Can we infer DCI before symptoms develop?

If a diver does something that might cause decompression illness, would it ever make sense to seek medical attention before symptoms develop?

Let's say, for example, that a diver comes back to the boat and says, "I stayed too deep too long, didn't notice my dive computer beeping at me, then when I realized I was in decompression mode, found out I was low on air, so had to surface without decompression stops." He says he's feeling fine. Do you do anything about it?

Put him on oxygen and transport to EMS. Unless, of course, he refuses. In which case I document his refusal and counter with my refusal to ever dive with him again.


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Matt Beckwith:

If a diver does something that might cause decompression illness, would it ever make sense to seek medical attention before symptoms develop?

Let's say, for example, that a diver comes back to the boat and says, "I stayed too deep too long, didn't notice my dive computer beeping at me, then when I realized I was in decompression mode, found out I was low on air, so had to surface without decompression stops." He says he's feeling fine. Do you do anything about it?

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The devil is in the details...
If his computer showed that he needed to do 4 mins at 15 feet and he stayed for 3, that's a lot different than if he blew off a multiple stop 30 minute obligation.
In the first case, I'd not get too excited. That's a situation that's covered in your PADI OW class.
In the second case, DCS is pretty likely, so 100% O2, head to EMS and get them someplace with a chamber. (Incidentially, and in keeping with another of your threads, regarding dive destinations, I always check chamber availability when I'm researching a location.)

One of the most puzzling and frustrating things about DCS is how unpredictable it is. People who dive perfectly normal profiles end up with symptoms; some people who blow off large amounts of deco do not.

For a recreational dive, where the diver had incurred only a few minutes of deco, if he was asymptomatic on boarding, I'd watch him closely. Putting him on O2 may well be a bad strategy, because you may mask symptoms with O2, only to have them crop up later, perhaps after the person has left the dive site or the boat. If there are any symptoms -- niggles or fatigue or dizziness or anything -- I'd put them on O2 and radio to have EMS at the landing (or have them come to the dive site). DCS very frequently worsens with time.

I don't think there is ever a point in presenting for medical treatment when the patient is asymptomatic (in the world of recreational diving, anyway). If enough deco has been blown to be able to say with near certainty that the person will have symptoms (probably at LEAST 30 minutes or more) that's a different story.

noob question:

If you did something that you are fairly certain is likely to lead to DCS....... why not just get situated at the surface for a few mins.. and then dive down a little ways to keep the off gassing from occurring at a dangerous rate? or is it one of those things that once the process starts.. your kind of screwed?

meebs86:

noob question:

If you did something that you are fairly certain is likely to lead to DCS....... why not just get situated at the surface for a few mins.. and then dive down a little ways to keep the off gassing from occurring at a dangerous rate? or is it one of those things that once the process starts.. your kind of screwed?

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Not a bad noob question. I'm going to answer it conservately for you as a dive operator, not what I might do myself.

You can dive whenever you want. If you blow a safety stop or you make your computer mad for an ascent rate violation, sure, get back in with a buddy (tender) and complete a stop. Use the gas left in your tank from the dive, or even swap tanks. If you do something you are sure is going to lead to DCS, do not get back in. You need medical attention, and you need it soonest. A recreational diver diving recreational profiles is very unlikely to run into this situation. If you do something you are sure will lead to DCS, you've been very deep, very long, and missed an O2 deco or lost gas. If you are doing that kind of diving, you'll be coming up with your own answer, which may be very different than the one I just gave you.

There are really two divisions of things . . . there's DCS that comes from overabsorption of nitrogen, with insufficient time to get rid of it on the way up. This is mostly Type I, thought to occur because of venous bubbling. And then there is Type II DCS, thought to occur from arterial bubbles, either from pulmonary trauma or shunting.

Type I DCS is almost hard to do in a lot of recreational diving, because the tanks used are small and the NDLs on air are short, so someone has to put himself in major risk of running out of gas, and well beyond his NDLs, or completely mess up an ascent to get there.

Type II DCS is sadly not uncommon in recreational diving, and is most often due to someone ascending out of control or in panic, and not breathing, thus developing arterial gas embolism. This type of DCS is frequently completely disabling, resulting in paralysis or severe balance loss. One would not want to be in the water when the worst of the symptoms developed. If you have had a profile that puts you at significant risk of Type II DCS, it would be my feeling that you should not attempt to reenter the water, even if you have a brief asymptomatic period.

On the other hand, something like a short violation of NDL limits, followed by a controlled ascent and attempt to do the required stops, probably does not put you at enough definite risk to merit an attempt at in-water recompression.

Just my take on it, for recreational diving. Tech diving is a whole 'nother animal.

