34 dives to 15 feet in 4 hours - symptoms

[Subcooled]

Just getting in and out of your gear and a boat that many times is going to wear you out. In addition to the EANx I would suggest bringing down the removal rope right from the start to save yourself some extra ups and downs.

I had been floating four hours in +7 C water, swimming to the next buoy, diving the site, then swimming to the next. If the distance to cover was a bit longer, I did hang on to a rope thrown from the boat. So this was constant down-up-down-up-... like a sewing machine

1. Nitox
Today I spent a longer time in the sea, five hours, and did around 30 dives again, but now on nitrox 40 as suggested.

2. Recovery rope
I did carry the recovery rope from the beginning on some dives today. It was not easy however. The buoy anchoring line needs to be followed (and not pulled) and two hands are needed for that. A line for circular search is also needed. And the recovery rope. There starts to be a lot of line and rope in the water. I also had to keep my forehead against the stake while attaching the rope to it, else I would have lost the stake. Lots of ropes, very short distances, can't see. You can guess what happens next...

With all those ropes to manage in zero viz, I managed to tie my other reg hose to a pole at depth. That very moment I felt Very Stupid. I had to undo the knots and be more aware of hose routings.

By taking the recovery rope with me immediately helped to cut the number of dives somewhat, but as is explaned above, it came with a cost.

3. Safety stops
I also started doing a short safety stop half way up to better control ascent rates. It was only half a minute though.

Result:

Cold stress was significant this time but now that I have warmed up I feel a little bit better than yesterday. At least I am not totally exhausted.

 

[Subcooled]

Let me be sure I understand. You spent 4 hours in 8 degree C water, I assume in a dry suit, and wonder why you felt tired?

It was the itching next morning, about 6 am, that made me a bit worried.

Especially, as one guy in our diving club got a major skin bend last monthon a leisurely dive to 60 feet, no dehydration, no sports, not cold, nothing to explain it. It was very strange.

 

[Subcooled]

Not in 2 hours as op described. Skin rash starts lightly as well until you acknowledge it, it will intensify and disappear.

Whatever it was it made me wake up 6am. By nine it was gone.

 

[Duke Dive Medicine]

Background

Recently I had to help a fisher to clear a bay for fyke net fishing. The place was littered with fyke net anchoring stakes that had to be removed before placing a new fyke net was deemed safe. Depth was 15 feet. Visibility varied between 0 and 25 inches. 13 stakes had to be recovered and they were initially located by side scan sonar and then more accurately by ordinary sonar. A buoy was then thrown in as close to the target as possible. No matter how close the buoy anchor weight landed a circular search was still required. One could not see a thing! The stakes had to be located and marked and after that a recovery rope had to be fetched and attached to the stake. Hence, a minimum of two dives per stake were required. I am pretty used to diving in zero viz but a number of resurfacings and new attemps were still required. All of this led to 34 dives to be performed.

The dives

I did do 34 dives to 15 feet in 4 hours. Time submerged was 90 minutes. Water temperature +8C on the surface, +6C on the bottom. I spent 4 hours in water.

The fears

I fear that no decompression algorithms (including the bubble models) have had their parameters statistically adjusted to guarantee such dives to be safe. A realized this a little bit too late having already taken the damage. My computer was happy, my body was not.

The symptoms:

1. I felt very exhausted the whole evening. No need to sleep, but physically very very tired.
2. Next morning I woke up and felt some itching. It felt like wool against the skin. I have never before had that sensation in the bed in the morning. Two hours later this symptom was gone.

The assumptions

I assume that those larger cavities in the bloodstream that play no role after 3-4 dives got pumped up enough with nitrogen during 34 successive dives to cause symptoms. So perhaps I suffered some nitrogen damage, while not full blown DCS.

The future

My plan for the next time is to replace air with nitrox 40 and limit the submersions to less than 30.

Recommendations and advice welcome!

DCS with dive profiles like this is not unheard of. If you did have DCS, it sounds like a mild case. Nitrox would almost certainly be safer, and I would limit the sewing machine up-and-downs as much as possible.

