Better anesthesia monitoring
When the researchers began to slowly decrease the dose of propofol, to bring the subjects out of anesthesia, they saw a reversal of the brain activity patterns that appeared when the subjects lost consciousness. A few minutes before regaining consciousness, the alpha oscillations flipped so that they were at their peak when the low-frequency waves were at their lowest point.
"That is the signature that would allow someone to determine if a patient is coming out of anesthesia too early, with this drug," Purdon says.
Cases in which patients regain consciousness during surgery are alarming but very rare, with one or two occurrences in 10,000 operations, Brown says.
"It's not something that we're fighting with every day, but when it does happen, it creates this visceral fear, understandably, in the public. And anesthesiologists don't have a way of responding because we really don't know when you're unconscious," he says. "This is now a solved problem."
Purdon and Brown are now starting a training program for anesthesiologists and residents at MGH to train them to interpret the information necessary to measure depth of anesthesia. That information is available through the EEG monitors that are now used during most operations, Purdon says. Because propofol is the most widely used anesthesia drug, the new findings should prove valuable for most operations.
In follow-up studies, the researchers are now studying the brain activity patterns produced by other anesthesia d
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology