Shallow water blackout

Shallow Water Blackout refers to a loss of consciousness caused by hypoxia (low oxygen) in the brain, occurring in shallow water typically during breath-hold diving or swimming. This condition can affect individuals regardless of their age, fitness level, or experience in water activities. It is a critical and often misunderstood risk associated with free diving, spearfishing, and competitive swimming.

Causes

Shallow Water Blackout results from a combination of hyperventilation and the body's response to oxygen and carbon dioxide levels in the blood. Hyperventilation before a dive lowers the amount of carbon dioxide in the blood, delaying the body's natural urge to breathe without affecting the drop in oxygen levels. As the diver ascends and water pressure decreases, oxygen levels in the lungs can fall rapidly, leading to unconsciousness without warning. This condition is particularly insidious because the victim often does not feel in distress before losing consciousness.

Symptoms and Signs

The primary symptom of Shallow Water Blackout is a loss of consciousness. Before this occurs, individuals may experience:

• Disorientation
• Light-headedness
• Tunnel vision
• Nausea
• Convulsions (in severe cases)

Prevention

Prevention of Shallow Water Blackout focuses on education and safe diving practices:

• Avoid hyperventilation before diving.
• Dive with a buddy who understands and can recognize the signs of Shallow Water Blackout.
• Limit the depth and duration of dives.
• Use a dive computer or depth gauge to monitor dive profiles.
• Educate oneself and others about the risks of breath-hold diving.

Treatment

Immediate response to a Shallow Water Blackout involves:

• Rescue and removal from the water.
• Calling for emergency medical help.
• Starting Cardiopulmonary Resuscitation (CPR) if the victim is not breathing.
• Administering oxygen if available and trained to do so.

Epidemiology

Shallow Water Blackout can affect individuals of all ages engaging in breath-hold diving activities. However, it is more commonly reported among competitive swimmers, free divers, and military personnel undergoing rigorous training.

See Also

• Drowning
• Hypoxia (medical)
• Free diving
• Spearfishing