Decompression sickness can stop even the best divers from continuing their dives. Improper attitude can lead to a careless flaunting or deliberate violation of the rules for safe, no-decompression diving.
What is the greatest cause of decompression sickness? Not what you might think. It is not regulator failure, dive computer malfunction or decompression table error. No, it is the same culprit that causes many kinds of accidents – personal attitude. Diver attitude (lack of respect) seems to play a big part in our sport’s battle with the bends.
DCS (decompression sickness) is a clear and ever present danger that cannot be ignored or minimized. It is really serious stuff. Any diver who scoffs at DCS preventive measures is asking for trouble.
Here are a just a few sobering thoughts worth mentioning. No diver is immune to DCS. This affliction has struck both the worst and the best divers, plus a lot of folks in between. DCS could end your diving forever. Bends can be so destructive to your body that it can result in permanent damage and prevent you from ever going underwater to any depth.
DCS can even cripple or kill. Bends rarely results in death but it can be terribly debilitating. There are a multitude of ex-divers who are wheelchair bound or experience recurring symptoms of numbness, deafness or other neurological disorders. Are you getting the point?
10 CARDINAL SINS OF DCS
If divers understand the consequences of DCS, why do they continue to get bent? Why are most DCS episodes self-inflicted? Researchers have studied the statistics in an effort to isolate and identify the contributing factors. I call these factors the cardinal sins of DCS – the careless flaunting or deliberate violation of the rules for safe no decompression diving. Here is a list of the 10 worst violations and how you can avoid them.
1 TABLE VIOLATIONS: This is one of the major causes of DCS. Bends victims often admit they made one or more violations, i.e., exceeding bottom limit, missing a decompression stop or not allowing a sufficient surface interval between dives.
Don’t kid yourself into thinking you can sneak past the decompression table limits just this one time. This sort of thinking is like playing Russian roulette – you just never know which chamber contains the bullet. Statistics indicate the odds are against you.
2 RAPID ASCENT: Another major contributor to DCS is a rapid ascent from depth – exceeding the maximum ascent rate of 60 feet per minute. Coming up too fast can result in bends, even if you have safely followed the dive table profile for time and depth.
To ensure your personal safety, do just the opposite. Concentrate on ascending slower than 60 feet per minute. In fact, some dive computers operate on much slower ascent speeds of 40, 33 or even 20 feet per minute at shallow depths. Just remember; slower is better, faster is bad.
3 PUSHING THE LIMITS: Every dive computer manufacturer and most instructors make a point of warning divers the tables are not infallible. There is a margin of error because the tables are based on averages. Consistently pushing the tables (or your computer) to the very edge of its limits is an invitation to the chamber. Sooner or later, you are going to get bent.
Again, the wisest procedure is to never allow yourself to get anywhere close to the limit. Begin your ascent from depth at least five minutes prior to reaching the no decompression limit. In doing so, your body will not be as saturated with nitrogen gas and the chances of DCS will be remote.
4 No SAFETY STOP: Another significant contributor to DCS is the lack of safety stops. Even though all live-aboards and most day boat operators recommend a safety stop at 15 feet for 3 to 5 minutes, many bends victims ignored this sage advice. Impatient to end the dive, many only pause at a safety stop for 30 to 60 seconds – not enough time to do much good.
Whether you think you need it or not, a safety stop at 15 feet can be the best insurance policy for bends prevention. Make that stop a regular part of your diving routine and take the full five minutes (or more) to rest, relax and offgas.
5 FATIGUE: Every once in a while we hear about a mystery case of DCS. The diver stayed well within the safe no de-compression limits and still got bent. How in the world can this happen? Easy – one of the contributing factors that is difficult to measure or document is diver fatigue. It comes from not getting enough rest the night or week prior to diving. When the body is fatigued, it cannot function at full capacity and has difficulty handling gas under pressure. Respiratory and circulatory functions are impaired.
Do not allow yourself to become run-down. Get plenty of sleep. Avoid making one of those all night drive-a-thons to the Florida Keys, expecting to start diving at 9:00 the next morning. Instead, try to get 8 to 10 hours of sleep during the days prior to your diving trip.
6 DEHYDRATION: Another factor contributing to DCS is dehydration. When the body does not get enough water, the blood thickens and loses some of its ability to carry and transfer gases. Dehydration can lead to bends, even if a diver stays well within the safe no decompression limits. Since dehydration is difficult to measure, it is virtually impossible to identify what role it played in a particular DCS event.
You can avoid dehydration by simply drinking plenty of water. Drink water on a regular and frequent basis, regardless of whether you feel thirsty or not. Dehydration is a silent stalker and many of its victims are not even aware of their state. Incidentally, make sure the liquid you drink is water – not coffee or alcohol, as they will cause you to urinate and result in greater dehydration.
7 MULTI-DIVES: There is a certain amount of DCS risk every time you make a dive. Fortunately, this risk is very, very small. Certain dive profiles can increase your risk of DCS and you should be aware of this. Studies indicate the risk increases slightly when making two or more dives in the same day. On live-aboards, some divers make as many as five dives per day – definitely an increase in risk.
If you are planning to make multiple dives in the same day, you need to balance the risk by using a conservative dive profile. Start your ascent a full five minutes prior to the bottom time limit. Ascend very slowly. Make a safety stop at 15 feet for each and every dive – progressively increasing the safety stop time on each dive.
8 REPETITIVE DEEP DIVES: Multiple dives in shallow water (40 to 100 feet) increase the DCS risk slightly. Making repetitive deep dives (100 to 130 feet) in the same day will increase the risk even further. You must balance this added risk by diving more cautiously and with more discipline – utilizing the safety procedures described above.
9 MULTI-DAY, MULTI-DIVES: So far, we have only described the risk of multi-dives and repetitive deep dives in a single day. The risk is compounded when multiple dives are made on multiple days. This is the kind of profile that occurs on live-aboard boats and at some dedicated dive resorts. The danger is very subtle, often resulting from the gradual build-up of residual nitrogen from diving day after day, dive after dive. Add to this problem the onset of general fatigue and you have an accident waiting to happen.
If you are planning a multi-day, multi-dive vacation, use caution and dive conservatively. Never push the dive table limits, always ascend slowly and make long safety stops as the day progresses. Reduce the number of dives per day as the week progresses and get plenty of rest in between, as well as at night. You may even want to consider taking a day off from diving midway through your trip.
10 EXTREME DEEP DIVES; Perhaps the highest level of DCS risk occurs when extreme deep dives to 165 feet or deeper are made. We do not condone this sort of diving but we cannot ignore that it happens. The point here is that diving to 165 feet is vastly different than diving to 100 feet. Aside from the fact that such deep dives require absolute self-discipline, perfect timing and careful preparation, researchers are convinced there is additional medical risk that may not be fully understood. The best advice is – don’t do it. But, if you find yourself at 170 feet by error or buddy emergency, take all possible precautions during ascent and decompression. Consider such a dive your last dive of the day. In other words, stop diving so your body can offgas for at least 24 hours. Also, do not plan on flying or driving to altitude for at least 48 hours.
The causes of decompression sickness are not limited to the 10 cardinal sins described above. Other contributing factors include poor physical condition, alcohol consumption, prior illness, strenuous exercise before or after diving, flying too soon after diving, running out of air at depth, becoming distracted at depth and so on.
The most important thing to remember is that your personal safety and health depend solely on what you do underwater, as well as what you do prior to and after the dives. Having the right attitude makes all the difference in the world.