Kategorie: News
Chronology of a diving accident
August 2019 Split Clinic, Croatia: Stefan is in intensive care in a foreign country. His state of health is uncertain, he is not conscious. A pressure chamber trip has not been possible because only patients with stable vital signs are admitted to the pressure chamber. Imaging of the brain and lungs would not look good, they say. Communication is difficult because of language problems. No one knows anything for sure. Stefan's wife is full of worry for her husband's life and she is on the way to Split ...
Report provided by aqua med
A day earlier: Kornati islands, near Murter. Stefan is an experienced diver. The biologist even completed the course to become a research diver during his studies. Even if the dives today are only recreational dives, the biologist in Stefan is always on board. He knows most of the dive sites in the area. Last year he was able to detect Caulerpa racemosa algae at a depth of 50 m here (a species of algae that has been introduced into the Mediterranean from the Indo-Pacific and is displacing other life forms there). Today he wants to try to find this algae again. At 09:40 he and his buddy descend, to resurface 38 minutes later after a deco at 6 and 3 m. The maximum diving depth is 59 m with air as breathing gas (pN2 = 5.45 bar; pO2 = 1.45 bar). At this depth, nitrogen becomes increasingly problematic. However, in the case described, this did not contribute to the accident.
At 11:33, Stefan dives again after a surface interval of 1.15 hr. Although this is a short surface interval, it is not evaluated as a violation by the dive computer. This time the diving depth is 50 m.
Although his computer only indicates a deco obligation of 3 minutes at 3m, he extends the deco and safety stop out of a sense of experience. But after surfacing, Stefan is not feeling well. He will only be able to remember this dive after some time and only partially. On board, he immediately receives oxygen and is handed over to the rescuers on shore, who drive him to the hospital in Sibenik, from where he is taken to the pressure chamber in Split the same day. But Stefan is now in such bad shape that he cannot be recompressed in the chamber. So he is transferred to the intensive care unit in Split. The diving equipment is confiscated by the police, but there were no technical defects, the computer shows no significant violations. So Stefan didn't do anything wrong, did he? According to the computer everything was ok.
The question is whether Stefan's behavior as shown above, which does not comply with the recommendations for safe recreational diving, led to the accident? Many "non-sport divers" dive outside the "rules" deeper, longer and on some dives alone. So disregarding common "recreational diving rules" does not automatically lead to a diving accident, but it is not recommended. Stefan is an experienced diver and followed the instructions of his dive computer, so why this serious diving accident?
But first things first... aqua med's diving doctors are informed by the diving center on the day of the accident by calling the emergency hotline and begin to classify the accident medically, to contact the doctors responsible for Stefan at the hospital and to coordinate the treatment procedures. Stefan cannot be taken to the pressure chamber, because most chambers abroad do not have the possibility to treat ventilated patients. The diving doctors and the aqua med assistance team are therefore examining the possibility of transporting Stefan back to Germany to have him treated in a pressure chamber with ventilation. After careful consideration by the doctors, however, the risk of transport is deemed to be considerably greater than the benefit of pressure chamber treatment on site. However, shortly after the decision against an immediate transfer to Germany, Stefan now also develops a fever and in a renewed medical evaluation of the situation it becomes clear that adequate care in the hospital is no longer guaranteed. Therefore, the aqua med medical and assistance team decides to transport Stefan back home as quickly as possible.
Since receiving the initial call on the aqua med diver emergency hotline, the medical team has already clarified various transport options in parallel with accompanying the treatment on site. Since Stefan is not yet stable enough for air transport and there is also no landing permit in Split for the required period of time, aqua med initially decides on intensive care transport by land. In addition to the intensive medical treatment options on board an intensive care transport vehicle, the advantage is also the possibility of making a stopover in the pressure chamber in Graz (Austria) or possibly Munich on the way to the desired pressure chamber in Wiesbaden. However, shortly before the organization of the return transport by land is completed, Stefan miraculously breathes on his own again and can be extubated. The changed situation is re-evaluated by the aqua med medical team and it is decided that a quick repatriation by ambulance flight is now the best thing for Stefan. The doctors on site and his wife also give their okay. Immediately after the flight lands in Frankfurt, Stefan is taken to Wiesbaden and receives his first pressure chamber treatment. Fortunately, the treatment works and he feels better after each pressure chamber trip. However, even after 10 treatments, he is still not fit enough to move around without assistance. It will still be a long way for him...
After now more than a year and a lot of time in rehabilitation Stefan is thankfully doing well again. He can work again and has even been diving after extensive medical checks.
Why did Stefan have such a serious diving accident?
The admittedly provocative statement would be: "He relied on his dive computer" - but let's look at it in detail:
1. Stefan felt safe with his dive computer. On the one hand, according to the user manual, the manufacturer advises against using the device for decompression dives, but on the other hand gives information such as decompression times when no-decompression times are exceeded. In a statement to aqua med, the manufacturer states that as a purely sport dive computer, the device cannot plan decompression dives, but does recommend appropriate decompression levels in the event that sport dive limits are exceeded during an emergency ascent. So it's worth looking into all the details surrounding your dive computer. I.e. just because a computer is advertised as calculating decompression levels does not mean that it is designed for decompression diving.
2. after a little more than an hour of surface interval after a dive requiring decompression, Stefan repeatedly descended to a similar depth. This second dive, which was rather unproblematic from a diving physiological point of view, was probably the final trigger for the severe DCS, but the cause was the first dive, the short surface interval until the following dive and the resulting further saturation of the tissues, which was not detected by the dive computer, which is why Stefan lulled himself into a supposed sense of security.
3. important is: the dive computer had no defect and calculated correctly for its purposes.
However, recalculation of the two deco dives from the day of the accident with specially designed decompression software revealed serious deco violations and omitted decompression stops that Stefan's dive computer did not calculate. Stefan's self-imposed extension of the deco times could no longer make up for this difference.
4. appropriate training, level of experience, proper equipment and its correct operation are interrelated and essential for a safe dive regardless of location, duration and depth.
We used the recreational dive computer in question and a technical dive computer to recreate the two dives, including a surface interval, in a pressure chamber. Despite aggressive gradient factors of 45/95, which is borderline for repetitive dives, there were very large differences in the required decompression time.
While the decompression dive computer scheduled the first decompression stage at a depth of 12 m during the chamber dive, the recreational dive computer did not require the first short decompression until 6 m depth. Both computers were set to the lowest possible conservatism to allow for comparability.
What do we learn from this case?
Know your dive computer. When buying it, the intended use should be clearly defined. The belief that all is well as long as the computer does not indicate any violations is not always enough to get out of the water unscathed.
In the past, you had to learn and understand tables. Today, at best, you learn how to use the dive school's dive computer. Very few divers deal intensively with the possibilities and limitations of their own computer. They blindly trust in the technology.
Always dive within your and your training's predetermined limits.
Note that individual limits may be well within the limits set by the certification due to age or health.
Be aware that even in Europe, optimal care for serious diving accidents is not always immediately available.
The aim of this article is to raise awareness that a dive computer cannot (yet) "think" for us and that it is therefore useful to know your own computer and its limits in detail.
Questions on the report? You can get answers via marketing@aqua-med.eu.
Note from aqua med: We receive many inquiries about the brand of the dive computer and the dive profiles. Since the computer, as already mentioned, has calculated correctly for its purposes and worked perfectly, we will not name the brand and for this reason we will not publish the dive profiles.
The point here is not to analyze a single model. Instead, we want to encourage divers to look at their own model and check it for the right application.