Holding breath for 15 minutes

[Humuhumunukunukuapua'a]

Actually, breathing 100% O2 doesn't give you a big boost.

Hmm...I'll not argue the science because I don't know it well enough, but people are able to hold their breath MUCH longer after breathing pure O2. That's a fact...

 

[rawls]

I read an article (cant find it now) that said people have been able to hold their breath for up to 15 minutes using a special technique. I believe the technique went like this : 20 deep breaths breathing normal air, then 20 breaths using 100% O2.

I cant find the article, so heres my questions. Does anyone know why this technique would increase breath-hold time? Is it possible for blood to become super saturated with oxygen?

I know its recommended that free-divers do not breath nitrox or pure O2 before diving. Why?

Twenty deep breaths...Can you say shallow water black out

 

[picksmither]

"Twenty deep breaths...Can you say shallow water black out"

Nope, because you'll already be unconscious.

~JMP

 

[Amphibious]

www.deeperblue.net.

I hate the shameless advertising, but if you guys want to stay current with Freediving related records and such you should really spend some time on DB.

haha, and the Idiot about that said freediving records have nothing to do with time, whew! hahahaha good one!

 

[freediver]

Twenty deep breaths certainly wouldn't necessarily mean immediate or subsequent blackout. The twenty breaths could be perceived as a slow and deliberate breathe up. It doesn't exactly say that it is twenty hyperventilations. I think of a hyperventilation as exhaling with enough force to blow out several candles. My breathe up consists of 3-5 minutes (12-20 breaths) of deep breathing to ventilate and fully oxygenate my lungs.

 

[John C. Ratliff]

Twenty deep breaths certainly wouldn't necessarily mean immediate or subsequent blackout. The twenty breaths could be perceived as a slow and deliberate breathe up. It doesn't exactly say that it is twenty hyperventilations. I think of a hyperventilation as exhaling with enough force to blow out several candles. My breathe up consists of 3-5 minutes (12-20 breaths) of deep breathing to ventilate and fully oxygenate my lungs.

I don't think you understand the mechanism for shallow water blackout. Nor do the people who posted above.

If you are breathing the twenty breaths of air, you are blowing off CO2, and not increasing the oxygen content of the air. By blowing off CO2, you have lowered your resistence to shallow water blackout, as the "must breath" signal to your brain comes from a buildup of CO2, and not from oxygen depletion. If your "must breath" signal comes after the oxygen has reached a critical level, you could black out.

This happens in two ways. One is straightforward, as mentioned above. You blow off so much CO2 that you can overcome the "must breath" signal and continue holding your breath until you essentially die. This typically happens in pool, with underwater swimming competitions.

Or you can hold off the urge to breath at depth until, with the lessening pO2 in the lungs as you ascend, the oxygen actually reverses and goes from your circulation to your lungs due to the pressure change. When this happens, the diver typically blacks out about 10 to 15 feet under the water. That is why the older generation of breathhold divers would take off their weight belt and hold it on the way up if they had pushed the limits. That way, if we did black out, then we would drop the weight belt and attain the surface through the positive buoyancy.

Now, if the person blows off the CO2 with twenty deep breaths, then uses oxygen for twenty breaths, there is little danger of blackout from lack of oxygen, and the "must breath" signal has been postponed. This would lead to longer underwater times. But pure oxygen is a respiratory irritant, and there can be some problems with long-term breathing of oxygen, which is why is is limited in recompression chambers at to specific times (which I've now forgotten). But this is in the several hours long exposure.

SeaRat

 

[freediver]

I don't think you understand the mechanism for shallow water blackout. Nor do the people who posted above.


SeaRat

Yes, actually I do and I will re-post what I did some time ago.
Here is a bit of clarification in terms that I have researched and found from some of the experts in freediving physiology. There are three different types of blackout associated with the sport of freediving. They are:

SHALLOW WATER BLACKOUT -- a state of unconsciousness preceded by carbon dioxide retention. Unconsciousness strikes most commonly within 15 feet (five meters) of the surface. This is generally what happens to the person that swims long horizontal distances as the CO2 builds up in the body.

BREATH-HOLD BLACKOUT -- a state of unconsciousness preceded by the gradual onset of hypoxia; risk is compounded by hyperventilation or increased (shallow) underwater activity. Generally occurs to those that are practicing static breath holds.

