lamont
Contributor
Crazy Fingers:
i don't know if it specified... have to google them up again...
...
i think they may have been in the www.iucrr.org collection of incident reports...
Oxygen toxicity and air diving depth records
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i don't know if it specified... have to google them up again...
...
i think they may have been in the www.iucrr.org collection of incident reports...
ianr33
Contributor
O.K Here is an incident from Cavediver.net An O2 hit (probably)after 45 minutes at 1.6
"O2 hit at 150 ffw
I debated whether or not to report this incident, but decided that the importance of relaying the information is more important than any future embarrassment that may result.
The short story is that I am guilty of one of the most dangerous behaviors that can result in a diver with more than 1,000 lifetime dives -- complacency. I did a dive where the PO2 hovered around 1.6 for about 40 minutes, at which point I developed oxygen toxicity. Thanks to me not losing my head and my quick-thinking buddy, I survived the episode.
We were doing a simple mainline dive in a system that we had been in before, but not with doubles. I was sidemounting with 28.3% in one 95 and 28.4% in the other. My buddy was diving with 20/17 trimix in his backmounted 104s. The cave we were diving drops quickly down a slope to 150 feet, where the ceiling stays at for the next 800 feet or so of penetration. My buddy lead the way in and kept up a rather brisk pace. I swam a tad faster than I would have preferred, but didn't feel too worked out. In hindsight the slightly extra resulting CO2 buildup more than likely contributed to the O2 hit.
We reached a huge room where the line continued over a large breakdown pile that rose to 120 feet. We were about 20 minutes into the dive and for the past 15 minutes or so my computer had been beeping and display 1.6 or higher PO2s. A combination of "not a problem for me" and complacency caused me to just ignore it.
I signaled to end the dive, as I didn't want to rack up too much deco and this seemed like a great stopping point (even though we had not hit thirds yet). We turned and I was now in the lead on the exit.
I kept up a fairly good pace, so as to again limit our deco. Even though we went upstream, this was a low-flow cave and riding out the current wasn't an option. We swam back towards a minor restriction that signals the transition from the slope that dumps into the 150 ft ceiling when I started to have trouble breathing.
It seemed that no matter how hard I tried, with each breath it got more and more difficult to breathe. I was scared, but didn't panic (thank God!). Gasping, I managed to turn and give the "out of air" signal to my buddy. He's a great buddy, who had already heard the strange breathing and when I turned he already had his long hose deployed, ready for me. I switched from my 28% side gas to his 20% (of O2) trimix and instantly was able to breathe easier and completely.
I took a moment to compose myself and re-establish that we were still right on the line. I OK'd my buddy and we proceeded to negotiate the minor restriction and start a slow ascent to his 80% deco gas, waiting at 40 feet. All the time I was shivering, 1/2 from the cold and 1/2 I'm convinced from a mild case of shock having survived a close call.
At 40 feet I began to trust my own gas again (since the PO2 was now low) and handed back my buddy's long hose reg. We then started our deco, within arm's reach of each other. The original plan was for me to breath my 100% deco bottle at 20 and above, while he deco'd on his 80%. I asked if we could switch so that I could continue the decompression with a lower PO2. He agreed and, after reprogramming the VR3 to reflect the different deco gas mix (the VR3 rocks) we proceeded to do our 30-40 minute deco, slowly moving up the gradient.
In hindsight I was damn lucky and thankfully didn't panic when a true "out of air" emergency presented itself. At 150 feet the gas I had was toxic and I was effectively out of air. Since we turned with more than 2/3rds left he had plenty of gas to donate. The actual incident only lasted a few minutes and luckily it wasn't complicated by loss of line or visibility. Neither of us resorted to panic or near panic behavior that could have added those complications.
I am amazed at a number of things, though. Why did I have the "difficulty in breathing" symptom? I didn't get any of the other typical O2 toxicity symptoms (the "CVENTID" ones) and especially thankfully didn't convulse. It felt like what is described in diving medical literature as the chokes, but that's a severe (usually fatal) decompression symptom as bubbles literally bubble out of the alveoli. Also curious was the immediate relief I experienced when switching from the > 1.6 PO2 gas at depth to the trimix. Gas never tasted so good. Perhaps it wasn't an O2 hit, but switching to the lower PO2 cured me quick.
Chagrined and mollified, I got a solid smack in the face of being too complacent. Nobody is immune from diving maladies. Ironically my symptoms hit right when the NOAA O2 exposure said they should -- 45 minutes at 1.6. I'll be sure to stay at 1.4 or below from now on and will spend the extra bucks for trimix when the conditions demand it. "
"O2 hit at 150 ffw
I debated whether or not to report this incident, but decided that the importance of relaying the information is more important than any future embarrassment that may result.
The short story is that I am guilty of one of the most dangerous behaviors that can result in a diver with more than 1,000 lifetime dives -- complacency. I did a dive where the PO2 hovered around 1.6 for about 40 minutes, at which point I developed oxygen toxicity. Thanks to me not losing my head and my quick-thinking buddy, I survived the episode.
