Fahlman A, Kayar SR. Nitrogen load in rats exposed to 8 ATA from 10–35°C does not influence decompression sickness risk. Aviat Space Environ Med 2006; 77:795800.
Introduction: Environmental temperature is commonly thought to modulate decompression sickness (DCS) risk, but the literature is mixed regarding which conditions elicit the greatest risk. If temperature is a risk factor, then managing thermal exposure may reduce DCS incidence. We analyzed whether hot or cold conditions during or immediately after a hyperbaric exposure altered DCS incidence in a rat model. Methods: Rats (eight groups of five animals in each of nine conditions; mean body mass ± SD = 259.0 ± 9.2 g) were placed in a dry chamber that was pressurized with air to 70 m (8 ATA) for 25 min, followed by rapid (< 30 s) decompression under a series of temperature conditions (35°, 27°, or 10°C during compression; 35°, 20°, or 10°C post-decompression). Animals were observed for 30 min post-decompression for signs of DCS. DCS incidence in the 27°C compression/20°C post-decompression group was 50% by design. Data from all nine groups of paired temperature conditions were compared with each other using analysis of variance, Chi-square tests, and logistic regression. Results: No significant differences in DCS incidence were found among the groups (30–52.5% DCS incidence per group, 42% DCS incidence overall). Discussion and Conclusions: This animal model emphasized potential temperature effects attributable to tissue N2 load acquired during compression; there was no evidence that environmental temperature from 10–35°C during or post-dive modulated DCS incidence. It remains to be determined if temperature modulates DCS risk as a function of variable N2 elimination rates.
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