“Scientist are now”
Climate scientists?
Once the brain is deprived of oxygen, you’re out. So say absolute max of two minutes for any form of consciousness.
But many electrical signals originate from the spine, not the brain. These are reflexes. They respond to not so gently prodding like bone saws and scalpels or that little rubber hammer the doctor taps your knee with in order to check your spine.
Anesthesia can suppress reflexes though.
How does the anesthesia circulate into the system if there’s no respiration or circulation? Is it local and they just administer it with a needle into likely reflex points?