The 46-year-old, healthy diver had undertaken a dive with compressed air to the Ledi wrecks in Lake Walensee with a bottom time of 35 minutes at 35 m (D12). Approximately 15 minutes after surfacing, he developed tingling, itching and cutis marmorata on his torso. At the nearest hospital, which he visited later the same evening, decompression syndrome type I (mild decompression syndrome) was suspected and he was treated overnight with normobaric oxygen therapy. The symptoms disappeared completely by the next morning and did not recur. The patient did not experience any further symptoms.
He had drunk almost nothing all day before the dive and was tired from work. He had not dived in the days before. He has been diving for 7 years with almost 300 dives and has a NAUI certification up to 40 m including Nitrox. He smokes about 15 cigarettes a day. Next year he would like to do a tech dive course with PADI (certification up to 50 m). He has not dived since suffering from decompression syndrome.
The diving medical examination including transthoracic echocardiography (heart ultrasound) showed no problems. However, an atrial septal aneurysm (lax atrial septum) was found. This is very often associated with a patent foramen ovale (PFO). The course and presentation of the decompression syndrome after a single bounce dive are also highly suggestive of the presence of a patent foramen ovale as a possible risk factor. Particularly noteworthy here is the appearance of cutis marmorata, a typical skin discoloration that is closely associated with the passage of gas bubbles into the large circulation through the foramen ovale. In addition, the unfavorable choice of breathing gas (compressed air with a bottom time of 35 minutes at 35 m diving depth) and a presumably poor state of hydration are causes of the decompression syndrome.
It is typical for decompression sickness to occur within the first hour after the dive, as this is when the greatest supersaturation is present and therefore the risk of bubble formation is greatest.
Normobaric oxygen therapy (i.e. “normal” oxygen administration) in hospital was justifiable under these circumstances. If there are no progressive or complicated symptoms, e.g. signs of paralysis, pressure chamber treatment may be dispensed with, provided the patient is observed.
What is the next step? Can the patient dive again?
He is strongly advised to have a transesophageal echocardiography to reliably detect or rule out a PFO, not least with a view to his future diving career. Irrespective of this, it is strongly recommended that he adheres to the “low bubble diving” guidelines. These primarily include measures to prevent the formation of gas bubbles per se. In particular, the consistent use of Nitrox should be mentioned here. For deeper, longer dives, decompression gases in the sense of “advanced Nitrox diving” should also be used. In addition, care should be taken to avoid dehydration or to drink enough, to avoid long decompression stops on shallow diving levels at the end of the dive, to avoid repetitive dives or long surface intervals. Also, no major exertion should be undertaken in the first hour after the dive, as this favours the formation of bubbles within the tissues.
If a PFO is present or is strongly suspected, as in this case, press maneuvers must also be avoided, as these can briefly open the PFO and thus promote bubble migration. This applies to spontaneous maneuvers such as coughing or sneezing as well as intentional ones. For this reason, it is absolutely forbidden for PFO affected to dive when they have a cold. For the same reason, it is recommended that diving equipment is removed in the water and carried ashore by buddies (unless they have a PFO!) Even a pressing maneuver when lifting the equipment can open a PFO. Because oversaturation and therefore the risk of bubble formation are greatest in the first hour after the dive, this applies to all activities in this phase. Finally, PFO affected persons must also urgently refrain from inflating their deco buoys by mouth. Every PFO opens during this maneuver and the longer and deeper the dive, the greater the bubble formation. This primarily affects technical divers who are reliant on deco buoys. The inflator hose on the stage provides a remedy here.
In principle, the person concerned may dive again. However, he must urgently adhere to the above recommendations. These are well summarized in a guideline from the SUHMS. Even demanding dives are possible with a PFO and it is not absolutely necessary to close the PFO. Closing can offer a certain degree of safety. However, as there is still a risk of decompression sickness in the future, the aforementioned precautions are much more important than undergoing a cardiac intervention.
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