Shallow Water Blackout

Hyperventilation coupled with underwater breath-holding is an extremely dangerous practice. Carbon dioxide (CO2) is the brain's stimulus for breathing. When CO2 builds to a certain level, it signals the brain that it's time to breathe. Hyperventilation lowers the amount of co2 in the blood and fools the body into believing it doesn't need to breathe even if available oxygen is nearing depletion. Low oxygen levels in the blood stream will cause loss of consciousness. Exercise compounds the problem by increasing the rate of oxygen consumption and drowning can result. Hyperventilation is so dangerous that the U.S. Navy diving manual issues a specific warning in red about it and professional aquatics organizations caution against it. Previous incidents highlight the dangers of this practice.

This latest mishap adds another name to the growing number of sailors and marines who have died from shallow water blackout. Losses will continue if we do not increase awareness of the deadly risk imposed by hyperventilation and breath-holding.

Commanders, ensure personnel are thoroughly briefed on a recurring schedule about the dangers of this practice. Personnel most at risk are those preparing for advanced diver or swimmer training such as basic underwater demolition swimmer or reconnaissance team member. Trainees required to participate in breath-holding exercises must be closely supervised and remain in direct line of sight of an observer. Hyperventilation shall not be practiced. Aquatics managers, prohibit swimmers from engaging in this activity and brief lifeguards to stop anyone from participating in this practice. Post warnings at pools. Swimmers, you are ultimately responsible for your own safety. Heed the warnings. Don't hyperventilate or practice breath-holding while swimming. Come back alive.

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