Waking During Surgery: Monitors May Not Help

March 13, 2008— -- When Mark Rosen was being prepped for emergency chest surgery, he had every expectation that his experience would be the same as that of most other surgical patients.

Instead, Rosen, a 20-year-old college student at the time, endured a nightmare experience — one that was far from the norm.

"I knew something was wrong," he recalled, "feeling them cutting. I remember wanting to push away, but you're paralyzed. You can't move, you can't open your eyes … the fright of being locked in."

Now a doctor, Rosen, ironically enough, is the vice chairman of anesthesiology at the University of California San Francisco Children's Hospital. He said his chosen career path was not a result of his terrifying memories, and he underscored the fact that cases such as his are, thankfully, few and far between.

But new research suggests that in the rare instances when a patient does become aware during surgery, a brain monitor specifically intended to alert doctors to this phenomenon is not doing its job.

In the study, published Wednesday in the New England Journal of Medicine, researchers looked at nearly 2,000 surgical patients at the Washington University School of Medicine who were determined to be at high risk of waking up during surgery. Half of the patients were monitored during surgery with a Bispectral Index System (BIS), while the other half were monitored using a different method.

BIS, also known as "the BIZ," reads brain waves from a sensor placed on the forehead and displays a score to help doctors give the best dose of medications to keep their patients sound asleep.

What the researchers found was that BIS did not increase the likelihood that doctors would be able to tell if a patient was regaining awareness during surgery.

"Reliance on BIS technology may provide patients and health care practitioners with a false sense of security," noted lead study author Dr. Michael Avidan of the Washington University School of Medicine.

Before this study, many doctors, including Rosen, were already skeptical of BIS.