Systematic review and meta‐analysis of the correlation between bispectral index (BIS) and clinical sedation scales: Toward defining the role of BIS in critically ill patients

Abstract

Introduction:The bispectral index (BIS) is an attractive approach for monitoring level of consciousness in critically ill patients, particularly during paralysis, when commonly used sedation scales cannot be used.Objectives: As a first step toward establishing the utility of BIS during paralysis, this review examines the strength of correlation between BIS and clinical sedation scales in a broad population of non-paralyzed, critically ill adults. Methods:We included studies evaluating the strength of correlation between concurrent assessments of BIS and Richmond Agitation Sedation Scale (RASS), Ramsay Sedation Scale (RSS), or Sedation Agitation Scale (SAS) in critically ill adult patients.Studies involving assessment of depth sedation periperative or procedural time periods, and those reporting BIS and sedation scale assessments conducted >5 min apart or while neuromuscular blocking agents (NMBA) were administered, were excluded.Data were abstracted on sedation scale, correlation coefficients, setting, patient characteristics, and BIS assessment characteristics that could impact the quality of the studies.Results: Twenty-four studies which enrolled 1235 patients met inclusion criteria. The correlation between BIS and RASS, RSS, and SAS overall was 0.68 (95% confidence interval, 0.61-0.74, Ƭ 2 = 0.06 I 2 = 71.26%). Subgroup analysis by sedation scale indicated that the correlation between BIS and RASS, RSS, and SAS were 0.66 (95% confidence interval 0.58-0.73, Ƭ 2 = 0.01 I 2 = 30.20%), 0.76 (95% confidence interval 0.69-0.82, Ƭ 2 = 0.04 I 2 = 67.15%), and 0.53 (95% confidence interval 0.42-0.63, Ƭ 2 = 0.01 I 2 = 26.59%), respectively. Factors associated with significant heterogeneity included comparator clinical sedation scale, neurologic injury, and the type of intensive care unit (ICU) population.Conclusions: BIS demonstrated moderate to strong correlation with clinical sedation scales in adult ICU patients, providing preliminary evidence for the validity of BIS as a measure of sedation intensity when clinical scales cannot be used. Future studies should determine whether BIS monitoring is safe and effective in improving outcomes in patients receiving NMBA treatment.

Survey of critical care pharmacists on sedation and analgesia practices in adult and pediatric patients receiving continuous neuromuscular blocking agents

“…The next most commonly reported system was BIS monitoring, which monitors electroencephalographic signals to obtain a value reflecting the patient's level of consciousness 10 . BIS monitoring is widely used in the operative setting and there is growing use in the ICU 11,12 . The Adult PADIS guidelines state that BIS monitoring may be useful in those requiring deep sedation or neuromuscular blockade; however, there are conflicting studies on the efficacy of BIS monitoring, with some reporting reduced prevalence of intraoperative awareness and others showing no difference 1,5 .…”

“…The Adult PADIS guidelines state that BIS monitoring may be useful in those requiring deep sedation or neuromuscular blockade; however, there are conflicting studies on the efficacy of BIS monitoring, with some reporting reduced prevalence of intraoperative awareness and others showing no difference 1,5 . While there is moderate to strong correlation between BIS and clinical sedation scales in critically ill patients, this has not been widely evaluated in critically ill patients receiving NMBAs 12 . There is some concern that NMBAs may interfere with BIS monitoring, limiting correlation with clinical sedation scales and leading to inadequate sedation in patients receiving continuous NMBAs 13–15 .…”

“…10 BIS monitoring is widely used in the operative setting and there is growing use in the ICU. 11,12 The Adult PADIS guidelines state that BIS monitoring may be useful in those requiring deep sedation or neuromuscular blockade; however, there are conflicting studies on the efficacy of BIS monitoring, with some reporting reduced prevalence of intraoperative awareness and others showing no difference. 1,5 While there is moderate to strong correlation between BIS and clinical sedation scales in critically ill patients, this has not been widely evaluated in critically ill patients receiving NMBAs.…”

“…1,5 While there is moderate to strong correlation between BIS and clinical sedation scales in critically ill patients, this has not been widely evaluated in critically ill patients receiving NMBAs. 12 There is some concern that NMBAs may interfere with BIS monitoring, limiting correlation with clinical sedation scales and leading to inadequate sedation in patients receiving continuous NMBAs. [13][14][15] Additionally, BIS and electroencephalogram monitoring may be an expensive and limited resource that may not be available for all institutions.…”

Management of traumatic brain injury in the non‐neurosurgical intensive care unit: a narrative review of current evidence

“…Although several processed electroencephalogram (EEG) devices are available, most of the published literature has focused on the use of the bispectral index system (BIS; Medtronic Ltd., Watford, UK). The utility of BIS in helping guide depth of sedation is routine in many centres, with moderate to strong correlation between BIS values and traditional clinical sedation scales[42]. Given the difficultly in using clinical sedation measurement tools in patients with TBI, BIS may help clinicians optimise sedation delivered on critical care.…”