Can freediving cause DCS?

[immerlustig]

hi,

i'd like to know what these AIDA tables are based on?

bubbles are forming due to increased ascent rates. a freediver will always be ascending faster than a scuba diver (>10-15m/min or 0.16-0.25 m/s) therefore there will be bubbles forming (what's regarded as a slow freedive ascent? 0.5-0.8 m/s?). when symptoms are being felt (or measurable) is a different thing, though. sooner or later the saturation (depth/time) is great enough to lead to dcs symptoms. playing with surface intervalls, breathing o2, etc will only delay the onset of symptoms, reducing the risk but not eliminating it. people can go deeper or dive repetitively more often without symptoms and that is obviously already fantastic.

what i don't quite understand is why dcs1 is occuring. i would have thought that is very unlikely.

anyhow, that's my understanding of the process. if i'm wrong or missed something please enlighten me. i had dcs on 3 different occasions so far, doing repetitive as well as deep dives.

cheers

 

[Lobo Marino]

Re: freedive cause bend?

This is not correct. I got bent 8 times while freediving and every single one was a type 1 hit.

After years of experiments, the primary factor in my hits was the ascent rate. A dangerous ascent speed is much more likely with a monofin, and in my opinion it is much easier to get bent when using a mono.

I was able to avoid DCS by controlling my ascent rate to less that 1.0m/s, with an additional reduction to 0.5m/s in the last 10m. Even better is a short apnea deco stop at 6m, but this can increase the risk of blackout.

For me, I found that with a very fast ascent (1.35m/s), it would take just two 40m dives to get a small type 1 hit.

The worst hit I ever had was in late 2005, during a wall diving session (30m, 44m, 48m, 51m, 30m, 32m). I ended up in the chamber on Navy Table 6 for several hours. Symptoms: tingling & numbness in fingers & toes, extreme unbelievable fatigue and weakness, pain in elbows, wrists, knuckles, and clouded thinking.

Thanks for sharing the information.
I was thinking that type 1 DCS like pain in the joints was linked to slow compartments and therefore rare with freediving but was wrong.
where this dives that get you bend Deep Hangs ?
By the way aren´t tingling ,numbness in fingers and fatigue or clouded thinking the symptoms of a possible type 2 DCS (or even AGE) ?
(involving nitrogen bubbles in the blood stream and/or neurological/nervous system DCS)

UKDivers.net - Decompression Sickness
[ame="http://en.wikipedia.org/wiki/Decompression_sickness"]Decompression sickness - Wikipedia, the free encyclopedia[/ame]

 

[efattah]

I never do deep hangs due to the DCS risk, and none of the time I got DCS was during deep hangs.

During my chamber day, all dives were around 2'10" in length with approximately equal ascent and descent times, and a short bottom time of about 5-7 seconds.

Another time I got bent on the Chaudiere wreck, I did 9 dives, 24-38m in depth, average dive 2'44", average interval 6'30", longest dive 3'35" at 24m.

In 2001 I did two 71m dives with a 12 minute interval, no DCS. But, I was ascending much more slowly due to tired legs. In many cases of deep diving, tired legs actually save the life of the diver because they limit the ascent rate.

If people say I'm 'susceptible' to DCS, they should consider that I was ascending (most likely) far faster than most people anyway. Very few people ascend at 1.3m/s, and I don't recommend it.

 

[Mullins]

How did you manage a 1.3m/s ascent rate - were they variable weight dives or were you deliberately sprinting? Just checked and I was doing 1.1 - 1.2m/s in the last 20m of those VW spearfishing dives.

 

[trux]

Recently I have found many interesting documents about DCS at freediving, and added them to my database. Some of them are quite interesting. Unfortunately, some of them are not available free in full text, but already the abstracts show some interesting facts and conclusions. Others are available in full extent on the web. Check them out here: DCS @ APNEA.cz

The document about detection of nitrogen saturation through tear film bubbles may be of a big interest for any deep freedivers.

I was also surprised by the freediving DCS/barotrauma mortality claim in the document eMedicine - Decompression Sickness : Article by Stephen A Pulley, because before that I did not hear about any DCS or barotrauma fatality at freediving:

(separating mortality data for DCS from those for barotrauma is impossible. One study reported that pathologists demonstrated little knowledge of diving accidents while performing autopsies and missed the more subtle diving injuries)

In the breath-hold free-diving group, fatalities have steadily increased worldwide over the past decade to 22 in 2004. Note that only 5 or less were related to free-diving competitive activities, either training or competition. Most fatalities were during snorkeling, spear fishing, or collecting of marine specimens.

