A model of extravascular bubble evolution: effect of changes in breathing gas composition

Area of Science:

• Physiology
• Biomedical Engineering
• Diving Medicine

Background:

• Previous studies in rats indicated safer bubble resolution with heliox compared to oxygen after decompression.
• Transient bubble growth observed during oxygen breathing transitions may explain these experimental findings.

Purpose of the Study:

• To develop a mathematical model to understand bubble evolution dynamics after decompression.
• To investigate the effects of different breathing gases (air, oxygen, heliox) on bubble resolution in various tissues.

Main Methods:

• A multigas-multipressure mathematical model was created, simulating a bubble in a well-stirred liquid.
• Gas exchange between liquid and blood was modeled using single-exponential time constants for inert gases.
• Model simulations analyzed bubble resolution rates in spinal, adipose, and aqueous tissues under different breathing gas scenarios.

Main Results:

• The model predicts the fastest bubble resolution in spinal, adipose, and aqueous tissues when switching to oxygen post-decompression.
• Conversely, the model suggests that switching to heliox may extend bubble persistence in spinal and adipose tissues compared to air breathing.
• Discrepancies between model predictions and prior experimental observations are noted and discussed.

Conclusions:

• Mathematical modeling provides insights into inert gas bubble dynamics during decompression.
• Oxygen breathing appears to promote faster bubble resolution in key tissues according to the model.
• Further investigation is required to address the divergence between model outcomes and experimental data, particularly concerning heliox effects.