Best regards,
DDM

 

[scubaozy]

So I stand corrected ;-)

Tasmania, not Norway

 

[chillyinCanada]

Sorry to hear that. I have seen more than 20 cases of C. Marmorata in my diving past. It is the easiest one to deal with because it is something you can see and it is probably most common. In each case I have seen there was enough insult in dive profile such as multi-day diving or diving > 45 feet.
General algorithm to look at dcs is very basic:
Dive profile, is there any (or enough) insult?
Symptoms will start short after dive, the later it starts less likely it will be dcs (80% within 8 hours), not the case for OP
After onset they will worsen
Breathing 02 will improve the symptoms
......

Btw, DCS related itching is generally around lymphatic nodes, like ears, armpits, groins. Exposure to the cold will make you tired and itchy as well. You have to understand that unexplained fatigue is a bit stronger than feeling tired.

I do understand that as well.
The way he described his itching was odd to my understanding but perhaps he developed on allergy.

 

[scubaozy]

Could something like this happen:

1. Nitrogen dissolves in blood at depth.
2. When one later ascends and the ambient pressure drops, that nitrogen wants to get out.
3. There are always bubbles in blood but they do have a surface tension that stops nitrogen from getting into them (unless the pressure gradient is high - hence, depth).
4. Bigger bubbles have smaller surface tension and can grow more easily, but there are less of them.
5. Deco algorithms contain lots of parameters and constants that are set based on dive statistics.
6. Those bubbles that can grow more easily are not a problem as we have seen from dive statistics (all of which are max 3-4 dives per day)
7. Frequent ups and downs could, however, pump those bigger bubbles and possibly case some harm.

This is a divers attempt to understand what is going on. I am not a decompression theorist.

I think there are many errors on these points. Most important one (1) is that you are referring to N dissolving in blood. It dissolves in body tissues. Upon ascent, bubbles damage the cells and trigger inflammation. This is when you feel typical signs or symptoms such as joint paint or skin bends.
On the other hand, if bubbles make their way into non venous circulation (shunt in heart or pulmonary barotrauma) you will experience AGE.
N get out from tissues (2) through venous blood when you ascent. Larger the bubbles, less likely they can be transferred out of the tissues and will do damage.
(3) There are always gasses in the tissues, even at the surface (it is like doing saturation diving in 1 ata), they will remain there dissolved until you change the environment pressure, like flying.
(4) Not sure about this point, I think you might want to read bubble mechanics section here -> Decompression theory - Wikipedia
(5) There are 2 main type of models; gas content and bubble. For gas content (Haldane) models, safe limits are based on experiment and adjusted by outcomes. Bubble models focus on limiting tissue supersaturation to minimize or prevent bubble growth. My guess is you are referring to RGBM with your point 3 & 4.
(6) Not sure about this, smaller bubbles are less likely to be a problem imho.
(7) Any yoyo profile is not desired but again, you need to accumulate some N (depth and time). I find AGE is more worrisome when making too many ascents in very shallow dives.

 

[uncfnp]

Sorry to hear that. I have seen more than 20 cases of C. Marmorata in my diving Btw, DCS related itching is generally around lymphatic nodes, like ears, armpits, groins. Exposure to the cold will make you tired and itchy as well. You have to understand that unexplained fatigue is a bit stronger than feeling tired.

Sorry to hear that. I have seen more than 20 cases of C. Marmorata in my diving past.
......

Btw, DCS related itching is generally around lymphatic nodes, like ears, armpits, groins. Exposure to the cold will make you tired and itchy as well. You have to understand that unexplained fatigue is a bit stronger than feeling tired.

I simply can not agree with this and you do realize that C. M. is just one manifestation of skin bends?

 

[OTF]

To add another anecdote, I too have experienced surprisingly strong exhaustion (the hallmark of subclinical DCS??) after very similar working dives with lots of repeated ascents in shallow water. I didn't have skin symptoms but extreme fatigue and drowsiness later in the day.

Maybe we'll see some interesting data on repeated ascent dives as more people use that new O'Dive gadget. I "believe" that repeatedly yo-yo-ing from 25 feet is more likely to mildly bend you than staying at 25 feet for several hours (even until saturated) and ascending once. I don't know why this would be. If I were going to throw some wild speculation up on the internet perhaps expanding then crushing "silent" bubbles allows them to migrate into places they normally wouldn't. Or perhaps the deco algorithms aren't modeling the behavior of fast tissues with total accuracy. Our models are just that, models, not precision measurements of what is really happening physiologically. We KNOW they're not always correct.

