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Physiopathology of decompression : risk factors for the formation of intravascular bubbles during decompression

Final Report Summary - PHYPODE (Physiopathology of decompression : risk factors for the formation of intravascular bubbles during decompression)

Decompression illnesses (DCI), or as they are called more scientifically: dysbaric disorders, represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change.
Available therapies alleviate symptoms in many cases, but not all and up to 13% of patients still had severe disability with substantial impact upon daily living. Moreover, apart from the more obvious acute manifestations of a single, sudden decompression, individuals who have experienced repetitive exposures (e.g. commercial or professional divers and active recreational divers) may also develop sub-acute or chronic manifestations, even if subtle and almost symptomless. Thus, improving prevention of DCI was the goal of the FP7 – Marie Curie ITN network PHYPODE Physiopathology of decompression (

In this aim, scientific and educational teams from universities, hyperbaric medical centres, non-profit diving institutions and industrial partners from France, Poland, Belgium, Italy, Croatia, Egypt and South Africa selected 14 excellent young researchers in a worldwide competition to develop a coherent and integrated research training program on decompression phenomena with specific attention to the formation of intravascular bubbles with their pathophysiological and clinical consequences, including DCS. They enthusiastically combined their excellent disciplinary education to exchange knowledge, share research techniques and resources, during joint-research activities for underwater experimental diving (Nemo33, Belgium; Lago d’Orta, Italy; Labin, Croatia), courses, seminars, workshops and congresses.

The unique epidemiological survey conducted by the DAN Diving Research Laboratory database allowed the analysis of more than 63 000 real dives, including 312 DCS cases. Analysis of the DSL database shows that the vast majority of all recorded DCS cases occurred without any violation of the respective algorithms, in other words, with compartment inert gas pressures well below the maxima allowed. In addition, the DSL database and field research also show that many other physiological variables may be involved in the pathogenesis of DCS, even within computed “safe” limits.
These physiologic variables include non-modifiable risk factors such as gender, age and genetic predisposition. Other modifiable risk factors include post-dive physical exercise, patent foramen ovale (PFO) and intrapulmonary arterial-venous anastomoses (IPAVAs).
The reciprocal relationships between diving and/or DCS with arterial endothelial function were also considered. Data show that diving alters not only endothelial function, as it was repeatedly reported post-dive, but also vascular smooth muscle both in large conductance arteries and in microvessels. This effect is probably due to the combined action of hyperoxia and hydrostatic pressure (i.e. before decompression) in all vessels, together with circulating bubbles in large conductance arteries. On the other hand, some pre-dive conditioning can give some protection against bubble formation or post-dive vascular dysfunction. They include pre dive oral hydration, heat preconditioning, vibration preconditioning, antioxidant intake pre-dive. Interestingly, not all preconditioning decreased the amount of circulating bubbles after the dive, and no evident relationship was found between the changes of post-dive bubble formation and endothelial dysfunction.
Some of these findings can be used immediately to up-date decompression procedures and recommendations given to divers. Investigations at the molecular level taught us a great deal more about DCS, providing insights that we hope will improve the effectiveness of both prevention and treatment.

From this body of research, 39 articles are already published in international peer reviewed journals, 141 communications were presented in scientific congresses and about 10 public conferences were organized. Furthermore, nearing the end stages of the project, the researchers who have been working in PHYPODE have summarized current concepts and ideas, as well as some results of their cutting-edge research projects into a book, this book “The Science of Diving”. It is not only written in such a way that it should allow divers to learn more about the modern approaches to understanding decompression and its problems, but also, contribute to expanding the diving decompression knowledge of physiologists, medical personnel and basically anyone with an interest in “the heart of the matter”.

The book is available online now on or on order via any bookstore using ISBN number. Book sale profits will be used entirely to promote and support diving medicine research via the European Baromedical and Underwater Society (EUBS).

Details on each author’s affiliation are available on the PHYPODE website: