Incident Insight reprinted from Alert Diver magazine
By Marty McCafferty
Time and Recovery
Injured divers should be treated promptly, but delays don't always mean bad outcomes.
>DIVER NO. 1
>The diver was a 45-year-old, healthy female with reasonably good physical fitness. She had been certified for five years and had done 15 dives in the previous year. She had no problems on the first day of her Caribbean dive vacation but reported minor difficulties with her rental BCD. On the following day she dived to 88 feet for 30 minutes and 30 feet for 30 minutes, using normal air and spending 90 minutes on the surface between dives. During the second dive, she attempted to vent air from her BCD but mistakenly depressed the inflator mechanism and made an uncontrolled ascent. She later reported feeling weak and unable to move her legs during the ascent. Upon reaching the surface she lost consciousness.
>The crew immediately brought her onboard the boat and administered oxygen with a demand mask. They recalled the divers who remained in the water and quickly proceeded to the dock. A local ambulance service had been contacted by radio and was waiting when they arrived. Upon arrival at the local hospital, the treating physician diagnosed arterial gas embolism (AGE), and the diver was taken into the hyperbaric chamber. The elapsed time from the onset of symptoms to entering the chamber was one hour, during which the diver's supply of 100 percent oxygen was interrupted only twice and for less than five minutes each time.
>The diver was treated with a U.S. Navy Treatment Table 6 (TT6). Within the first 20 minutes in the chamber, at 60 feet, she regained consciousness. The treatment was extended by three oxygen periods (about five hours), but her symptoms improved only slightly. Despite the treatment, she was unable to urinate on her own and needed a catheter. The next morning she was treated again with another extended TT6. Motor function in her legs did not return but sensation did. She still required a urinary catheter. In consultation with DAN®, the decision was made to evacuate her to the U.S. in an air ambulance at sea-level pressure for further treatment. Upon arrival in the U.S., she was treated aggressively with multiple hyperbaric treatments totaling 57 hours. Ultimately, she was discharged with residual weakness and numbness in her legs. After three months she was able to urinate on her own, but she reported persistent sexual dysfunction. After a year of following this diver's progress, it was determined that the weakness, numbness and sexual dysfunction were likely permanent.
>DIVER NO. 2
>The diver was a 50-year-old male who had been diving actively for 20 years. He was traveling on a liveaboard in a remote area. On the fourth day of his trip he made two dives, the first to 133 feet for 37 minutes and the second to 88 feet for 47 minutes. He used normal air on both dives and spent two hours on the surface between them. During the second dive the sea conditions changed. The waves became larger, causing the divers to move up and down vigorously during their 15-foot safety stop. Within five minutes of boarding the boat the diver began to complain of severe right shoulder pain that quickly progressed to numbness and weakness. He became unable to stand or walk normally. The crew helped him find a seat and began to evaluate him. He had impaired sensation and motor function in both legs and diminished strength and reduced sensation in his right arm. The crew provided oxygen via demand mask. The boat had a two-hour supply of oxygen, and it would take eight hours to get to the closest medical facility.
>The island with the medical clinic had no chamber, so it was determined the diver should be promptly evacuated to the U.S. Unfortunately, the island's runway was not lit, making flights after sunset impossible. The boat was scheduled to make landfall at 10 p.m., so DAN TravelAssist® arranged for an air ambulance to arrive on the island at sunrise, approximately 7:15 a.m. the next day. The aircraft would be pressurized to sea level for transporting the diver.
>On the way to the island, the diver's strength and sensation in his right arm returned to normal. He was still unable to move his legs but was beginning to sense pain in his left leg. He also became aware he was unable to urinate. The oxygen supply lasted the expected two hours, and he went without oxygen for more than six hours. The boat made landfall at 10:45 p.m., and the diver was transferred to the clinic in a personal vehicle belonging to one of the clinic staff.
>On examination the diver had no strength in either leg, only painful sensation in the left leg and no sensation in his right leg. He required a catheter to urinate. The doctor diagnosed acute neurological decompression sickness (DCS). He remained on oxygen through the night and received fluids through an IV. Due to the clinic's limited supply of oxygen, they could provide only 6 liters per minute instead of the recommended 10 to 15. The air ambulance arrived at 7:30 a.m. and landed in the U.S. with the diver three hours later. Upon arrival, he was transferred by ambulance to the closest chamber, which had been waiting for him since being notified by DAN the day before. He entered the chamber at 11 a.m. The elapsed time from the onset of symptoms to entering the chamber was approximately 20 hours.
>The patient was treated with an extended TT6 and improved measurably. He received four additional TT6s over the next two days and continued to improve. In the following days he underwent five more, shorter treatments (U.S. Navy Treatment Table 9s). He was discharged with some residual loss of sensation in his legs as well as persistent sexual dysfunction and inability to urinate. Within one month the diver was able to urinate on his own, and over the next three months all residual symptoms completely resolved.
>Decompression illness (DCI), which includes both AGE and DCS, is not always predictable with regard to when and to whom it occurs. It can be equally difficult to predict with regard to recovery. DCI should always be treated within as short a time span as possible, but as these cases illustrate, prompt treatment does not always guarantee a positive outcome. Conversely, a significant delay does not guarantee a negative outcome. The variables affecting final outcomes are far too many to allow reliable projections. The importance of administering oxygen promptly and seeking definitive care as soon as possible cannot be overstated. Contact DAN early in the process to obtain the assistance and guidance we can provide. Research is ongoing, but the ability to make dependable predictions about DCI is elusive.
>© Alert Diver — Winter 2012