Decompression comparison of helium and hydrogen in rats

E.C. Parker, R.S. Lillo, W.R. Porter

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DOI: 10.1152/jappl.1997.82.3.892 DOI is the universal ID for this study.

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The hypothesis that there are differences in decompression risk between He and H2 was examined in 1,607 unanesthetized male albino rats subjected to dives on 2% O2-balance He or 2% O2-balance H2 (depths < or = 50 ATA, bottom times < or = 60 min). The animals were decompressed to 10.8 ATA with profiles varying from rapid to slow, with up to four decompression stops of up to 60 min each. Maximum likelihood analysis was used to estimate the relative decompression risk on a per unit pressure basis (termed 'potency') and the rate of gas uptake and elimination, both factors affecting the decompression sickness risk, from a specific dive profile. H2 potency for causing decompression sickness was found to be up to 35% greater than that for He. Uptake rates were unresolvable between the two gases with the time constant (TC) estimated at approximately 2-3 min, leading to saturation in both cases in < 15 min. Washout of both gases was significantly slower than uptake, with He washout (TC approximately 1.5-3 h) substantially slower than H2 washout (TC approximately 0.5 h). It is unknown whether the decompression advantage of the faster washout of H2 or the disadvantage of its increased potency, observed in the rat, would be important for human diving.

Publish Year 1997
Country United States
Rank Neutral
Journal Journal of Applied Physiology
Primary Topic Whole Body
Secondary TopicDiving
Model Rat
Tertiary TopicDecompression Sickness
Vehicle Gas
pH N/A
Application Inhalation
Comparison Helium