American tourist dies while diving Cozumel caves.....

[swamp diver]

How was it determined that carbon monoxide poisoning was the cause of death?

Last time I checked it was not possible to get a blood carboxyhemoglobin level on the island so one would assume the tank gas was analyzed using a portable CO monitor?

The concentration of CO in the tank would have to be quite high on a shallow dive of only 15 minutes to cause loss of consciousness likely well over 200 ppm, however in most of these CO incidents there are other co-contaminants (volatile hydrocarbons, CO2) which act synergistically to impair the diver.

There was a double CO fatality involving a US physician and Canadian diver across the straight near Tulum in 2004. Both filled up at the same fill station and died in different caves that morning.
The Deco Stop

[ianr33]

This is the post from Cavediver.net. If I'm out of line copying it here am happy to remove it.

<<:arrowblack Report on accident at Sisteme Cocodrilo

I am writing this today as a chosen representative of the Cocodrilo/Dos Coronas Exploration and Mapping Expedition. On Sun October 16 we had a member of our team (Brendan Lee Nappier) die during a survey dive in the Sisteme Cocodrilo System on the island of Cozumel. The team has asked me to post this report to prevent and dispel any misinformation or misconceptions of this tragic accident. The team is understandably distraught about the loss of our good friend. I will use no names in this report other then the victim’s.
The Expedition was to survey, map and document the Sisteme Cocodrilo cave system. Sisteme Cocodrilo is a land locked system that contains several thousand feet of passage most never getting deeper than 40 feet. The Cocodrilo team arrive onsite at approximately 10 am and began gearing up in the parking lot of the dive site. The team consisted of 5 divers. The dive plan was to swim to the “Air Dome ” approximately 4200 feet into the cave and video map the room. The plan was cut very short.
Two divers were using Passive Semi-closed Rebreathers driven by two Al 80’s. One Al 80 had 32% nitrox while the other contained air. The 32% drove the rebreathers while the air was bail out. The other 3 divers were on open circuit side mount. Each open circuit diver carried an addition stage. All open circuit tanks contained air. The day before the dive 3 more 80 cubic foot tanks containing air were staged along the dive route. These were placed as additional emergency bailouts bottles.
At 11:19 am the team entered the water. The victim led the team. The team planned on a slow paced swim. At about 15 minutes in to the dive the victim began to accelerate his swim pace causing the team to string out into two groups, two divers in front trying to kept pace with the leader, followed by the second pair falling behind. At approximately two minutes later, the victim had outpaced the second and third diver and began convulsing, he then drifted to the ceiling. When the two closest buddies got to him he was unconscious and his regulators were out of his mouth. The victim’s bailout regulator was observed to be deployed and dangling. His Rebreather loop and his bailout tank had been closed, however neither buddy saw when he closed it. Both buddies, each, deployed and attempted to get a regulator in the victim’s mouth. The victim’s jaw was clenched and had to be pried open to insert the regulator. The regulator was purged into his mouth. By this point all 5 members had got to the victim and began a coordinated rescue attempt. Three divers began swimming the victim out of the system while also keeping the regulator in his mouth and purging it. The last team member kept the line out well lit and guided the team out of the system. It took approximately 18 minutes to get the victim to the surface. His gear and suit was cut away and CPR was administered in round robin by three team members. The last member called for help and got people on the surface to call for EMTs. After about 20 minutes an ambulance and local police arrived and took control of the body.
An autopsy was performed and the team was informed by local officials that the cause of death was carbon monoxide poisoning. Both Brandon’s rebreather and one other teammate’s rebreater were found to be in working order. We, the team have now been led to believe (but we have no way of verifying ) that this is not the first case of “bad” nitrox fills on the island. We have halted all diving till we can be certain of what we are breathing. We also urge anyone going on any similar expedition to please add a carbon monoxide analyzer to their dive kit. We all are buying one now. We all are emotional, stressed, and angry by Brendon’s passing. We ask out of respect for the victim and his family, to please refrain from any online speculation or comments that might cause additional stress. Brendon was young, intelligent and in shape, he did nothing wrong nor was any rules broken. There is no good reason why Brendon was taken from us. He died because he had the misfortune of breathing “bad” air. Brendon was our friend and he was taken from us too soon.
Thank you
Michael Angelo Gagliardi

>>

[gypsyjim]

Thanks

[firstdive2005]

Family, my heart goes out to you and team, please dive again. I am heading down on November 9th with a rebreather, kinda scary. Will also be heading down with a tester for the first time.

