DECOMPRESSION CONTROVERSIES

[@The_NoBrainer]

I'm from Panama City and I have a story for this: "The navy divers were falling over themselves [to participate in the NEDU study]" - My SCUBA instructor was a retired Navy Dive Instructor. He has a tattoo on his calf of a rat wearing SCUBA gear with the caption "Sat Rat." I asked about it and he said he was part of study that gave him the bends, and he and his fellow participants all got commemorative tattoos. I just realized - THIS was the study he participated in, the NEDU study. The Navy divers who participated in that were so proud of their courage (I'm proud of them too) that they went out and got tattoos! I'm proud to have trained with one. Also excellent work as always, Dr. Mitchell. Your talks are always as informative as they are entertaining.

[@DANSouthernAfrica]

Thank you for sharing your experience and your support.

[@basementchemistry2334]

Dr. Simon Mitchell is such a fantastic presenter and a treasured resource to us all. To have a renowned and leading expert in hyperbaric medicine who is also an experienced and avid diver himself is valuable beyond measure to the entire diving community. This video is so incredibly useful, from building a basic knowledge of decompression theory to going into recent advances in our physiological understanding. It's all here. A well put-together presentation that is truly useful to all skill levels and experiences. Thank you sir!

[@DANSouthernAfrica]

Glad to know you enjoyed the presentation.

[@hiimpercy]

I don't dive and don't ever want to, and this was FASCINATING. I love this kind of in-depth analysis of life-threatening issues.

[@DANSouthernAfrica]

Glad you enjoyed it.

[@stanmoderate4460]

I'm 79 now and no longer dive but about 20 years ago my VR3 (latest technology at the time) got me bent following a deep dive on tri-mix, now I understand why!

[@mattg3191]

extremely interesting and informative! this gave me a better understanding of the Models used and clarified WHY deep stops don't appear to be beneficial. similar to another presentation, i can't believe no one has commented and thanked you for this presentation! all divers should watch this (especially Technical divers, rebreather divers and those interesting in Technical Diving). i appreciate this presentation very much! thank you!

[@DANSouthernAfrica]

Thank you for your feedback.

[@Acid741981]

Probably the best visualisation I have ever seen in a comparison of deco models! I wish there was a dive software available that gave you this exact output in your dive planning... You could arguably tinker around with your (GF-)settings until you are okay with the "graphic" of saturation you desire. What a wonderful tool that would be in decompression planning and informing yourself before the dive of what your different settings do to your tissues... I really hope someone comes up with something like this! Great work!

[@DANSouthernAfrica]

Thank you for your feedback.

[@snarf9455]

I am not even a diver (nor do i really aspire to be one) but listening to theese presentations is really interesting. It’s a pleasure to listen to a passioned professional talk.

[@DANSouthernAfrica]

Thank you for your positive feedback.

[@richardmooney8378]

This is a great presentation! Most divers don't get the differences in the compartments and their effects. The five minute compartment fills rapidly and limits a 100' air dive to 20 minutes. But it also off-gasses just as fast. Slower compartments fill more slowly and may not control the 100' dive, but they also off-gas more slowly. Simply put: This is why deep stops can be a problem.

[@DANSouthernAfrica]

Only a pleasure and thank you for sharing your insights.

[@nateelliot3759]

Very informative, well illustrated and explained! This answered so many questions I had on deco theory. Thank you!

[@DANSouthernAfrica]

Glad it was helpful!

[@scubaengineering]

Agreed with all conclusions at 39:42. The proceeding heat charts are fantastic in showing whats really going as to the cause of the DCS. The simple solution is to add 3 missing 'hyper fast tissues' into Buhlmann ZLH16 and and use this model to generate the dive profile and all will be good without having to use gradient factors to devine a model that actually works. Here's the tissues :- #1(t=1.1mins, m=2bars), #2(t=1.8mins, m=2.72bars), #3(t=3mins, m=2.94bars) Cheers.

[@DANSouthernAfrica]

Thank you for your feedback.

[@ATAtudeDiving]

Excellent talk. It could have done with a note on how gas choices might influence supersaturation under various profiles, as air dives dominated the discussion, but really a really good discussion.

[@DANSouthernAfrica]

The following article by the DAN America Team may offer some additional insights: www.ncbi.nlm.nih.gov/pmc/articles/PMC5351842/

[@mohamedamr875]

You just have to like Simon Mitchell :) Great presentation!

[@DANSouthernAfrica]

Thank you for your feedback.

[@DanielRicardo42]

This was the best explanation of deco models I've ever seen. Have there been any updates on the matter in the past 5 years since this talk? Where would one look for new publications in this field?

[@DANSouthernAfrica]

Good to know you enjoyed the lecture. Here is a YouTune link to consider kzbin.info/www/bejne/epuyqWShmK6lisU

[@HealthCareUndelegated]

Excellent, succinct statement of the physics of what is happening during compression at 6:40. Good enough for a five year old, good enough for me. :)

[@DANSouthernAfrica]

Thank you for your comment. Its good to know the lecture is still relevant.

