[Conscious sedation and amnesic effect of intravenous low-dose midazolam prior to spinal anesthesia].

Background: The pain associated with spinal puncture is severe, and the memory of this uncomfortable procedure often deters patients from undergoing the procedure again. Therefore, it is important to make the patient as comfortable as possible when this procedure is performed.

Methods: We administrated a low-dose (1-2.5 mg) of midazolam intravenously several minutes before conducting a spinal-tap in 200 patients undergoing elective surgery of the lower limb. The dose of midazolam used was based on the patient's age and weight, and we investigated remaining of a memory concerning the spinal-tap procedure and side effects of midazolam at the end of surgery.

Results: Memory of the spinal-tap procedure remained in 14.0%, 1.9%, and 32.7% of the patients who had received benzodiazepine preoperatively and in 25.0%, 40.0%, and 60.9% of the patients who hadn't received benzodiazepine preoperatively in the age group <60, 60-70, and > or =70 years, respectively. No patient experienced severe respiratory depression, but an excessive sedation or restlessness was experienced in 1.6%, 4.8%, and 5.2% of the patients.

Conclusions: In the patients aged <70 years, intravenous administration of 0.023-0.044 mg x kg(-1) of midazolam was very effective in preventing a bad memory concerning the spinal-tap procedure; however, it is important to note that the number of side effects associated with this procedure increases in patients aged > or =60 years.