RESUMO
BACKGROUND AND OBJECTIVES: This prospective, double-blind, randomized, placebo-controlled study was designed to determine the efficacy of dexmedetomidine compared with lidocaine in reducing the pain of propofol and rocuronium injection pain. METHODS: One hundred and fifty patients, scheduled for elective surgery with general anaesthesia, were divided into five groups: saline (Group 1), dexmedetomidine 0.25 microg kg(-1) (Group 2), lidocaine 0.5 mg kg(-1) (Group 3), dexmedetomidine 0.25 microg kg(-1) plus lidocaine 0.25 mg kg(-1) (Group 4) or dexmedetomidine 0.25 microg kg(-1) plus lidocaine 0.5 mg kg(-1) (Group 5) were administered at a rate of 0.5 mL s(-1) after tourniquet application. The occlusion was released after 1 min and 5 mL of propofol was injected over 20 s. Pain was evaluated by use of a 10-point verbal analogue scale. Then, the rest of the induction dose of propofol, 3 mL of saline bolus and 0.6 mg kg(-1) of rocuronium, was injected. The response to injection of rocuronium was assessed with a four-point scale (0-3). RESULTS: Groups 1 and 2 were found to have higher propofol injection pain scores than Groups 3, 4 and 5 (P < 0.05). When the study groups were compared according to the overall incidence of withdrawal movements due to rocuronium (1 response) in Groups 1, 2, 3, 4 and 5, they were different (86.7%, 60%, 36.7%, 50% and 40%, respectively) (P < 0.05). Except Group 1, there was no significant difference between the groups according to incidence of withdrawal movement after rocuronium injection (P = 0.325). CONCLUSIONS: Pretreatment with dexmedetomidine is not effective in reducing injection pain of propofol, but may attenuate the hand withdrawal associated to rocuronium, as lidocaine does.
