It's not a case of losing blood, it's a case of failing to move blood to the right place. If the shot took out the carotid, then (nearly) 50% of the blood supply to his brain is gone because of a piping failure. That can absolutely cause instantaneous loss of consciousness, no direct brain trauma necessary.

This is very different than bleeding from, say, a major artery in a leg. In that case the issue isn't loss of piping to the brain, it's losing blood until the total blood volume in the body isn't sufficient to maintain a workable blood pressure, and yes that can take multiple minutes before a person loses consciousness.

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nicce 5 days ago | parent [-]

You can live with single carotid [1]. But maybe the change is too fast. It is exremely difficult to say without knowing more.

1: https://biologyinsights.com/can-you-live-with-one-carotid-ar...

	▲	Calavar 5 days ago \| parent [-]
		I am a physician, so I can say this with a high degree of confidence. That snippet is referring to the circle of Willis, which is a "backup" circuit that can route around a blockage to the blood flow to the brain on one side. The thing is the circle of Willis is tiny and near vestigial (there is a substantial fraction of the population where it doesn't even make a full circuit), whereas the carotid is one of the largest blood vessels in the body. The circle of Willis isn't nearly large enough to reroute all that flow. It has to be made bigger over time through a process called collateralization, and that's a process that happens over months to years, not minutes or seconds. In short, the circle of Willis will save you from years of high cholesterol that lead to a huge cholesterol plaque completely blocking off one of your carotids. It won't save you from your carotid being severed by a bullet. And some other tinier vessels, but mainly the circle of Willis