Decompression profile and bubble formation after dives with surface decompression: experimental support for a dual...

Area of Science:

• Physiology
• Diving Medicine
• Biomedical Engineering

Background:

• Surface decompression using oxygen is a common practice in diving.
• Understanding the impact of different decompression profiles on bubble formation is crucial for diver safety.
• Previous models like the Reduced Gradient Bubble Model (RGBM) have been used to simulate decompression sickness.

Purpose of the Study:

• To evaluate the effect of various decompression profiles on bubble formation after surface decompression.
• To compare a USN staged decompression profile with two linear continuous decompression profiles (ABI and ABII).
• To assess bubble formation in vascular and venous systems following different decompression strategies.

Main Methods:

• Pigs were subjected to an air dive to 496 kPa (130 fsw) for 90 minutes.
• Three decompression profiles were tested: USN staged, linear continuous (ABI), and a faster linear profile (ABII).
• Surface decompression at 220 kPa lasted 68 minutes for all profiles, with bubble formation assessed in the pulmonary artery and jugular vein.

Main Results:

• Both linear decompression profiles (ABI and ABII) resulted in lower amounts of vascular gas compared to the USN profile.
• The fastest linear profile (ABII) produced significantly fewer bubbles in the pulmonary artery and jugular vein.
• Results aligned with RGBM simulations, indicating reduced controlling tissue half-times with linear profiles.

Conclusions:

• Linear decompression profiles are more effective than traditional staged profiles in minimizing bubble formation after oxygen surface decompression.
• Faster linear decompression schedules show superior performance in reducing gas load and potential for decompression sickness.
• The findings support the refinement of decompression algorithms based on linear profiles for enhanced diver safety.