 

[unobreath]

DCS.
How you get bent is unknown. It usually happens when your tissues are saturated with nitrogen and off gassing is not done properly i.e. missed deco stops or omitting decompression all together. relying on your computer to let you know you are still in no d limits when in fact you aren't. technology can sometimes fail resulting in injuries, but it is mostly human error. overdoing your limit, over diving your rig, wrong air mix. a number of factors can go into how or why or what causes dcs, A.G.E. and other diving related injuries.

who is immune and who is not is based on genetics. this is why when diving you may get bent but your buddy doesn't yet you have the same dive profile. There are guys at NEDU (navy experimental diving unit) that just can't get bent (within a realm of somewhat safe diving).

DSC may be possible from freediving but I have never treated anyone for dcs or any other diving related injury because of spearfishing or freediving.

Im sure it is possible and has happened but it is just not likely.

anytime you descend into a world we are not meant to be in, the risks become apparent. If we were meant to breathe under water then we would have gills. So dive safe and dive responsible. knowledge can be your greatest ally or your worst enemy.

 

[trux]

Im sure it is possible and has happened but it is just not likely.

I am not sure if you have read the previous posts, wisdoms of those who already got bent, and/or the documents linked earlier here in the thread. Apparently, DCS at freediving (including accidents, and even fatalities) is much more likely than most freedivers admit, and it does not concern only extreme sled performances as some may believe.

As for the mechanism of DCS at freediving, it is described in the documents linked above. Of course, basically it is quite similar to scuba, but there are some factors at freediving that are not usual at scuba: i.e. high alveolar pressures, rapid changes of intrapulmonary pressures from high positives (packing) to negatives and back again, often amplified by involuntary diaphragm contractions, rapid ascent velocities, high physical effort during ascent, repetitive dives, and more. All that contributes to a risk that cannot be evaluated only based on experience gained from scuba diving.

I highly recommend studying the available documents before doing the conclusion that DCS at freediving is unlikely!

 

[unobreath]

I am not sure if you have read the previous posts, wisdoms of those who already got bent, and/or the documents linked earlier here in the thread. Apparently, DCS at freediving (including accidents, and even fatalities) is much more likely than most freedivers admit, and it does not concern only extreme sled performances as some may believe.

As for the mechanism of DCS at freediving, it is described in the documents linked above. Of course, basically it is quite similar to scuba, but there are some factors at freediving that are not usual at scuba: i.e. high alveolar pressures, rapid changes of intrapulmonary pressures from high positives (packing) to negatives and back again, often amplified by involuntary diaphragm contractions, rapid ascent velocities, high physical effort during ascent, repetitive dives, and more. All that contributes to a risk that cannot be evaluated only based on experience gained from scuba diving.

I highly recommend studying the available documents before doing the conclusion that DCS at freediving is unlikely!

Even after reading a few of the posts and links, I still would say it is unlikely to get DCS from breath hold diving. I live in Hawaii and there are quite a few freediver's and spearo's here and not once have I ever treated a person that had gotten DCS from freediving, or even heard of it here or anywhere for that matter. Im not saying that it cannot happen but still as the ratio to people who freedive and the few that have gotten DCS over the last 10 or 20 years I would still say that it is unlikely. But that is my opinion and I am entitled to it. I am sure in a few of these cases if not most they are not giving all the information to why they got bent.

As to my experience... it is not based on scuba diving. I hold some of the highest certifications for surface supplied diving, rebreathers, recompression chambers, and scuba. I am the person you come to see when you get bent.

 

[Mullins]

So you think it will be fine for me to do 4x80m CW dives in a row with brief intervals? DCS still 'unlikely'?

There are plenty of freedivers around these days who could easily get themselves bent if they were not cautious about surface intervals and # of repetitions. If you haven't come across any DCS incidents, it is probably because you haven't dealt much with this group of freedivers.

 

[billieball]

I know of cases whereby it would be wise to monitor one's nitrogen loading when freediving and SCUBA diving in the same day. My handy dandy freediving/mixed gas Oceanic Geo dive computer even shows a hypothetical buildup of nitrogen in my tissues after repetitive deep freedives...all to err on the side of caution, I am quite sure. That being said, in my studies it would appear that DCI/DCS is improbable during freediving excursions. Sure, it could happen. It just isn't an issue I would waste too much time worrying about.

