Lowest SAC possible ? (without being dead)

[mech]

thanks man

 

[Charlie99]

IThe reasons that I asked was in one of my tech classes the instructor talked about N2testing/loading and how it applied in the real world.
One thing that he mentioned was that the local tech boat skipper is a freaking freak when it comes to SAC.
After a dive (while on the boat) they did testing.
Skipper was way spiked with N2 and the concenses was he needed to breath more because he was loading up.
Would not a freakishly low SAC spike the N2 a person is retaining?
Andy

Interesting. I haven't heard of any method of "N2testing/loading" to determine that someone was "way spiked with N2". Could you fill us in on the details?

BTW, you and your instructor DO understand that the conventional wisdom is that if you are underbreathing that you will have a tiny, tiny bit less N2 absorbed than when breathing normally. Right? (The reason is that the higher ppCO2 in your lungs means that ppN2 is lower. High CO2 is a bad thing for other reasons, but it does mean ppN2 is lower).

 

[mech]

Hi Charlie,
I believe that test is called "ultra sound" but I could be mistaken.
I do understand your second part about the ppC02 slightly reducing the ppN2 during slow breathing,but to be honest with you I'm not sure how that would pertain to or effect the test result.
The way I see it you would do extra loading of both N2 and Co2 with extream slow breathing.
By no means does a couple classes make me an expert.
I asked Fred because I wanted to know more.
Andy

 

[Charlie99]

"ultrasound" aka "doppler" testing simply looks for bubbles in the veins. Doesn't test N2 loading. Whether or not you have venous bubbling is a combination of your loading and your ascent profile. You can find some interesting test results at https://www.daneurope.org/eng/lettmed1.htm which show the "doppler" results of various ascent profiles. Pick any of the many articles with "Asymptomatic Circulating Venous Gas Emboli" in the title.

No study that I have seen show low SAC correlated with high bubbling. There is a small correlation in the other direction --- heavy exertion leads at depth leads to increased blood circulation, leads to increased N2 loading. Uwatec attempts to compensate for this by making their computer deco model go more conservative when it detects increased breathing. (i.e. High breathing rate implies exertion, which means higher loading).

Charlie Allen

p.s. I have more than just an academic interest in the relationship between SAC and DCS. Although nothing compared to Fred's SAC, I run towards the low side. For example, this mornings dive was 2:07, 41' max, 22' average on 3100 to 400 psi on an AL80. About 0.62 cu ft per minute actual consumption at depth, or 0.37cfm SAC.

 

[Derek S]

Pondfrog, among others, has dived with me. I do not think he would describe my diving as 'passing for dead'. I lead dives, every day (give or take a few bad weather days) Leading means, among other things, I stay ahead of divers. This is also not 'passing for dead'.

When I met/dove with Fred last October, Hurricane Wilma had just come strollin' through a few days earlier, and on our dives, Fred was leading, being just as active or more active than the rest of us. On every dive he was doing what he could to help repair some of the damage that Wilma had done to the reefs, ect.

It honestly doesn't matter to me if Fred's SAC is 0.001 or 1.11, he is a great diver, and an even better person. If he says his SAC is 0.15, I believe him.

I look forward to reading your book Fred, having even more great conversation, learning a bunch and diving again this October! :14:

 

[Tavi]

...........[snip]..................

See you on Saturday Fred!!

Mike Rushton
PADI DM 174448

Wish I could say that!!

 

[teknitroxdiver]

I know a DM in the BVI, Kevin J***s, who can get 2 'real' dives out of a 63. And he smokes.

 

[Diver0001]

I did some meditation and relaxation exercises this morning and monitored my respiration rate. I discovered that a sustained respiration rate of 3-4 breaths per min isn't only realistic, it isn't even particularly difficult. I don't know if I could apply it on a dive unless conditions were ideal and I spent some time preparing myself before submerging but the idea that someone somewhere *can* do it is suddenly much more believable to me.

To be perfectly honest, I'm a little surprised about this outcome. I'm not a super athlete but I did KungFu for about 10 years so I know how to meditate. I figure if *I* can do this, then with a little practice anyone can.

Incidentally, I feel great right now. I should do this every morning... LOL

R..

 

[TSandM]

It's great preparation for standing on the table and screaming, huh, Rob?

 

[rockjock3]

It honestly doesn't matter to me if Fred's SAC is 0.001 or 1.11, he is a great diver, and an even better person. If he says his SAC is 0.15, I believe him.
QUOTE]

I don't care who is who I believe nothing that I read and only half of what I hear. On the other handI have heard more than enough first hand accounts as to Fred's SAC rate and I am good to my word.

My most humble apologies Fred I can only hope that I can one day breath a tank down like you. Best of luck with your book as well.