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Study finds device fails to decrease anesthesia awareness

By Julie Bierach, KWMU

SAINT LOUIS, MO – A study conducted by scientists at Washington University shows that a popular monitoring device used to ensure patients have no memories of their surgeries fails to lower the risk of anesthesia awareness.

The bispectral index monitors brain waves during surgery.

According to a 2004 study, using the monitor could reduce the risk of anesthesia awareness, a finding that researchers say lacks sufficient evidence.

Principal investigator Dr. Michael Avidan said they studied the outcomes of 2,000 surgery patients at Barnes Jewish Hospital in St. Louis. They monitored half with the bispectral device, and the others with a gas device.

"We were unable to demonstrate that the addition of the bispectral index decreased the incidence of anesthesia awareness compared with an alternative protocol which was based on an alarm going off if the anesthesia gas dropped below a certain level," said Avidan.

Dr. Avidan said they found that two patients in each group experienced awareness during their operation.

Anesthesia awareness is rare in healthy patients, but in higher risk patients it has been reported to be as high as 1 in 100.

The study is published in the March 13 issue of the New England Journal of Medicine.


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