onestandingstill
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quote:
ORIGINAL: Rover
I believe the safety issue is in regards to compression of the carotid arteries (to induce oxygen deprivation of the brain and/or unconsciousness) moreso than "breath play". Specifically, the issue surrounds the accumulation of plaques on the interior walls of the arteries, which under compression, may stick to one another leaving the arteries closed shut even when the compression is removed (ie: CPR ain't gonna save you).
John
I read the article I've pasted below on the subject. From what I gather it's not the thought the artery wil stick together.
suzanne
The primary danger of suffocation play is that it is not a condition that gets worse over time (regarding the heart, anyway, it does get worse over time regarding the brain). Rather, what happens is that the more the play is prolonged, the greater the odds that a cardiac arrest will occur. Sometimes even one minute of suffocation can cause this; sometimes even less.
Quick pathophysiology lesson # 1: When the heart gets low on oxygen, it starts to fire off "extra" pacemaker sites. These usually appear in the ventricles and are thus called premature ventricular contractions -- PVC's for short. If a PVC happens to fire off during the electrical repolarization phase of cardiac contraction (the dreaded "PVC on T" phenomenon, also sometimes called "R on T") it can kick the heart over into ventricular fibrillation -- a form of cardiac arrest. The lower the heart gets on oxygen, the more PVC's it generates, and the more vulnerable to their effect it becomes, thus hypoxia increases both the probability of a PVC-on-T occurring and of its causing a cardiac arrest.
When this will happen to a particular person in a particular session is simply not predictable. This is exactly where most of the medical people I have discussed this topic with "hit the wall." Virtually all medical folks know that PVC's are both life-threating and hard to detect unless the patient is hooked to a cardiac monitor. When medical folks discuss breath control play, the question quickly becomes: How can you tell when they start throwing PVC's? The answer is: You basically can't.
Quick pathophysiology lesson # 2: When breathing is restricted, the body cannot eliminate carbon dioxide as it should, and the amount of carbon dioxide in the blood increases. Carbon dioxide (CO2) and water (H2O) exist in equilibrium with what's called carbonic acid (H2CO3) in a reaction catalyzed by an enzyme called carbonic anhydrase. (Sorry, but I can't do subscripts in this program.)
Thus: CO2 + H2O H2CO3
A molecule of carbonic acid dissociates on its own into a molecule of what's called bicarbonate (HCO3-) and an (acidic) hydrogen ion. (H+)
Thus: H2CO3 <> HCO3- and H+
Thus the overall pattern is:
H2O + CO2 <> H2CO3 <> HCO3- + H+
Therefore, if breathing is restricted, CO2 builds up and the reaction shifts to the right in an attempt to balance things out, ultimately making the blood more acidic and thus decreasing its pH. This is called respiratory acidosis. (If the patient hyperventilates, they "blow off CO2" and the reaction shifts to the left, thus increasing the pH. This is called respiratory alkalosis, and has its own dangers.)
Quick pathophysiology lesson # 3:
Again, if breathing is restricted, not only does carbon dioxide have a hard time getting out, but oxygen also has a hard time getting in. A molecule of glucose (C6H12O6) breaks down within the cell by a process called glycolysis into two molecules of pyruvate, thus creating a small amount of ATP for the body to use as energy. Under normal circumstances, pyruvate quickly combines with oxygen to produce a much larger amount of ATP. However, if there's not enough oxygen to properly metabolize the pyruvate, it is converted into lactic acid and produces one form of what's called a metabolic acidosis.
As you can see, either a build-up in the blood of carbon dioxide or a decrease in the blood of oxygen will cause the pH of the blood to fall. If both occur at the same time, as they do in cases of suffocation, the pH of the blood will plummet to life-threatening levels within a very few minutes. The pH of normal human blood is in the 7.35 to 7.45 range (slightly alkaline). A pH falling to 6.9 (or raising to 7.8) is "incompatible with life."
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