Intravenous Midazolam as More Effective Than Propofol for Preventing Pruritus After Intrathecal Sufentanil in Surgical Patients: A Randomized Blinded Trial

BACKGROUND: Pruritus is a troublesome side effect of intrathecal opioids. Midazolam can reinforce GABA-mediated inhibition of the medullary dorsal horn neurons, and thus theoretically has potential to suppress opioid-induced pruritus. OBJECTIVES: This prospective double-blinded randomized trial aimed at comparing the effects of propofol, midazolam, and a combination of the two on the prevention of pruritus induced by intrathecal sufentanil. METHODS: Eighty-four patients undergoing spinal anesthesia with 3 mL hyperbaric bupivacaine 0.5% and 5 μg sufentanil (1 mL) were randomly allocated to one of the three study groups: Group 1, who were administered 20 mg intravenous (IV) propofol bolus, then 50 μg/kg/min IV infusion; Group 2, who were administered 0.03 mg/kg IV midazolam bolus, then 0.02 mg/kg/h IV infusion; and Group 3, who were administered 10 mg IV propofol and 0.015 mg/kg IV midazolam bolus, then 25 μg/kg/min propofol and 0.01 mg/kg/h midazolam IV infusion. The incidence rates and severity of pruritus were assessed intraoperatively and postoperatively for 24 hours. RESULTS: The Ramsay Sedation Score was highest for the propofol group throughout the duration of the anesthetic process. Overall, 17 patients in the propofol group (60.7%), eight patients in the midazolam group (28.6%), and nine patients in the propofol-midazolam group (32.1%) developed pruritus (P = 0.027). Intraoperative pruritus was observed in seven patients in the propofol group (25%), two patients in the midazolam group (7.1%), and five patients in the midazolam-propofol group (17.9%) (P = 0.196). Postoperative pruritus developed in 12 patients in the propofol group (42.9%), six patients in the midazolam group (21.4%), and four patients in the midazolam-propofol group (14.3%) (P = 0.041). There was no significant difference between the groups with respect to the severity of pruritus (P > 0.05). CONCLUSIONS: This study showed that in comparison with propofol, the administration of 0.03 mg/kg IV midazolam bolus followed by 0.02 mg/kg/h could be more effective in the prevention of intrathecal sufentanil-induced pruritus without increasing sedation and other side effects.