 

[unobreath]

So you think it will be fine for me to do 4x80m CW dives in a row with brief intervals? DCS still 'unlikely'?

There are plenty of freedivers around these days who could easily get themselves bent if they were not cautious about surface intervals and # of repetitions. If you haven't come across any DCS incidents, it is probably because you haven't dealt much with this group of freedivers.

What if's are just not practical. I dont know what your body can handle and what it can't. There are super human freaks out there that can omit 2 hours of decompression and not get bent. then you have a normal person who does the same things and they spend the next three weeks in a recompression chamber for serious type 2 DCS.

I asure you I have dealt with a lot more then I care to tell.

 

[chrismar]

I know of cases whereby it would be wise to monitor one's nitrogen loading when freediving and SCUBA diving in the same day. My handy dandy freediving/mixed gas Oceanic Geo dive computer even shows a hypothetical buildup of nitrogen in my tissues after repetitive deep freedives...all to err on the side of caution, I am quite sure. That being said, in my studies it would appear that DCI/DCS is improbable during freediving excursions. Sure, it could happen. It just isn't an issue I would waste too much time worrying about.

It may not be something we all need to stress about, but it*is* something that top spearos and freedivers should worry about, on every trip. Dave's example above is something that he would be physically capable of (probably!), but could never do because of the massive DCS risk. Heck, even the way Dave spearfishes would put some people at DCS risk! He's far from the only one too; plenty of top guys are capable of getting DCS and some have actually done it.

In fact, a little while ago at least a couple of spearos ended up in chambers after a spearing comp. I'm sure someone else has more details on that incident.

 

[Mullins]

What if's are just not practical. I dont know what your body can handle and what it can't. There are super human freaks out there that can omit 2 hours of decompression and not get bent. then you have a normal person who does the same things and they spend the next three weeks in a recompression chamber for serious type 2 DCS.

Given this, it seems a bit unwise to suggest DCS is unlikely. An "I don't know" sounds much more accurate?

Also, it's not a 'what if'. That example is quite a similar to how I would actually be training were I not worried about DCS risk. I'm going to train CW this weekend - would you suggest I tried it? I hope not.

 

[unobreath]

It may not be something we all need to stress about, but it*is* something that top spearos and freedivers should worry about, on every trip. Dave's example above is something that he would be physically capable of (probably!), but could never do because of the massive DCS risk. Heck, even the way Dave spearfishes would put some people at DCS risk! He's far from the only one too; plenty of top guys are capable of getting DCS and some have actually done it.

In fact, a little while ago at least a couple of spearos ended up in chambers after a spearing comp. I'm sure someone else has more details on that incident.

DCS is being used very vaguely. DCS is hard to diagnosed by someone who doesn't know what they are doing.

DCS is treated by a re compression chamber.

Other related injuries not associated with DCS could happen while freediving, but they are not DCS.

Such as pneumothorax, Mediastinal Emphysema, or subcutaneous emphysema

It is very possible to get DCS from freediving after scuba diving even if you scuba dived the day before. But just freediving alone is still not likely.

Many people may say they got bent but until someone of a somewhat professional diganosises them with DCS or a.g.e or any other diving related injury I would not take their word for it. becuase like I said before DCS is being used very vaguely, where as DCS is a type of illness and not a synonym for "bent"

 

[unobreath]

Given this, it seems a bit unwise to suggest DCS is unlikely. An "I don't know" sounds much more accurate?

Also, it's not a 'what if'. That example is quite a similar to how I would actually be training were I not worried about DCS risk. I'm going to train CW this weekend - would you suggest I tried it? I hope not.

I give up with you guys. I dont know and I don't care is more accurate.

IN MY PROFESSIONAL DEEP SEA DIVER OPINION WITH MANY YEARS OF EXPERIERENCE WITH DCS, A.G.E., AND ALL OTHER DIVING RELATED INJURIES I WOULD STILL SAY THAT DCS TYPE 1 AND TYPE 2 ARE UNLIKELY UNDER NORMAL FREEDIVING CONDITIONS, OR EVEN NOT SO NORMAL FREEDIVING CONDITIONS. BUT THEN AGAIN WHAT THE HELL DO I KNOW.

