This is prompted by this answer and the description of blood chokes included. It states that:
Cerebral blood flow (CBF) chokes involve restricting the flow of blood to the brain, thereby denying it of oxygen
As far as I have learned, the blood choke rather effects the veins, because arteries are under the muscles or within them and often quite well protected by them, while the veins are prominently positioned right under the skin, e.g. vena jugularis externa.
Therefore, the effect is that no blood can go out of the head or at least much more goes in than out, resulting in:
- red face because of blood coming in, but not out
- higher pressure until no new blood may enter the head
- the oxygen within the blood getting used without proper replenishment
- unconsciousness due to lack of oxygen
And so aneurysms are the main danger due to the higher pressure, but this is not a problem for most healthy people if the hold is not maintained more than ~1 minute (see DaveLiepmann's answer). I always found this to be very convincing compared to the "we primarily attack arteries", which lay under the muscular structures or are embedded.
Is that what blood chokes really work like? What is the actual mechanism going on?
- Mechanism of loss of consciousness during vascular neck restraint, Journal of Applied Physiology (2012)
The findings are
That any effect of baroreceptors (blood pressure receptors) being irritated could not be shown. This quite popular theory seems to be simply wrong.
They claim it is due to compression of the carotid arteries.
My objection to this study is that the method of pressure measurement (kind of a tube-collar with tubes in two different heights, see Fig. 1.B) and the data that are measured could - in my understanding, which is limited as I'm no physician - equally like be explained by the theory presented earlier. Some phenomena like the face getting read and the veins swollen even moreso.
Any answer (not necessarily that technical and medical) addressing this is welcome.