As others have said, the scientific data is missing, but there appears to be a large enough body of anecdotal evidence to consider shallow dives with repeated ascents a hazard that should be mitigated with precautions as we do for deep dives. Minimize ascents, use nitrox, ascend REALLY slowly, stay warm during the dive, stay very hydrated, don't overwarm yourself or exercise hard immediately following the dive. Even if taking these measures seems silly for 30ft dives.

Being cold is a big predisposition to DCS hits, you've mentioned being cold a few times. Up your thermal protection. We do a lot of cold dives here and I try to make a point of planning those more conservatively. One way to minimize ascents on working dives is to stay on the bottom and use an SMB to signal when you want your surface support to lower a mooring chain or do whatever you need them to do.

As for the argument over the statement "all dives are deco dives" - I like the adage. Of course "deco dive" does have a specific meaning as it relates to mandatory ceilings. But it's important to remind ourselves that we absorb and offgas nitrogen on EVERY dive and we shouldn't be cavalier about rapid ascents even on recreational profiles.

 

[Subcooled]

I think there are many errors on these points. Most important one (1) is that you are referring to N dissolving in blood. It dissolves in body tissues. Upon ascent, bubbles damage the cells and trigger inflammation. This is when you feel typical signs or symptoms such as joint paint or skin bends.
On the other hand, if bubbles make their way into non venous circulation (shunt in heart or pulmonary barotrauma) you will experience AGE.
N get out from tissues (2) through venous blood when you ascent. Larger the bubbles, less likely they can be transferred out of the tissues and will do damage.
(3) There are always gasses in the tissues, even at the surface (it is like doing saturation diving in 1 ata), they will remain there dissolved until you change the environment pressure, like flying.
(4) Not sure about this point, I think you might want to read bubble mechanics section here -> Decompression theory - Wikipedia
(5) There are 2 main type of models; gas content and bubble. For gas content (Haldane) models, safe limits are based on experiment and adjusted by outcomes. Bubble models focus on limiting tissue supersaturation to minimize or prevent bubble growth. My guess is you are referring to RGBM with your point 3 & 4.
(6) Not sure about this, smaller bubbles are less likely to be a problem imho.
(7) Any yoyo profile is not desired but again, you need to accumulate some N (depth and time). I find AGE is more worrisome when making too many ascents in very shallow dives.

I have to admit that I was not thinking that much about terminology, be it DCS or AGE, as I was mostly concerned about possible bubble growth in blood and what that might cause. If there are shunts you mentioned, then these bubbles might block more or less important veins I guess. There are some really small ones in the skin, right? Hence skin reactions?

I can only comment on physics, as medicine is beyond my understanding (I've read something but its laymans knowledge).

1: Nitrogen gas does actually dissolve in blood (too), which is said to be a fast tissue. It takes more time for nitrogen to get into other tissues (well because they are slower tissues; I don't want to delve too deep into this detail). Given the length of submersions (very short), that part is probably not relevant at all. Sorry for not being clear on this.

2: You say: "N get out from tissues (2) through venous blood when you ascent." This is true, when nitrogen escapes solution and gets into the air in the lungs instead, but it can alternatively / in addition go from dissolved state into existing gas bubbles in the bloodstream. Nitrogen does not care where the gas phase is (with lesser ppN2), in the lungs or in a bubble. And there are always some bubbles in blood, or so have I read (see Wikipedia: Cavitation). The classical soda can example is a prime example of this. CO2 in the beverage causes bubbles, it does not escape through the surface only.

4: In an equilibrium state pressure inside the bubble is slightly bigger than outside (and surface tension keeps it stable). Water molecules cling to each other (we call that surface tension) and trap the gas bubble. The bigger the bubble the smaller the difference in pressure and the easier it is for nitrogen to get from supersaturated tissue to the bubbles inside. The surface tension is actually the surface tension of blood of course. Blood is largely water and countless other things that I do not know. For equations, see for example Surface Tension There you see the the pressure difference is a positive number divided by bubble radius (i.e. its size). Thank you for the link to deco theory on Wikipedia. It was an excellent read. Another good reference would be Deco for Diving by Colin Powell. And there may be more good books.

5: In #3 and #4 I refer to physics, in #5 I was thinking of versions of VPM with critical bubble radius, critical volume and other parameters. RGBM I know even less about.

6: You are correct. Larger bubbles have less overpressure inside (see the equations in the link I gave in 4) and they are more likely to let nitrogen in, grow, and become a problem. Smaller bubbles are less of a concern.