ASCENT BLACKOUT -- a state of unconsciousness preceded by sudden onset of hypoxia during ascent; risk is compounded by hyperventilation or increased (shallow) underwater activity. This is what most refer to as Shallow Water Blackout. It is actually termed Ascent Blackout as the diver ascends and, upon expansion of the lungs, vital O2 is taken away from the brain and utilized by the lungs. A rapid ascent may increase likelihood as well as exhalation on ascent. Unlike Scuba, exhalation during the entire ascent is not stressed. It is only within the final 5m - 8m that the diver should start to exhale.

Now for the other..... it appears that there is confusion between twenty deep breaths and hyperventilation. I'm unclear why you are saying that twenty deep breaths is purging CO2 (hyperventilation). I can take twenty deep breaths here at my computer without the intent of blowing off excessive CO2. The distinction would be the deliberateness in the exhalation. If I take 20 deep breaths with the sole intent of purging the CO2 then I must exhale forcefully (again the candle analogy). This will suppress my urge to breath and, yes we agree, this is not a wise thing to perform.
If you observe any knowledgeable and experienced freediver, you will likely notice that he/she is doing a slow, deliberate breathe up that may last for several minutes.
As far as my pre-dive preparation, I breathe deeply utilizing my diaphragm. Using the diaphragm ensures that you are using your lungs fully and not just the upper lobes (shallow chest breathing). This is what I meant by saying that I fully ventilated and oxygenated my lungs. I am getting oxygen to the lower areas that are sometimes left out. I did not mean to imply that I was saturating my lungs with O2.
I do understand the mechanisms involved in blackout and I agree with most of your descriptions.
I think we simply disagree on exactly what it takes to get there.

 

[picksmither]

I believe that you are both right. The confusion must lay in how long it takes to do 20 deep breaths. That many breaths during an hour is under ventilation, that many breaths during a minute is over ventilation. That many breaths over the right amount of time could be a good pre-dive ventilation.

It seemed from the context of the original "20 breaths" post that he was talking short term. This is all that I at least was referring to.

It's a good description to suggest trying not to blow out a candle with your exhale, gives a good breathing pace. Then it just depends on how long you keep that pace. Thanks for the suggestion. Dive safe...

~JMP

 

[John C. Ratliff]

Yes, actually I do and I will re-post what I did some time ago.
Here is a bit of clarification in terms that I have researched and found from some of the experts in freediving physiology. There are three different types of blackout associated with the sport of freediving. They are:

SHALLOW WATER BLACKOUT -- a state of unconsciousness preceded by carbon dioxide retention. Unconsciousness strikes most commonly within 15 feet (five meters) of the surface. This is generally what happens to the person that swims long horizontal distances as the CO2 builds up in the body.

Actually, according to Terry Maas in Blue Water Hunting and Freediving, "Shallow-water blackout is the sudden loss of consciousness caused by oxygen starvation. Unconsciousness strikes most commonly within 15 feet (five meters) of the surface, where expanding, oxygen-hungry lungs literally suck oxygen from the diver's blood." (page 49) This is the mechanism I'm talking about.

BREATH-HOLD BLACKOUT -- a state of unconsciousness preceded by the gradual onset of hypoxia; risk is compounded by hyperventilation or increased (shallow) underwater activity. Generally occurs to those that are practicing static breath holds.

This is not a term I recognize.

ASCENT BLACKOUT -- a state of unconsciousness preceded by sudden onset of hypoxia during ascent; risk is compounded by hyperventilation or increased (shallow) underwater activity. This is what most refer to as Shallow Water Blackout. It is actually termed Ascent Blackout as the diver ascends and, upon expansion of the lungs, vital O2 is taken away from the brain and utilized by the lungs. A rapid ascent may increase likelihood as well as exhalation on ascent. Unlike Scuba, exhalation during the entire ascent is not stressed. It is only within the final 5m - 8m that the diver should start to exhale.

This is the definition of Shallow-Water Blackout, above. From what I can tell, some new terms have been invented here. These are not the definitions I have learned from the past.

Now for the other..... it appears that there is confusion between twenty deep breaths and hyperventilation. I'm unclear why you are saying that twenty deep breaths is purging CO2 (hyperventilation). I can take twenty deep breaths here at my computer without the intent of blowing off excessive CO2. The distinction would be the deliberateness in the exhalation. If I take 20 deep breaths with the sole intent of purging the CO2 then I must exhale forcefully (again the candle analogy). This will suppress my urge to breath and, yes we agree, this is not a wise thing to perform.

You don't "try" to exhale CO2; it simply happens whenever we breath, and the deeper we breath, the more we exhale it. By blowing off CO2, we think we can extend underwater times by not recognizing the "must breath" signals that CO2 causes in our brain. In fact, all we are doing in getting closer to the point of blackout.

