Shallow Water Blackout

The term shallow water backout has been commonly used as a term for drowning, particularly when preceded by hyperventilation. Other terms used to describe this syndrome include: “underwater blackout,” “underwater blackout syndrome,” “sudden underwater blackout syndrome (SUBS),” “breath-holding blackout,” and “free-diver blackout.” Shallow water blackout means unconsciousness in water typically less than 15 feet (5 m) either due to equipment failure or prolonged breath-holding. This language can be misleading as drowning can occur at depths greater than 5 m as well.  The American Red Cross, YMCA, and U.S.A. swimming have since redefined the term as a hypoxic blackout. Hypoxic blackout is defined as “the loss of consciousness in the underwater swimmer or diver, during an apnea submersion preceded by hyperventilation, where alternative causes of unconsciousness have been excluded.”  Shallow water blackout has the potential to affect anyone in the water, even fit and experienced swimmers. This condition can occur in any body of water, no matter the depth. Some people survive such an event as a result of prompt and effective rescue efforts. Others are not as fortunate. Preventive measures through an increased understanding of hypoxic blackouts are crucial to prevent tragic and unnecessary deaths.