Comparison of anterograde amnesia produced by midazolam, propofol and dexmedetomidine when used to supplement sedation during neuraxial anesthesia

Objective To compare the anterograde amnesia produced by midazolam, propofol and dexmedetomidine when used to supplement sedation during neuraxial anesthesia. Methods Sixty patients of both sexes, aged 18-50 yr, with body mass index of 23-26 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective operation on lower limbs with neuraxial anesthesia, were divided into 3 groups(n=20 each)using a random number table: midazolam group(group M), propofol group(group P)and dexmedetomidine group(group D). When the height of anesthesia was kept below T10, midazolam in a loading dose of 0.05 mg/kg was intravenously injected in group M, propofol in a loading dose of 0.4 mg/kg was intravenously injected in group P, and dexmedetomidine in a loading dose of 0.6 μg/kg was intravenously injected in group D. The infusion rate of the 3 drugs was adjusted to maintain bispectral index value at 82-86.When Observer′s Assessment of Alertness/Sedation Scale scores achieved 3 or 4 after administration, anterograde amnesia was measured by postoperative recall of cards.The development of intraoperative hypotension, bradycardia and respiratory depression was recorded. Results Compared with group M, the incidence of global amnesia was significantly decreased in P and D groups(P 0.05). No patients developed hypotension, bradycardia or respiratory depression in three groups. Conclusion Midazolam produces better anterograde amnesia than propofol and dexmedetomidine when used to supplement sedation during neuraxial anesthesia. Key words: Midazolam; Propofol; Dexmedetomidine; Amnesia, anterograde