RESUMO
AIM: To investigate the efficacy of the Bispectral Index monitor (BIS) in monitoring patients receiving intravenous midazolam for dental treatment. BACKGROUND: The BIS monitor has been proposed as an objective form of monitoring the level of consciousness in patients undergoing sedation and anaesthesia. It analyses electroencephalogram wave forms and quantifies this information to produce a numerical value of 0-100. To assess its efficacy,this study investigates if BIS correlates with the Observer's Assessment of Alertness/Sedation scale (OAA/S). METHOD: 50 episodes of intravenous sedation using midazolam were provided for anxious adults. Sedation proceeded in the standard manner but with the addition of BIS monitoring and assessment of the depth of sedation using the OAA/S scoring system.The operator was blinded to the BIS monitor. Information from the BIS monitor and corresponding OAA/S scores were recorded at 5-minute intervals and at clinically significant points, and correlation was tested using Spearman's Rank test.The effect of electromyographic interference (EMG) on the BIS reading was also investigated. RESULTS: A strong positive correlation was found between BIS and OAA/S.The mean range of BIS values recorded during sedation was 81+8.The BIS value was found to be most accurate at the end point of sedation. CONCLUSION: BIS monitoring may be a useful adjunct in monitoring patients receiving sedation for dental treatment using midazolam.