Holding breath during CESA and buoyancy exercises

[adamscuba]

Hey,

I took a scuba refresher course this morning in preparation for an upcoming trip and practiced a controlled emergency swimming ascent.

For the CESA, at the bottom of the pool, 15 feet down, the instructor shut off my air. I got about 1/2 or 3/4 of a lung-full of air before tank went empty and forgot to exhale on way up, so held my breath on way up. Later we re-did the CESA and I did it properly exhaling through my regulator all the way up.

(In retrospect, I should not have held my breath during any of the techniques - so I'm glad that I went through the course and had a chance to practice.)

Doing some research online, I am not noticing any obvious symptoms related to over-expansion (AGE, Pneumothorax, Mediastinal Emphysema, Subcutaneous Emphysema). I noticed a red bruise on my shoulder immediately after getting out of the pool that does not feel spongy and is painful to the touch, which could be explained by my BCD rubbing a bit against my shoulder. A few hours after getting out of the pool I'm a little bit tired, but that's also normal for me during this time of the day.

A few questions:

1. I am guessing that although over-expansion is most likely to occur with a full lung of air while holding your breath, it is still possible with a 1/2 - 3/4 lung-full of air coming from 15 feet to surface?
2. It has been about 3 hours since I got out of the pool. How much longer should I be on the look out for symptoms? When can I consider myself "in the clear"?

Thanks,
Adam

 

[fmerkel]

You are already 'in the clear'. A lung over expansion injury will show itself quickly, and most likely in a (very) nasty way, which would be various neural symptoms.
Subcutaneous emphysema most likely would not be red and is not on the surface, which is what subcutaneous means. Think of having tiny little bubbles like bubble wrap underneath all the skin layers. It feels kind of 'crinkly' when pushed on. There would be minimal if any pain, just a weird feeling.

It is possible to get an injury from 15', depending on how much air was in the lungs, and how vigorously you held your breath. Remember your depth math: 33 feet is 1 atm, so would be a doubling of volume from there.
Most of these injuries are from diver panic that are paying attention to nothing but getting to the surface.

BTW - there are 2 ways to hold your breath. The normal one is a big breath and a glottic stop; you close your epiglottis over the trachea, much like a cork. While 'corked, you will not be able to exhale unless you remove the block.

The other is simply take a big breath, then DO NOT close the epiglottis, and simply keep your diaphragm contracted (down). The airway is still open and air can escape but you still have a lung full of air. If you relax the diaphragm at all the air immediately escapes. It's harder to do and I would not recommend this for any kind of an ascent of more than a few feet.

 

[tursiops]

What agency was this refresher being done under?

 

[guruboy]

That sounds like the completely wrong way for an instructor to conduct a CESA.

The instructor should have never let you hold your breathe. Even if you had tried to, he/she should have noticed and worst case punched you in the gut or something.

BTW, good that you are analyzing what you did and recognizing and correcting mistakes.

 

[tursiops]

That sounds like the completely wrong way for an instructor to conduct a CESA.

Agreed; that's why I was asking about the agency.

The instructor should have never let you hold your breathe. Even if you had tried to, he/she should have noticed and worst case punched you in the gut or something.

No, no reason to attack the student! Just terminate the CESA, i.e. stop ascending.

BTW, good that you are analyzing what you did and recognizing and correcting mistakes.

Agreed.

 

[guruboy]

In a pool, there usually isn't a line you can use to stop the ascent. Also, stopping is a little complicated if the diver doing the CESA has his air shutoff....

 

[boulderjohn]

As I am sure many readers know, shutting off the air is also not allowed by most agencies.

 

[guruboy]

I'll turn their air off BUT only in the shallow end of the pool as a standalone "this is what it feels like when you run out of air" experience. I never let go of the valve and they know it's coming. NEVER as part of a skill or in deep water.

 

[tursiops]

In addition, under PADI the CESA is horizontal. That's why I was asking the agency.
If this was a PADI refresher, it was not done to standards, at all, especially the air shut-off.

 

[Marie13]

In addition, under PADI the CESA is horizontal. That's why I was asking the agency.
If this was a PADI refresher, it was not done to standards, at all, especially the air shut-off.

Horizontal?! For my recent SDI OW class, CESA was vertical from the deep end of the pool, about 12', and for the check out dive, from about 23'. I suspect the instructor who shut off the student's air was doing it on the sly (aka not agency sanctioned).