The Facts About Shallow Water Blackout
- Underwater breath-holding and underwater swimming have been proudly practiced for decades.
- Coaches and military trainers teach hypoxic training and breath-holding, which can be deadly.
- Lifeguards and parents routinely accept and admire breath-holding drills conducted in swimming pools.
- Swimming Pools are typically where SWB occurs although SWB can also occur in the open-water.
- Free divers and spear fishermen practice hyperventilation routinely.
- Internet sites promote and encourage breath-holding contests, games and records.
- Hypoxic training, breath-holding, and underwater swimming leads to drowning and sudden deaths that are disregarded and often misdiagnosed as traditional accidental drowning.
- Shallow Water Blackout (SWB) is not well known because when Coroners rule “drowning” it masks the real problem: hyperventilation combined with competitive, repetitive breath-holding.
- Shallow Water Blackout often precipitates other unknown and underlying medical causes like Long Q-T, RyR2, seizures, etc.
- Only the best of athletes and swimmers succumb to SWB.
- The ARC, YMCA and USA Swimming now ban hypoxic training and prolonged underwater swimming although far too many still practice it.
- An SWB victim is very difficult to detect underwater.
- SWB may be the leading cause of swimmer death.
- As a swimmer reduces both oxygen and carbon dioxide levels, unconsciousness and death occur quickly, without warning.
- Physical exertion increases the risk.
- Repeated hyperventilation and breath-holding increases the risks of SWB.
- Deep water blackout occurs as the surface is approached following a breathe-hold dive of over ten metres and typically involves deep, free-divers practicing dynamic apnoea depth diving usually at sea. The immediate cause of deep water blackout is the rapid drop in the partial pressure of oxygen in the lungs on ascent.
Shallow water blackout only occurs where all phases of the dive have taken place in shallow water where depressurisation is not a factor and typically involves dynamic apnoea distance swimmers, usually in a swimming pool. The primary mechanism for shallow water blackout is hypocapnia brought about by hyperventilation prior to the dive.