Freediving DCS?

[efattah]

I recently had a freediving experience where I may have had mild DCS, I'm not sure, and maybe someone can help me.

I was diving in cold water (as usual), on a ship wreck in 20-30m of water. My dives were around 1:45, with surface intervals of about 2 minutes. Then, on the last dive on the wreck, I found an air pocket at 22 meters. I am quite experienced at breathing from compressed air pockets while freediving, and I'm well aware of the free-ascent dangers. I took several breaths from this air pocket, then continued my dive down to about 31 meters. I exhaled during the ascent, and the dive ended up lasting 3:47. Only a few minutes later, I started diving a shallower wreck, in 13-15m of water. Now my dives were a bit shorter, with shorter surface intervals. Then, I found an air pocket on this wreck, and after taking a breath from that pocket, my dive lasted for 4:25. I surfaced, made a few more dives, then, after about 2 hours of total diving, I went back to shore with my buddy. I took my gear off. My hands and feet were quite frozen from the cold, which is nothing new in Vancouver. However, after I warmed up, my right thumb was numb, from the knuckle onward. Touching it to my face, it was no longer cold, and the rest of my fingers were all feeling fine and warm. It concerned me. It stayed numb for about 15 minutes, then slowly the feeling came back.

Was this DCS?


Eric

 

[Cliff Etzel]

Eric - Did you exhibit any of the the other symptoms of DCS? I am wondering if you actually got bent or not. You have described a very localized occurance of numbness on your body, where typically DCS symptoms occur in the major joints (Elbows, etc). I could be wrong though.

Based upon the information you presented, You might have getten a very mild case of DCS. Breathing from the pockets and doing such long dives (for freediving) and the water temp are all factors that could lead to DCS.

You might try asking a tank diver who is well versed in this (instructor level) - they may be able to give you a better answer than I could.

Hope this helps.

 

[Jon]

It sure sounds like you could have gotten bent to me. There have been cases where instructors got bent by doing reptetive ascents/decents with begining students all day long- like practicing free ascents. Just the constant up and down can cause problems, let alone staying down for a few minutes while breathing from an air pocket. As soon as you start breathing like that at depth you might as well have a tank strapped to your back. You now have to switch to "scuba" mode and slow your ascents WAY down- we use 30' a min. instead of the old 60' a min. for a safe ascent rate. When I scuba I go even slower on the last 10' of ascent- where the biggest pressure change occurs.
I wouldn't breath out of air pockets in the future- you never know exactly what gas is in them and you can get DCS.
I understand the freediving on wrecks though- that's where I do almost all of mine. I also carry a spare-air when I use my scooter on a wreck. I haven't had to use it yet, but if I would I would go very slow on the way up.
I assume that you also know about exhaling on the way up after breathing compressed gas at depth- or you would be dead already.
One thing that you could try to do is see if you would be allowed to do these dives on a scuba computer. Switch your stinger into dive mode and try to do it. I bet that it will make you do three minute stop from all of the dives you did- I have had it do that to me already. I came up after a dive and realized I had lost the macro attachment from my camera. I jumped back in and freedove down to 55' to pick it up off the bottom. The thing went crazy and I finally jumped back in with a tank on to clear the 5 min. stop that it gave me.
I hope that this helps.
Jon

 

[amr]

I suppose there is also an outside chance that could be Raynaud's phenomenon (caused by cold). However, Raynaud's most commonly affects fingertips, and not usually the thumb.

 

[Erik]

Eric, I would have to say that is extremely unlikely that you got a hit. The possibility is there, because of the few compressed air breaths you took, followed by the relatively quick freediver ascent, but if you have a look at any dive table, even the conservative, cold water based DCIEM tables from the Canadian Military, you will see that one must spend a fair amount of time at depth, breathing compressed air to be subsceptible to DCS. I know that deco theory is a large part art as well as science, but given the tremendous condition that you are in, etc, my guess would be that your thumb was merely numb from the cold. Cold presented a big problem when I worked on a cold water live aboard dive boat....divers would complain of sore shoulders, elbows, and fatigue after a few cold dives, and we would automatically put them on O2, just to be safe, but the actual incidence of DCS was approximately 1 in 6000 dives..very low.
If you ever do think that you been hit, then get on O2 asap, then talk to Divers Alert Network. Actually, you might want to tell them your scenario; they could probably use the stats for developing a knowledge of DCS for freedivers.
Cheers buddy,
Erik Y.

 

[Pekka]

I would like to bring some of my personal experiences about diveing and breathing "extra" under water..
As I started freediveing I get interested in taking some air with me first in a bottle and later on with a plasticbag, I didn't do so long times as eric...but definately longer than my limit, and I did it for every dive, The optimal volume was about 5-6litres of air, I would do dives not deeper than 16m. I never experienced any problems...I am still here.
What I would like to know is do the pearldivers use such extra air when diveing? and have you guys tried anything like that?
I know it is not a thing to do and I am not doing that anymore..

