Physiological responses to cold exposure in men: a disabled submarine study

Area of Science:

• Environmental Physiology
• Human Physiology
• Submarine Medicine

Background:

• Disabled submarines (DISSUB) pose risks of cold, hypercapnia, and hypoxia for survivors.
• Understanding thermoregulatory responses in these conditions is crucial for rescue protocols.

Purpose of the Study:

• To investigate the impact of combined hypoxia, hypercapnia, and cold on thermoregulation in simulated DISSUB environments.
• To assess the risk of hypothermia in DISSUB survivors under these adverse conditions.

Main Methods:

• Seven male submariners underwent cold-air tests (CAT) simulating DISSUB conditions.
• Tests included varying levels of oxygen (hypoxia), carbon dioxide (hypercapnia), and ambient temperature.
• Thermoregulatory responses, including skin temperature and metabolic heat production, were monitored.

Main Results:

• Mild hypoxia alone reduced vasoconstriction and delayed shivering onset compared to normoxic conditions.
• The addition of hypercapnia and cold exposure did not further impair thermoregulatory responses.
• No significant differences in heat storage or rectal temperature were observed across trials.

Conclusions:

• Mild hypoxia impairs key thermoregulatory mechanisms in cold environments.
• The combination of hypoxia, hypercapnia, and cold does not exacerbate these impairments.
• Adequately clothed DISSUB survivors are unlikely to face increased hypothermia risk due to these factors.