If you aren't bent, then no sense in going through all the motions as if you were. What one set of tables say compared to another (VPM vs Buhlmann is an easy comparison, they produce quite different results from time to time), or what one computer says compared to another shows just how much gray area there is in decompression. That combined with individual physiology, how cold (or not, or when, if you were cold), hydration level, post dive exertion, nutrition status, and a myriad of other factors all go into the decompression puzzle. Getting back in the water for a quick 'bounce' might actually get you bent if you weren't before. In water recompression and omitted deco procedures are far outside the scope of basic scuba.

Bottom line is that if you're asymptomatic, then you beat the odds (or the model you're using) that day. Don't do it again unless you really know what you're doing. By that point, you need to ask If you are, get on the o2 and seek proper medical attention.

TSandM:

There are really two divisions of things . . . there's DCS that comes from overabsorption of nitrogen, with insufficient time to get rid of it on the way up. This is mostly Type I, thought to occur because of venous bubbling. And then there is Type II DCS, thought to occur from arterial bubbles, either from pulmonary trauma or shunting.

Type I DCS is almost hard to do in a lot of recreational diving, because the tanks used are small and the NDLs on air are short, so someone has to put himself in major risk of running out of gas, and well beyond his NDLs, or completely mess up an ascent to get there.

Type II DCS is sadly not uncommon in recreational diving, and is most often due to someone ascending out of control or in panic, and not breathing, thus developing arterial gas embolism. This type of DCS is frequently completely disabling, resulting in paralysis or severe balance loss. One would not want to be in the water when the worst of the symptoms developed. If you have had a profile that puts you at significant risk of Type II DCS, it would be my feeling that you should not attempt to reenter the water, even if you have a brief asymptomatic period.

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@TSandM:
I thought that DCI (decompression illness) is an umbrella term referring to both DCS (decompression sickness) and AGE (arterial gas embolism).
DCS is further subdivided into Type I (cutaneous, minor joint pain, or pain only symptoms) and Type II (severe symptoms linked to cardiopulmonary and neurological systems).
I think Bove came up with "Type III" DCS, which he defined as an amalgam of AGE and DCS with neurological symptoms.

Such classification implies that, strictly speaking, AGE is distinct from Type II DCS (although neurological symptoms may be appreciated in both). Your post seems to imply that AGE commonly gives rise to Type II DCS.
Furthermore, as I understand it, the hyperbaric treatment algorithm for AGE differs from that of DCS (Type 1 and Type II).

Bubbles in DCS originate from the dissolved biologically inert gas in the blood and tissues which comes out of solution as the ambient pressure decreases.
Contrastingly, intravascular bubbles in AGE originate from the introduction of air into ruptured alveoli due to pulmonary barotrauma.

Is my knowledge of DCI/DCS/AGE antiquated...or just flat out wrong?

Normally, I wouldn't be nit-picky about stuff like this, but the OP is a physician, so I thought it would be good to clarify this point.

TSandM:

There are really two divisions of things . . . there's DCS that comes from overabsorption of nitrogen, with insufficient time to get rid of it on the way up. This is mostly Type I, thought to occur because of venous bubbling. And then there is Type II DCS, thought to occur from arterial bubbles, either from pulmonary trauma or shunting.

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What you're calling type 1 DCS is what the PADI courses call DCS. What you're calling type 2 DCS is what the PADI courses call a lung overexpansion injury. The two taken together are called DCI.

DCS according to PADI's definition is nitrogen bubbles coming out of solution, caused by ascending too quickly. A lung overexpansion injury has nothing to do with nitrogen coming out of solution; rather, it's due to ascending while breath holding. One or more of the alveoli burst, allowing the air in the lungs to escape the lungs and go into the surrounding tissue. If the surrounding tissue that the air goes into is an artery, and the air travels along the artery, it's an arterial gas embolism.

Regarding the practice of re-descending in order to recompress, PADI teaches that this is not effective because, once you've been bent, the time it takes to recompress to undo the damage is hours, and in a diving situation you don't typically have that many full cylinders available, and that much time underwater would result in hypothermia. This is only done in extremely remote locations where a hyperbaric chamber is unavailable, and according to PADI should only be done with special training.

This principle is nicely illustrated in a recent post by an experienced diver who was bent. His recompression is done in the hospital over hours and hours of hyperbaric time over a several-day period.

Of course, in this thread we're not talking about symptomatic bends, but rather having come up too quickly without decompressing, without having any symptoms. In this case, I just don't know whether re-descending is a good idea. It makes a certain sense. If the gas bubbles have already formed in the tissue, it's too late. But if they haven't yet formed, then perhaps it would help. But this is something that in my opinion can't be determined in a speculative discussion. We're talking about life-threatening issues here, so shouldn't just speculate in my opinion.