Does dexmedetomidine reduce the injection pain due to propofol and rocuronium?

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.