Effects of Cold Decompression on Hemodynamic Function and Decompression Sickness Risk in a Dry Diving Rat Model

Area of Science:

• Physiology
• Diving Medicine
• Cardiovascular Research

Background:

• Cold water exposure during diving is suspected to elevate decompression sickness (DCS) risk.
• Hypothermia during decompression may exacerbate DCS.
• This study examines hemodynamic responses and DCS risk in a cold decompression model.

Purpose of the Study:

• To investigate the impact of cold decompression on hemodynamic function in an animal model.
• To assess the potential link between cold-induced hemodynamic changes and DCS risk.
• To evaluate the effect of rewarming after cold decompression on physiological parameters.

Main Methods:

• Nine female Sprague Dawley rats underwent dry air dives with normothermic compression, cold (35°C) decompression, and normothermic surface recovery.
• Left ventricular and femoral artery pressure-volume data were collected.
• Cardiac output (CO), stroke volume (SV), and venous gas bubbles were measured.

Main Results:

• Both cold and control rats showed decreased CO and SV during decompression.
• CO and SV transiently recovered post-dive but declined again in cold rats.
• No significant difference in venous bubble grades was observed between groups.

Conclusions:

• A post-dive fall in CO and SV in cold rats suggests potential pulmonary circulation obstruction by gas emboli.
• The study could not definitively conclude an increased DCS risk due to cold decompression.
• More sensitive methods for bubble detection are required to clarify the relationship between cold, hemodynamics, and DCS.