Effects of combination of intrathecal lidocaine and two doses of intrathecal midazolam on post-operative pain in patients undergoing herniorrhaphy: a randomized controlled trial

Assessment of the effect of combination of intrathecal midazolam and lidocaine on postoperative pain was the aim of this study. This randomized controlled trial was performed during 2007 in a teaching hospital of Arak University of Medical Sciences. Forty five male patients who were candidates for elective inguinal herniorrhaphy entered the study and randomly divided into three groups of control (lidocaine 5% plus normal saline), M 0.5 (lidocaine 5% and midazolam 0.5 mg) and M 1.0 (lidocaine 5% and midazolam 1 mg) according intrathecal solution injected for spinal anesthesia. Mean arterial blood pressure, heart rate, post-operative pain, narcotic requirements and complications (nausea, vomiting, pruritic, headache, hypotension and bradycardia) were recorded. The severity of post-operative pain was lowest in M 1.0 group in all postoperative measurements except at 2 h after operation. With regard of complications, only there was significant difference in vomiting between three groups which had the highest frequency in M 0.5 group. No severe hypotension was seen; though, bradycardia occurred in one patient in M 0.5 group which needed treatment. Present findings suggest that administration of intrathecal midazolam (especially 1 mg) together with lidocaine is effective in reducing post-operative pain in patients undergoing open inguinal herniorrhaphy and is not associated with adverse effect.