According to Spitz and Fisher (the bible of the forensic pathologist), five pounds of pressure per square inch are sufficient to occlude the carotid arteries and jugular veins. Thirty-two pounds are required to block the airway. Therefore, it is easier to strangle than to choke. In the case of hangings, death usually comes not from compression of the airway by the noose (choking), as evidenced by finding vomitus in the airway of numerous hanging victims, but by jugular/carotid compression. Obstruction of the airway usually elicits a violent struggle, a dramatic condition known as "air hunger." However, judging from the circumstances in which jugular/carotid compressed individuals are found, there is no indication that this is an unpleasant mode of death.
Considerable scientific research has been done by the Japanese and published in two reports of the Bulletin of the Association for Scientific Studies on Judo, Kodokan, in 1958 and 1963. The following are some of the conclusions made based on their experiments.
- Unconsciousness occurs approximately 10 seconds (8-14 seconds) after choking. After release from the chokehold, the subject regains consciousness naturally (spontaneously) without difficulty in 10-20 seconds.
- Pressure on the larynx and trachea produced excruciating pain but there was no pain in other techniques before unconsciousness.
- The unconsciousness resulting from choking is mainly due to lack of oxygen and metabolic disturbances created in the brain, as a result of disturbance of cerebral circulation.
- The appearance of flushing of the face is due to disturbance in pressure in the carotid arteries and jugular veins.
- Tachycardia (increased heart rate), hypertension (increased blood pressure), and mydriasis (dilation of the pupils) were caused by stimulation of the sympathetic nervous system (vagus nerve).
- Tachycardia and hypertension may be also attributed to the carotid sinus reflex.
- All other laboratory studies show changes that are similar to condition accompanying central shock. Choking acts as a stressor on the circulator and hypophysio-adrenocortical system.
- According to their experience, no deleterious after effects remain after being "choked."