During a second substantial dive a diver follows a grouper away from a shipwreck and makes an ascent without a reference, then exhibits symptoms associated with decompression sickness.
This was the second dive of the day. The first was on a wreck to maximum depth of 78 fsw (24 msw), total time around 40 minutes followed by a surface interval of around one hour. The second dive to 78 fsw (24 msw) was for about 45 minutes. The victim, (58-year-old male) was diving with air (many others in the party, including myself, were diving 33 percent nitrox).
He missed the anchor line we had used for the descent and came to the surface after a free ascent. He was the last diver up and did not appear to have a buddy with him. We subsequently weighed anchor and headed back to port. The victim began developing symptoms of decompression sickness (DCS) within 15 minutes of surfacing. His symptoms started with left scapular pain, though he remained in no acute distress. He progressed quickly to right hand paresthesia in the median nerve distribution. We were concerned for DCS and administered oxygen. Unfortunately the dive boat only had access to nasal cannula so the victim was given 6L per minute via nasal cannula. The US Coast Guard was contacted for assistance and the decision was made to head to port as fast as possible. The patient subsequently developed left great toe and foot paresthesia as well as vertigo. He had one episode of emesis (vomiting).
The diver stated that he got lost following a grouper and lost sight of the wreck. He stated that he’d performed a safety stop and dove to his computer without entering decompression mode but he seemed somewhat evasive during this questioning. It is unclear if he had any air left upon surfacing.
The return trip was about 1 hour 45 minutes to the dock. The US Coast Guard met and escorted the boat at the inlet to the dock and we were met by EMS. The patient was able to ambulate with assistance and was taken by EMS to a local hospital.
This dive profile would fall outside the limits of most, if not all, recreational diving table planners but the diver stated his dive computer did not mandate decompression. This may have been due to a number of reasons, including multi-level profiles in each dive, or the gas setting in the dive computer. Regardless, the diver suffered what appears to have been DCS. To be cautious many other divers on the boat elected to dive with nitrox, which gives a longer no-stop time than air at these depths. We will never know what caused this diver’s DCS but when planning relatively long dives to similar depths then, if any diver thinks the dive might be near the recreational time limit for air, using nitrox with the same plan adds a measure of safety. Remember, proper training is required to plan dives using nitrox.
Peter Buzzacott, MPH, Ph.D.