Fatal dive accident - Lake Werbellin, Germany

[DandyDon]

Why is ppo decreasing faster then ppco? This doesnt make sense to me, can you please explain?

As I mentioned, CO binds to hemoglobin with an affinity 250 times greater than that of oxygen. As you descend, the pressure causes increases in both, and as you ascend, decreases in pressure allow for the release of both, but with the great binding of CO that release is much slower. It's a wicked trap, but your only hope.

I also experienced CO poisoning for sure at the house. First the CO alarm went off. But by that time my mind was not working properly and I could not make the connection between the alarm and possibly elevated CO levels. I then became sleepy. When I started to get a headache, I finally figured out wat was going on. We probably would have died without the CO monitor.

That was a close one. One of the complications of CO poisoning is that it dulls your mind so some self training and discipline are needed. Hear an alarm? Leave first, think about it later. My old home dive bud had CO alarms save him from his fireplace at home and his shop heater as his vacuum cleaner store, but most stores don't have CO alarms. It's geeky, but I wear my Sensorcon CO on my cargo pants everywhere.

Searching carbon monoxide on google news any week can give several scary stories. This week a young south Texas boy with cerebral palsy crawled to his parents' room to wake them when he was the only one who heard the CO alarm. Perhaps they need more than one CO alarm. I like one for every bedroom, one near a heater, one near a fireplace, etc. I have a reminder on my phone to test all Smoke and CO alarms on the first of every month.

 

[abnfrog]

in the autopsy they will detect quantity of co2 or co

 

[Catito]

That was my thought while hopefully awaiting information. Max depth of 125 feet, OOG at 20 feet, both Instructors. Impossible in normal circumstances.


Not hardly.


CO binds to hemoglobin with an affinity 250 times greater than that of oxygen at one atmosphere. At depth, the increase of PPCO increases the bonding, but that varies with the rate of CO in the tanks, then ascending releases PPO faster than the release of PPCO so that toxicity increases rapidly so you become trapped in the cycle. The actual effects can vary greatly. People die asleep in bed from CO poisoning every week, year-round.

Empty tanks would make post-accident tests of tank air challenging if not impossible.


Don't miss my comment immediately above.


What were their blood carboxyhemoglobin test results at the hospital?

Did they test their tanks for CO before diving? Either they did or they dived on hope.


So do you check every tank now or just risk it?

Dan:

Update us please. Best device for measuring whether there is a dangerous level of CO in a tank?

 

[DandyDon]

Dan:

Update us please. Best device for measuring whether there is a dangerous level of CO in a tank?

Various products have come and gone in recent years, probably because most divers don't want to spend a few hundred dollars on a device that they shouldn't have to buy if all fill stations ran CO inline testers with auto-shutoff. Very few do tho.

CHEAPEST: Portable Carbon Monoxide Detector Meter (CO Inspector) used with gallon zip lock bags. Skill is needed in capturing a quart or two of tank air with the unit on and inside without sucking in outside air. Some have developed kits that blow tank air into the unit but I think the pressure gives false positives. Pack the unit inside the bag, carry to the tank, capture tank air, seal, and wait a few minutes. Use a new bag each day as they develop leaks.

EASIEST: Nuvair – DE-OX CO Analyzer – Aquarius Scuba or Palm CO Carbon Monoxide Analyzer.

WORTHLESS: Any unit costing less than $100. Household units don't measure in the minute amounts we need to measure. I tried the Pocket CO at first but it was very problematic. Color-changing papers give only vague indications.

READINGS: All tanks should test at zero, and it gets boring testing tank after tank until you find your first bad one, then it all makes sense. If I find 2 or 3 or even 5 ppm and I am confident that I did a good test, I'll probably dive the tank but send a stern message to the dive op owner. If I get 10 or more, nope! If I get 50 or more, I'd secure the tank, report to any authorities, call news media, hire a lawyer, and anything else I could do to make trouble.

CALIBRATIONS: Frequent celebrations are a challenge for professional air testing labs, but I think all of the current units have software that makes those less important. It's worth calling to talk with the manufacturer's engineer.

 

[Curious_George]

Agree with Dandy, test every tank. Doubly important for anyone using a gas powered compressor. Just standing near the compressor engine when it’s running will periodically exceed 50ppm depending on the odd gust of wind. 50ppm at 4atm is 200 ppm right?

Also true that in some instances one can get false positives if too much pressure across the sensor while using the sensorcon. I worry about making mistakes diving but with CO, you don’t know you made a mistake until it’s too late.

Cheap insurance compared to the cost of the hobby.

 

[DandyDon]

Doubly important for anyone using a gas powered compressor.

Yes, but fill stations running on electricity are not exempt from CO risks. Any overheated compressor can burn its own lubricating oil.

This is at best a hypothetical discussion tho. As usual, we don't know if these two instructors bothered to test their tanks, if their empty tanks could still be tested for CO and were, or any results on their blood gases postmortem.

 

[Dan]

50ppm at 4atm is 200 ppm right?

Concentration does not change under pressure. Partial pressure does.

 

[Johnoly]

.... results on their blood gases postmortem.

CO blood gas tests in autopsy very rapidly degrade in time after death. Even at 1-2 hours, the half life results degrade at 50% or more considering variables. It's generally considered completely unreliable in a death investigation. An MRI on the brain to indicate CO damage also is almost never done in autopsy since the time delay results are wildly variable and unreliable. As you have always said, the gold standard is test the actual air source or you may never know if CO was one of the critical links in the accident chain of events.
{speculation>>} Very unusual accident but I would strongly suspect arterial gas embolism in just one of the divers who was most likely in full blown panic ascent resulting from the other diver's unknown at depth emergency. Only if a family member reading this chooses to publish the dive computer profiles here, will a probable cause be determined. Given that 2 people's bodies' don't react exactly the same to CO, and at the exact same time duration would make it a low probability IMHO{\speculation}

 

[KevinNM]

Why is ppo decreasing faster then ppco? This doesnt make sense to me, can you please explain?

At sufficient depth (which I forget but isn’t super deep) oxygen will be dissolved into your plasma as well as being carried by you RBCs. This works to get oxygen to your cells. But as you ascend that stops working and your cells can’t get enough oxygen.

It’s part of why hyperbaric oxygen treatment is used for CO poisoning, though apparently it doesn’t work as well as you might hope.

 

[Angelo Farina]

During the period I was working as a professional instructor and dive master (1985 to 1989) in resorts of the leading tour operator Club Vacanze here in Italy and at Maldives I was often in charge of the filling station (also being an engineer with a Ph.D. In Applied Physics).
We were equipped with a complex gas analysisis system based on Draeger hand pump and glass tubes:
https://www.draeger.com/en-us_us/Products/Short-term-Tubes?s=255
We had to run an analysis with 5 different tubes, including CO, CO2, humidity, hydrocarbures, etc.
Each batch of cylinders had to be tested (not each cylinder).
As this was the standard mandatory procedure back in the eighties, I did assume that every filling station is routinely doing the same since then. I think it would be criminal not doing so.