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
With nitrox you can calculate Equivalent Air Depths for any planned depth and blend that you want to use and then you can just take that depth and use the Air table (although you still need to monitor your ppO2 obviously).
