On this list, in our GUE classes, and within our projects we have
consistently reiterated that divers must carefully identify the true risk
of a given dive. With gas diving, oxygen toxicity remains the most
consistent and yet often under appreciated risk. Irresponsible mixing,
convoluted marking/procedures, and careless divers are almost exclusively
the culprit in these cases. The following actual account depicts an all too
common over confidence that nearly cost one diver their life. I encourage
everyone to read this report and to appreciate the risk to which divers
expose themselves and their team.

While conducting a Tech 1 in Croatia this last week we were faced with the
following incident, one that should prove educational to all. It is for
this reason that we wanted to bring it public attention. The course was
conducted in Croatia, on an Island called Pag. The initial part of the
training, DIR fundamentals and critical skills went well, with students
undergoing training with myself and Richard Lundgren. After two days of
fundamentals and 4 days of critical skills training, we were ready to move
forward to the experience portion of the class. During this portion, the
students plan and execute two dives to a max depth of 36 m, on a 30/30
triox mix and decompress on Nitrox 50.

The logistics of the course were coordinated by the local dive facility.
The owner of the facility was involved with the class. Upon returning from
the sixth day of training, Diver X who also is the facility owner, began
the nightly filling process for the next day of diving. Oddly enough in
Croatia, the same valve fitting (threads) is used for all gases,
facilitating confusion for those that are not properly vigilant. In fact,
diver X confused the supply bottles, accidentally filling oxygen instead of
Helium into his own back tanks. Failing to heed the directions of his
instructors to properly analyze his gasses, diver X marked all his
cylinders as analyzed while, in fact, his back tanks were never analyzed.
Clearly such a mistake placed the diver and his team at tremendous risk; in
this instance it almost cost him his life. Individuals must bear in mind
that these actions do not occur in a vacuum, and that rescuers and other
team members are compromised when they must take extreme actions to
safeguard the safety of other members.

Following the execution of all pre-dive drills (conducted in seven minutes)
both groups proceeded with their dive. Nineteen minutes into the dive,
Diver X gently flashed me with his light to get my attention. He pulled his
regulator out of his mouth (as if he was giving me an OOA) but instead
began to convulse at 36m. I immediately donated my regulator, grabbed his
harness (with my left hand) and tried to put a regulator in his mouth. His
convulsions were very strong and I could not initially get the regulator in
his mouth. I proceeded to swim him closer to the wall to avoid being swept
away by the current. Diver X convulsed for a solid two minutes. We then
started up, my right arm under his right arm, holding him firmly while
keeping the regulator in his mouth. During this process I tried to remain
conscious of maintaining an open airway.

We then proceed up, with the help of my assistant, controlling all buoyancy
with my left hand. It took about one minute to reach 17m; there Diver X
began to convulse again. Following this convulsion I slowly led him to the
surface. Upon surfacing, I called for the surface support boat, which
initiated an emergency response. I removed my mask and his and prepared to
start mouth-to-mouth breathing. Fortunately he was breathing, making this
unnecessary. We then removed his gear and put him on the Zodiac.
Upon establishing that all divers were safely at the surface with no need
for additional decompression, we decided to start back to the dock, where
we could meet the ambulance. During the ride to shore, Diver X began to
come around, his color improved and his breathing became more rhythmic. We
administered oxygen during the return trip to the dock and by the time we
had arrived, he was feeling and looking much better. Upon reaching the dock
the ambulance took over, taking him to the hospital for further testing.
Further testing proved that there was no lung damage or bends and only as a
precaution did they treat him for near drowning.

Subsequent analysis proved that Diver X's cylinders had been improperly
marked. At this point we re-analyzed all diving cylinders, demonstrating
that the only improper marking had been on Diver X's cylinders. It turns
out that although his tanks were marked for 30/30 he was, in fact,
breathing 50.1%.

Although this event ended well it was clearly filled with dangerous
potential. All divers should use this as yet another example of the
importance in following careful procedures for gas analyzation and tank
marking. This must be the case whether they fill themselves or whether
others fill the tanks for them. In this particular case Diver X allowed his
personal filling of the tanks and the accuracy of the other mixes to induce
a false sense of confidence. The diver later told me that he is keenly
aware of his error, embarrassed by his arrogance and grateful to be alive.
It is my hope that this account will help others realize that short cuts
often fail and seemingly impossible things can and do occur. Ignoring the
proper procedures can cause an accident very quickly.

Andrew Georgitsis
GUE Training Director

Good post !

Sobering thought for sure, but it raises one question in my mind that maybe someone more qualified can answer ?

If an ox-tox incident like this occurs, why would you put the casualty on O2 on the surface as AG said they did ? Surely that could just compound things ?

Is that aspect of things covered on T1 T2 ?

Cheers

In the event of a diver having a CNS Oxygen Toxicity Episode underwater, they will have spent some time not breathing, and it's likely that other issues may occur during rescue (DCS/Burst Lung) especially if lifted quickly and missing stops.

Added to this, 1Bar O2 is not likely to cause further issues, and if they do, it's not underwater and so convulsions are manageable.

All in all, it's better to put them on O2 just as you would any other diving related accident.

HTH

John

After cruising the interwebby thing this afternoon, I found this post which is a very valid reminder to all why they should analyse their gas. Taken from a report by AG following a course he did with Richard L in Croatia in 2002 where someone had an ox-tox incident. Sobering reading.

And for a second lesson in why you should always analyze your tanks :

Two friends and past DIR-F students diving locally shortly after the incident in AG's course.

Diver 1 had just purchased a set of used double PST 130 tanks as his first set of double tanks. The tanks had approx. 1200 psi in them. Rather then dump the tanks and refill the decision was made to dive them in order to check buoyancy with a minimum reserve. Both were recreational divers and they assumed the tanks were filled with air or Nitrox 32. Plans were made for a skills dive with a max depth of 30 feet.

Divers descended into 20-25 feet of water, Diver 1 took a few breaths off the tanks and then passed out. Diver 2 performed an unconscious diver recovery, on the surface breathed a couple of breaths into him and Diver 1 began breathing and regained consciousness.

They swam into shore and then analyzed the contents of the tanks - pure helium.

Later we tracked down the history of the tanks. Diver 3 had borrowed the tanks from Diver 4 who originally owned them. Diver 3 had dumped the tanks, filled them with He and let them sit unmarked, planning on topping with nitrox 32 in the near future. Plans changed, a period of time went by and Diver 3 returned the tanks to Diver 4 still unmarked. The tanks sat until Diver 4 changed jobs and was leaving the area. At this time he advertised the tanks for sale and Diver 1 bought them.

So

1. Label the tanks properly at the time of filling
2. Analyze the contents of tanks personally prior to the dive.

Enjoy
Marc Hall

Oh...My...God.

Thanks for the post

A quick mix up of two identical sets of tanks meant a diver a done a 62 metre dive on a fill of 32 per cent.

Why nothing went wrong is open to interpretation - and we will never know whether it was the short bottom time, the back gas deco at 21 or just sheer luck that prevented a problem.