High pressure nervous syndrome

High pressure nervous syndrome (HPNS) is a dangerous diving disorder that can arise when a diver spends too much time breathing a high-pressure mixture of helium and oxygen (heliox) at depths in excess of 130 metres (430 feet). Its symptoms include dizziness, nausea, vomiting, tremors, myoclonic jerking, and decreased mental performance. It can be avoided by including small amounts of other gases in the mix, such as nitrogen (creating trimix) or hydrogen (hydreliox).

Additional recommended knowledge

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Essential Laboratory Skills Guide

HPNS was first described and named by Royal Navy doctor Peter B. Bennett, who also founded the Divers Alert Network. Bennett was a consultant on the James Cameron underwater science fiction film The Abyss, in which a character experiences HPNS.[1]

See also

• decompression sickness
• nitrogen narcosis

References

• High Pressure Nervous Syndrome, Diving Medicine Online (viewed 5 Apr 2005)