Dehydration effects on the risk of severe decompression sickness in a swine model

Aviat Space Environ Med. 2006 Feb;77(2):102-6.


Background: Several physiological factors have been suspected of affecting the risk of decompression sickness (DCS), but few have been thoroughly studied during controlled conditions. Dehydration is a potential factor that could increase the risk of DCS. It has been suggested that hydration may enhance inert gas removal or increase surface tension of the blood.

Hypothesis: Dehydration increases DCS risk.

Methods: Littermate pairs of male Yorkshire swine (n=57, mean +/- 1 SD 20.6 +/- 1.7 kg) were randomized into two groups. The hydrated group received no medication and was allowed ad lib access to water during a simulated saturation dive. The dehydrated group received intravenous 2 mg x kg(-1) Lasix (a diuretic medication) without access to water throughout the dive. Animals were then compressed on air to 110 ft of seawater (fsw, 4.33 ATA) for 22 h and brought directly to the surface at a rate of 30 fsw x min(-1) (0.91 ATA x min(-1)). Outcomes of death and non-fatal central nervous system (CNS) or cardiopulmonary DCS were recorded.

Results: In the hydrated group (n=31): DCS=10, cardiopulmonary DCS=9, CNS DCS=2, Death=4. In the dehydrated group (n=26): DCS=19, cardiopulmonary DCS=19, CNS DCS=6, Death=9. Dehydration significantly increased the overall risk of severe DCS and death. Specifically, it increased the risk of cardiopulmonary DCS, and showed a trend toward increased CNS DCS. In addition, dehydrated subjects manifested cardiopulmonary DCS sooner and showed a trend toward more rapid death (p < 0.1).

Conclusion: Hydration status at the time of decompression significantly influences the incidence and time to onset of DCS in this model.

Publication types

  • Evaluation Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Analysis of Variance
  • Animals
  • Decompression Sickness / etiology
  • Decompression Sickness / physiopathology*
  • Dehydration / physiopathology*
  • Disease Susceptibility / physiopathology*
  • Diving / adverse effects*
  • Logistic Models
  • Male
  • Random Allocation
  • Risk
  • Statistics, Nonparametric
  • Survival Analysis
  • Swine