[@alexandros8361]

Trouble is that the theory never fully worked like that for me. Getting 1st or 2nd degrees of bent seemed to relate far more to my emotional state on diving, seasickness, cold, dramas and traumas (fears, lost, tangled in guideline etc) than the depth involved. (on air to 30-55m). Best wishes. Dr Alex.

[@DANSouthernAfrica]

Thank you for your comment.

[@marcelohernandez7215]

What an impressive way of presenting a complex topic in a simple way. Thanks for sharing!!!!!

[@DANSouthernAfrica]

Glad you enjoyed the presentation.

[@subsurface3102]

Very interesting and informative talk. Thanks!

[@DANSouthernAfrica]

Good to know the lecture was helpful.

[@AndreiAstrakharchik]

Great presentation! Easy to follow and understand.

[@DANSouthernAfrica]

Wonderful!

[@welwellwell71]

Thanks very much, that was excellent. Easy to understand.

[@DANSouthernAfrica]

You are welcome!

[@12336992]

This is really useful info!!! Excellent presentation.

[@DANSouthernAfrica]

Thank you for the great comment!

[@mustanggun]

Very interesting, good info. Thank you

[@DANSouthernAfrica]

Glad it was helpful!

[@piradapearisc4496]

Can you explain more about how deep is shallow and deep stop in meters and how long should we wait until surfacing? Can we trust our dive com for each stop it tells us ? Excellent presentation indeed

[@robertcavoli4351]

Excellent video! Very informative.

[@DANSouthernAfrica]

Glad you enjoyed it!

[@AdamReidBSc]

This is brilliant! So many questions answered in an excellent and clearly presented way. I’ll try some dive plans based on GF50/75 and see if I like ‘em 😀

[@DANSouthernAfrica]

Thank you for your feedback.

[@pmiron]

Awesome presentation, I'm not an expert at all and could follow everything clearly!

[@DANSouthernAfrica]

Good to know your found the video helpful.

[@Igzanda135]

great presentation, super informative!

[@DANSouthernAfrica]

Glad you liked it!

[@adamfilipovich6553]

this is a fantastically interesting video. true science

[@DANSouthernAfrica]

Glad you think so!

[@quintindeboer2075]

Awesome presentation and well illustrated!

[@DANSouthernAfrica]

Thank you for your comment!

[@amgoldi]

What an excellent lecture! Thanks a lot!

[@DANSouthernAfrica]

Only a pleasure!

[@grp1294]

Lovely to hear you again Simon after your helpful advice back in 2012 re my son's lung problem!

[@DANSouthernAfrica]

Wow that is amazing! Thank you for your comment.

[@TnEEn]

very informative, thanks!

[@DANSouthernAfrica]

Thank you for your feedback.

[@Sombre____]

Great video. It demonstrate than trying to be smarter than the rules are not always a good idea.

[@DANSouthernAfrica]

Glad you enjoyed it!

[@thedarkplayer]

Excellent video and presentation.

[@DANSouthernAfrica]

Thank you kindly!

[@marcdennis6374]

Hello Simon. Thanks very much for the brilliant presentation.

[@DANSouthernAfrica]

Thank you for your comment.

[@Raphael_NYC]

Thank you. Raphael Santore

[@DANSouthernAfrica]

Only a pleasure!

[@johnchatterton4645]

Very well done, Simon. I provide this to my students, as part of their Basic Trimix training course.

[@DANSouthernAfrica]

Good to know that you are able to use the lecture for your students.

[@MrUdtabn]

fantastic vid much information how do i get a copy ?

[@DANSouthernAfrica]

You can use a tool to download it from You Tube or simply download it to your device using the mobile phone or tablet You Tube app.

[@funcionando]

Are there any kind of studies of this type (bülhman) for recreational divers profiles? Very very interesting indeed.

[@DANSouthernAfrica]

For a rather exhaustive review on Decompression the following article by Bruce Wienke may be useful: www.researchgate.net/publication/335368243_DOWNS_AND_UPS_OF_DECOMPRESSION_DIVING_A_REVIEW For a slightly less intimidating article, the following reference is recommended by the DAN Europe Team: www.ncbi.nlm.nih.gov/pmc/articles/PMC5610843/

[@seymourpro6097]

I'll suggest that the tables should ensure that the first stop is a decompression stop NOT a continuing absorption stop.

[@DANSouthernAfrica]

Thank you for sharing your opinion and experience.

[@nickieshadowfaxbrooklyn5192]

But alas deep stops give several times more frequent DCS and larger bubbles. I stick to shallow stops with the upper GF’s. Statistics is such. Btw, There were 11 DCS with bubble model, but that case was considered as inconsistent.

