Shallow water blackout is a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive in water typically shallower than five metres (16 feet), when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be caused by taking several very deep breaths, or hyperventilating, just before a dive. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers, and have not experienced problems before.
Many drowning and near drowning events occur among swimmers who black out underwater while free-diving or doing breath-hold pool laps. Blacking out, or greying out, near the end of a breath-hold dive is common. Although the mechanism is well understood, it is not common knowledge among breath-hold divers.
Shallow water blackout is related to, but differs from deep water blackout in its characteristics, mechanism and prevention; deep water blackout is precipitated by depressurisation on ascent from depth. Blackout may also be referred to as a syncope or fainting.
Read more about Shallow Water Blackout: Hyperventilation, Deep Water Blackout, See Also
Famous quotes containing the words shallow water, shallow and/or water:
“What is more hopelessly uninteresting than accomplished liberty? Great swarming, teeming Sydney flowing out into these myriads of bungalows, like shallow waters spreading, undyked. And what then? Nothing. No inner life, no high command, no interest in anything finally.”
—D.H. (David Herbert)
“What is more hopelessly uninteresting than accomplished liberty? Great swarming, teeming Sydney flowing out into these myriads of bungalows, like shallow waters spreading, undyked. And what then? Nothing. No inner life, no high command, no interest in anything finally.”
—D.H. (David Herbert)
“For months it hasn’t known the taste of steel
Washed down with rusty water in a tin.
But standing outdoors hungry, in the cold,
Except in towns at night, is not a sin.”
—Robert Frost (1874–1963)