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

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: A Prospective, Randomized, Controlled Trial Comparing Bispectral Index Monitoring to Electronic Alerts for Prevention of Awareness During Anesthesia in the General Populat

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 Summary:

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 compa
     Sponsor: University of Michigan
     

     Current Primary Outcome: 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: The incidence of awareness with explicit recall in the BIS versus MAC alert groups.
     
     

     Current Secondary Outcome:

     • 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: Outcome of post-traumatic stress disorder as it relates to awareness 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 ]
     • Incidence and Type of Dreams During Anesthesia in Conjunction With MAC or BIS Values. [ Time Frame: Outcomes of dreams is assessed ]
     • The Relationship Between Cumulative Deep Hypnotic Time, Anesthetic Doses, and Mortality. [ Time Frame: Outcome of mortality is assessed ]
     • Relationship Between BIS Values and Hemodynamic Parameters. [ Time Frame: Outcome of hemodynamic stability is assessed ]
     • Analysis of Interrupted Monitoring During the Use of the BIS. [ Time Frame: Outcome of BIS monitoring is assessed ]
     • Effect of Electronic Alerts on the Clinical Behavior of the Anesthesia Provider. [ Time Frame: Outcome of the number of electronic alerts generated is assessed ]
     • BIS Values and Anesthetic Dosing of Chronic Pain Patients. [ Time Frame: Outcome of chronic pain patients will be assessed ]
     • Overall Use of Anesthetics Comparing the BIS to MAC Alerts. [ Time Frame: Anesthetic dosing will be assessed ]
     • PACU Pain Scores, Neurologic Exam, and Discharge Time in Relationship to BIS Values. [ Time Frame: Outcome of pain scores, neurologic exam and discharge time will be assessed ]
     • Incidence of Post-operative Nausea and Vomiting in Relationship to BIS Values. [ Time Frame: outcome of post-operative nausea and vomiting will be assessed ]
     • Anesthetic Induction Doses, Hypotension, and BIS Values. [ Time Frame: Outcome of hypotension in relationship to induction doses and BIS values will be assessed ]
     • Comparison of Retrospective vs. Prospective Approaches to Assessing the Incidence of Awareness [ Time Frame: Outcome of awareness will be assessed ]
     • Comparison of the Prospective and Retrospective Approaches to the Study Awareness Incidence. [ Time Frame: Outcome of awareness will be assessed ]
     
     
     

     Original Secondary Outcome:

     • 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.
     
     
     Information By: University of Michigan
     

     Dates:
     Date Received: May 29, 2008
     Date Started: May 2008
     Date Completion:
     Last Updated: November 14, 2014
     Last Verified: November 2014