

Raising the Dead (2005) - Tomte
http://www.outsideonline.com/1922711/raising-dead

======
jdietrich
For anyone interested in this article, I would recommend this documentary
about Dave Shaw's last dive.

[https://www.youtube.com/watch?v=rTlmJeP2Cr0](https://www.youtube.com/watch?v=rTlmJeP2Cr0)

~~~
dvdkhlng
Thanks for sharing. Following the comments on youtube and the wikipedia page
[1] I found this scientific analysis [2] about probable causes of the
accident. My layman summary: rising pressure of respired gas at high depth
(about 26 atmospheres at the bottom) increases the respiratory resistance both
in the diver (lungs, larynx) and the diving equipment. There is a limit to
exhaled volume flow-rate called "effort independent flow" where compression of
air-ways due to exhalation keeps air-flow from increasing further. This limit
lies at lower flow-rates when breathing high-pressure gas. Physical exertion
causes increased CO2 production by the diver which needs to be matched by
correspondingly increased air-flow for CO2 removal. Once point of effort-
independence is reached, lots of respiratory effort is wasted, contributing to
further CO2 production. This causes a downward spiral of increased CO2
accumulation in the diver that could only be broken by switching to
alternative breathing equipment that reduces respiratory effort (i.e. open-
circuit gear).

Seems that close-circuit diving equipment is generally more risky to use [3]
due to difficult to detect and non-correctible failure modes.

[1]
[https://en.wikipedia.org/wiki/David_Shaw_%28diver%29](https://en.wikipedia.org/wiki/David_Shaw_%28diver%29)

[2]
[http://www.ingentaconnect.com/content/asma/asem/2007/0000007...](http://www.ingentaconnect.com/content/asma/asem/2007/00000078/00000002/art00001)

[3]
[https://en.wikipedia.org/wiki/Rebreather_diving#Risk](https://en.wikipedia.org/wiki/Rebreather_diving#Risk)

