Study Evaluating Ways of Preventing Patients From Being Awake During High-Risk Surgery and Anesthesia

B-Unaware Study: Comparison of BIS-guided Anesthesia With End-Tidal Volatile-Guided Anesthesia to Decrease The Incidence of Awareness During High-Risk Surgery

The overall purpose of this study is to see if a Bispectral Index (BIS) monitor, a Food and Drug Administration (FDA) approved brain monitoring device, will help to reduce the risk of patients remembering being awake during surgery. The BIS monitor may be able measure how asleep a patient is during surgery. Using the BIS monitor to guide anesthesia will be compared with using the concentration of anesthetic gas to guide anesthesia.

Study Overview

• Status: Completed
• Conditions: Explicit Recall of Intra-operative Events
• Intervention / Treatment: Device: BIS Monitor guided algorithm; Behavioral: Volatile anesthetic guided algorithm

Detailed Description

General anesthesia is a state of drug-induced unconsciousness, during which patients should neither perceive nor recall noxious stimuli. Many patients facing surgery dread the prospect of being awake, in pain and unable to move owing to inadequate general anesthesia. A large multi-center study in the USA showed that, despite modern anesthesia techniques, the overall incidence of awareness or conscious recall remains about 0.1-0.2%. For high-risk (for awareness) surgery, such as cardiac surgery, trauma surgery and obstetric surgery, the incidence of conscious recall approaches 1%. This can lead to extreme anxiety and even posttraumatic stress disorder. Several monitors, including the Bispectral Index (BIS), which is based on processed electroencephalographic information, have been developed in an attempt to monitor depth of anesthesia. A recent landmark study suggested that harnessing the information provided by the BIS monitor decreases the incidence of explicit recall during high-risk surgical procedures from almost 1% to 0.1%. The possible impact of this study is enormous. The American Society of Anesthesiologists and the American Association of Nurse Anesthetists do not currently consider neurological monitors an essential part of routine anesthesia care. Increasingly, members of the anesthetic community are suggesting that for every patient undergoing general anesthesia, especially for procedures where the risk of awareness is considered higher, a neurological monitor, such as the BIS monitor, should be routinely applied.

Explicit recall under general anesthesia is a major concern among members of the public and has even been featured on the popular Oprah Winfrey Show. Several patients presenting for surgery at Barnes Jewish Hospital have questioned whether the anesthesia provider would be using a BIS monitor to "prevent awareness". Excluding the cost of the BIS monitor itself, the cost to use BIS is $17.50 for the disposable strip. If this monitor was to be used for every anesthetic administered at Barnes Jewish Hospital, this might translate to an annual cost of about $500,000. Explicit recall, especially when patients have been aware and unable to move, is a serious complication that frequently precipitates posttraumatic stress disorder. If indeed the BIS monitor does decrease the incidence of explicit recall, this could translate into a cost effective and more importantly clinically imperative intervention. Currently BIS monitors, or similar alternatives, are not used routinely to monitor depth of general anesthesia at Barnes Jewish Hospital.

However, there are several concerns regarding the studies that have been conducted using the BIS monitor. There have been no parameters guiding administration of anesthesia in the control groups. BIS data have not been collected for patients in control groups, which prevents retrospective analysis and assessment of the true sensitivity, specificity, positive and negative predictive values of the BIS recordings. Most of the studies have been funded by the manufacturer of the device, which introduces a potential conflict of interest and investigator bias. In view of the current pressure to adopt BIS monitoring or an equivalent into the standard of anesthesia care, it is essential to conduct a study to address some of the concerns. The hypothesis of this proposed study is that an anesthetic algorithm can be designed for high-risk surgical patients such that the incidence of awareness will be equivalent to or lower than that in a group where anesthesia depth is guided by the BIS monitor.

• Study Type: Interventional
• Enrollment (Actual): 2000
• Phase: Phase 2; Phase 3

Contacts and Locations

Study Locations

• United States
  • Missouri
    • St Louis, Missouri, United States, 63110
      • Barnes-Jewish Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

MUST HAVE:

General Anesthesia with volatile anesthetic

PATIENT CHARACTERISTICS

Major Criteria (any 1 of the following:)

1. Medications - anticonvulsants, abuse of opiates, benzodiazepines, cocaine
2. EF<40%
3. Prior history of awareness (recall)
4. History of difficult intubation or anticipated difficult intubation
5. ASA IV or V status
6. Aortic stenosis
7. End stage lung disease
8. Marginal exercise tolerance not secondary to musculoskeletal dysfunction
9. Pulmonary hypertension
10. Daily alcohol consumption

