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Bispectral Index (BIS) Versus Electronic Alerts in the Prevention of Anesthesia Awareness: the Michigan Awareness Control Study (MACS)

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ClinicalTrials.gov Identifier: NCT00689091
Recruitment Status : Completed
First Posted : June 3, 2008
Results First Posted : November 17, 2014
Last Update Posted : December 7, 2017
Sponsor:
Collaborators:
Foundation for Anesthesia Education and Research
American Society of Anesthesiologists
Washington University School of Medicine
University of Chicago
University of Manitoba
Information provided by (Responsible Party):
George Mashour, University of Michigan

Tracking Information
First Submitted Date  ICMJE May 29, 2008
First Posted Date  ICMJE June 3, 2008
Results First Submitted Date  ICMJE December 12, 2013
Results First Posted Date  ICMJE November 17, 2014
Last Update Posted Date December 7, 2017
Study Start Date  ICMJE May 2008
Actual Primary Completion Date April 2010   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: November 14, 2014)
The Percentage of Incidences With Explicit Recall in the BIS Versus MAC Alert Groups. [ Time Frame: Outcome of awareness is assessed 30-days after the operation ]
By modified intention-to-treat analysis
Original Primary Outcome Measures  ICMJE
 (submitted: May 29, 2008)
The incidence of awareness with explicit recall in the BIS versus MAC alert groups.
Change History
Current Secondary Outcome Measures  ICMJE
 (submitted: November 3, 2017)
  • Number of Participants With Dreams During Anesthesia Compared Between MAC or BIS Monitoring [ Time Frame: During surgery (45 minutes - 18 hours), measured based on 30 day interviews ]
    Binary variables for whether participants recall dreaming or not.
  • Percentage of Cases With Electronic Alerts [ Time Frame: During surgery: (45 minutes - 18 hours) ]
  • Overall Use of Anesthetics Comparing the BIS to MAC Alerts. [ Time Frame: During surgery (45 minutes - 18 hours) ]
  • Time Till Discharge Readiness [ Time Frame: During recovery room stay: 30 minutes to 6 hours ]
    measured in time within Post Anesthesia Care Unit ( PACU) until the participant is ready for discharge from PACU based on a composite of factors, including pain and neurologic status
  • Number of Participants Without Nausea or Vomiting [ Time Frame: During recovery room stay: 30 minutes to 6 hours ]
  • Comparison of the Prospective and Retrospective Approaches to the Study Awareness Incidence. [ Time Frame: 30 days after surgery ]
    There is controversy regarding the appropriate technique for assessing awareness during anesthesia with explicit recall. A total cohort was utilized to compare the incidence of awareness with recall as determined by formal interview vs. the incidence of awareness with recall based on spontaneous reports (in the same cohort).
Original Secondary Outcome Measures  ICMJE
 (submitted: May 29, 2008)
  • Meta-Analysis of Awareness Events in Conjunction With the BAG-RECALL Study Based at Washington University.
  • Incidence of Post-traumatic Stress Disorder.
  • Predictors of Post-traumatic Stress Disorder Based on the Type of Awareness Event.
  • Incidence and Type of Dreams During Anesthesia in Conjunction With MAC or BIS Values.
  • The Relationship Between Cumulative Deep Hypnotic Time, Anesthetic Doses, and Mortality.
  • Relationship Between BIS Values and Hemodynamic Parameters.
  • Analysis of Interrupted Monitoring During the Use of the BIS.
  • Effect of Electronic Alerts on the Clinical Behavior of the Anesthesia Provider.
  • BIS Values and Anesthetic Dosing of Chronic Pain Patients.
  • Overall Use of Anesthetics Comparing the BIS to MAC Alerts.
  • PACU Pain Scores, Neurologic Exam, and Discharge Time in Relationship to BIS Values.
  • Incidence of Post-operative Nausea and Vomiting in Relationship to BIS Values.
  • Anesthetic Induction Doses, Hypotension, and BIS Values.
Current Other Pre-specified Outcome Measures
 (submitted: November 3, 2017)
  • Relationship Between BIS Values and Hemodynamic Parameters. [ Time Frame: Outcome of hemodynamic stability is assessed ]
  • The Relationship Between Cumulative Deep Hypnotic Time, Anesthetic Doses, and Mortality. [ Time Frame: Outcome of mortality is assessed ]
  • Predictors of Post-traumatic Stress Disorder Based on the Type of Awareness Event. [ Time Frame: Outcome of post-traumatic stress disorder is assessed with the covariate of awareness ]
  • Anesthetic Induction Doses, Hypotension, and BIS Values. [ Time Frame: Outcome of hypotension in relationship to induction doses and BIS values will be assessed ]
  • Meta-Analysis of Awareness Events in Conjunction With the BAG-RECALL Study Based at Washington University. [ Time Frame: Outcome of awareness is assessed ]
  • Incidence of Post-traumatic Stress Disorder. [ Time Frame: NEED VALUE HERE ]
Original Other Pre-specified Outcome Measures Not Provided
 
Descriptive Information
Brief Title  ICMJE Bispectral Index (BIS) Versus Electronic Alerts in the Prevention of Anesthesia Awareness: the Michigan Awareness Control Study
Official Title  ICMJE A Prospective, Randomized, Controlled Trial Comparing Bispectral Index Monitoring to Electronic Alerts for Prevention of Awareness During Anesthesia in the General Population
Brief Summary Awareness during anesthesia is a problem receiving increased attention by patients, clinicians, and the general public. The incidence of intraoperative awareness has been reported to be between 1-2/1000 cases, but recent data suggest that this may be an overestimate. The Bispectral Index (BIS) Monitor is an electroencephalographic method of assessing depth of anesthesia that has been shown in one study to reduce the incidence of awareness during anesthesia in the high-risk population (Myles et al, 2004). In the study of Myles et al, the number needed to treat (NNT) in order to prevent one case of awareness in the high-risk population was 138, with an associated cost of approximately US$2200. Since the NNT and the associated cost of treatment would be much higher in the general population, the efficacy of the BIS monitor in preventing awareness in all anesthetized patients needs to be clearly established. Furthermore, recent data suggest that the BIS may not be useful in the high-risk population. The investigators propose a prospective, randomized, controlled trial comparing the BIS monitor to electronic alerts based on non-electroencephalographic gauges of anesthetic depth.
Detailed Description

