Apnea, vasoconstriction, and dynamics

[Will]

Eric, your B-value is 4 (B-value basically equates to the weight of your body in water with completely deflated lungs: LV=0).
With the neckweight you have a B-value of about 6, same as me.
For B = 4 FRC has lower buoyancy related energy costs for depths up to 40m. For greater depths, or for B=6 (neckweight) inhale diving is more energy efficient.
I will explain myself better and upload the formulas etc tonight.
Buoyancy loss: this can be experimentally tested in dives to 80%max with something as simple as a fish weigher. Could be a project for Sharm.

 

[wet]

No matter how you configure it just don't stack-up! Its probably no coincidence that a variety of animals have been found E-diving. These include: seals (Scholander 1940), sea-otters (Snyder 1983), sea-snakes (Murdaugh & Jackson 1962), alligators (Andersen 1961), and a variety of diving-birds (Eliassen 1960; Ross 1976; Tome & Wrubleski 1988; Sato et al. 2002). Seb

Seb, I'm including this reference to insects (no lungs) to consider what happens when too much oxygen is a problem. I know it's not directly relevant, but just as background. DDeden

Tim Bradley of UC Irvine in Nature Feb 3 (2005?)
Many ants, grasshoppers, moths close their respiration airholes that
line the sides of their bodies to avoid over-oxygenating. Their breathing systems are so efficient that resting insects must close their spiracles to avoid overdosing on O2 [parallel to E-dive?]. Studies of a pupal moth indicate internal O2 remains same even when surrounded by higher concentrations of oxygen. Spiracles lead to branching trees of internal airways that let in oxygen for fueling metabolism 200,000 times as fast as a mammals blood vessels do, and remove CO2 10,000 times as fast. Some lung fish and amphibians also do stop-and-start breathing.

 

[trux]

No matter how you configure it just don't stack-up! Its probably no coincidence that a variety of animals have been found E-diving. These include: seals (Scholander 1940), sea-otters (Snyder 1983), sea-snakes (Murdaugh & Jackson 1962), alligators (Andersen 1961), and a variety of diving-birds (Eliassen 1960; Ross 1976; Tome & Wrubleski 1988; Sato et al. 2002).

Yes, also Galapagos Marine Iguanas (no amphibians, originally land animals that started to dive of necessity when searching for food) dive with empty lungs. I saw it in an old documentary of J-J. Cousteau and was quite amazed seeing them diving over 20m and up for an hour with empty lungs (that was the first time I heard about E-dives). Another amazing moment was when they measured the heart rate of the Iguanas, and it stopped completely for several tens of seconds. They thought the animal was dead, but it then woke and swam to the surface (from 20m, additinally towing all the cables they attached to him)

There are plenty of [ame="http://www.google.com/search?num=100&hl=en&lr=&rls=GGLD%2CGGLD%3A2004-26%2CGGLD%3Aen&q=galapagos+marine+iguana&btnG=Search"]articles and documents about Marine Iguanas on the web[/ame]. For example this one could be of an interest: [ame="http://www.princeton.edu/~wikelski/Publications/2002JEB205.pdf"]The relationship between heart rate and rate of oxygen consumption in Galapagos marine iguanas (Amblyrhynchus cristatus) at two different [/ame][ame="http://www.princeton.edu/~wikelski/Publications/2002JEB205.pdf"]temperatures[/ame] (PDF), or [ame="http://compphys.bio.uci.edu/BENNETT/pubs/23.pdf"]this PDF document[/ame] containing several references to scientific articles about heart rate and oxygen consumption at these animals.

 

[Fondueset]

Just subscribing to this beauty.

I have no problem getting tense

 

[naiad]

Tim Bradley of UC Irvine in Nature Feb 3 (2005?)
Many ants, grasshoppers, moths close their respiration airholes that
line the sides of their bodies to avoid over-oxygenating. Their breathing systems are so efficient that resting insects must close their spiracles to avoid overdosing on O2 [parallel to E-dive?]. Studies of a pupal moth indicate internal O2 remains same even when surrounded by higher concentrations of oxygen. Spiracles lead to branching trees of internal airways that let in oxygen for fueling metabolism 200,000 times as fast as a mammals blood vessels do, and remove CO2 10,000 times as fast. Some lung fish and amphibians also do stop-and-start breathing.

Interesting. I have noticed that many animals such as fish and amphibians do not breathe continuously. Obviously animals such as seabirds, seals and otters do not breathe continuously when they are diving, but maybe on land they do the same. I noticed that penguins have a different way of breathing from similarly sized land birds. They breathe much deeper and slower, even when they are resting out of the water.

I don't know if this is relevant to anything, but when I have been training a lot I often catch myself not breathing. I am not usually holding my breath, but just passively not breathing in after exhaling. It happens when I am relaxed, and most of all when I have just been doing static training. I don't know how long it is most times, but I once timed it for about a minute, and there was no urge to breathe.

