotal number of sixty ASAⅠ~Ⅱadult patients who undergone the operation of cranio-cervical regionwere assigned to three groups randomly,controlled group(Group C), tramadol group(GroupT) and low-dose ketamine group(Group K). Before the end of surgery, Group T was given tramadol 0·3 mg/kg, Group K was given ketamine 0·5 mg/kg and Group C wasn′t given any medicine. When the visual analogue scale (VAS) score of the group C was over five, tramadol 0.3 mg/kg was given to the patients. The four-level verbal rating scale after trachea extubation, VAS score, the time of requiring analgesia again by patients and adverse drug reactions such as nausea, vomit, diplopia and hallucination were recorded for 24 hours after surgery.Results After operation, the VAS score of Group Cwas much higher than that of Group K in the first 4 hours and Group Twas higher than Group K during 2, 3 and 4 hours (P
