First, time for another disclaimer. I am not a medical doctor or health care professional. I am also not an expert in diving related health or medical issues. What follows is only a combination of personal opinion and my interpretation of articles I have read. If you think you might have a diving injury, don't just go by this article, seek professional medical attention immediately! If you use the information provided here, you do so at your own risk.
Now that that's out of the way, on to the subject of this little essay. One of the main concerns of those of us lucky enough to have discovered diving is decompression sickness (DCS), otherwise known as the Bends. Over the years I've seen hundreds of articles, book chapters, etc. on how to recognize the symptoms of DCS. The intent of all these writings is, of course, to allow us to determine if we might have suffered a "hit". The problem is that the symptoms of DCS cover just about every possible "odd" feeling you can imagine. Even the professionals can have a hard time diagnosing DCS, with the definitive test being to actually recompress the patient and see if the symptoms go away. As an example, the only time I've been treated in a chamber, it turned out that I was just coming down with the flu. But the symptoms were classic DCS.
In the last few years, the number of reported DCS cases has been on the rise. This has been attributed to several things, including an increase in the number of certified divers, and better education on the importance of seeking prompt treatment. One thing I've noticed in that same time period that I think may also be a factor is that, with all this increased emphasis on DCS, many people become worried about any pain that they have after diving. Don't get me wrong, this is not necessarily a bad thing. Divers should take DCS seriously. However, I think many of us worry unnecessarily over symptoms that could probably be easily ruled out.
Any of us who have been diving long have experienced this, the little ache that we write off as a strain or bump, but deep down suspect just might be the bends. My involvement over the last few years with biology and research courses that utilize SCUBA has allowed me to witness an increase in the level of concern that these little aches cause. Many times it's very clear that the diver is not bent, but in our litigious society, it's not the kind of thing you take lightly, especially when dealing with students.
One of the biggest causes of this that I see is that, out of all that has been written about what IS DCS, very little has been said about what is NOT DCS. This is not too surprising given people's eagerness to sue in order to make others pay them for what is often the consequence of their own stupidity. Hence my disclaimer. You don't want someone claiming they suffered permanent injury because you told them they weren't bent. So, as far as I'm concerned, you all are.
Diving can be a strenuous activity. There is a lot of heavy gear that needs to be moved around, weight belts that ride uncomfortably on the hips, small boats and motors to be dealt with, etc. There are a lot of opportunities to suffer strains and bumps that may seem like DCS symptoms later. Unless you have some criteria for ruling DCS out, you will of course suspect it.
How then do you know if you're bent? Well, first of all, consider your dive profile and diving routine for the past few days. If you have only done one dive in the last couple of days, and that was at sea-level, to 30ft. for 45 minutes, with no rapid ascent, no saw-tooth profile, no subsequent change in altitude, blah, blah, blah, then it's probably safe to say that you are NOT suffering from DCS. On the other hand, if you've been doing 4 dives a day, pushing your computer for every second of no-decomp time, with maybe a little rapid ascent this morning, and a couple of margaritas last night, I'd say you better go see the doc.
One of the big misconceptions about the whole dive table/DCS/no-decompression limit thing is that we have any idea who's going to get the bends given a set of circumstances. There's just no way to know. Dive tables are just a set of guidelines based on the statistical PROBABILITY of getting bent. It's POSSIBLE that someone with the first dive profile spelled out above could get DCS, but it's also possible that they'll win the lottery and be struck by lightning on the same day. It's just not very likely. That probability increases as you get closer to the limits of your dive table or computer. Just as an example, the old navy tables were based on a 5% bend-rate, meaning that if you did one square-profile dive to the max time for your depth, you would have a 5% chance of getting DCS. Another way of looking at it is that if 100 people did this same dive, about 5 of them would get DCS, on the average. Most tables and dive computers are more conservative than the old navy tables, and most of us don't push even those limits, so the chance that you'll get DCS is small. If you're a certified diver, you should already know the risk factors for DCS. If you don't, go look them up. If a list of your recent diving activities have more of these than your latest issue of Alert Diver, then I see a field trip to the closest recompression chamber in your near future. If you're not even close, there's a good chance it's not DCS.
Probably the most frequent symptom people worry over is post-dive pain. We all know that this is a classic red flag for DCS, especially if it occurs in a joint or the lower back, but how do you know if that ache you feel should have you making sure your DAN dues are paid up? First, does the pain occur or worsen when you move or apply pressure to the affected area? If the answer is "yes", then it's probably not DCS. Also, if the pain comes and goes, it's not likely to be the bends either. If the pain is in the lower back, is it accompanied by a burning sensation? If so, it's more likely that you need to take it easy slingin' your tank around than takin' a trip to the E.R. Also, if it's a shooting pain, it's probably just a back injury. DCS pain is often described as a constant, deep ache. Be aware of the things you do during your dive day, and take note of the things that could cause pain later. Also remember that poorly fitting gear can be a big cause of aches, espcially back and lower extremity pain.
Some of the other symptoms of DCS that are also commonly encountered by divers who are not bent are fatigue and headache. I don't know about you, but I'm always pooped after a day of diving. Some of that is just normal fatigue due to exertion and mild hypothermia. Some of it is also due to decompression. DCS is when bubbles form in your tissues because of a decrease in pressure, AND those bubbles cause clinical symptoms. We've probably all heard of "silent bubbles". These are bubbles that form in our tissues after diving that don't cause symptoms. The point is that, even if you feel alright, your body is still dealing with the excess nitrogen you loaded into it. One consequence of that is the fatigue you feel after diving. Saturation divers are familiar with this. During their long decompression, they are often required to rest and minimize activity. Even so, they often complain of feeling wiped-out. The problem is when it's accompanied by other symptoms, or when it's really severe.
As far as the headaches go, if you've ever had a nice CO2 headache, you know that this can be an all too common side-effect of diving. Again, it's when this is present with other symptoms, or unusually severe, that you need to see your doctor.
What about some of the other symptoms of DCS? Well, as far as things like loss of consciousness or unexplained changes in personality, I'd personally be running down to the nearest hospital if I had any of these, even if I hadn't been diving.
Like so much of diving, deciding whether your post-dive symptoms warrant a trip to the doctor or not can be handled, to a large extent, by the use of a little common sense. The most important thing is to be decisive. If you really think that you might have DCS, don't wait to see if you feel better tomorrow. Go to the doctor, or call DAN, immediately. Yes, you might have to sit out the rest your vacation on the beach, sipping more of those margaritas and watching the beautiful, swimsuit-clad hardbodies (male and/or female, however your tastes run) romp around, but quick treatment can mean the difference between being back to try it again in a couple of weeks, and sitting in a wheel chair, urinating through a catheter, wearing a diaper for the rest of your life. Probably the biggest factor in permanent injuries from DCS is the fact that most people wait until the next day or later to seek treatment.