Bispectral Index Alterations and Associations With Autonomic Changes During Hypnosis in Trauma Center Researchers: Formative Evaluation Study (Preprint)

Abstract

BACKGROUND Hypnosis was induced to enhance reductions in Bispectral Index™ (BIS) values. OBJECTIVE Autonomic monitoring was used to assess physiologic relaxation and explore their associations with BIS values. METHODS Each session consisted of reading a 4-minute baseline neutral script and playing an 18-minute hypnosis tape to 3 researchers involved in the BIS neurofeedback study. In addition to BIS monitoring, autonomic monitoring was performed and included measures of electromyography, skin temperature, skin conductance, respiratory rate, expired carbon dioxide, and heart rate variability. The t-test, correlation analyses, and multivariate linear regression analyses were used in data analysis. RESULTS Hypnosis was associated with reductions in BIS (P<.001), electromyography (P<.001), respiratory rate (P<.001), skin conductance (P=.006), and very low frequency power (P=.04) and with increases in expired carbon dioxide (P<.001), skin temperature (P=.04), high frequency power (P<.001), and successive heart interbeat interval difference (P=.04) values. Decreased BIS values were associated with reduced electromyography measures (R=.76; P<.001), respiratory rate (R=.35; P=.004), skin conductance (R=.57; P<.001), and low frequency power (R=.32; P=.01) and with increased high frequency power (R=-.53; P<.001), successive heart interbeat interval difference (R=-.32; P=.009), and standard deviation of heart interbeat interval (R=-.26; P=.04) values. CONCLUSIONS Hypnosis appeared to induce mental and physical relaxation, enhance parasympathetic neural activation, and attenuate sympathetic nervous system activity, changes that were associated with BIS values. Findings of the preliminary formative evaluation suggest that the current hypnosis model may be useful for assessing autonomic physiological associations with changes in BIS values, thus motivating us to proceed with a larger investigation in trauma center nurses and physicians. CLINICALTRIAL None