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Decompression comparison of N2 and O2 in rats
1Naval Medical Research Institute, Diving Medicine Department, Bethesda, Maryland 20889-5055.
Undersea Biomedical Research
|July 1, 1991
Summary
Oxygen (O2) significantly increases decompression sickness risk in rats, even with rapid O2 washout. Nitrogen (N2) washout is slower, but O2 remains a key factor in diving risks.
Area of Science:
- Physiology
- Diving Medicine
- Toxicology
Background:
- Previous research indicated oxygen's significant contribution to decompression sickness (DCS) risk in rats following rapid decompression.
- Oxygen uptake is rapid, reaching equilibrium within a minute, unlike slower inert gases like Helium (He) and Nitrogen (N2).
Purpose of the Study:
- To investigate the role of oxygen in diving physiology and its impact on decompression outcomes.
- To further define the contribution of oxygen to decompression sickness risk under controlled diving conditions.
Main Methods:
- Unanesthetized male albino rats were subjected to 60-minute Nitrogen-Oxygen (N2-O2) dives at varying pressures (1-3 atm abs O2, 6.26 or 7.26 atm abs total depth).
- Slower decompression profiles, including 20-minute stops, were employed to assess N2 and O2 elimination rates.
- The probability of DCS was analyzed using maximum likelihood modeling.
Main Results:
- Oxygen (O2) was confirmed to significantly contribute to the risk of decompression sickness (DCS).
- Despite rapid O2 elimination during decompression, it remained a significant risk factor.
- Nitrogen (N2) washout was considerably slower compared to O2 elimination.
Conclusions:
- Oxygen significantly enhances decompression risk, even when eliminated rapidly.
- The findings suggest that while O2 poses a risk, it may not be a primary concern in typical human diving due to slower decompression rates and lower partial pressures of oxygen (PO2).