Am I too afraid of lung barotrauma? Remedies/Techniques?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

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.
 
It was not risky at all, as being done without reg is actually safer.
The current procedures for doing the CESA are based on a UHMS study that concluded the exact opposite, that 1) the CESA was the most dangerous part of instruction leading to (by far) the most student fatalities, and 2) having the regulator out of the mouth was (by far) the primary reason for those fatalities. That is why almost all agencies stress keeping the regulator in the mouth.
 
The current procedures for doing the CESA are based on a UHMS study that concluded the exact opposite, that 1) the CESA was the most dangerous part of instruction leading to (by far) the most student fatalities, and 2) having the regulator out of the mouth was (by far) the primary reason for those fatalities. That is why almost all agencies stress keeping the regulator in the mouth.
I know that the procedures changed. The period I was referring to was 1985 to 1989 and my cert agency was CMAS.
I think that now in CMAS courses there is no CESA exercise anymore.
Nor sudden removal of mask and regulator..
 
I know that the procedures changed. The period I was referring to was 1985 to 1989 and my cert agency was CMAS.
I think that now in CMAS courses there is no CESA exercise anymore.
Nor sudden removal of mask and regulator..
My point was that doing the CESA without the regulator was discovered to be the single most dangerous aspect of scuba instruction. I don't want ScubaBoard readers to think it is safe to do it that way and risk their lives by practicing it like that. All it does is take one little inhalation of water to start the gag reflex and begin the process of drowning. If nothing else, keeping the regulator in the mouth prevents that potentially fatal mistake.

In addition, I think the current process of teaching CESA is flawed because it does not teach students that the regulator will be able to deliver air in shallower water, which is certainly not going to do a diver much good if the regulator is not in the mouth.
 
Now, I can only assume that at some point during one of these courses there will be a deep emergency ascent exercise, from whichever depth but most certainly deeper than the CESA during my OW certification.
This assumption is NOT correct. There is NO CESA exercise in ANY course beyond OW, in ANY agency I am aware of, at any level through Advanced Trimix and Rebreather. So stop worrying about it.
 
You probably are not going to be asked to do it in training. If you are worried about doing it in an actual emergency then you have good reason to worry. An emergency ascent with no air supply has a track history of being a dangerous practice. It is the last ditch effort when all better options have been exhausted.

Two suggestions.. 1: get a pony bottle so you can drastically reduce the chance of being required to do a "no air" ascent; 2: As mentioned, the most rapid change in pressure is the last several feet of ascent, so if you can calmly exhale from a depth of 5 feet to the surface without injury, then a lung expansion issue should not arise from an ascent at a similar speed from deeper water. If you can acknowledge this, you may be able to retire most of your fears over a lung expansion injury.
I need to make a correction here. The most rapid change in volume happens in the last atmosphere, not the last several feet. If you remember Boyl's law, it is about pressure and volume and temperature. If the temperature remains the same, then it is a pressure-volume equation. Now, from memory, in sea water for every foot of depth, the pressure changes 0.445 psig. So in five feet of sea water, there is a 2.23 psig increase over sea level, or a total pressure of 16.93 psig. Now, remember,

P1V1/T1 = P2V2/T2
If the temperature is the same on both sides, then,

P1*V1= P2*V2
Or

P1*V1/P2 = V2

If we assume that the absolute pressure inside a diver's lungs is 16.93 psi, and that at a full breath the diver has 4 liters of air, we can plug the numbers in:

16.93 psi * 4 liters / 14.7 psi = 4.61 liters

This amount of air from five feet may not be enough to cause an overexpansion injury. This is because people rarely inflate their lung fully during normal breathing. But, that same lung full of air, from 33 feet of sea water will result in 8 liters of air from the expansion, which is definitely enough to cause an embolism. Now, running this same equation from 10 feet results in an expansion to 5.21 liters, which may be enough to cause an embolism, and hence all the cautions of instructors in a 9-10 foot pool.

