Underwater Swimming Dangers: Shallow Water Blackout

The tragic incidents of drowning in course of underwater swimming are by no means something exceptional.

Quite ironically, on the list of victims are even famous water sportsmen. In 1999, a member of the Mexican National Jr. and Senior Water Polo teams Omar Ortega, drowned during the national team scheduled practicing of underwater swimming. The sportsman, who was highly conditioned waterman, just fainted in the water and drowned in the swimming pool. When someone noticed his absence, and the body was found on the swimming pool's bottom, it was already too late to save the 19 year old male's life.

What happened to Ortega, is known and commonly referred to as Shallow Water Blackout, or to put it plain, underwater fainting, which is attributed to hyperventilation, causing cerebral hypoxia, i. e. a lack of oxygen to the brain.

This possible consequence of hyperventilation is what every skin diver or snorkeller should bear in mind while swimming underwater.

Shallow-water blackout (SWB) is normally related to skin diving and snorkeling and hardly ever happens in scuba diving. The loss of consciousness strikes most commonly at the depth of 15 feet (five meters) from the surface. This is the depth where oxygen-hungry human lungs start actively re-absorbing oxygen from divers blood causing very quick development of hypoxia (oxygen starvation).

The curious thing about this dangerous condition is that it practically never occurs with inexperienced divers due to their lack of adaptation to swimming under water keeping their breath for too long. It is intermediate diver who is mostly at risk, whose physical adaptations in the course of training starts allowing such sportsman dive deeper and, what is more important, longer with each new dive, often hardly realizing the next dive could be fatal. Advanced divers normally know about the need of controlling the situation, but nonetheless they also belong to the risk group.

Contrary to common belief, Shallow Water Blackout incidents in swimming pools hardly happens rare than those occurring during dives in open water environment. Many medical researchers support the opinion that quite a number pool drownings too in fact result from shallow-water blackout.

To avoid shallow-water blackout it is highly recommended to observe several simple basic rules:

  • Be aware that practicing endurance breath-holding in a swimming pool offers no safety to a diver's life and therefore requires supervision. Never practice unobserved!
  • Don't overexcercise. Three or four quick consecutive breaths should be the maximum for diver to stick routinely to.
  • When exercising in the depth head for the surface much sooner compared with the time you surface normally.
  • Dispose of your weight belt immediately should you start perceiving something's wrong. Adjust its weight to ensure floating at the depth of 15 feet.
  • Don't combine deep dive with a long distance swimming to avoid getting exhausted.
  • Learn yourself and teach your dive buddies the way Cardio Pulmonary Resuscitation (CPR) is done in case of emergency.

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Underwater Swimming Dangers: Shallow Water Blackout


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