Can the Bispectral Index Monitor the Sedation Adequacy of Intubated ED Adults? MICHELLE GILL, MD,* KORBIN HAYCOCK, MD,* STEVEN M. GREEN, MD,* AND BARUCH KRAUSS, MD, EDM† The Bispectral Index Monitor (BIS) is validated as a measure of sedation depth during general anesthesia, but its value otherwise remains un- clear. We hypothesized that BIS scores would correlate with standard subjective measures of assessing sedation in intubated adult ED pa- tients and that BIS would predict inadequate sedation. Sedation was assessed by recording clinical features and by having treating physi- cians complete a visual analog scale (VAS; rated “not sedated” to “com- pletely sedated”) at 10, 30, and 60 minutes after intubation. Measure- ments of BIS were later paired with sedation assessments. Despite being statistically significant (p  .002), the correlation between BIS and VAS in our 147 paired readings was fair (Pearson’s rho 0.37) and displayed wide variability. Receiver operating characteristic curve analysis of BIS demonstrated no discriminatory power in predicting sedation adequacy (area under curve 0.53). BIS is not associated with and did not predict standard measures of sedation adequacy in intubated adults. (Am J Emerg Med 2004;22:76-82. © 2004 Elsevier Inc. All rights reserved.) There is currently no standard or reliable objective method for the assessment of the adequacy of sedation for intubated patients in the ED. As a result, EPs use clinical parameters, subjective sedation scales, and “gut instincts” to monitor sedation adequacy in these patients. The Bispectral Index Monitor (BIS) could potentially replace this deficit in the ED by providing an objective measurement of a pa- tient’s level of consciousness while they are intubated, and is already being used by some intensivists for the continu- ous assessment of intubated patients in the intensive care unit (ICU) setting. 1-3 The BIS, which is approved by the Food and Drug Administration for the assessment of pa- tients’ level of consciousness during general anesthesia, has been found to decrease the likelihood of recall during sur- gery 4-8 and to shorten postoperative recovery times. 9,10 The bispectral analysis of an electroencephalogram (EEG) is represented as a unitless numerical value ranging from 0 to 100, with “0” representing patients with no brain activity and “100” representing patients who are fully awake. The numbers between 0 and 100 represent a con- tinuum of level of consciousness, with 60 or less reflecting a hypnotic state consistent with general anesthesia. 4,5,7,11-14 If validated for use in the ED for the purpose of assessing intubated patients, the BIS could quickly alert staff when undersedation is present or being approached. Such a device could potentially allow for faster, more predictable patient assessment and precise titration of sedatives in this patient group. We hypothesized that BIS values would be associated with clinical assessments of unsatisfactory sedation (ie, lacrimation, mydriasis, increases in pulse and blood pres- sure) in intubated, mechanically ventilated adult ED pa- tients, and that the BIS scores would correlate with visual analog scale (VAS) assessments of sedation adequacy com- pleted by the treating physician. Our second study objective was to descriptively screen for BIS thresholds that might predict sedation adequacy in this patient population. METHODS Study Design This prospective observational study was approved by the hospital’s Institutional Review Board, which approved a waiver of informed consent through an expedited review process for this study. Study Setting and Population This study was performed in the ED of an integrated medical center and children’s hospital with an annual cen- sus of 44,000 patients per year. We studied a convenience sample of intubated, mechanically ventilated ED adults, including those intubated prehospital. We excluded patients with known or subsequently established abnormal baseline mental status (eg, dementia, mental retardation), ongoing seizure activity, severe ophthalmologic trauma (which might prevent assessment of lacrimation and mydriasis), or cardiac arrest. Study Protocol We entered patients into the study at the earliest possible time after intubation. Treating physicians (typically post- graduate year 3 EM residents) were asked to provide seda- tion in their usual manner. We asked them to grade sedation adequacy approximately 10, 30, and 60 minutes after en- rollment using an unmarked 100-mm VAS labeled “not sedated” on the left and “completely sedated” on the right. To prevent reference to earlier measures, treating physicians were given different VAS cards at each assessment. Con- From the *Department of Emergency Medicine, Loma Linda Uni- versity School of Medicine, Loma Linda, California; and the †Divi- sion of Emergency Medicine, Children’s Hospital and Harvard Med- ical School, Boston, Massachusetts. Presented as a poster at the American College of Emergency Physicians conference, Seattle, WA, October 8, 2002. Manuscript received December 1, 2002; accepted January 11, 2003. Address correspondence to Michelle Gill, MD, Loma Linda Uni- versity Medical Center, 11234 Anderson St., P.O. Box 2000, Rm. A-108, Loma Linda, California 92354. Email: mgill@ahs.llumc.edu Key Words: Bispectral Index Monitor, intubation, sedation, neu- romuscular blockade © 2004 Elsevier Inc. All rights reserved. 0735-6757/04/2202-0003$30.00/0 doi:10.1016/j.ajem.2003.12.006 76