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.

Introduction: Because a significant association between training to perform emergency free ascent (EFA) and the occurrence of pulmonary barotrauma (PBT) was demonstrated in 2006, the Belgian Underwater Federation (BUF) decided to discontinue this procedure. An evaluation was needed 10 yr after the implementation of this change. Methods: All medical records with a diagnosis of PBT that occurred in Belgium from November 2006 to September 2016 were prospectively collected. Data on the proportion of in-water skills training dives were obtained from BUF.

Despite the abundance of telemetric applications for ecology, behavior and physiology of marine life, few efforts were reported about the use of acoustic telemetry for SCUBA divers. Such systems are required to study the medical conditions of some type of divers such as diabetic ones. This study communicates the details of a study to design, manufacture and test a prototype system that measures the blood glucose while diving and transmit the results in real time to the surface. The system design consists of a subcutaneous sensor to measure interstitial glycaemia, a microcontroller based RF receiver board in a custom built waterproof casing, a pair of acoustic modems to transmit data underwater and a computer on the surface to log the received data.