If you observe any knowledgeable and experienced freediver, you will likely notice that he/she is doing a slow, deliberate breathe up that may last for several minutes.
As far as my pre-dive preparation, I breathe deeply utilizing my diaphragm. Using the diaphragm ensures that you are using your lungs fully and not just the upper lobes (shallow chest breathing). This is what I meant by saying that I fully ventilated and oxygenated my lungs. I am getting oxygen to the lower areas that are sometimes left out. I did not mean to imply that I was saturating my lungs with O2.
I do understand the mechanisms involved in blackout and I agree with most of your descriptions.
I think we simply disagree on exactly what it takes to get there.

Actually, what we disagree on is the "slow, deliberate breathe up that may last for several minutes..." This is again decreasing the CO2, and can precede a shallow-water blackout event. What I use is a bit different, and involves a conditioning period of 20 to 30 minutes to allow my body to adapt to breathhold diving. I take a maximum of three deep breaths, but do it on a cycle of diving until I am uncomfortable, then surfacing for a set time (usually one or 1.5 minutes) and diving again. My time underwater steadily progresses from the 30-45 second range to 1:15-1:45 minute range during this time (and I'm no longer in "my prime"). I have in the past extended that time to three minutes too, and done it without hyperventilation. Here is what Terry Maas recommends in the above-mentioned book (page 56):

--Do not hyperventilate to excess--no more than three or four breaths.

--Recognize that any strenuous exercise will limit your bottom time drastically; when you exercise, head for the surface much sooner than usual.

--Recognize a dangerous situation when your mind starts to focus on a goal, and drop your weight belt.

--Treat your weight belt as a disposable item; if in doubt, drop it. Bring a spare weight belt to deccrease your hesitancy to drop it.

--Avoid endurance dives. If you must make a long or deep dive, make sure you have a biddy standing by on the surface.

--Adjust your weight belt so that you will float at 15 feet.

--Consider a swimming pool a dangerous place to practice endurance breath-holding. Always have an observer standing by to assist.

--Learn the basics of CPR and think about adapting them to your diving arena, whether diving from shore, board or boat.

SeaRat

 

[John C. Ratliff]

These are interesting papers:

Ascent exhalations of Antarctic fur seals: a behavioural adaptation for breath-hold diving?

Hooker SK, Miller PJ, Johnson MP, Cox OP, Boyd IL.

Sea Mammal Research Unit, University of St Andrews, Fife KY16 8LB, UK. s.hooker@st-andrews.ac.uk

Novel observations collected from video, acoustic and conductivity sensors showed that Antarctic fur seals consistently exhale during the last 50-85% of ascent from all dives (10-160 m, n > 8000 dives from 50 seals). The depth of initial bubble emission was best predicted by maximum dive depth, suggesting an underlying physical mechanism. Bubble sound intensity recorded from one seal followed predictions of a simple model based on venting expanding lung air with decreasing pressure. Comparison of air release between dives, together with lack of variation in intensity of thrusting movement during initial descent regardless of ultimate dive depth, suggested that inhaled diving lung volume was constant for all dives. The thrusting intensity in the final phase of ascent was greater for dives in which ascent exhalation began at a greater depth, suggesting an energetic cost to this behaviour, probably as a result of loss of buoyancy from reduced lung volume. These results suggest that fur seals descend with full lung air stores, and thus face the physiological consequences of pressure at depth. We suggest that these regular and predictable ascent exhalations could function to reduce the potential for a precipitous drop in blood oxygen that would result in shallow-water blackout.

PMID: 15734689 [PubMed - indexed for MEDLINE]

------------------------

[Breath-hold diving--an increasing adventure sport with medical risks]

[Article in Swedish]

Lindholm P, Gennser M.

Sektionen for omgivningsfysiologi, institutionen for fysiologi och farmakologi, Karolinska institutet, Stockholm.

Breath-hold diving as a recreational and competitive sports activity is on the increase. In this review physiological limitations and medical risks associated with breath-hold diving are discussed. Specific topics include hypoxia, ascent blackout, hyperventilation, squeeze or barotrauma of descent including effects on the pulmonary system, glossopharyngeal breathing, and decompression illness. It is also concluded that the health requirements for competitive breath-hold diving should follow essentially the same standards as used for SCUBA-diving.

Publication Types:
Review

PMID: 15045843 [PubMed - indexed for MEDLINE]

-------------------

So apparently there is a term called "ascent blackout" in the medical literature. I stand corrected.

SeaRat