The Effectiveness of Bispectral Index Monitoring on Intraoperative Awareness in Adult Surgical Patients Undergoing General Anesthesia

Intraoperative awareness (IA), or the unexpected and explicit recall by patients of events that occurred intraoperatively, is a rare but serious event. Incidences of IA have been associated with extreme anxiety, physiologic stress, and the development of post-traumatic stress disorder. Anesthesia has debated the efficacy of brain monitoring devices, such as the Bispectral (BIS) index monitor, to reduce the incidence of IA. By analyzing EEG waves, these monitors can be used to alert the anesthesia provider when the patient may not be sufficiently anesthetized. An integrative review was conducted to evaluate the current evidence on the use of BIS monitoring in reducing IA. The review was comprised of 10 articles which were randomized control trials, prospective studies, literature reviews, and a practice advisory. Articles were critically appraised and a cross analysis comparing similarities and differences was conducted. In the articles reviewed, similarities existed regarding IA patient risk factors and prevention strategies. Anesthesia providers must conduct a thorough preoperative assessment to determine if a patient may be high risk for experiencing IA. Risk factors included: type of surgery, history of IA, opiate or alcohol use, and significant co-morbidities. Prevention strategies included: pre-medicating patients with an amnestic such as a benzodiazepine and discussing the possibility of IA with high-risk patients. Findings of this review indicated BIS monitoring may serve as a useful adjunct monitoring tool but should not be utilized as a primary source in determining a patient’s anesthetic. Evidence does not support BIS monitoring as a means of preventing IA.