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| Title: | MODULATION OF DECOMPRESSION SICKNESS RISK IN PIGS BY CAFFEINE ADMINISTRATION DURING H2 BIOCHEMICAL DECOMPRESSION. |
| Authors: | Kayar, SR
Fahlman, A
Lin, WC
Whitman, WB |
| Keywords: | decompression
ONR
biochemical
hydrogen
hyperbaric
chamber
pig
animal
CAFFEINE |
| Issue Date: | 2001 |
| Abstract: | BACKGROUND: Hydrogen biochemical decompression is a process in which intestinal microbes remove some of the H2 dissolved in the tissues of animals breathing hyperbaric H2, thereby lowering their risk of decompression sickness (DCS; Kayar et al., AJP 275:R677, 1998). We hypothesized that increasing intestinal perfusion would increase the supply rate of H2 to Methanobrevibacter smithii, a microbe that metabolizes H2 to CH4, further lowering DCS incidence in pigs following a simulated dive with H2. METHODS: In 1 atm air, caffeine ingestion (5 mg(sum)kg-1) increased oxygen consumption rate of pigs by 20percent and heart rate by 8percent for greater than 3h. Animals were given caffeine alone (Ca+INJ-, n = 10, 20.0 +/- 2.0 kg), or caffeine and intestinal injections of M. smithii (Ca+INJ+, n = 10, 18.9 +/- 1.7 kg). They were placed in a hyperbaric chamber, compressed to 24 bar (20.5 - 23.1 bar H2, 0.3 - 0.5 bar O2) for 3 h, then decompressed to 11 bar and observed for 1 h for severe signs of DCS. Chamber concentrations of O2, H2, and CH4 were measured by gas chromatography throughout the dive. The rate at which pigs released CH4 ( ) was used to monitor microbial activity. RESULTS: Ca+INJ+ animals had a significantly (t-test, P less than 0.05) higher than Ca+INJ- animals (104 +/- 14 vs. 67 +/- 9 mmol CH4(sum)min-1). However, the DCS incidence in Ca+INJ+ was 90percent (9/10) versus 40percent (4/10) in the Ca+INJ- animals (c2, P less than 0.05). CONCLUSIONS: The higher DCS incidence in M. smithii-injected pigs was unexpected. It may be attributable to increased tissue H2 loading due to the caffeine, combined with unknown effects on intestinal perfusion following microbial injections. There is much we must learn about biochemical decompression before it can be offered to human divers. Support: ONR 603706N 00096.133. |
| Description: | Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org ) |
| URI: | http://archive.rubicon-foundation.org/1027 |
| Appears in Collections: | UHMS Meeting Abstracts
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