When is Safe not Safe Enough?
Recently, there have been several reported cases of DCI from divers, who by all accounts didn't take any undue risk. One case tells the story of a 26 year old diver returning to Denver after his honeymoon in Cancun. The other, recounts the experience of a 16 year old returning home from the Caribbean who developed joint pains 8 hours post diving, but who then saw increased severity and development of new symptoms on the flight home. For the sake of thoroughness, the links to the articles being described can be found at the bottom of this post.
There are several factors to discuss within the context of these articles, but to start, it is important to refresh our background of DCI or Decompression Illness. DCI, or DCS as it was formerly known is the group of medical problems caused by a rapid decrease in the pressure that surrounds a person, of either air or water. It occurs most commonly in scuba or deep-sea divers.
When scuba diving with compressed air, a diver takes in extra oxygen and nitrogen. The body uses the oxygen, but the nitrogen is dissolved into blood, where it remains during the dive. Asa diver ascends after a deep dive, the water pressure around you decreases.
If this transition occurs too quickly, the nitrogen does not have time to clear from the blood. Instead, it separates out of the blood and forms bubbles in the diver's tissues or blood. It is these nitrogen bubbles that cause decompression sickness.
Evaluating these two events then, we can understand the physiological process that is occurring, with bubbles of nitrogen expanding in the blood and tissues, causing the symptoms they are experiencing. Furthermore, it becomes apparent that each of the two cases experienced worsening symptoms during flight, as they were both exposed to a lower atmospheric pressure than they had previously been at. This lowering of pressure is known to exacerbate the formation of DCI symptoms, which is why most recreational SCUBA agencies recommend waiting to fly for a minimum of 12 hours after a single dive, or 18 hours after a series of dives.
In the cases presented within these articles, several things are striking. First, neither of the two victims were diving particularly aggressively, nor did either of them violate an appropriate ascent rate, or fly too quickly after diving. By all accounts, they followed all the rules and waited the proper time. Thus, this can be called an underserved hit. Meaning, that statistically they should have been fine and did nothing to increase their personal risk of DCI. Second, despite both following the appropriate procedures, they both ended up with DCI symptoms and required decompression in a hyperbaric chamber. Lastly, both were relatively young and fit, which should cause them to have a lower risk for DCI compared to someone with a higher body fat percentage or whose systems were not able to off gas the nitrogen as effectively.
What can be said than of the safety factors that we consider as gospel in diving? Do we take too much risk? An appropriate amount? Do we as divers just accept the inherent risk that come with diving? I think for many people there are two categories. The first is those who understand and accept the risk. They have been student of dive and know that on any dive, even a conservative one there is the potential for a DCI. These divers will likely identify DCI should it occur and seek out appropriate care. What is more concerning is the other category, those who don't know and who might not recognize a DCI if it occurred. Most dive certifying agencies don't publicize that there is around a 1% chance of DCI even when following dive tables perfectly and doing everything right. Therefore, the potential of a decompression injury is often not thought about until long into the illness process. When we talk about DCI, one of the primary ways to mitigate long term effects is by early recompression. If DCI isn't considered because divers assume they have been safe, there is the potential for DCI to be missed as a diagnosis, especially in places not expecting to deal with barotrauma.
Are we safe enough in diving then? I would argue the answer is yes, but each person has to make their own judgment call. Are the safety factors that have been built into diving enough for you? That isn't a question this post can answer. What I will say, it that regardless of whether you are a new diver or one who has thousands of dives, don't underestimate the need to have a safety plan and to consider the risks on every dive. We can make diving as safe as possible, but there will always be factors beyond our control.
Until Next Time,
- The Lonely Tech Diver
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