Table 8: Summary of Results From the Bi-Aware Trial^*.

Study (year)	Myles et al. (2004) (23)
Type of study	RCT (with an intention-to- treat analysis)
Level of evidence	1
Purpose and outcome measures	Purpose: To see if BIS-guided anesthesia reduces the incidence of intraoperative awareness Outcome measures: Awareness, recovery times, hypnotic drug administration, incidence of marked hypotension, anxiety and depression, patient satisfaction, major complications (myocardial infarction, stroke, acute renal failure, and sepsis), and 30-day mortality
Number of patients and type of surgery	2,463 adult patients who had at least 1 of these risk factors for intraoperative awareness: Cesarean section High-risk cardiac surgery (e.g., ejection fraction < 0.30, cardiac index < 2.1 L/min per m2, severe aortic stenosis, pulmonary hypertension, CABG surgery) Acute trauma with hypovolemia Rigid bronchoscopy Significant impairment of cardiovascular status and expected intraoperative hypotension requiring treatment Severe end-stage lung disease Past history of awareness Anticipated difficult intubation where an awake intubation technique was not planned Known or suspected heavy alcohol intake Chronic benzodiazepine or opioid use Current prostate inhibitor therapy 1,225 patients (49.7%) were randomized to the BIS group, 1,238 (50.3%) to the SP group. 6 patients in the SP group received BIS monitoring mistakenly, and 14 patients randomized to the BIS group were not monitored. All of these patients were included in their allocated groups for all analyses; none had awareness.
Mean age, yrs (SD)	BIS: 58.1 (16.5) SP: 57.5 (16.9)
Female/male, n	BIS: 473/752; SP: 454/784
Premedication, %	BIS: 55; SP: 57
Anesthetic agent	Midazolam, propofol, and thiopentone (the technique was the same in the groups)
Tracheal intubation	Not reported
Muscle relaxant	Yes
Methods	For patients randomized to the SP group, the monitor was not turned on. For patients randomized to the BIS group, the delivery of anesthesia was adjusted to maintain a BIS score of 40–60 from the start of intubation to the time of wound closure. Postoperative interviews were scheduled 3 times: after recovery from general anesthesia (2–6 hours after surgery), 24–36 hours after surgery, and 30 days after surgery. All potential awareness episodes were coded independently by 3 experienced anesthetists who were members of the independent endpoint adjudication committee. Potential awareness cases were coded as awareness, possible awareness, or no awareness. Confirmed awareness was defined as a unanimous coding of awareness or 2 members coding as awareness and the third coding as possible awareness. Possible awareness was defined as 1 or more coding of awareness or possible awareness.
BIS values	The time-averaged BIS reading throughout the procedure was 44.5.
Incidence of recall	65 patients (30 BIS, 35 SP) did not provide any interview data, mainly owing to experiencing critical illness or dying during the postoperative period. Awareness: 2 patients (0.17%) in the BIS group reported awareness under anesthesia versus 11 patients (0.91%) in the SP group (odds ratio, 0.18; 95% adjusted confidence interval, 0.02–0.84;P = .022). The absolute reduction in the risk of awareness was 0.74%. Possible awareness: 20 patients (1.63%) in the BIS group had possible awareness under anesthesia versus 16 patients (1.29%) in the SP group (P =.5). Potential awareness episodes: 22 patients (1.8%) in the BIS group had potential awareness episodes under anesthesia; 27 patients (2.2%) in the SP group had the same (P =.49). Recalling pain: 2 patients in the BIS group recalled pain; 9 patients in the SP group did so (P =.065). Dreaming: 62 patients (5.2%) in the BIS group had intraoperative dreaming; 83 patients (6.9%) in the SP group reported intraoperative dreaming (P =.079).
Accuracy data	Not available
Recovery time	Median time to eye opening: BIS: 9 minutes SP: 10 minutes (P =.003) Time to discharge from PACU: Similar (P = .28) Time to extubation on patients admitted to the ICU: BIS: 10.8 SP: 10.2 (P =.89)
Other endpoints	Major complications: similar Patients’ scores for satisfaction, anxiety, and depression after surgery were similar. The anxiety and depression scores of those with and without confirmed awareness were similar for anxiety (P = .06) and depression (P = .27) 30 days after the operation. Patients with confirmed awareness reported less satisfaction than those without confirmed awareness at the 24-hour and 30-day interviews (P< .001).

^*BIS indicates bispectral index; CABG, coronary artery bypass graft; ICU, intensive care unit; PACU, post anesthesia care unit; RCT, randomized controlled trial; SD, standard deviation; SP, standard practice.