"In our last episode" [grin] of discussion on this subject, I made a post to the general effect that possibly the difference between fatal and non-fatal chokings had something to do with the relative levels of catecholamines in the systemic circulation of the victim. I'm making this as a follow-up post to that one. I'm not trying to start a flame war or anything like that. It's just that I'm aware that a number of people put the "smoking gun" essay on their web pages and stuff like that, and I'd therefore like them to include this essay as well.  

Brief review of terms: The sympathetic aspect of the autonomic nervous system puts out the catecholamines called epinephrine and norepinephrine (the "fight or flight" response) and these chemicals, among other things, speed up the heartbeat. The parasympathetic nervous system puts out a chemical called acetylcholine (the "feed and breed" response) and this chemical, among other things, slows down the heartbeat. Fear or anger can cause sympathetic outflow. Sexual arousal, eating (and, interestingly enough, being choked) can cause parasympathetic outflow.  

Basically, my hypothesis was that high levels of catecholamines significantly predisposed the heart to fatal arrythmias, and people who were "really" being assaulted/choked/etc. (people being choked by cops/criminals/etc.) presumably had significantly higher levels of catecholamines than people who were "not really" being assaulted/choked/etc (people being choked by martials artists during a match).  

In other words, high levels of both sympathetic and parasympathetic stimulation, at the same time, significantly increased the risk of a cardiac arrest as opposed to high levels of either sympathetic or parasympathetic stimulation alone.  

Therefore one had a plausible explanation regarding the difference in death rate between the two groups, and _possibly_ reason to believe that most BDSM play fell into the "not really being choked" category.  

(I have to tell you that I've been somewhat nervous about the conclusions, and the behavior, that could result from my previous post. I believe that I now have some empathy with the people who said that oral sex was a "relatively low risk" behavior in terms of transmitting HIV. Yeah, the data probably supports that conclusion, but what does one say to the family and friends of the "exceptional" person who gets it anyway. Hell, for that matter, what does one say to the  "expectional" person themself?)  

Anyway, while I still like this hypothesis, I definitely don't feel that it's an all-inclusive explanation and I've felt the need to make a follow-up post.  

In particular, there are a very large number of cases in which "purely" parasympathetic outflow is what appears to be what stopped the heart. The most common examples of this seem to be people who suffer a cardiac arrest while having a bowel movement. These are mostly people over 50 with a prior history of heart disease who arrest while engaged in heavy straining during a bowel movement. (This is one example of what's called a Valsalva Maneuver -- a term which I think anybody doing 
breath control play should be able to define.)  

Such people are often put on laxatives and stool softeners by their physicians, and advised to "never hold your breath during a bowel movement" for just this reason. (By the way, this type of heavy straining can also sometimes cause a cerebral hemorrhage.)  

In any event, we see that there is reason to believe that "purely" parasympathetic outflow can cause such an arrest. This risk seems to be especially higher in "older, sicker" people but I can't conclude that it's non-existent in younger people. (I do admit that it's stastically lower, although how low it would be for a given person on a given day is impossible to know in advance.)  

I've also made two posts in another forum that contained some academic citations, so I thought I'd pass (a lightly edited version of) them along:  

(copy-and-paste post # 1)  

Hi folks,  

I have some new information regarding breath control play.  

Some of you may remember that I have noted in the past that there seems to be considerably more information on exceptionally quick, sudden deaths from choking or suffocation in the British forensic pathology literature than there is in the American literature (perhaps because they seem to lose more politicians from it than we do [grin]), and once more we have heard from our friends across the big pond.  

There is a newly published forensic pathology textbook: "Simpson's Forensic Medicine" (11th edition. ISBN # 0340 61370X) by B. Knight -- a physician and a distinguished expert in the field of forensic pathology. He has quite a bit to say in the chapter on asphyxiation, particularly on the matter I have expressed so much concern about: vaso-vagal-induced sudden cardiac arrest secondary to only a few seconds of choking.  

Dr. Knight states, in so many words, on page 89: "Choking can lead to a rapid, silent death from vaso-vagal cardiac arrest." He goes on to discuss this in much greater depth on pages 90-92. Furthermore, he notes earlier in the chapter, on page 77, at least two case reports of people who died this way secondary to brief self-strangulation with their own bare hands.  

I hope the above will be regarded as credible supportive evidence of my concerns.  

Regards,  

Jay  

(copy-and-paste post # 2)  

[question # 1]  

Someone asked: However, do you think the British study may be revealing cases of Sudden cardiac death due to ventricular tachy-dysrrhythmias, secondary to the changes in vagal tone? And perhaps they were not well versed enough in cardiac electrophysiology (the study of abnormal heart rrhythms)to recognize the connection?  

I replied: I have read very substantial amounts of both British and American forensic pathology literature (and, for that matter, literature from many other countries as well), and I have detected no reason whatsoever to conclude that the British are anything but 100% up to speed on their cardiac electrophysiology -- and on all other aspects of medicine. The only difference seems to be that one finds more case reports of this type of incident in the British literature. (American forensic pathology 
literature, on the other hand, devotes a lot of space to serial killers.) Certainly the vaso-vagal-induced cardiac arrest syndrome -- cardiac arrest caused by only a few seconds of choking -- is also well-known to American forensic pathologists; see "Forensic Pathology" by DeMaio and DeMaio for starters.  

[question # 2]  

Someone also asked: If this is the case, is it possible , those who might be effected negatively by this type of "Breath control" play, are those who have a strong predisposition to sudden death anyway?  

I replied: This has been a subject of some study. The article "Death from Law Enforcement Choke Holds" (American Journal of Forensic Medicine and Pathology, Volume 3, Number 3, September 1982, pages 253-258) outlines five types of persons who are believed to be of above average risk, but cautions that the risk is never non-existent. There are all-too-many case reports of people who were apparently in excellent health (and in none of the categories listed below) and yet suffered a sudden death due to only brief periods of choking anyway.  

Just so you know, the five populations deemed by the authors to be of above-average risk are:  

1. Men over age 40.  

2. Persons with a history of a seizure disorder.  

3. Mentally disturbed persons, particularly the manic-depressive while in the manic phase.  

4. Persons using street drugs and alcohol.  

5. Persons taking prescription drugs, particularly digitalis preparations and tricyclic antidepressants.  

The article goes on to say: "Use of neck holds must be viewed in the same way as use of firearms; the potential for a fatal outcome is present each time a neck hold is applied and each time a firearm is drawn from its holster. The neck hold differs in that its fatal consequence can be totally unpredictable."  

The article concludes: "Any law enforcement agency who prescribes to the policy of using the carotid  sleeper should have frequent reinstruction in its use and continued reinforcement of the potential fatal results. No officer should be lulled into the false confidence that squeezing an arm about the neck is a safe and innocuous technique of subduing a suspect. It must be viewed as 
a potentially fatal tactic and reserved to situations which merit its risk."  

Regards,  

Jay  

(end of copy-and-paste # 2)  

OK, I just wanted to throw those citations out there. As you can see, they help (at least a bit, I hope!) in defining some of the "higher-risk" populations regarding strangulation.  

Regards,  

Jay