4 ms·

Yeah, the "no-limits" with weights/bags is very dangerous. After a 240m/800ft free-dive, Herbert Nitsch had severe decompression sickness and needed a hyperbari

Yeah, the "no-limits" with weights/bags is very dangerous. After a 240m/800ft free-dive, Herbert Nitsch had severe decompression sickness and needed a hyperbaric chamber[1]. I thought AIDA stopped tracking WRs for it because of the absurd risk, but all I can find is that they stopped doing competitions for it, though the article is dated 2011[2]. At least if you swim yourself down, you have time to listen to your body. Note that these depths are absolutely insane for anything an ambient SCUBA diver would do, even for many technical saturation divers. If you want an actual breathing gas mix for that depth, using a mix of hydrogen, oxygen, and helium[3] may be the safest way (too much helium can cause HPNS). [1]: https://web.archive.org/web/20121105083822/http://www.deeperblue.com/herbert-nitsch-receiving-treatment-after-failed-record-attempt https://web.archive.org/web/20121105083822/http://www.deeper... [2]: https://gulfnews.com/uae/a-limit-on-no-limits-freediving-1.827009 https://gulfnews.com/uae/a-limit-on-no-limits-freediving-1.8... [3]: https://en.wikipedia.org/wiki/Hydreliox https://en.wikipedia.org/wiki/Hydreliox

mannykannot 2y ago
Until reading the first article, I was unaware that one could get decompression sickness from free diving. The Wikipedia article on this dive also says that Nitsch passed out from nitrogen narcosis (and specifically not oxygen starvation) towards the end of the ascent, something else that I was unaware of being a risk (not that I have any intention of trying deep free diving.) https://en.wikipedia.org/wiki/Herbert_Nitsch#Later_attempt_and_serious_injury https://en.wikipedia.org/wiki/Herbert_Nitsch#Later_attempt_a... With regard to the hydreliox mix, I see it has a scant 0.8% oxygen, and needs to be less than 5% to avoid having an explosive mixture. Even the latter figure, I think, would lead to hypoxia in most people at atmospheric pressure, so I imagine these ratios are adjusted with pressure, and probably that these mixtures are only used in saturation diving.
- nradov 2y ago
  Don't believe everything you read. While an extremely high PPN2 can cause unconsciousness due to narcosis, it wouldn't be possible to definitively identify that as the cause. There could have been something else going on physiologically. Hydreliox has only been used in a few experimental or scientific dives, mostly with saturation procedures but at least once by cave divers. (It's possible that militaries could have done some secret dives as well.) https://indepthmag.com/hydrogen-dreamin/ https://indepthmag.com/hydrogen-dreamin/
  - mannykannot 2y ago
    > While an extremely high PPN2 can cause unconsciousness due to narcosis, it wouldn't be possible to definitively identify that as the cause. In a later post, I wondered (without any particular reason to think it might be so) whether the decompression sickness Nitsch experienced was manifest in neural tissue, and now I am wondering whether this 'nitrogen narcosis' was an early instance of the strokes which occurred during his treatment for that decompression sickness.
2-3-7-43-1807 2y ago
you're confusing something. as your thread sibling explains you cannot get the bends if you're not breathing. he got the bends from aborting the descent, requesting oxygen at that point from a scuba diving regulator and then ascending too fast (while breathing). the too fast ascent of course was medically correlated with why he aborted the free dive.
- nick238 2y ago
  There wasn't any aborting of the dive, it went to plan going down and back up, until he blacked out during ascent at 100 m ("I lost consciousness due to narcosis (a first in free diving)"). The rescue divers surfaced him as he was unconscious, and then he asked for oxygen (presumably 100%) to do some (emergency) decompression at 10 m for 20 min. Here's a statement from the guy: https://www.deeperblue.com/herbert-nitsch-talks-about-his-fateful-dive-and-recovery/ https://www.deeperblue.com/herbert-nitsch-talks-about-his-fa... Red Bull—naturally—also produced a whole movie about the thing: https://www.youtube.com/watch?v=lcrz2YNBAw8 https://www.youtube.com/watch?v=lcrz2YNBAw8
  - 2-3-7-43-1807 2y ago
    i stand corrected. so, one can get dcs even from free diving. i guess it makes sense considering the extreme depth and pressure. given that 80% of his last breath is nitrogen eventually enough will diffuse into the tissue and accumulate to cause dcs.
- mannykannot 2y ago
  >...you cannot get the bends if you're not breathing. Whether you are breathing is not fundamentally the issue - what matters is what gases you have in your lungs, under what pressure, and for how long. If you have nitrogen in your lungs, it will diffuse into your bloodstream, and thence to tissues, until the partial pressures are equalized. This is not normally a problem for free divers - even most deep free divers - because the combination of time and pressure are not great enough, but it seems that Nitsch might have crossed a line here. I tried doing a back-of-envelope calculation to see if this seemed plausible. No-decompression limits in dive tables for air breathing bottom out at 5 minutes at about 60 m, and while the depth cutoff is presumably set by nitrogen narcosis and/or oxygen toxicity, it is clear that nitrogen absorption is quickly reaching the bends-risk level (for comparison, this dive reached a depth of 253m and lasted about 4 1/2 minutes.) There are several factors to be taken into consideration. Firstly, Nitsch's lungs would have been considerably collapsed at depth, and so presumably less-effective at gas transfer. secondly, dive tables are conservative. On the other hand, though, they are based on the tissues in which the diffusion is slowest (if it was effectively instantaneous, there would be no risk of the bends on ascent) and assume the diver is ascending slowly even when they are not taking decompression stops, so maybe in Nitsch's case, the problem arose in different, faster-diffusing tissue (neural tissue?) than that on which the tables are based. Given all this, I'm inclined to believe Nitsch's own claim that he had a case of decompression sickness from this dive.

