How to determine whether an unresponsive patient is conscious? Introducing the PCI, a technique that involves measuring the brain's response to a magnetic pulse, reports LiveScience. “You’re kind of banging on the brain and listening to the echo,” explains a UK neuroscientist to ScienceNow. The new Perturbational Complexity Index, developed by researchers in Italy, could help doctors better treat patients with brain injuries—though they emphasize it shouldn't be used to determine when to pull the plug.
The index translates the brain's level of consciousness into a numerical scale from 0 to 1. Some examples from the study: Fully awake, 0.6 and higher; light sleep, 0.4; deep sleep, 0.2; anesthetized, 0.12. The last one reflects deep unconsciousness, and people in a vegetative state ("awake but completely unconscious") were in that ballpark, while people with locked-in syndrome ("fully aware but unable to respond") were on par with fully awake people, say the two science reports. If tests on a bigger pool of subjects are consistent, the index might find its way into hospital trauma units. Theoretically, it could help doctors gauge how effective drugs and brain-stimulation procedures are working on particular patients, says the lead researcher.