title: Nitrogen load in rats exposed to 8 ATA from 10-35 degrees C does not influence decompression sickness risk.
abstract: BACKGROUND
  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 degrees, 27 degrees, or 10 degrees C during compression; 35 degrees, 20 degrees, or 10 degrees C post-decompression). Animals were observed for 30 min post-decompression for signs of DCS. DCS incidence in the 27 degrees C compression/20 degrees 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).
  
  
  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 degrees 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.
authors.affiliation: Diving and Environmental Physiology Department, Naval Medical Research Center, Silver Spring, MD, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fahlman
authors.forename: Susan R
authors.initials: SR
authors.lastname: Kayar
mesh_terms: D000818:Animals; D001274:Atmospheric Pressure; D003665:Decompression Sickness / Q000453:epidemiology / Q000517:prevention & control*; D004195:Disease Models, Animal; D015994:Incidence; D008297:Male; D009584:Nitrogen / Q000097:blood*; D051381:Rats; D012307:Risk Factors; D013696:Temperature
chemical_list: D009584:Nitrogen