[@DANSouthernAfrica]

Thank you for your feedback.

[@tamarugodive]

Excelente presentación.

[@DANSouthernAfrica]

Good to know you enjoyed the lecture!

[@deepprey2776]

It seems like everyone wants that 1 magical answer that tells them what profile to dive. From my perspective there seems to be too many variables to nail down a “one size fits all” answer. It seems the best answer (at least to me) is to learn the model you use and stick with it. I’ve had older tec divers tell me they been using the same profile for 20 years and to not break what works.

[@DANSouthernAfrica]

Thank you for sharing.

nice presentation, thanks!!

[@DANSouthernAfrica]

Only a pleasure!

[@mattg3191]

Thank you so much for this presentation. Very interesting and informative. Definitely makes me want to stick with GCM over Bubble Models. I've watched this at least 3x

[@DANSouthernAfrica]

Thank you for your feedback.

[@karlmarx7450]

thanks a million

[@DANSouthernAfrica]

Only a pleasure!

[@dataf0rce]

Great overview! Is this still true today or are there already new studies suggesting/proofing otherwise? Is there a number telling us how many Tec Divers do use GF / VPM ?

[@DANSouthernAfrica]

The best review of the current analysis of PDE / DSL is summarised in the following article: www.ncbi.nlm.nih.gov/pmc/articles/PMC5610843/

[@rangerdanger9485]

Imo especially in the military decompression is simple u make ur stops at the proper depths for your body and the depth u dived def make sure u have enough fuel(air/oxy/helium/trimix/etc) def don’t dive alone if possible and def plan dives on the surface with plan abcd

[@DANSouthernAfrica]

Thank you for your feedback.

[@louis840]

Hi, at the end he says that he likes GF 50/75 ... but without saying for what deco gases ...?

[@Spacefish007]

Does the navy use gradient factors in their gas content models? Probably not right?

[@DANSouthernAfrica]

The Navy has been developing Wayn Gerth's probabilistic model of immediate vs. eventual decompression sickness: www.ncbi.nlm.nih.gov/pmc/articles/PMC5351842/. This article (abstract) addresses the issue: www.ncbi.nlm.nih.gov/pubmed/29161578

[@PaulAnthonyDuttonUk]

Am not a diver but the notion of fast tissue vs slow tissue rate absorption has been known for so long I can not for the life of me understand how the dive community could not see the issue with deep deco stops. It’s elementary and even surprised the navy chased the theory because it was an incomplete theory that surely could have been exposed by modelling known slow tissue deco profiles. Very strange.

[@DrFJCronje]

Hi Paul. Can I refer you a KZbin clip that may help a lot by David Doolette kzbin.info/www/bejne/pnmYq6qVm85oiKc. It is brilliant! Dr Frans Cronje

[@ReefPatrol]

great content...

[@DANSouthernAfrica]

Good to know you enjoyed the lecture.

[@InternationalScubaDiversClub]

This is just GREAT!

[@DANSouthernAfrica]

Thank you!

[@morleymichael]

44:25 - GF 50/75 -> 50/70

[@DANSouthernAfrica]

Thank you for your feedback and support.

[@sadrhogollsodia9505]

Could this be used in the development of drug delivery or treatment procedures?

[@DrFJCronje]

Inhalation therapies are used to deliver certain medications, but uptake makes the delivery a bit unpredictable and the exhaled gas still contains active medication which poses different challenges. Great question though. Dr Frans Cronje

[@timblomeke5249]

Thank you for uploading.

[@DANSouthernAfrica]

Only a pleasure!

[@adamrogers9386]

Am i the only one who is watching this and then all of a sudden my left ear gets blocked rofl

[@uncatila]

I'm working on the jab deco tables. We must cut down on clotting.

[@DANSouthernAfrica]

Thank you for your comment.

[@elliottoppenheim9871]

If you dive deeper than 40m, recreational dept, listen and learn.

[@DANSouthernAfrica]

Thank you for your feedback and support.

[@frankdieber7090]

I can’t believe theirs no discussion on this!

[@DANSouthernAfrica]

Thank you for your feedback and support.

[@HealthCareUndelegated]

I'm afraid the # of forum hits alone is not a relevant metric for determining the popularity of anything. Much like the number of pages Google serves up in response to any given key phrase: it is simply not indicative of anything by itself. Most sites don't track "hits" anymore for this reason. More than half of that traffic is robotic anyway.

[@DANSouthernAfrica]

Not sure what to make f this comment.

[@qubei]

You should turn off comments instead of deleting them (assuming that's happening because there's 48k views and 0 comments). Please do it to stop people wasting their time commenting.

[@DANSouthernAfrica]

No comments are deleted... unless bad language is associated with a comment.

[@johnmilsom2179]

Nope way toooo much talk………KISS theory mate

[@DANSouthernAfrica]

Thank you for your feedback.