A patient's chronic use of alcohol, sleeping pills, tranquilizers or illicit drugs increases their tolerance for anesthetic agents, reducing their effectiveness. Plourde's studies try to take a more global approach than most earlier work which generally focused on one specific part of the brain, such as the hippocampus. He and his colleagues are looking at different sorts of brain activity, and examining what happens when anesthetics are introduced. Three years ago, Plourde and Fiset began using brain imaging, through the McConnell Brain Imaging Centre at the Montreal Neurological Institute, to see which parts of the brain are active depending on different levels of consciousness. Electrodes on the person's scalp detect the brain's response seen in the electroencephalogram.
Individuals can detect the sound when they're regaining consciousness.
While the monitoring device's prototype is the size of a dresser, a smaller, recently completed version resembles an EKG monitor.