[buton]

So he was breathing from a rebreathing then..I don't know how they exactly work but isn't it supposed to measure the levels of carbon monoxide in the circuit?

[swamp diver]

So he was breathing from a rebreathing then..I don't know how they exactly work but isn't it supposed to measure the levels of carbon monoxide in the circuit?

I am not a rebreather diver but I have not seen a recreational or military rebreather with the capacity to measure CO in the circuit. I have seen one commercial rebreather which did have this capacity.

The only way to detect this odorless, colorless, and tasteless toxic contaminant whose effect on the diver increases with depth is to purchase a handheld CO monitor and use it on every tank you dive particularly when in the tropics where the high ambient heat increases the risk of CO production by the compressor. The US laboratories which receive compressed air samples from all over the globe still report a rate of CO contamination at 3 to 5 percent in samples received which is the best data we have as to the extent of this unacceptable continued problem which often presents with tragic consequences.

Every diver, buddy team, or dive club should have a portable CO monitor and the only diver-specific unit available is from Analox. It can be purchased from Leisurepro, Scubatoys, or Dive Right In Scuba (Dan's Dive Shop in Canada) for $289 to $325. There is a review of the product by Dive Magazine on this page near the bottom.
EII CO Carbon Monoxide Analyzer: Analox - Looking after the air you breathe.

Divers just need to realize that CO contamination in compressed dive air is far more common than we like to admit. These incidents are global and sporadic but until we get in the habit of checking each and every tank prior to use we are going to read about these unfortunate fatalities which can be prevented using the technology available today. We will never get a CO monitor on every compressor so it behooves the individual diver to take responsibility for the quality of the air/gas he or she breathes.

We would never accept a pint of blood for transfusion which has not been checked for Hep C or HIV, both blood borne pathogens which can cause fatalities, yet we blindly accept a tank of compressed air with a potential gaseous 'pathogen' and hope for the best in a hostile environment where if carbon monoxide contaminates the breathing air we are likely to drown. Hope is not the answer to this problem.

[IXΘYΣ]

... only diver-specific unit available is from Analox...

Nay, nay... see Oxycheq... and C-Squared...
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[swamp diver]

Nay, nay... see Oxycheq... and C-Squared...
><>

Sorry yes you are right. I had forgotten about that product which are one and the same. C-Squared is the manufacturer of the units which are then rebranded.

Now that I've had my morning coffee I recall Nuvair also has a unit on the market.
Nuvair - CO Alarm Analyzers

The one potential advantage of the Analox product is that eventually Analox claims they will have a network of service centers the world over which will offer a calibration service. All of these CO units require a calibration every six months or so and if one has to purchase the calibration gas and regulator that will add significantly to the cost of purchase ($200 to $300 depending on source). Instead once the Analox network is setup one would just send the unit back to them and they will look after the calibration for a fee.

[Texas Torpedo]

Working to find out where the tanks were filled. I'd be surprised if it was at Meridiano (where most of the dive ops get their tanks filled) considering they have CO Analyzers now installed there.. Not to mention the fact that I've heard no reports of open water divers become Ill, or worse, dead, during the same time period. One could deduce that multiple (maybe hundreds) of divers, some going deep, would be much more likely to succumb to the effects of CO poisoning than a short duration shallow cave dive.

I hope the tragic lesson here is to do what Don and a few others have been advocating for some time now... Always test your air! It's a small price to pay to stay alive..
Here is the best price I've found to date for the portable Amoxtec model:
Carbon Monoxide Analyzer discounts on sale Amoxtec

And for anyone diving deeper than 100 feet (anywhere), I recommend that you 02 test your "air" as well... I've come across a number of rental tanks where my tests showed a higher level of 02 than air...
This happens when a tank that previously had nitrox in it was topped off with air without emptying the the original contents. Chances are low anyone is going to get hurt diving within the recreational limits but I still want to know exactly what is in my tank..
Amoxtec O2EII Oxygen Analyzer discounts on sale Amoxtec

[WSOPFAN]

IANR33...Thanks for posting the report......another bad air tragedy........sad.