SeaRat
 
Yes, many threads on CESA. I will just add that I practice it regularly, though only from 20-30 feet. I also know of no (PADI anyway) advanced course that includes it, or a deeper version of it.
I too don't feel the sensation that my lungs will never get empty.
I agree that you should never have to resort to a CESA, but perhaps if you have a catastrophic failure (busted reg hose, or for some reason it doesn't free flow?). No point in having it in the OW course if that never happened. No point in doing it in a course unless you practice it once in a while (like all the skills). Can't hurt to have it in your tool box.
I've probably done a hundred CESAs over the years with no lung problems, but that's just me.
 
Actually it was just an uneducated guess, that if you would get the "Deep" Specialty and later on the Rescue Diver, the curriculum would have something like a CESA or EBA (if EBA is even taught anymore) to exercise from a depth deeper than in the OW Course.
I only found vague descriptions like "self rescue" in the rescue diver course descriptions.

Thank you for your tip by the way.

Here is the thing about CESA; it is an emergency procedure, not a standard practice. It can be a valuable tool to have in your toolbox if you really need it one day, but more than likely you never will. And in reality, you never should. If you ever need one for real, you messed up big time way before and the fan is already beyond dirty.
As others pointed out, I do not know about advanced courses that require a deep CESA or anything like that. In fact, proper deep dive training provides you with better alternatives. Redundant gas supply, gas planning, gas management, and general dive planning are even more important on deeper more advanced dives and those are the skills thought during those courses.
Your fear of barotrauma can be turned in a desired to do proper planning, train team skills, work with redundant equipment and become a better diver that way. Do a few CESA's in a pool and exhale during every normal ascent, especially the last few meters. That way, you can condition yourself to take the sharp edges of CESA bit. You do not need to get really really comfortable with it, just enough so your fear doesn't paralyse you. Use the remaining bit of fear (hopefully by then more like "healthy respect") as a driver to take more advanced training.
 
oh and "Self rescue" is a generic term for your ability to, well, "rescue" yourself. That means for example you are capable of removing cramp without a buddy, can recover masks and regs when needed, that kinda thing. It is not really a big scary rescue like you might think of (with helicopters and coastguard swimmers involved) but the ability to handle small issues before they become major incidents.
 
Once your airway is open, if any air needs to leave your lungs, it WILL leave your lungs. The only threat is closing the airway. You do not need to worry about letting out too little air. I spoke with two different divers who experienced real CESAs from around 100 feet. They said that once the air started coming out, there was no stopping it.

You should also know something not mentioned in most OW classes--when your tank is out of air, it is not out of air. It just thinks it is out of air. That is because the tank must have enough air in it to deliver it at a greater pressure than the pressure you are under at that depth. When you ascend to a shallower depth, the pressure around you drops, and the regulator will be able to give you some air again.

So can you inhale safely as you ascend? Yes, and thinking about why that is true may help you understand the whole situation. When you inhale, you use the diaphragm to expand chest volume, and this pulls in new air to fill that volume. If your lungs are full enough to risk barotrauma, than you cannot inhale. If you are able to inhale, then it is safe to do so.
Hey, John. Great point....Although, many divers understand the priciple/law. They seem to sometimes forget in this instance. I have had to do three C.E.S.A.'a in my twenty years. (1) at 63ft fsw (1) at 67ft fsw, and (1) at 96 ft fsw. Admittedly, the last one was a bit unnerving.
@Fexei So, as we descend, the volume in the tank decreases.....As, we ascend the volume in the tank increases. Hypothetically, if you were doing a C.E.S.A. from approximately 60 ft and you reached 20 ft or less, and you felt like you couldn't exhale anymore, and you also felt the urge to inhale (which would be normal.) The volume in your take will have increased enough for you to take a breathe and make it the rest of the way to the surface.
Cheers.
Edit; I am so scared of rupturing my lungs that I think I exhale way too much. It distracts quite a chunk of my mind
Why am I so scared?

It's most certainly, a healthy fear. The goal of man.......is to "Survive."
 

Back
Top Bottom