Minor Criteria (any 2 of the following)

1. Beta blockers
2. COPD
3. Moderate exercise tolerance not secondary to musculoskeletal dysfunction
4. Smokes ≥2 packs per day
5. Morbid obesity BMI>30 -

Exclusion Criteria:

1. Surgical procedure that prevents the use of the BIS (e.g surgery of forehead)
2. Patient positioning prevents use of the BIS
3. Surgery with wake-up test.
4. Less than 18 years of age
5. Vulnerable populations, such as those with dementia and those unable to provide informed consent.
6. Stroke with residual neurological deficits

Study Plan

How is the study designed?

Design Details

• Primary Purpose: PREVENTION
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: DOUBLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: BIS Monitor guided algorithm; BIS guided algorithm (BIS target 40 to 60) during anesthesia. Alarms when BIS is outside this range.	Device: BIS Monitor guided algorithm; BIS guided algorithm (BIS target 40 to 60) during anesthesia. Alarms when BIS is outside this range.
ACTIVE_COMPARATOR: Volatile anesthetic guided algorithm; Volatile anesthetic guided algorithm. Target anesthetic concentration 0.7 to 1.3 minimum alveolar concentration during anesthesia. Alarms when anesthetic concentration not in this range.	Behavioral: Volatile anesthetic guided algorithm; Volatile anesthetic guided algorithm. Target anesthetic concentration 0.7 to 1.3 minimum alveolar concentration during anesthesia. Alarms when anesthetic concentration not in this range.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
The incidence of explicit recall of events during the surgical and anesthetic periods.	30 days

Secondary Outcome Measures

Outcome Measure	Time Frame
1 Anesthetic concentrations & BIS values in each group.	1 day
2 Implicit memory (number).	30 days
3 Dreaming.	30 days
4 One-year mortality (and "anesthetic depth").	1 year
5 Relation of assessment to BIS value.	30 days
6 Relation of events (e.g. movement) to BIS & ETAG.	1 day
7 Relation of EMG to BIS.	1 day

Collaborators and Investigators

• Sponsor: Washington University School of Medicine
• Collaborators: The Foundation for Barnes-Jewish Hospital
• Investigators: Study Director: Beth Burnside, Washington University School of Medicine

Publications and helpful links

General Publications

• Myles PS, Leslie K, McNeil J, Forbes A, Chan MT. Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. Lancet. 2004 May 29;363(9423):1757-63. doi: 10.1016/S0140-6736(04)16300-9.
• Willingham M, Ben Abdallah A, Gradwohl S, Helsten D, Lin N, Villafranca A, Jacobsohn E, Avidan M, Kaiser H. Association between intraoperative electroencephalographic suppression and postoperative mortality. Br J Anaesth. 2014 Dec;113(6):1001-8. doi: 10.1093/bja/aeu105. Epub 2014 May 22.
• Avidan MS, Palanca BJ, Glick D, Jacobsohn E, Villafranca A, O'Connor M, Mashour GA; BAG-RECALL Study Group. Protocol for the BAG-RECALL clinical trial: a prospective, multi-center, randomized, controlled trial to determine whether a bispectral index-guided protocol is superior to an anesthesia gas-guided protocol in reducing intraoperative awareness with explicit recall in high risk surgical patients. BMC Anesthesiol. 2009 Nov 30;9:8. doi: 10.1186/1471-2253-9-8.
• Avidan MS, Zhang L, Burnside BA, Finkel KJ, Searleman AC, Selvidge JA, Saager L, Turner MS, Rao S, Bottros M, Hantler C, Jacobsohn E, Evers AS. Anesthesia awareness and the bispectral index. N Engl J Med. 2008 Mar 13;358(11):1097-108. doi: 10.1056/NEJMoa0707361.

Study record dates

Study Major Dates

• Study Start: August 1, 2005
• Primary Completion (ACTUAL): October 1, 2006

Study Registration Dates

• First Submitted: January 20, 2006
• First Submitted That Met QC Criteria: January 20, 2006
• First Posted (ESTIMATE): January 24, 2006

Study Record Updates

• Last Update Posted (ESTIMATE): July 23, 2012
• Last Update Submitted That Met QC Criteria: July 20, 2012
• Last Verified: July 1, 2012

More Information

Terms related to this study

• Keywords: Anesthesia; Awareness; BIS; Recall; Explicit Recall
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Central Nervous System Depressants; Anesthetics
• Other Study ID Numbers: 04-1112