A study shows that brain monitors often used in hospitals don't reduce the chance of waking up during an operation.
The monitors are simplified versions of EEG's, which track the brain's electrical waves.
The easy-to-read devices, called Bispectral Index System, or BIS, give anesthesiologists a score of 1 to 100 they can use to assess a patient's awareness. They were supposed to reduce the odds of awaking during surgery, although they've never been approved for surgery on children.
In addition to the monitors, most hospitals do use other means to make sure patients are asleep.
Recently, the movie "Awake" focused on this problem, which is believed to happen in 1 to 2 of every thousand operations. Patients who have cocaine addictions or are morbidly obese may have a risk of 1 in 100.
