Many swimmers could be putting themselves at risk for shallow water blackout and not even know it. Shallow water blackout is the term ascribed to unexplained loss of consciousness in divers at shallow depths. Few statistics exist on shallow water blackout because many times it is classified as a simple drowning.
Most deaths from shallow water blackout occur under the water instead of on the surface. This makes it harder for lifeguards to detect. Lifeguards can miss the victim thinking they were blemish or towel instead of a person.
Swimmers who engage in underwater breath-holding contests for time or distance are at higher risk for shallow water blackouts. It is one of the greatest dangers in free diving. Many times the victim is a strong, fit, experienced swimmer who have not experienced problems before.
Many blackouts underwater have been associated with the practice of hyperventilation. Hyperventilation is the practice of breathing faster and deeper than the body naturally demands. Many swimmers believe that hyperventilating will increase oxygen saturation in the bloodstream. What really happens is the diver is shutting down the body’s natural breathing mechanism. Carbon dioxide levels in the blood stream is what triggers the urge to breath. Hyperventilation washes carbon dioxide out of the lungs. In a healthy person, hyperventilation will reduce respiratory drive and leave the person susceptible to loss of consciousness due to hypoxia. There is little warning to the diver of the coming blackout. Unconsciousness underwater triggers a series of events including cardiac arrest, inhaling water, brain damage and death.
Beginner divers are very sensitive to carbon dioxide levels. These levels build are what cause the lungs to feel as if they were on fire. The trained diver blows off massive amounts of carbon dioxide with hyperventilation, thus outsmarting the brain’s breathing center. Shear willpower in trained divers can also short-circuit the desire to breath.
Signs of shallow water black is swimmer passing out usually without warning and on the ascent. First aid is the same as with any drowning including CPR and medical attention.
Here are some tips to prevent Shallow Water Blackout. Never attempt excessive hyperventilating keep breaths to four or five. After holding your breath underwater breath normally and relax. A good rule is to rest at least two times the total time spent underwater Never use tricks to cheat the urge to breath. Always remember to dive with an experience diver and never alone.