OBJECTIVETo compare the suppressive effects of tramadol and low-dose ketamine on postoperative hyperalgesia after remifentanil-based anaesthesia.

METHODSA total number of sixty ASA I - II adult patients who undergone the operation of cranio-cervical region were assigned to three groups randomly, controlled group (Group C), tramadol group (Group T) 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.

RESULTSAfter operation, the VAS score of Group C was much higher than that of Group K in the first 4 hours and Group T was higher than Group K during 2, 3 and 4 hours (P < 0.05). The time of requiring analgesia by patients in Group C and Group T was earlier than Group K. The adverse drug reaction showed no significant difference in three groups.

CONCLUSIONLow-dose ketamine had significant suppressive effect on patients with postoperative hyperalgesia and acute opioid tolerance after remifentanil-based anaesthesia.