Oxygen or carbogen breathing before simulated submarine escape

Area of Science:

• Physiology
• Hyperbaric Medicine
• Submarine Operations

Background:

• Submarine escape carries risks of bubble formation and decompression illness due to increased internal pressure.
• Venous gas emboli are a key indicator of decompression stress following submarine escape.

Purpose of the Study:

• To investigate the efficacy of short-duration oxygen prebreathing in reducing decompression stress before simulated submarine escape.
• To assess the impact of oxygen prebreathing on the formation of Doppler-detectable venous gas emboli.

Main Methods:

• Two series of experiments were conducted using goats under simulated submarine escape conditions.
• In the first series, goats breathed oxygen or air before a simulated escape from 2.5 MPa.
• In the second series, goats breathed air, oxygen, or carbogen before escape, with bubble scores monitored.

Main Results:

• Oxygen prebreathing significantly reduced the duration of high bubble scores (Kisman-Masurel >=3) in the first series.
• In the second series, oxygen breathing reduced initial bubble scores and the period of high bubble scores.
• While one case of decompression sickness (DCS) occurred in the carbogen group, oxygen prebreathing showed promise in reducing bubble formation.

Conclusions:

• Oxygen breathing before submarine escape effectively reduces initial bubble scores.
• The potential of oxygen prebreathing to reduce central nervous system decompression sickness requires further investigation.