Commercial saturation diving involves divers living and working in an enclosed atmosphere with elevated partial pressure of oxygen (ppO2) for weeks. The divers must acclimatize to these conditions during compression, and for up to 28 days until decompression is completed. During decompression, the ppO2 and ambient pressure are gradually decreased; then the divers must acclimatize again to breathing normal air in atmospheric pressure when they arrive at surface. We investigated 51 saturation divers’ subjective evaluation of the saturation and post-decompression phase via questionnaires and individual interviews.

Hyperbaric oxygen therapy, apart from some acute and very specialized indications regarding the treatment of decompression disorders and arterial air/gas embolism, is generally aimed at treating serious and complex disorders, generally reluctant to standard treatment and requires prolonged and reiterated hospitalization/rehabilitation periods as well as elevated technical, social and human costs.

Purpose: Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver’s safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release. Methods: Sixty experienced divers breathing Air, Trimix or Heliox, were studied during an open water dive to a depth of 6 ATA with a square profile testing CFFF measurement before (T0), during the dive upon arriving at the bottom (6 ATA) (T1), 20 min of bottom time (T2), and at 5 m (1.5 ATA) (T3).

In situ evaluation of human brain performance and arousal remains challenging during operational circumstances, hence the need for a rapid, reliable and reproducible tool. Here we hypothesized that the Critical flicker fusion frequency (CFFF) reflecting/requiring visual integration, visuo-motor skills and decision-taking process might be a powerful, fast and simple tool in modified gravity environments. Therefore 11 male healthy volunteers were assessed for higher cognitive functions with CFFF during parabolic flights. They were assessed at different time points: upon arrival to the base, 30 min after subcutaneous scopolamine administration, before parabolas, during hypergravity and microgravity at break time (between the 16th and the 17th parabola), on the return flight and on the ground after landing.

By using dive tables or diving computers, divers are effectively using decompression algorithms to manage the risk of developing decompression sickness (DCS). They dictate the time allowed at each depth before the dive converts from no-decompression dive into a decompression dive, as well as the decompression stops needed for a decompression dive (time to spend at various depths on the way up to the surface). These algorithms are calculations that follow from the principles of a given decompression theory; of these, different ones exist with wildly different approaches. It is clear that the principles of those algorithms are very different in terms of what the mathematical modelling translates to in reality. This highlights that we still do not know exactly how bubbles form and grow in the body and when they trigger DCS.