Poster Presentation: Bispectral Index (BIS) Does Timing of Commencement of Monitoring Impact the BIS Score Related to Muscle Relaxant Administration-Bispectral Index (BIS) Does Timing of Commencement of Monitoring Impact the BIS Score Related to Muscle Relaxant Administration

Bispectral Index (BIS) Does Timing of Commencement of Monitoring Impact the BIS Score Related to Muscle Relaxant Administration

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The 2024 Mayo Foundation study investigates whether the timing of initiating bispectral index (BIS) monitoring relative to paralytic administration impacts BIS values. BIS monitors are FDA-approved devices used to measure anesthesia depth by analyzing brain activity. Notably, patients who were awake but paralyzed exhibited significant BIS value drops after neuromuscular blocking agent (NMBA) administration, suggesting BIS integrates electromyography (EMG) data into its readings.<br /><br />The study involved 22 patients undergoing elective cardiac surgery, where BIS monitors were placed pre- and post-induction. Key measures included BIS values, signal quality index (SQI), EMG, EEG suppression ratios, and asymmetry, recorded manually every 15 seconds during the study's 25-minute window.<br /><br />Results indicated minimal bias between BIS readings taken before and after paralytic administration; a Bland-Altman plot revealed an average difference of -0.32 between BIS values, showing no significant statistical difference. Linear mixed model analysis for BIS and EMG values supported these findings, with p-values of 0.142 and 0.49, respectively.<br /><br />The study concluded that the timing of BIS monitor initiation relative to NMBA administration does not significantly influence BIS scores, hence, it is unnecessary to start BIS monitoring before muscle relaxant administration. Such findings are relevant given concerns that EMG activity might interfere with BIS readings, potentially indicating deeper anesthesia than present.<br /><br />The study faced limitations, including the risk of manual data entry errors and biases due to convenience sampling. Moreover, variations in induction agents reflect real-world practice settings but could affect results' generalizability.<br /><br />In essence, the study validates the reliability of BIS monitoring independent of NMBA administration timing, simplifying protocols for anesthesia depth monitoring.

Keywords

Mayo Foundation study

2024

bispectral index

BIS monitoring

paralytic administration

neuromuscular blocking agent

elective cardiac surgery

anesthesia depth

EMG data

study limitations