High pressure nervous syndrome

From Wikipedia, the free encyclopedia

High pressure nervous syndrome (HPNS) is a neurological and physiological diving disorder that results when a diver spends too much time breathing a high-pressure mixture of helium and oxygen (heliox).[1] HPNS is a limiting factor in future deep diving.

"Helium tremors" were first described in 1965 by Royal Navy physiologist Peter B. Bennett, who also founded the Divers Alert Network.[1][2] Zal'tsman also reported on helium tremors in his experiments from 1961. Unfortunately these reports were not available in the west until 1967.[3]

The term high pressure nervous syndrome was first used by Brauer to describe the combined symptoms of tremor, electroencephalography (EEG) changes, and somnolence that appeared during a 1,189 foot chamber dive in Marseilles.[4]

Contents

[edit] Symptoms

Symptoms of HPNS include tremors, myoclonic jerking, somnolence, EEG changes[5], visual disturbance, nausea, dizziness, and decreased mental performance.[1][2]

The susceptibility of divers and animals to HPNS does depend on the individual.[1]

[edit] Suppressive Measures

It is not likely that HPNS can be prevented entirely but there are effective methods to delay or change the development of the symptoms.[1][6]

[edit] Rate of Compression

Utilizing slow rates of compression or adding stops to the compression have been found to prevent large initial decrements in performance.[1][7]

[edit] Breathing Mixture

It can be avoided by including small amounts of other gases in the mix, such as nitrogen[8] (creating trimix) or hydrogen[9] (hydreliox)[10].

[edit] Drugs

Alcohol, anesthetics and anticonvulsant drugs have had varying results in suppressing HPNS with animals.[1] None are currently in use for humans.

[edit] See also

[edit] References

  1. ^ a b c d e f g Brubakk, A. O.; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed.. United States: Saunders Ltd., 800. ISBN 0702025712. 
  2. ^ a b Bennett, P. B. (1965). "Psychometric impairment in men breathing oxygen-helium at increased pressures". Royal Navy Personnel Research Committee, Underwater Physiology Subcommittee Report No. 251. 
  3. ^ Zal'tsman, G. L. (1967). "Psychological principles of a sojourn of a human in conditions of raised pressure of the gaseous medium (in Russian, 1961)". English translation, Foreign Technology Division. AD655 360. 
  4. ^ Brauer, R. W. (1968). "Seeking man's depth level". Ocean Industry 3: 28-33. 
  5. ^ Brauer, R. W.; S. Dimov; X. Fructus; P. Fructus; A. Gosset; R. Naquet. (1968). "Syndrome neurologique et electrographique des hautes pressions". Rev Neurol 121 (3): 264-5. PMID 5378824. 
  6. ^ Hunger Jr, W. L.; P. B. Bennett. (1974). "The causes, mechanisms and prevention of the high pressure nervous syndrome". Undersea Biomed. Res. 1 (1): 1-28. ISSN 0093-5387. PMID 4619860. OCLC 2068005. 
  7. ^ Bennett, P. B.; R. Coggin; M. McLeod. (1982). "Effect of compression rate on use of trimix to ameliorate HPNS in man to 686 m (2250 ft)". Undersea Biomed. Res. 9 (4): 335-51. ISSN 0093-5387. PMID 7168098. OCLC 2068005. 
  8. ^ Vigreux, J. (1970). "Contribution to the study of the neurological and mental reactions of the organism of the higher mammal to gaseous mixtures under pressure". MD Thesis. 
  9. ^ Fife, W. P. (1979). "The use of Non-Explosive mixtures of hydrogen and oxygen for diving". Texas A&M University Sea Grant TAMU-SG-79-201. 
  10. ^ Rostain, J. C.; M. C. Gardette-Chauffour; C. Lemaire; R. Naquet. (1988). "Effects of a H2-He-O2 mixture on the HPNS up to 450 msw.". Undersea Biomed. Res. 15 (4): 257-70. ISSN 0093-5387. PMID 3212843. OCLC 2068005.