emergancy ascending

[HPT3]

Ok, I've ask this questioned to experienced divers and I get the cookie cutter answer. First, if one has to do an emergancy ascend, from what depths can this be done safely? The key word here is "safely". Has anyone here done it? If so, what did you experience? Second, I'm completing my ow this weekend. I've past the written and the pool time and so for, but still have a curious question for the instructors out there. If in a pool enviroment on compressed air and a student losses his reg and pops to the surface without exhaling. What if any problem may he incur? Mind you I didn't do this, but I'm sure people have and yes, I do understand Boyle's Law.

 

[DA Aquamaster]

Worst case, a lung over expansion injury can occur in as little as three feet of water. I would not even attempt to experiment with this.

From worst to best, these are some of the possibilties....

Arterial Gas Embolisim can occur when air enters the blood stream from the lungs with serious consequences a the bubbles will circulate through the blood system and possibly block blood flow to a vital organ (like the brain). This one can kill you really quickly and needs immediate treatment.

Pneumothorax can result if air enters the chest cavity and disrupts the negative pressure that keeps the lungs inflated. This can cause the lung to collapse causing pain and shortness of breath. This one also requires treatment and if it is large a chest tube may be needed to release the trapped air.

Mediastinal Emphaysema can occur if air escapes from the lung into the mediastinum which is the space that contains the heart and related major blood vessles. This one also needs treatment.

Subcutaneous Emphaysema can occur if air escapes from the lungs and is trapped under the skin. This one is normally not life threatening and the air will eventually be re-absorbed, but I'd still seek treatment.

When I learned to dive, we made emergency swimming ascents from 30 ft. And of course being young and stupid I practised it from 60 ft shortly after being certified. It works but you need to be careful not to get too excited and exhale too much too fast or else you find yourself rushing the ascent. Done right, it is possible to sustain a 60 fpm ascent rate all the way to the surface. Of course I also free dove for several years before scuba diving so I think doing a reasonably slow emergency swimming ascent from significant depth requires some degree of mental control and CO2 tolerance. Panic in an out of air situation is not consistent with a safe or successful ESA.

You should also ideally do this with your reg in your mouth and attempt to inhale on the way up, which I was told at the time may help prevent a lung injury. In most cases there is also another breath available from the "empty" tank as you get shallower.

I would not however recommend practicing this under any circumstances as I think it is one of those skills that is potentially dangerous to practice. Some of the above mentioned aliments can occur in a rapid ascent even if you do not hold your breath. In 18 years of diving I have never actually needed to do it. OOA emergencies are 100% preventable with proper maintainece and diving technique, so I really do not see the need to practice an emergency ascent. You are far better off focusing on preventing the OOA situation in the first place.

 

[ScubaRon]

See http://www.scubaboard.com/showthread.php?s=&threadid=37780&highlight=bought .
ScubaRon

 

[Drew Sailbum]

done by an instructor just to prove that it could be done maintaining a 60' per minute ascent rate. That said, one should not plan to do CESAs from 120' as a means of bailout. Diving at that depth requires other planning for a potential OOA.

 

[Zept]

HPT3 said...
First, if one has to do an emergency ascend, from what depths can this be done safely? The key word here is "safely".

There's no hard-and-fast answer to this. An emergency ascent from 5m (15ft) is safer than an emergency ascent from 10m (33ft). An emergency ascent from 10m (33ft) is safer than an emergency ascent from 18m (60ft), etc.

Avoiding the need for an emergency ascent is safer than any of these options.

Z

 

[FFMDiver]

I've never seen anyone suffer embolisms or broken eardrums while diving from spring boards at the YMCA. I've never seen them equalize as they plunge into the deep end into 18' of water. Doesnt mean barotrauma doesnt happen while using diving boards. But thinking about pool divers might help you in your pool sessions if you panic and have to surface.

=-)

 

[DA Aquamaster]

FFMDiver once bubbled...
I've never seen anyone suffer embolisms or broken eardrums while diving from spring boards at the YMCA. I've never seen them equalize as they plunge into the deep end into 18' of water. Doesnt mean barotrauma doesnt happen while using diving boards. But thinking about pool divers might help you in your pool sessions if you panic and have to surface.

=-)

There is a serious and ignificant difference between diving to 3,6, or 18 ft with 1 ATM of air pressure in your lungs and coming up from those same depths with full lungs. When spring board diving free diving etc, the air in the lungs is compressed and you have to go quite deep (a couple hundred feet or so) before the pressure begins to cause damage to your lungs in the form of filling the lungs with fluid once they can no longer compress enough to compensate for the increasing depth.

With scuba you are starting at the bottom with air in the lungs equal to ambient pressure that is higher than 1 ATM and if there is no room for the air to expand on ascent, an over pressure injury will occur.

 

[FFMDiver]

That was the dumbest post I ever made. Sorry, about that.:whack:

 

[Dr Deco]

Dear HTP3:

The record for pulmonary barotraumas injury is from about three feet to the surface. In this case, the individual took a full breath of air. If it is a full inhalation, then you are in great risk with only a small ascent to the surface.

This is different than taking a breath of air at the surface and diving into the water. You return to the surface with the same 1 atmosphere of pressure in your lung.


Dr Deco :doctor:

References :book2:

Benton PJ, Woodfine JD, Westwood PR. Arterial gas embolism following a 1-meter ascent during helicopter escape training: a case report. Aviat Space Environ Med. 1996 Jan;67(1):63-4. [Institute of Naval Medicine, Hants, United Kingdom.]

We present the case of a helicopter pilot who suffered an arterial gas embolism following instruction in the use of the Short Term Air Supply System (STASS) at a depth of 1 meter of water. This is believed to be the shallowest depth from which a case of arterial gas embolism associated with the use of compressed air breathing apparatus has been reported.

 

[HPT3]

Wow! This is very good information that all of you have posted. I read somewhere, on this site, that many instructors may be very experienced divers,but are poor at instructing. I have found through my own experience, which is very little, that I must search, read, and discuss with other divers to get a good feel for this sport. One of the first statements my instructor made to us was "We want you to have fun in this class." Stressing the importance of the dangers of diving was not on the top of the list. Yes, we read about it in the manual and yes, it was said in the classroom. It was never stressed. I mean pounded into our little brain that ASCENDING TO FAST, WHILE HOLDING YOUR BREATH AT ANY DEPTH, WILL KILL YOU! I think this is an important piece of information. The more I read, the more I am amazed. So called experienced dives dieing from panic drowndings, because of stupid stuff. Spitting out their regulator, dropping their weights and dashing to the surface. The whole time holding their breath. I do believing in practicing for an emergancy. That is why I posted this question. I will take your advice and also check with DAN before doing anything extreme. I basically wanted to know if I were to practice this with a reg in my mouth from depths no greater than 20 feet would it put me in the hospital?