Electronic alerts have been developed and employed at our institution and have been shown to increase compliance with both clinical and administrative tasks (O'Reilly et al, 2006; Kheterpal et al, 2007). The investigators have developed electronic alerts for the purpose of informing the clinician of potentially insufficient anesthesia based on minimum alveolar concentration (MAC). The algorithm is as follows:

  • Every 5 minutes the alerting system checks every active case in our operating rooms. It takes approximately 1 second for this scan of all active cases to occur.
  • Conditions for an "active case" are:

    1. data capture is possible (i.e., not a paper record)
    2. data capture is active (i.e., "patient in room" has been electronically entered and end-tidal [Et] CO2 is detected)
    3. case has been identified as a general anesthetic
    4. "anesthesia induction end" has already been documented
    5. request for recovery room bed or transport to an intensive care unit has not been documented
    6. surgical dressing completion has not been documented
  • The alerting system checks the most recent value (within a specified time period) of:

    1. Et Sevoflurane (MAC=2.0)
    2. Et Isoflurane (MAC=1.2)
    3. Et Desflurane (MAC=6)
    4. Et Nitrous Oxide (MAC=105) and compares it to the MAC of each agent. It adds the resulting MAC values together for "current total MAC."
  • The system then checks for a charted propofol infusion in mcg/kg/min and divides by 150, assuming that 150 mcg/kg/min is "1.0 MAC" for propofol. The analogous concept of MAC for propofol is "Cp50"- the plasma or blood concentrations at which 50% of patients do not move in response to a noxious stimulus. Since the investigators do not have the technology at our institution to calculate Cp50 or Cp50-awake, the investigators have chosen the above propofol dose as an initial value based on clinical experience. The resultant MAC equivalent is added to current total MAC.
  • The system next checks for a dexmedetomidine infusion with a rate of 0.2 mcg/kg/hour or greater. If present, it multiplies the current total inhalational MAC by 2, as dexmedetomidine can reduce MAC by 50%.
  • At this point, the "current total MAC" is defined as: Et Sevo /2 + Et Iso /1.2 + Et Des/6 + Et Nitrous /105 + propofol rate (in mcg/kg/min)/150. If dexmedetomidine is >0.2 mcg/kg/hour, inhalational MAC is multiplied by 2.
  • If this total mac < 0.50, it checks to see if a bolus of propofol, midazolam, etomidate, or thiopental has been given in the preceding 10 minutes.
  • It alerts the clinician signed into the case within 30-60 seconds if total age-adjusted MAC < 0.50 AND no bolus has been documented in the last 10 minutes.

This will be the protocol in the MAC-guided group. In the BIS-guided group an electronic alert will be sent if the BIS value is >60. If an alert is triggered, the clinician electronically signed into the case receives an alphanumeric page stating "Potentially insufficient anesthesia, please check vaporizers and intravenous lines."

The investigators are collaborating with Washington University, the University of Chicago, and the University of Mannitoba, who will also be testing a MAC-based protocol in comparison to the BIS.

Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Prevention
Condition  ICMJE Awareness During General Anesthesia
Intervention  ICMJE
  • Device: Bispectral Index Monitor
    Comparison of two different alerting protocols. One using the bispectral index monitor and one using the MAC alerting protocols.
  • Device: Electronic MAC alert
    Comparison of two different alerting protocols. One using the bispectral index monitor and one using the MAC alerting protocols.
Study Arms  ICMJE
  • Experimental: BIS group
    This group will have BIS values visible and will receive alerts when the value is >60.
    Intervention: Device: Bispectral Index Monitor
  • Active Comparator: MAC Alert
    This group will receive an alert if total MAC (including intravenous infusions) is <0.5 age-adjusted.
    Intervention: Device: Electronic MAC alert
Publications *

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruitment Information
Recruitment Status  ICMJE Completed
Actual Enrollment  ICMJE
 (submitted: June 12, 2012)
22185
Original Enrollment  ICMJE Not Provided
Actual Study Completion Date  ICMJE June 2010
Actual Primary Completion Date April 2010   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

Inclusion Criteria:

  • At least 18 years of age, English-speaking, available for follow-up interview at one month.

Exclusion Criteria:

  • Pre-existing neurologic or neuropsychiatric condition, surgical manipulation around forehead, not available for follow-up interview.
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 18 Years to 100 Years   (Adult, Older Adult)
Accepts Healthy Volunteers  ICMJE No
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE United States
Removed Location Countries  
 
Administrative Information
NCT Number  ICMJE NCT00689091
Other Study ID Numbers  ICMJE HUM00013626
Has Data Monitoring Committee Yes
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party George Mashour, University of Michigan
Study Sponsor  ICMJE University of Michigan
Collaborators  ICMJE
  • Foundation for Anesthesia Education and Research
  • American Society of Anesthesiologists
  • Washington University School of Medicine
  • University of Chicago
  • University of Manitoba
Investigators  ICMJE
Principal Investigator: George A. Mashour, M.D., Ph.D. University of Michigan
PRS Account University of Michigan
Verification Date November 2017

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP