Device prevents awakening during surgery

You may soon have a device that promises to alleviate anxiety for surgery patients. Anesthesiologists may at last be able to gauge doses of anesthesia more accurately so that this scenario can be avoided: the surgical patient who unexpectedly regains consciousness but is unable to communicate. The Bispectral Index, introduced at Strong Memorial Hospital in Rochester, NY, helps doctors calibrate doses to prevent patients from regaining awareness in the operating room. A flexible sensor attaches to the patient's forehead and records EEGs, giving anesthesiologists a direct measure of how deeply the patient is asleep.

Unexpected wake-ups occur in at least 40,000 of the nation's 20 million surgeries.