My experience with risky CESA is related to doing it without the mask. When I was working as a professional instructor, a CESA from 15m without reg in mouth, but wearing the mask, was a standard exercise for certifying students. It was not risky at all, as being done without reg is actually safer. The instructor is coming up in front of you, face-by-face, watching your mouth for continuous bubble exhalation, and intervenes immediately if the air flow stop. There is nothing to be worried by this kind of exercise, there is no risk.
As said, the risk comes doing other exercises, as when the instructor suddenly removes your mask AND reg for checking your ability to retrieve them and to evacuate the mask. Doing a CESA in that situation is considered wrong, and the student will not pass the exam. But it is also very dangerous, first because the instructor is not really expecting that the student boosts towards the surface, so he could lag behind instead of staying face-to-face.
But the real risk is another. The skin around your nose contains some sensors, which, when suddenly hit by water, can trigger a neonatal reflex which closes your glottis, making it impossible to exhale (and to inhale, of course, which was the purpose of the reflex).
Being an involuntary reflex, once the glottis closes you cannot easily open it voluntarily. And as the CESA is being done in panic conditions, there is little chance that the student can stop it.
I had two cases of my students doing this unexpected CESA (being it un-controlled, it should be named UESA, not CESA).
In both cases I managed to reach them during the ascent (thanks to my long free-diving fins), insert a finger in their mouth reaching the epiglottis and triggering the cough reflex, which opens the glottis, making the air exiting. In one of the two cases the student reacted chewing strongly my fingers, but there was no other way (apart using the knife for an underwater tracheotomy). In the other case the student was a girl, who vomited the hell after surfacing. Both students were not certified and I suppose they gave up diving at all.
For avoiding the risks connected with the neonatal reflex, it is better to assess which students suffer of it, by doing the sudden mask removal in one meter of water, in the pool.
In my experience, 20-25% of students suffer of this reflex at some degree. With them there are only two options: tell them they will never be safe divers, or retrain them completely with months of exercises breathing underwater without mask, until the glottis reflex disappears completely.
Back to the OP: did you check what happens when your mask is suddenly removed? Do you can still breath easily through your reg? If this is fine, do not be afraid of a CESA: you have full voluntary control of your glottis, if you want to keep it open, it will stay open, and the risk of lung over-expansion is zero.
On the other hand, if you are one of those 20% of students who suffer of glottis blockage, then you have to evaluate seriously if diving is a sport suitable for you (spending some months of proper training for bringing the reflex under control) or if your better change to another sport.
As said, the risk comes doing other exercises, as when the instructor suddenly removes your mask AND reg for checking your ability to retrieve them and to evacuate the mask. Doing a CESA in that situation is considered wrong, and the student will not pass the exam. But it is also very dangerous, first because the instructor is not really expecting that the student boosts towards the surface, so he could lag behind instead of staying face-to-face.
But the real risk is another. The skin around your nose contains some sensors, which, when suddenly hit by water, can trigger a neonatal reflex which closes your glottis, making it impossible to exhale (and to inhale, of course, which was the purpose of the reflex).
Being an involuntary reflex, once the glottis closes you cannot easily open it voluntarily. And as the CESA is being done in panic conditions, there is little chance that the student can stop it.
I had two cases of my students doing this unexpected CESA (being it un-controlled, it should be named UESA, not CESA).
In both cases I managed to reach them during the ascent (thanks to my long free-diving fins), insert a finger in their mouth reaching the epiglottis and triggering the cough reflex, which opens the glottis, making the air exiting. In one of the two cases the student reacted chewing strongly my fingers, but there was no other way (apart using the knife for an underwater tracheotomy). In the other case the student was a girl, who vomited the hell after surfacing. Both students were not certified and I suppose they gave up diving at all.
For avoiding the risks connected with the neonatal reflex, it is better to assess which students suffer of it, by doing the sudden mask removal in one meter of water, in the pool.
In my experience, 20-25% of students suffer of this reflex at some degree. With them there are only two options: tell them they will never be safe divers, or retrain them completely with months of exercises breathing underwater without mask, until the glottis reflex disappears completely.
Back to the OP: did you check what happens when your mask is suddenly removed? Do you can still breath easily through your reg? If this is fine, do not be afraid of a CESA: you have full voluntary control of your glottis, if you want to keep it open, it will stay open, and the risk of lung over-expansion is zero.
On the other hand, if you are one of those 20% of students who suffer of glottis blockage, then you have to evaluate seriously if diving is a sport suitable for you (spending some months of proper training for bringing the reflex under control) or if your better change to another sport.
