Will http://www.ncbi.nlm.nih.gov/pubmed/25525213 change deco procedures?

[Agility]

I wonder whether anyone will adapt the Bühlmann algorithm for Trimix diving?

 

[PfcAJ]

There's a great thread about this over on CCRExplorers with people like Simon Mitchell and David Doolette chiming in.

 

[tursiops]

There's a great thread about this over on CCRExplorers with people like Simon Mitchell and David Doolette chiming in.

Yeah, it is an interesting thread, particularly for the egos and group dynamics, but the study the OP quoted is 30 years old, so it seems like any effect is was going to have has pretty much already taken place.

ADDED: My date was wrong. It is a 2015 publication. (It was the journal that began in 1985....). I apologize for any confusion caused.

 

[PfcAJ]

wait 30 years old? wat?

Doolette (one of the authors) was in highschool 30 years ago! That can't be right!

Edit: according to the internet its a late 2014 study published in 2015.

 

[tursiops]

wait 30 years old? wat?

Doolette (one of the authors) was in highschool 30 years ago! That can't be right!

Edit: according to the internet its a late 2014 study published in 2015.

You are correct! My bad. My REALLY bad. I read the wrong date in the citation when i went to the publication.
Sorry for any confusion.

 

[boulderjohn]

Here is the link in clickable form: Altering blood flow does not reveal differences between nitrogen and helium kinetics in brain or in skeletal miracle in sheep. - PubMed - NCBI

There's a great thread about this over on CCRExplorers with people like Simon Mitchell and David Doolette chiming in.

Can you provide a quick summary of your impressions?

 

[PfcAJ]

Here is the link in clickable form: Altering blood flow does not reveal differences between nitrogen and helium kinetics in brain or in skeletal miracle in sheep. - PubMed - NCBI



Can you provide a quick summary of your impressions?

In a nutshell

1 - You might need the longer deco that the 'helium penalty' gives you (maybe even more), but not because of the helium, but because longer and deeper dives (where you're apt to use helium) carry a higher % of DCS risk.
2 - For a given gradient factor setting, decompression profiles are not iso-risk across depth and time combinations.
3 - Common deco algorithms aren't great on very long and/or very deep dives.

 

[Agility]

In a nutshell

Thank you for the summary.
I wonder how to set a DC for the correct gases but honoring the longer time He takes according to this study.

 

[JohnnyC]

I wonder how to set a DC for the correct gases but honoring the longer time He takes according to this study.

Read this again.

"1 - You might need the longer deco that the 'helium penalty' gives you (maybe even more), but not because of the helium, but because longer and deeper dives (where you're apt to use helium) carry a higher % of DCS risk."

Note the words helium penalty are in quotes, as the study is showing that the required decompression obligation (which probably isn't long enough) is due to the length and depth of the dive. The helium is incidental in that you're more likely to use helium on these types of dives, not that the helium content is the cause for the extended decompression obligation. Basically, for years we've been blaming helium, when really it's just the length and depth of the dive.

 

[PfcAJ]

Read this again.

"1 - You might need the longer deco that the 'helium penalty' gives you (maybe even more), but not because of the helium, but because longer and deeper dives (where you're apt to use helium) carry a higher % of DCS risk."

Note the words helium penalty are in quotes, as the study is showing that the required decompression obligation (which probably isn't long enough) is due to the length and depth of the dive. The helium is incidental in that you're more likely to use helium on these types of dives, not that the helium content is the cause for the extended decompression obligation. Basically, for years we've been blaming helium, when really it's just the length and depth of the dive.

This exactly. Our deco algorithms (probably) don't prescribe enough deco time on long/deep dives, and maybe over prescribe on shorter/shallower dives.