 

[Mullins]

That's more like it. This is an important issue for us. You can expect us to demand a bit of clarity when people with medical experience offer their input. Not because we don't respect that experience, but because we take it seriously and make use of it when we decide how we are going to dive.

One thing, assuming you haven't stormed off already - you'd consider competitive freedive training to be outside the bounds of what is normal?

 

[unobreath]

That's more like it. This is an important issue for us. You can expect us to demand a bit of clarity when people with medical experience offer their input. Not because we don't respect that experience, but because we take it seriously and make use of it when we decide how we are going to dive.

One thing, assuming you haven't stormed off already - you'd consider competitive freedive training to be outside the bounds of what is normal?

There has been a study on freediving and DCS.

It is possible I dont deny you that. But they were diving for 5 hours to 130-150ft with small SI. So after making 40-60 dives some did get DCS. But I dont see 40-60 dives as normal in one day.

My training is well outside the bounds of normal but I would more than likely use the term above average, as i train hard and long just like any professional athlete. Your normal may be different from my normal. As I enjoy living on the edge of my fingertips and like the fact that the ocean can swallow me whole whenever she wants. I have a dangerous job but I like it that way. Now if I were standing from the outside looking in I am sure everyone thinks we are crazy. Especially when we can hold our breath for 6, 7, or 8 minutes and dive 100m underwater. That is not normal for most but for us it is.

For me I would worry more about shallow water black out then DCS. I have had guys come in like two weeks after a dive complaining of pain or loss of sensation, or whatever, and make a full recovery after a few treatments.

Every person I have know to get shallow water black out I have either attented their funeral or heard the story of how their buddy saved their life.

I try not to worry about any thing, if it happens it happens and then I will worry about it.

 

[chrismar]

There has been a study on freediving and DCS.

It is possible I dont deny you that. But they were diving for 5 hours to 130-150ft with small SI. So after making 40-60 dives some did get DCS. But I dont see 40-60 dives as normal in one day.

Sounds a bit like your spearfishing profile, eh Dave!

Nobody is saying that all freedivers are at DCS risk. All we are saying is that it is a serious consideration for some. Agreed? The reason Dave is hot on the issue is that DCS, oxygen toxicity and nitrogen narcossis are the big unknowns in his dives. He may not be a normal case, but he at the very least is quite interested to see what the implications of his training are.

 

[BennyB]

Unobreath, I don't think anyone is saying that you aren't knowledgeable in your area of expertise, nor are they doubting your experience and credibility, but to come onto a freediving website and say that DCS is unlikely when freediving is a fairly tough sell.

There was a study was published in 2006, "Decompression Sickness in Breath-Hold Diving", by Robert M. Wong, MB, FANZCA, Department of Diving & Hyperbaric Medicine, Fremantle Hospital, Freemantle WA. This study tested a group of spearfishermen and included a table of DCS symptoms and the percentage of subjects who encountered them:

Headache - 50%
Nausea - 50%
Dizziness/Vertigo - 50%
Lacks concentration - 37.5%
Fatigue/lethargy - 37.5%
Visual disturbance - 25%
Lacks coordination - 25%
Disorientation - 12.5%
Speech disturbance - 12.5%
Vomit - 12.5%
Paresthesia - 12.5%
Joint pain - 12.5%

It's an interesting read if you get a chance to look at it.

There may not a great deal of published scientific evidence of DCS in freediving, but it would be pretty unwise for most breath holders to dive thinking it's unlikely to happen to them.

Cheers,
Ben

 

[Mullins]

Unobreath - Interesting to hear about that study, I sure wouldn't like to be one of the workhorses they used as subjects! A 45m dive every 6mins for 5 hours.....

As a high level freediver you would be in a position to do dive sequences that I would like to do, but avoid due to perceived DCS risk - the sort of sequence I mentioned above, give or take a few m. I am interested to hear if you dismiss DCS risk as a factor when you decide how you are going to train? This would put you at odds with the majority of divers at or near your level, so the more info you can provide about this the better. E.g. "I did x dives to xm with x interval and suffered no ill effects." There is no reason to keep quiet about your freediving experience.

The risk of BO is something we have pretty much under control. We know roughly why and when it is likely to happen, and can plan for when it happens (I'm talking comp. diving here, spearfishing is obviously different). DCS risk we know relatively little about, hence all the questions.