The relationship among the depth of midazolam-induced sedation, plasma midazolam concentration and quantified electroencephalogram / 中华麻醉学杂志

ABSTRACT

Objective To investigate the relationship among the depth of midazolam induced sedation, the plasma midazolam concentration and quantified electroencephalogram(EEG) and determine the appropriate depth of sedation during regional anesthesia Methods Twenty adult ASA I II patients(male 7,female 13)scheduled for thyroid adenoma or cyst operation under cervical plexus blockade were studied The age ranged from 19 57 years [mean (46 4?9 5)yr] and weight from 40 83kg[mean (63 1?10 3)kg] Patients with liver or kidney disorders or habitually taking benzodiazepine were excluded The patients were premedicated with phenobarbital sodium 0 1g Dorsalis pedis artery was cannulated for blood sampling Besides blood pressure, heart rate and SpO 2, quantified EEG (BIS and 95%SEF) were continuously monitored and recorded Level of sedation was assessed using the modified observer's assessment of alertness/sedation (OAA/S) scale The BIS, 95%SEF and plasma midazolam concentration (Cm)were correlated with the OAA/S scores using nonparametric Spearman's rank correlation analysis Results As depth of sedation deepened from an OAA/S score of 4 to 1, BIS value decreased from 91 5?2 6 to 63 1?5 7, 95%SEF from 21 4?2 0 to 15 2?2 9 and plasma midazolam concentration increased from (120 8?55 2)ng/ml to (533 0?139 4)ng/ml BIS, 95%SEF and Cm were all well correlated with the OAA/S score The coefficients of correlation between BIS, 95%SEF, Cm and OAA/S score were 0 952,0 674 and -0 856 respectively Conclusions Cm, BIS and 95% SEF are all well correlated with the depth of midazolam induced sedation and can all be used to monitor the depth of midazolam induced sedation, but BIS is the best among them BIS value 75 82 and OAA/S score 2 3 are the most appropriate level of sedation during regional anesthesia