Feature Article - April 2006
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Safe Swimming

Managing risk at aquatic facilities

By Kyle Ryan


Genetic triggers and shallow-water blackout

Simply because of their DNA, some people may have a genetic predisposition to drowning. Saving them typically requires more than lifeguard vigilance. Griffiths uses the example of a young woman from Chicago who died twice in water: once when she swam in a lake (emergency personnel revived her) and once in a pool (her parents revived her through CPR). Now she's not allowed to swim, and her mother carries an automated external defibrillator (AED) with her at all times.

"We've had a number of seizures and heart attacks in pools," Evans says. "For some reason, they may have had a heart attack on land, and it could have resulted in the same death, but the fact that it was in the water, for some reason, CPR does not seem to be as effective after a two-minute period."

Griffiths' research has examined two genetic drowning triggers: long QT syndrome and a "rogue" drowning gene called RyR2. Both reportedly predispose people to sudden cardiac arrest. Long QT syndrome is an abnormality in the heart's electrical system from defects in muscle cell structures. It predisposes people to a fast heart rhythm that can lead to sudden loss of consciousness and, eventually, death. Both RyR2 and long QT syndrome only can be detected by EKGs and DNA mapping, and the latter is not a cheap undertaking (roughly $5,000).

"Just because somebody dies in the pool…doesn't mean the lifeguard's at fault," Griffiths says. "Even with the quickest response and most efficient resuscitation efforts, a lot of these people would still die…so we have to anticipate these emergencies and be ready to resuscitate when we can."

Another problem, which isn't genetically based, is shallow-water blackout. That occurs when people hold their breath for too long and lose consciousness. What makes it more insidious is that it typically affects skilled athletic swimmers, the very people who are usually less of a concern to lifeguards. These athletic swimmers will often try to keep their breathing to a minimum for stroke efficiency, but that can easily lead to blackout. To combat that, Griffiths suggests establishing a clear rule that prohibits prolonged breath-holding to go along with a facility's other well-established rules.