Decompression Sickness in CCR Diver


  • 4 technical Closed Circuit Rebreather (CCR) divers onboard a vessel 
  • 2 days of CCR decompression dives were conducted 
  • One diver began reporting, and was treated for, decompression sickness on day 2 

Reported Incident

Diver A is an experienced older CCR diver who had planned 3 days of technical CCR dives with decompression on several wrecks during this trip. Before the first dive day, Diver A reported feeling uncomfortable with the heat and humidity as well as only having had 2 hours of sleep the night prior. All dives conducted this day went as planned. 

On the second day, Diver A is feeling much better rested but reports only having 2 cups of water from the on-board cooler during another hot and humid morning. After entering the water, Diver A descended to the wreck and explored the ship from a depth of 60 fsw (18 msw) to 124 fsw (38 fsw) for roughly 1.5 hours before beginning the ascent. 

Diver A reports stopping at 20 fsw (6 msw) for 24 minutes of decompression as dictated by a gradient factor of 60/85 with a set pO2 of 1.3 while holding onto the downline. Diver A reported staying an extra 3 minutes on decompression to wait for his buddy’s decompression to clear as well.  

Once back on the boat, Diver A developed a dry cough and nausea that was attributed to the high ppO2 he had been exposed to and motion sickness. However, upon reaching the docks, the nausea worsened, and he noted significant dyspnea on exertion. He was then placed on 50% O2 (the highest available) until they reached the dive shop and began breathing 100% O2. 

At this point (1hour 20min post dive), Diver A noticed some paresthesia and weakness of the right thumb and arm with worsening nausea. He was transported to Mariner Medical Center where a mottled rash was noted on the chest, shoulder, flanks, and thighs. Paresthesia resolved prior to hyperbaric treatment. 

Diver A was then run through a Navy Table 6 which resolved the rash. After the treatment, the diver reported fatigue, but no recurrence of symptoms. The diver then abstained from diving and flew home after 72 hours. 


Early recognition of their symptoms leads to rapid response and lessens the delay in treatment. The diver and crew having recognized the symptoms of decompression sickness so quickly after the dive helped the diver get the proper treatment without much delay. If a diver is exhibiting signs of decompression sickness immediately activate EMS and provide emergency oxygen. 100% oxygen should always be available on all dive vessels. If 100% oxygen is not available, the highest percentage should be what is administered.  


The divers in this incident were well trained, planned their dive, dived their plan and still encountered decompression sickness. As divers we understand there is always a possibility of decompression sickness. This is why it is important to stay hydrated, monitor dive computers and complete decompression obligations and safety stops as directed. Adequate rest and limiting exertion during the dive are important as well. If you would like to know more about decompression sickness and diving, please visit