 

[ickledevil]

I remember when I first started diving and wanted to be underwater longer, so started to thing of a way to take air with me for a while it seemed a brilliant idea but as I read more into the subject I got scared and rightfully so I think.
Having Scuba dived since I know about the need to exhale on ascent to prevent an embolism, but back then I didnt. The way I thought of it was after being under water for X amount of time my lungs are empty... simple take a breath and stay longer, of course this isnt how it works, your lungs hold the same volume of gas, it has less O2 in it after a time when you get the empty feeling, also if at depth it has been compressed along with your lungs but to a further extent, so physically you could 'fit a second breath in, and knowing how valuble air is probaly woulnt want to let any out? So you stay a bit longer, then start to swim up the air in your lungs expands again filling them as when you breathed up for the dive down.... but wait now you have an extra 2 litres, thats expanding too... Oh dear this volume represents your total lung capacity plus 2 litres..... POP! embolism. True it can be avoided/dealt with but Id rather not take the risk, if youve got 'Freedive!' read the embolism section. Terry nearly had one himself breathing from an air pocket 15m down and not thinking.
Any way
Dive safe all of you.
Joe

 

[Pekka]

I am still temped sometimes....the extra air, and the simple way it works with bag of air although now I know the dangers...
What I actually wanted to know if anyone knows someone who dives with "bag" all the time? like some native people somewhere in the tropic, or..you know.. cause it is such a easy way to get little more working time underwater, and it seems that reading this thread; breathing from air pockets no danger of DCS, if you know how to deal with the extra air, breath out as you start to swim up...
thats what I am after..

 

[ickledevil]

When I was on holiday in Fiji I was diving a reef 200m out from our hotel, the reef was used by locals, mostly kids to catch fish, while I was messing around I saw one kid using a 2litre coke bottle to take extra breaths from, thing is from where I was he seemed to be down longer when not using the bottle to when he did?! As for knowing anyone who does all the time, I dont, but I wouldnt look upon it as simply breathing out all the time and youll be OK, theres a lot of physilogical and chemical changes that can take place doing this that probally differ from one to the other... I know how you feel though, just an extra minute........
Mind you then Id be cheating myself.
Joe

 

[Erik]

Originally posted by ickledevil
Mind you then Id be cheating myself.
Joe

Exactly....it's called scubadiving
Cheers,
Erik Y.

 

[Pekka]

What then is the difference between scuba and free, I mean not to mention the whole gear issue... Isn't it the freedom underwater you can relate your self to a fish easily when moveing deep down and being able to be aquadynamic, wery much different than scuba monsters crawling like crabs on the bottom makeing loud noise with their bubbles..So you wouldnt really lose the freedom if breathing from airpocket..right you would still be free from all the gear and fast like fish. I know that the risks are there..
Just a thought..:duh

 

[Jon]

There is still a real DCS risk if your going down 30 meters and hanging out for 4-5 minutes and makeing a rocket ascent- normal for freediving. Even if you stay within the total bottom time limits for a specific table you can get bent on the ascent rate that freedivers follow.
If you were a scuba diver and went back down to depth within less than a ten minute surface interval, which is what most freedivers do, you would still be considered on one long continuous dive. Spending two hours out there, or more, will violate any table. The Freediving tables talk about bottom times and surface intervals- a good place to start. Once you add compressed gas, whether it be from a tank or an air pocket, you have moved into the scuba dive tables.
Scuba instructors have been bent while staying inside the tables just becasue of their repeated quick ascents, while conducting basic diver training. I have helped treat divers who got bent even though they were well within the limits of the tables.
Going down once or twice to try it probably won't do much to you; however, doing this repeatedly for two hours to depths as deep as 30 meters will. Kirk has been bent, Pipin has been bent, and countless "native" divers have also experienced "taravana". It is a real risk if you push it.
Just my 2 cents.
Jon

Also, I tired the "rebreathing" my own air with a milk jug when I was about 8 in the bottom of the swimming pool. This was well before I knew about the dangers of embolisims. It's amazing what we get away with when were young.

 

[efattah]

DCS again

I'd like to clear up that your risk of DCS has nothing to do with breathing compressed air; if you go down to 30m and breathe from a pocket, staying down for 3 minutes, you run the same risk of DCS as an expert diver going down to 30m, for the same 3 minutes, without breathing from an air pocket. Each diver has the same pressure of nitrogen in their lungs during the dive. But, if you stay down for 4+ minutes because of an air pocket, it will be difficult to find a freediving table to follow, so you might as well use scuba tables.

Eric

 

[Jon]

Eric,
You are correct with one small exception- the rate of ascent. Once you stay down there and breath the gas you need to make a scuba ascent < 33' a min. This is very hard to accomplish as a freediver.
Jon

 

[Erik]

I may be misunderstanding you Eric, but if you breath air from a pocket at -30 metres, that pocket of air is compressed gas (4 atmospheres), so if you were to say, breath off a scuba source for 3 minutes, would the absorption of nitrogen change in your body? What I'm asking is: is the rate of nitrogen absorption different during a breath hold than a scubadive at (x) depth? I would think that the rate of absorption would be higher with scuba, based on more gas passing through the lungs, higher heart rate, less relaxed state (maybe), etc.
Cheers,
Erik Y.

 

[thands]

DCS and FReediving

You may want to check out the following article by Dr. Fred Bove

http://www.skin-diver.com/departments/ScubaMed/FreedivingCauseDCS.asp?theID=626