European Journal of Biomedical and Pharmaceutical Sciences

CONSCIOUS SEDATION WITH MIDAZOLAM AND PROPOFOL CONTROLLED BY AUDITORY EVOKED POTENTIALS INDEX DURING SPINAL ANESTHESIA

*Tomoki Nishiyama, MD, PhD 

ABSTRACT

The purpose was to arrive adequate doses of midazolam and propofol infusion for sedation during spinal anesthesia, and whether AAI could be an indicator of adequate sedation level. Thirty patients aged 30 to 70 years scheduled for spinal anesthesia were premedicated with midazolam 0.06 mg/kg and atropine 0.01 mg/kg intramuscularly 15 minutes before anesthesia. Spinal anesthesia was performed with 10 mg hyperbaric tetracaine. Midazolam 0.02 mg/kg was intravenously administered and propofol infusion was started at 2.5 mg/kg/h and stopped at the end of surgery. To keep auditory evoked potentials index (AAI) between 40 and 60, propofol infusion dose was up and down by 0.5 mg/kg/h every 5 minutes. The Observer’s assessment of alertness/sedation (OAAS) scale was checked every 10 minutes. The discrepancy was judged as AAI outside of 40 to 60 when OAAS scale was 3 or 4. Recovery time was measured as the time from the end of surgery to when OAAS scale became 5. AAI decreased below 40 in 10 minutes after start of sedation. The propofol infusion dose was 1.5 ± 0.75 mg/kg/h. In 180 points measured AAI and OAAS scale simultaneously, 12 points had discrepancy between them. Recovery time was 8.5 ± 2.6 minutes. In conclusion, during spinal anesthesia, after premedication with intramuscular midazolam 0.06 mg/kg, intravenous midazolam 0.02 mg/kg followed by propofol infusion at 1.5 mg/kg/h could provide rapid and adequate sedation. AAI might be useful to keep adequate sedation.

Keywords: Conscious sedation, midazolam, propofol, auditory evoked potentials index.