New Technology No Better at Spotting 'Anesthesia Awareness'

For this study, 2,000 patients undergoing general (inhaled) anesthesia were randomly assigned to BIS-guided anesthesia or to conventional anesthesia. They were then assessed for anesthesia awareness at 0 to 24 hours after the procedure, 24 to 72 hours after, and 30 days after.

Two patients experienced definite anesthesia awareness in each group, an overall incidence of 0.21 percent. Five more patients (four in the BIS group and one in the control group) had possible awareness.

The device may be of benefit to patients receiving intravenous anesthesia, which is used in a minority of surgical procedures and which is considered to be a risk factor for anesthesia awareness, the authors stated.

One of the problems is that administering anesthesia is such a finely calibrated, delicate procedure that other important variables need to be taken into account.

"It's sort of like flying an airplane. There are a lot of dials to look at," Frye said. "Maintaining proper air speed is important in flying and, in anesthesia, sometimes you have to lower the depth of the anesthesia to maintain stable vital signs in the patient."

More information

For more information, visit the Anesthesia Awareness Campaign, founded by a patient who experienced the phenomenon.

SOURCES: Michael S. Avidan, M.B., B.Ch., associate professor, anesthesiology and surgery, and division chief, cardiothoracic anesthesia and cardiothoracic intensive care, Washington University School of Medicine, St. Louis; Gerald Frye, Ph.D., Joseph H. Shelton professor, neuropharmacology and neurotoxicology, department of neuroscience and experimental therapeutics, Texas A&M Health Science Center College of Medicine; Gary H. Morton, M.D., associate professor, anesthesiology, Texas A&M Health Science Center College of Medicine, and vice chairman, anesthesiology, Scott & White, Temple, Texas; March 13, 2008,New England Journal of Medicine