The method in question involves a rapid reduction in oxygen supply to the brain (cerebral hypoxia) by simultaneously
• activating the carotid baroreceptors in the neck • direct stimulation of the vagus nerves, • restricting the carotid arteries
Carotid restriction is achieved by applying bilateral pressure onto the location in the neck where the two carotid arteries (L & R) that take blood to the brain, divide into the internal and external carotid arteries.
At this point the carotid vessels are surrounded by the fibrous carotid sheath, which also contains the main blood-returning vessel (internal jugular vein) and the important vagus nerve.
The ‘carotid bifurcation’ is where the important pressure sensing baroreceptor/ carotid sinus is located. This sensor monitors blood pressure in the arterial blood to the brain, and by feedback through the nervous system, controls the cardiac output of the heart. The nerves involved are the ‘glossopharyngeal and vagus’ nerves and sympathetic system.
A sudden activation of the baroreceptor, or direct stimulation of the vagus nerve can even result in ‘asystole’, where the heart stops beating.
Pressure on the carotid-bifurcation has several important effects:
1. The constriction of the artery by mechanical pressure impairs blood flow and, therefore, the oxygen supply to the brain.