O. A. was a Technical Diving Instructor with several years of experience in teaching all levels of technical diving. The events leading to his tragic death started on Saturday, the 27th December 2008, when he made a Trimix dive to the depth of 100 meters in the area of Marsa Alam in order to locate the body of a dead friend. The dive itself from a technical point was uneventful and O. A. was successful in locating the body of his friend which he intended to retrieve the following day.
O.A. planned to dive to a depth of 110 meters with a Trimix depth mix of 10% O2, 35% N2 and 55% He in a 12L twin set. He had for travel and early decompression a mix of 35% Nitrox in a 12L tank and a shallow decompression mix of 55% Nitrox in a 12L Tank. All 4 tanks were pressurized to +/- 200 Bars. The actual gas supply he took on him was less than the calculated gas requirements, a decision that he knowingly took based on the fact that he had a good rate of gas consumption. The planned profile itself was square with an ascent that should have started after exactly 20 minutes from submerging. The ascent time together with the decompression time were planned to be 187 minutes with a total (dive run time) of 207 minutes.
On the 28th December at 3.20 p.m., O. A. started his dive. The descent went as planned but it took him longer than expected to find the body and by the time he was able to attach the body to his lift bag and inflate it towards the surface he realized that he was still at 97 meters with a bottom time of 27 minutes and a mix that was starting to be heavy on breathing, yes the depth mix was running out. As a very experienced diver, he realized that switching to either Nitrox tanks might cost him his life, so he started to speed up to the first stop, he managed to stop at 46 meters and probably switched to the 35% Nitrox tank but his stop did not last more than 20-30 seconds after which he was blown up to the surface having an ascent time of 3 minutes from 97 meters to 0 and a total dive time of 30 minutes. His failure to sustain the stops could have been due to failure in controlling his buoyancy, but it is more likely due to severe decompression sickness symptoms that had already started at depth. The accidental low on gas situation could be explained by the fact that in planning his gas supply requirements O. A. did not take into consideration the possible stress factor which could cause him to hyperventilate nor the possibility that the body might shift or move from the original position requiring an additional effort on his part to relocate. It is most probable that in his desire to retrieve his friend's body he neglected to monitor his time and supply pressure properly.
A simple calculation on this dive will reveal that O. A. had an omitted decompression of 177 minutes, which would only be applicable if the diver would have stuck to the planned profile. The fact that he actually exceeded the planned time by 7 minutes at depth would have add at least 50-60 minutes to the planned decompression time. Another factor that could affect the actual decompression time 2required is if the decompression time was originally calculated using air or the depth mix instead of hyperoxigenated mixtures. In this case the decompression time would have increased by 15-20%, which leads me to believe that the estimated omitted decompression time in this case should have exceeded 4 hours.
O. A. surfaced at 4.50 p.m.. He was screaming of severe generalized body pain especially in the chest. He was transported to the chamber within 10 minutes and was recompressed to 18 meters within another 5 minutes. After two chamber oxygen breathing periods he started to feel a marked relief from the pain but his breathing was still labored. He was conscious, alert cooperative and could say a few words about his dive. No one really asked about details as all were focusing on his condition.
The fact that his urine was retained together with the chest (girdle) pain he was suffering from suggested a spinal affection. He was catheterized, rehydrated and corticosteroids loaded. The diver was kept at 18 meters on oxygen on extended table 6 USN but still started to undergo deterioration in the form of weakening of the muscles followed by loosing the motor power of his legs confirming the spinal injury. The spinal affection experienced a very fast ascent of the level with an increase in the intensity of the edema till he could not move any muscles in both lower limbs. The level was still rising till his arms started to feel numb and weak, then he started loosing the power of the arm muscles. The expected outcome was death from respiratory failure when the ascending spinal edema would reach the cervical segments or the brain stem.
Arrangements were done to conduct a deeper Heliox table, which was carried out to 30 meters (Comex 30), apparently this table could slow down the speed of the pathology but the diver was not improving. Approaching the end of the table that lasted more than 17 hours, O. A. could only use his belly to breathe (abdominal breathing) which indicated paralysis of the inter-costal muscles denoting thoracic spinal edema, he was starting to loose concentration and seemed to be confused.
On the morning of the 29th, O. A. came out of the chamber and started to deteriorate even further. He was transported to an intensive care unit in the area of Marsa Alam where it was recommended that he should be transported to a more advanced facility in Hurghada.
O. A. was transported to an intensive care center in Hurghada where he was put on a ventilator as he could no longer breathe spontaneously. He developed an unexplained fever of 40° later that evening which suggested that the spinal edema had ascended to reach his brain stem. On the 30th December at 12 noon O. A. was reported to have gone into a coma and CT scan of the brain revealed edema. He passed away on the morning of the 31st December 2008. He was only 29 years old. The cause of death was reported to be brain edema.
Diagnosis:
The initiative pathology is Venous Gas Embolism (VGE) with a massive amount of gas bubbles forming in the venous circulation and lodging into the lungs causing serious lung decompression (Chokes) then overcoming the lung filter passing to the arterial circulation leading to Arterial Gas Embolism (AGE).
The spinal affection can be the result of venous or arterial embolism of the circulation of the spine or even due to the formation of gas bubbles within the spine itself.
According to a German study in Murnau, the cause of death in all cases of massive decompression is always brain edema regardless of the treatment.
*In this study, four cases out of five died despite the intensive chamber treatment, they were all on ventilator wit hyperbaric treatment. The longest survival was five days and the worst profile had an omitted decompression of 45 minutes without mentioning any fast ascents.
Comments:
-The case is normally not a chamber treatment case as divers who conduct such dives usually die long before they reach any facility.
-No one can claim that a particular treatment table could have saved the life of the diver as there is no documentation (world wide) of treatment of a similar case with nearly 4 hours of omitted decompression together with a very high rate of ascent.
-Deep air tables (like US Navy table 6A) are contraindicated in such cases for 2 reasons:
1- Air should never be used in recompression of Helium dives.
2- Any case with respiratory distress should not be subjected to breathing dense mixtures (air) as this normally aggravates the condition and reduce oxygen saturation.
- Though saturation treatment table (as table 8 US Navy) are the ones thought to have the most satisfactory results in saturation divers' incidents, they do not have any scientific proof that they can adequately deal with such a case. These tables are deeper tables (starting at 70 meters), and require a large amount of helium (starting with 84% Heliox at 70 meters) for very long duration of time (the shortest is 56 hours without extensions). These tables can not be conducted in any treatment facility that is designed to handle recreational diving incidents in almost the whole world.
Technical diving is a practice that should really be taken with great respect. Inadequate knowledge or violation of even the simplest details of the profiles, such as the depth or accurate timing, is unforgiving. The treatment of massive violations of technical diving is extremely difficult with very unpredictable results.
I have always said "One dive a day keeps the doctor away" but this seems not to apply to technical diving so I guess what I can only say now is:
"It is better to be safe than sorry".
Dr. Hossam M. Nasef
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