“Normal” dive resulted in Decompression Sickness
A diver made multiple dives over three days and needed hyperbaric treatment
>It was the third day of a two dives a day series at an island resort. This was the first dive in the morning. Normal dive, less than a minute at 101 fsw (30 msw), the swim through exit was at 95+ fsw (29 msw). I spent about 10 minutes at 80 fsw (24 msw), then another 15 minutes around 60 fsw (18 msw). I made a slow ascent with a 3 minute safety stop at 18 fsw (5 msw). After surfacing, I experienced a searing bilateral shoulder and arm to fingertip pain and bilateral leg to toes tingling and numbness. I started breathing oxygen on the boat and continued in the car on the way to the ER. During the ER visit that day, I had some improvement on oxygen but had recurrent neurologic symptoms that required six hours per day of hyperbaric treatment for the following two days. I returned home after 72 hours and had two more 2-hour treatments in the hyperbaric chamber in my home state to see if the residual tingling/numbness in my toes and fingers would abate. 99% has resolved.
>Two decades ago the maximum allowable total dive time if a diver reached 30m depth would have been around 20 minutes if the dive was planned using tables, as it commonly was. This dive profile may even have been permitted using multilevel planning techniques, but today modern dive computers do the work for us and such a profile is considered a "normal dive". The risk of decompression sickness is thought to be low among recreational divers because the majority of dives come nowhere near the no-decompression limits. After two previous days of repetitive diving, this diver suffered an injury which was diagnosed as a serious case of decompression sickness, probably without violating the dive computer's limits. That the diver made a safety stop was prudent, but of particular note is that there was oxygen onboard the boat, and the diver continued breathing oxygen on the way to the ER. After multiple hyperbaric treatments the diver is 99% recovered, which is good news, though it should be pointed out that bilateral symptoms affecting all four limbs are not typical of decompression sickness. Regardless, this case serves as a reminder that our dive computer may well keep recalculating our allowable limits but that does not mean we should dive to those limits. If 100,000 divers dive to the limits then, even though they did not "break the rules", by probability alone some will get the bends.
>~ Peter Buzzacott, MPH, PhD