An interesting anecdote related to this column:
http://www.straightdope.com/columns/read/2942/can-brainwaves-be-detected-in-lime-jell-o
Years ago I worked in a general hospital, the only real hospital along a 300 mile stretch of interstate way out west.
We admitted the victim of a train/pedestrian altercation to our ICU. He was a hobo. He’d been trying to climb in a boxcar of a moving train. He was kinda drunk. He fell beneath the wheels. Major parts of him had been left on the tracks, and the bones he had left were all broken. Important bones, like the neck bones. He was comatose; we placed him on life support - ventilator and the works.
He had no ID. The cops couldn’t find anybody who knew him or saw the accident. If he was traveling with anyone, they caught the train he missed and were long gone.
The neurologist couldn’t find any sign of brain activity, but without next-of-kin to make decisions for him we weren’t sure if we could legally withdraw life support. Advice from the state was this: do 2 EEG’s 36 hours apart. If neither shows any brain activity or change, we could take him off life support and call the meat wagon.
The first EEG was done. It was readable, but the tech complained about interference from all the electrical equipment in the room. So for the next one we turned off all non-essential electrical equipment, including the heart monitor. During the EEG I chatted with the tech. “Any brain activity?” I asked, looking at the needle jiggle around a little. “About the same as an apple” he said. He finished the test and we turned on the heart monitor. At some point during the half-hour test his heart had stopped.
Problem solved.
Wonder what kind of waves they’d get from this
OK, now, suppose that he did have measurable brain activity when the test was beginning, but that his heart failed seconds after you turned off the heart monitor. How long would you be able to detect brain activity with a standard EEG after the cessation of blood flow to the brain? I know people lose consciousness after 10-15 seconds without oxygenated blood to the brain, and brain damage occurs after 5-6 minutes, followed quickly by brain death … but how quickly does brain activity cease to be distinguishable from Jell-O or an apple?
The story in Cecil’s reply about the english guy waking up when they went in to get his organs… I wonder if that is where the myth started that if you are an organ donor that the docs won’t try to save you, they’ll just go get those organs.
I don’t know enough about EEG’s to answer your question. I would guess that if brain waves were normal to begin with but the heart stopped the moment you started the EEG that the brain waves would change profoundly over the next 15 minutes or so.
I’m not sure why the state wanted us to do 2 EEG’s in 36 hours. If the first one shows no brain activity then the chance of the second one showing brain activity is nil. But you know how lawyers are. The first one was essentially a flat line, though the needle always jumps around a little just from all the random currents in the room. This was before the days of CT scans and MRI. I’m not sure what the protocol would be today. I’d been on quite a few cases where we established brain death, but never one on a John Doe. And it was the most gruesome injury I saw in my many years in medicine. I omitted the details of the case; it’s not pertinent to the comment on the column, and the details are likely to squick some people out.