The Correlation of Narcotrend Index and OAA/S Scale in Monitoring Sedation Level With Different Doses of Dexmedetomidine

60 patients,aged 20～60,American Society of Anesthesiologists (ASA) physical status ⅠorⅡ, scheduled for electively lower limb surgery undergoing combined spinal epidural anesthesia were randomly divided three group. In each group,a bolus of dexmedetomidine was administered intravenously 15 min after spinal anesthesia. The initial dose in group 1, group 2 and group 3 was started from 0.9 µg/kg,1.0 µg/kg and 1.1 µg/kg, respectively. HR、MAP、SpO2、the Observer's Assessment of Alertness/Sedation（OAA/S）scale and the corresponding Narcotrend index were recorded at 5-minute intervals until 30 minutes after administration. The relationship between OAA/S scale and Narcotrend index was analyzed by a Spearman analysis. The cutoff values of Narcotrend index for OAA/S≤2 were obtained by analysis of receiver operating characteristic curves(ROC).