Venous gas bubbles in breath-hold divers remains a focus of researchers, with a notable presentation coming from Danilo Cialoni and his EDAN team.1 At the European Underwater and Baromedical Society’s (EUBS) 2017 conference, they presented the extension of the study previously reported and described in the blog “Breath-Hold Diving, Circulating Gas Bubbles, and Neurological Symptoms.” After discovering post-dive venous gas embolism (VGE) in one breath-hold diver, they studied VGE in 37 elite breath-hold divers during their training in 42 meter deep pool with water temperature of 32oC.
Divers underwent echocardiographic monitoring before the series of dives, after a number of training dives, and every 15 minutes for up to 90 minutes after the last dive. Bubbles were detected in 39 percent of divers (28 percent low VGE grade and 11 percent high VGE grade). Bubblers did significantly longer and deeper dives with shorter surface intervals. The data from this study will be used to correct the decompression algorithms for breath-hold divers, which primarily means extending the time between the dives to prevent carrying over dissolved gas from one dive to another. Four divers did develop neurological symptoms of taravana during the study. All symptoms were mild and divers recovered after breathing oxygen at surface. Most notably, in one diver with taravana, bubbles were not discovered.
Another taravana case unrelated to this study was presented by another group.2 A 39-year-old diver performed about 30 dives over the course of five hours to depths between 29 and 32 meters, with dive times between 2 and 2.5 minutes each. A few minutes after his last dive the individual developed expressive aphasia (difficulty speaking and expressing thoughts) and a headache. The aphasia resolved shortly but the headache persisted and diver was admitted to an emergency department 48 hours post dive. The diagnostic workup included the brain MRI which revealed a brain injury. The patient was treated with one Table 6 and five HBO treatments at 2.5 ATA on the following days. His conditions significantly improved after the treatment and at two months follow up he was completely recovered.
Competitive breath hold divers should be aware that postdive symptoms may be caused by brain injury, and regardless of assumed cause (decompression or hypoxic) they need neurological examination and treatment in case of confirmed injury.
References
- Cialoni,D. et al. Prevalence of venous gas emboli in repetitive breath hold diving. Proposal for a new decompression algorithm. P 17.
- Guerreiro F, et al. Decompression illness in extreme breath hold dive (Taravana syndrome) – A case report. P 47.