BACKGROUND: Rocuronium can cause pain on injection in awake patients. We compared the effect of ketamine at three different small doses (0.1 mg/kg, 0.2 mg/kg, 0.3 mg/kg) and saline (placebo) for reducing pain on injection in awake patients.

METHODS: 80 patients (aged 19-63 yr) scheduled for elective surgery were randomized to four groups in double-blind manner. Patients received the study drug intravenously, with venous occlusion for 20 seconds, followed by rocuronium 0.6 mg/kg into the dorsal vein over 10 seconds. Patient's response torocuronium injection was graded by four-point verbal rating scale.

RESULTS: The incidence of pain was significantly less in patients receiving ketamine 0.3 mg/kg (55%) than in patients receiving saline (85%)(P < 0.05). But, No difference was found between ketamine 0.1 mg/kg, 0.2 mg/kg and saline groups. The pain score was significantly less in patients receiving ketamine 0.2 mg/kg and 0.3 mg/kg than in patients receving saline (P < 0.05).

CONCLUSIONS: We concluded that pretreatment of ketamine 0.3 mg/kg with venous occlu-sion for 20 seconds, effectively decreases the incidence of pain caused by rocuronium injection.