mannykannot 2y ago

Until reading the first article, I was unaware that one could get decompression sickness from free diving. The Wikipedia article on this dive also says that Nitsch passed out from nitrogen narcosis (and specifically not oxygen starvation) towards the end of the ascent, something else that I was unaware of being a risk (not that I have any intention of trying deep free diving.) https://en.wikipedia.org/wiki/Herbert_Nitsch#Later_attempt_and_serious_injury https://en.wikipedia.org/wiki/Herbert_Nitsch#Later_attempt_a... With regard to the hydreliox mix, I see it has a scant 0.8% oxygen, and needs to be less than 5% to avoid having an explosive mixture. Even the latter figure, I think, would lead to hypoxia in most people at atmospheric pressure, so I imagine these ratios are adjusted with pressure, and probably that these mixtures are only used in saturation diving.

nradov 2y ago
Don't believe everything you read. While an extremely high PPN2 can cause unconsciousness due to narcosis, it wouldn't be possible to definitively identify that as the cause. There could have been something else going on physiologically. Hydreliox has only been used in a few experimental or scientific dives, mostly with saturation procedures but at least once by cave divers. (It's possible that militaries could have done some secret dives as well.) https://indepthmag.com/hydrogen-dreamin/ https://indepthmag.com/hydrogen-dreamin/
- mannykannot 2y ago
  > While an extremely high PPN2 can cause unconsciousness due to narcosis, it wouldn't be possible to definitively identify that as the cause. In a later post, I wondered (without any particular reason to think it might be so) whether the decompression sickness Nitsch experienced was manifest in neural tissue, and now I am wondering whether this 'nitrogen narcosis' was an early instance of the strokes which occurred during his treatment for that decompression sickness.

2-3-7-43-1807 2y ago

you're confusing something. as your thread sibling explains you cannot get the bends if you're not breathing. he got the bends from aborting the descent, requesting oxygen at that point from a scuba diving regulator and then ascending too fast (while breathing). the too fast ascent of course was medically correlated with why he aborted the free dive.

nick238 2y ago
There wasn't any aborting of the dive, it went to plan going down and back up, until he blacked out during ascent at 100 m ("I lost consciousness due to narcosis (a first in free diving)"). The rescue divers surfaced him as he was unconscious, and then he asked for oxygen (presumably 100%) to do some (emergency) decompression at 10 m for 20 min. Here's a statement from the guy: https://www.deeperblue.com/herbert-nitsch-talks-about-his-fateful-dive-and-recovery/ https://www.deeperblue.com/herbert-nitsch-talks-about-his-fa... Red Bull—naturally—also produced a whole movie about the thing: https://www.youtube.com/watch?v=lcrz2YNBAw8 https://www.youtube.com/watch?v=lcrz2YNBAw8
- 2-3-7-43-1807 2y ago
  i stand corrected. so, one can get dcs even from free diving. i guess it makes sense considering the extreme depth and pressure. given that 80% of his last breath is nitrogen eventually enough will diffuse into the tissue and accumulate to cause dcs.
mannykannot 2y ago
>...you cannot get the bends if you're not breathing. Whether you are breathing is not fundamentally the issue - what matters is what gases you have in your lungs, under what pressure, and for how long. If you have nitrogen in your lungs, it will diffuse into your bloodstream, and thence to tissues, until the partial pressures are equalized. This is not normally a problem for free divers - even most deep free divers - because the combination of time and pressure are not great enough, but it seems that Nitsch might have crossed a line here. I tried doing a back-of-envelope calculation to see if this seemed plausible. No-decompression limits in dive tables for air breathing bottom out at 5 minutes at about 60 m, and while the depth cutoff is presumably set by nitrogen narcosis and/or oxygen toxicity, it is clear that nitrogen absorption is quickly reaching the bends-risk level (for comparison, this dive reached a depth of 253m and lasted about 4 1/2 minutes.) There are several factors to be taken into consideration. Firstly, Nitsch's lungs would have been considerably collapsed at depth, and so presumably less-effective at gas transfer. secondly, dive tables are conservative. On the other hand, though, they are based on the tissues in which the diffusion is slowest (if it was effectively instantaneous, there would be no risk of the bends on ascent) and assume the diver is ascending slowly even when they are not taking decompression stops, so maybe in Nitsch's case, the problem arose in different, faster-diffusing tissue (neural tissue?) than that on which the tables are based. Given all this, I'm inclined to believe Nitsch's own claim that he had a case of decompression sickness from this dive.