Abstract:

The story of ultra-deep diving is also the story of the High Pressure Nervous Syndrome. Before 1970, the High Pressure Nervous Syndrome was known as the helium tremors or the helium shakes. Some people believed in it, notably in the Royal Navy. Others disbelieved its existence, notably in the US Navy. Since then, the High Pressure Nervous Syndrome has been widely described in all aspects of deep helium-oxygen diving. It is associated with gross abnormalities of the electro-encephalogram, severe tremors, micro-sleep (when divers appear to drift off to sleep and wake up a few moments later), gross discoordination, nausea, vomiting and a marked incapacity to work. All dives deeper than about 1300 feet have been largely limited by the High Pressure Nervous Syndrome. The Atlantis series of dives at the F.G.Hall Environmental Laboratory at Duke University was designed to explore the effects of adding nitrogen to the helium-oxygen mixture to offset the effects of the High Pressure Nervous Syndrome.