Maybe an explanation here...
[ame="http://forums.deeperblue.net/showthread.php?p=511520#post511520"]Compensated respiratory alkalosis[/ame]

 

[wet]

Some links of possible interest:
Diving & the lung: mammalian pulmonary surfactants
http://thesis.library.adelaide.edu....-SUA20050815.120303/public/02chapters1-3.pdf\
http://tinyurl.com/ralle
(page 148-152 has charts comparing human to other mammals)

(These 2, I forget the specifics but might relate)
http://darwin.wcupa.edu/~biology/fish/pubs/pdf/2000PBZ-PlatToWhale.pdf
http://www.archaeocete.org/EAT 2005 Abstracts.pdf
DDeden

 

[Will]

There is an interesting debate between Italian professors that specialise in medicine for apnea diving at the apnea academy forum regarding the cause of pulmonary oedema (blood spitting) in freediving.
Does anyone know a value for the compliance of pulmonary capillaries?
Seb, do you have the references handy for:
- the amount of nitrogen & oxygen absorbed into blood during a freedive
- lung expansion-induced hypocapnia during the final part of the ascent

 

[trux]

There is an interesting debate between Italian professors that specialise in medicine for apnea diving at the apnea academy forum regarding the cause of pulmonary oedema (blood spitting) in freediving.

There was a similar discussion here at DB in this thread not a long time ago:
[ame="http://forums.deeperblue.net/showthread.php?t=66867"]http://forums.deeperblue.net/showthread.php?t=66867[/ame]

 

[wes]

Great thread!! Don't know if this fits in though found it interesting. An Emergency room doc recently told me that people with emphysema (usually from smoking too much) that have a very hard time breathing eventually loose the urge to breath from C02 as thier inefficient breathing always leaves them with high residual C02 so their bodies become numb to it. The urge to breathe is from a lack of oxygen not build of of C02. He said that when treating them in the emergency room if you give them 100% oxygen they take one breath and then stop breathing as they have plenty of O2. This bothers the docs so they give them a mix of O2 with high levels of C02 so they breathe more and fully oxygenate themselves better. This numbing to CO2 build up could explain the benfits of C02 training and also the lack to breathe after training that I have experienced also (though never measured). Cheers Wes

 

[naiad]

That is interesting. It probably happens to freedivers who do lots of hard CO2 training. A few days ago, after a few dry statics, I found myself passively not breathing for at least 2 minutes, I didn't time it from the beginning.

 

[sebastien murat]

Will,

I'm presently in transit through Europe/Mid-East and do not have access to my references which are probably on their way to Singapore on a container ship for the next 2 months.

Pulmonary capillary wall rupture is unlikely. Check refrences by West, as well as Lin. The problem is more about a lack of compliance in some divers resulting in leakage, but not rupture. The squeeze could either be due to and inadequate or excessive blood shift.

Amount of N2 absorbed always less than O2. Amount absorbed related to descent speed, depth time, cardiac output, pulmonary capillary blood volume, [Hct], alveolar-capillary wall thickness. Most important is the promptness and strength of the DR during descent.

Lung-expansion induced (relative) hypocapnia is related to ascent speed (actually deco. rate). This stuff is purely from my own research and modelled from some observations made by Luft, hesser & Bjurstedt in the 1940s regarding explosive (high altitude) decompression (which is equivalent, in terms of pressure change, to shallow-water decompression. Consequently, you wont find a reference for it as it has not previously been considered as a potential cause of SWB.


Cheers
Seb

 

[Will]

Many thanks Seb, this is a big help. I will see you in 12 days when I arrive in Dahab (if you are stil there?)
Will

 

[sebastien murat]

Will,

In Sharm late today (7th) ... out on the 14th...sadly, it doesn't look like we'll catch-up.

S

 

[Schmalensee]

A tight suit can prevent pooling of (venous) blood in the extremities but it cannot cause peripheral arterial vasocosntriction. For that you'd need a tourniquet.

Have anybody here ever tried to use a tourniquet for a maximal attempt DNF/CNF and are there any disadvantages that could affect the performence negative except of hypoxi in your legs/arms. Are there any rules against it?

By the way a very interesting debate, first time for me at deeperblue and I´m really impressed. People here unlike other forums really refers from reliable sources, seems to be a whole lot of smart people here, wish I were one of them.

 

[efattah]

My friends and I have hypothesized for years about using a 'band' around the thighs or arms to impede blood flow.... however we still have not tried it yet...

I did (for a while) do apnea stairmaster with thigh-blood-pressure cuffs around my thighs. My legs certainly got tired very fast.

 

[shoutatthesky]

Welcome Schmalensee,

I think you find that these guys (Will and Sebastien) are saying vasoconstriction is a good thing. In fact Sebastien is well known for his theories regarding enhancing the Diving Reflex of which vasoconstriction is one part. They are talking about things that might interfere with that beneficial process.
Maybe some reading about FRC diving would help?
http://forums.deeperblue.net/general-freediving/40688-mammalian-diving-reflex-just-romanticism.html

 

[DeepThought]

Welcome aboard Schmalensee.
I will never use a tourniquet for diving but the idea interest me. Anyone has medical info on the risks involved (such as blood clots)?

 

[alix.leclerc]

Does anyone know of any experiments conducted into peripheral vasoconstriction in human freedivers? I'm finding it hard to find data for my experiment...

 

[trux]

Well, there is plenty of documents written on the topic. If you are searching in Google, maybe you need to be more specific. However most of the scientific documents are usually available only in the form of an abstract on the web, so you may need to have access to academic library if you want to get the full text.

I have some documents related to vasoconstriction listed in the Freediving Media Base, but the list available online is much longer - it takes time to sort through them, and add them into the database. However, already those documents listed may be a good starting point - each of the documents usually has a long list of references attached in the appendix.

vasoconstriction @ APNEA.cz

Also, as usually at physiologic questions, I recommend registering at the forum of the World Freediving Medical Association and asking your questions there.

WFMA @ APNEA.cz

 

[alix.leclerc]

thats fantastic! I actually couldn't find the right info on google at all. these are much more helpful.

Thank you again