We were doing a simple mainline dive in a system that we had been in before, but not with doubles. I was sidemounting with 28.3% in one 95 and 28.4% in the other. My buddy was diving with 20/17 trimix in his backmounted 104s. The cave we were diving drops quickly down a slope to 150 feet, where the ceiling stays at for the next 800 feet or so of penetration. My buddy lead the way in and kept up a rather brisk pace. I swam a tad faster than I would have preferred, but didn't feel too worked out. In hindsight the slightly extra resulting CO2 buildup more than likely contributed to the O2 hit.
We reached a huge room where the line continued over a large breakdown pile that rose to 120 feet. We were about 20 minutes into the dive and for the past 15 minutes or so my computer had been beeping and display 1.6 or higher PO2s. A combination of "not a problem for me" and complacency caused me to just ignore it.
I signaled to end the dive, as I didn't want to rack up too much deco and this seemed like a great stopping point (even though we had not hit thirds yet). We turned and I was now in the lead on the exit.
I kept up a fairly good pace, so as to again limit our deco. Even though we went upstream, this was a low-flow cave and riding out the current wasn't an option. We swam back towards a minor restriction that signals the transition from the slope that dumps into the 150 ft ceiling when I started to have trouble breathing.
It seemed that no matter how hard I tried, with each breath it got more and more difficult to breathe. I was scared, but didn't panic (thank God!). Gasping, I managed to turn and give the "out of air" signal to my buddy. He's a great buddy, who had already heard the strange breathing and when I turned he already had his long hose deployed, ready for me. I switched from my 28% side gas to his 20% (of O2) trimix and instantly was able to breathe easier and completely.
I took a moment to compose myself and re-establish that we were still right on the line. I OK'd my buddy and we proceeded to negotiate the minor restriction and start a slow ascent to his 80% deco gas, waiting at 40 feet. All the time I was shivering, 1/2 from the cold and 1/2 I'm convinced from a mild case of shock having survived a close call.
At 40 feet I began to trust my own gas again (since the PO2 was now low) and handed back my buddy's long hose reg. We then started our deco, within arm's reach of each other. The original plan was for me to breath my 100% deco bottle at 20 and above, while he deco'd on his 80%. I asked if we could switch so that I could continue the decompression with a lower PO2. He agreed and, after reprogramming the VR3 to reflect the different deco gas mix (the VR3 rocks) we proceeded to do our 30-40 minute deco, slowly moving up the gradient.
In hindsight I was damn lucky and thankfully didn't panic when a true "out of air" emergency presented itself. At 150 feet the gas I had was toxic and I was effectively out of air. Since we turned with more than 2/3rds left he had plenty of gas to donate. The actual incident only lasted a few minutes and luckily it wasn't complicated by loss of line or visibility. Neither of us resorted to panic or near panic behavior that could have added those complications.
I am amazed at a number of things, though. Why did I have the "difficulty in breathing" symptom? I didn't get any of the other typical O2 toxicity symptoms (the "CVENTID" ones) and especially thankfully didn't convulse. It felt like what is described in diving medical literature as the chokes, but that's a severe (usually fatal) decompression symptom as bubbles literally bubble out of the alveoli. Also curious was the immediate relief I experienced when switching from the > 1.6 PO2 gas at depth to the trimix. Gas never tasted so good. Perhaps it wasn't an O2 hit, but switching to the lower PO2 cured me quick.
Chagrined and mollified, I got a solid smack in the face of being too complacent. Nobody is immune from diving maladies. Ironically my symptoms hit right when the NOAA O2 exposure said they should -- 45 minutes at 1.6. I'll be sure to stay at 1.4 or below from now on and will spend the extra bucks for trimix when the conditions demand it. "
Crazy Fingers
Contributor
lamont:
Although I didn't find them, this is a really good link. The statistics of cave diving deaths are quite interesting... It looks like if you carry at least 2 backup lights and use a damn guildeline and your risk drops dramatically! Although that surely doesn't make it s-a-f-e.
- Messages
- 22,171
- Reaction score
- 2,790
- # of dives
- 5000 - ∞
I suspect that's the telling point. With high CO2 all bets are off.ianr33:
lamont
Contributor
Crazy Fingers:
yeah, i don't think that was it. there's another link to tech diving fatalities which has multiple oxtox incidences in it but i didn't turn it up quickly in google. one of them was the oxtox rescue on the monitor, some of the other ones were low ppO2 ones (possibly that cavediver.net incident).
There are several good articles on the DAN wesite about OxTox.
The following link is to an article that addresses some of the issues raised in this thread:
http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=35
I suspect the Navy divers discussed in the various studies were young and in excellent shape.
The following link is to an article that addresses some of the issues raised in this thread:
http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=35
I suspect the Navy divers discussed in the various studies were young and in excellent shape.
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