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    Recent Studies, Movie Put Spotlight on Anesthesia Awareness

    By Jennifer Huddleston, staff writer   

    Coverage of a recent study on anesthesia awareness and “Awake,” a film that opened in November 2007 with a tagline promising to “do to surgery what ‘Jaws’ did to swimming in the ocean,” has put anesthesiologists, certified registered nurse anesthetists (CRNAs) and the entire anesthesia industry under the spotlight. However, a recent study has put the focus on various ways to monitor patients during surgery in order to detect the depth of the patients’ anesthesia and reduce the chances of awareness. To prevent awareness from occurring, however, requires an understanding of how and why it happens in the first place. 

    What is anesthesia awareness?

    According to The Joint Commission’s 2004 Sentinel Event Alert on preventing and managing the impact of anesthesia awareness, unintended intraoperative awareness (another term for anesthesia awareness), “occurs under general anesthesia when a patient becomes cognizant of some or all events during surgery or a procedure, and has direct recall of those events.”

    During anesthesia, three drugs are typically administered: one to put the patient to sleep, one to kill the pain and one to avoid movement during the procedure. However, when the anesthesia fails, the temporary paralysis from the paralytic drug disables the patient from conveying that to doctors. [1]

    The American Society of Anesthesiologists (ASA) reports that intraoperative awareness occurs in approximately one or two of every 1,000 surgical patients, translating to about 30,000 Americans annually. About half of the patients who wake up can hear or feel what is happening and almost 30 percent can feel pain. [2]

    Experiencing this awareness, especially episodes in which pain is felt, can lead to long-term psychological issues, even post-traumatic stress disorder. However, the American Association of Nurse Anesthetists (AANA) states that patient awareness happens very infrequently and that the “remote possibility” should not deter a patient from having a needed surgery.

    Study finds few differences in success rates

    The findings of the first large, independent study on bispectral index (BIS) monitoring were released in the March 13 issue of the New England Journal of Medicine. The study, conducted by researchers at Washington University School of Medicine in St. Louis, revealed that the BIS monitoring devices are no better than older monitoring technology.

    BIS monitoring works by placing a plastic censor on the patient’s forehead, which then sends brain waves to a computerized unit where they are converted to a number between zero and 100, with 100 representing complete consciousness. Aspect Medical Systems, the primary maker of BIS devices, recommends keeping patients between 40 and 60. [3]  

    The researchers compared two groups of about 1,000 patients who were all considered to be at high risk of waking during surgery. One group used the leading BIS device while the other used older technology that analyzes exhaled anesthetic gas. Two people in each of the groups experienced awareness, but in two of those cases (one with each system), the monitors indicated no problems. However, the devices used in the other two cases did signal problems. [4]

    The Food and Drug Administration (FDA) has stated that BIS devices “may be associated” with reducing intraoperative awareness. The devices are used currently in about 17 percent of the 20 million U.S. surgeries that use anesthesia gas each year. It is important to note that this study does not apply to surgical patients who receive intravenous anesthesia without any gas. [5]

    Aspect’s medical director and Boston anesthesiologist Dr. Scott Kelly said the results of the study prove that the technology helps anesthesiologists “achieve a very low incidence in high-risk patients.” [6] However, many anesthesiologists believe the device’s effectiveness has yet to be proven.

    Dr. Jeffrey Apfelbaum, president of the ASA, has reported “tremendous pressure” from industry and patient advocates to use the technology even though there has been no direct evidence proving its effectiveness. Despite a lack of direct proof, Orin Guidry, an anesthesiologist in New Orleans and a former ASA president, says that patients “are reassured when we tell them we will use a monitor.” [7]  

    In 2005, the ASA approved a Practice Advisory for Intraoperative Awareness and Brain Function Monitoring recommending that individual practitioners make the decision to use or not use a brain function monitor on a case-by-case basis for selected patients. In the practice advisory, the ASA also advocates using multiple monitoring options, including conventional monitoring, clinical techniques and level-of-consciousness monitoring, to assess the depth of anesthesia and reduce the likelihood of awareness.

    For now, with the success rates of BIS devices and other monitoring options remaining fairly close, the anesthesiologist’s expertise continues to be the greatest tool for controlling the depth of anesthesia and awareness.


    [1]  Stoeltje, Melissa Fletcher. Anesthesia Awareness Isn’t Just in the Movies. San Antonio Express-News. Dec. 9, 2007.

    [2]  Ibid.

    [3] Comarow, Avery. Anesthesia Awareness: Brain Monitors Get a ‘Tepid’ Endorsement. U.S. News & World Report. Oct. 26, 2005.

    [4] Associated Press. 30,000 People a Year Wake During Surgery. March 12, 2008.

    [5]  Ibid.

    [6]  Ibid.

    [7] Comarow, Avery. Anesthesia Awareness: Brain Monitors Get a ‘Tepid’ Endorsement. U.S. News & World Report. Oct. 26, 2005.



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