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Hub AI
Freediving blackout AI simulator
(@Freediving blackout_simulator)
Hub AI
Freediving blackout AI simulator
(@Freediving blackout_simulator)
Freediving blackout
Freediving blackout, breath-hold blackout, or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, 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 provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.
Divers and swimmers who black out or grey out underwater during a dive will usually drown unless rescued and resuscitated within a short time. Freediving blackout has a high fatality rate, and mostly involves males younger than 40 years, but is generally avoidable. Risk cannot be quantified, but is clearly increased by any level of hyperventilation.
Freediving blackout can occur on any dive profile: at constant depth, on an ascent from depth, or at the surface following ascent from depth and may be described by a number of terms depending on the dive profile and depth at which consciousness is lost. Blackout during a shallow dive differs from blackout during ascent from a deep dive in that blackout during ascent is precipitated by depressurisation on ascent from depth while blackout in consistently shallow water is a consequence of hypocapnia following hyperventilation.
Different types of freediving blackout have become known under a variety of names; these include:
In this article constant pressure blackout and shallow water blackout refers to blackouts in shallow water following hyperventilation and ascent blackout and deep water blackout refers to blackout on ascent from depth. Some free divers consider blackout on ascent to be a special condition or subset of shallow water blackout but the primary underlying mechanisms differ. This confusion is exacerbated by the fact that in the case of blackout on ascent, hyperventilation induced hypocapnia also may be a contributory factor even if depressurisation on ascent is the actual precipitator.
Some scuba diving curricula may apply the terms shallow-water blackout and deep-water blackout differently; deep-water blackout being applied to the final stage of nitrogen narcosis while shallow water blackout may be applied to a blackout from a deep free dive. Nitrogen narcosis does not normally apply to freediving as free-divers start and finish the dive with only a single lungful of air and it has long been assumed that free divers are not exposed to the necessary pressure for long enough to absorb sufficient nitrogen. Where these terms are used in this manner there is usually little or no discussion of the phenomenon of blackouts not involving depressurisation and the cause may be variously attributed to either depressurisation or hypocapnia or both. This problem may stem from the origin of the term latent hypoxia in the context of a string of fatal, shallow water accidents with early military, closed-circuit rebreather apparatus prior to the development of effective oxygen partial pressure measurement. In the very different context of dynamic apnea sports careful consideration of terms is needed to avoid potentially dangerous confusion between two phenomena that actually have different characteristics, mechanisms and prevention measures. The application of the term shallow water blackout to deep dives and its subsequent association with extreme sports has tended to mislead many practitioners of static apnea and dynamic apnea distance diving into thinking that it does not apply to them even though isobaric shallow water blackout kills swimmers every year, often in shallow swimming pools.[citation needed]
The CDC has identified a consistent set of voluntary behaviors associated with unintentional drowning, known as dangerous underwater breath-holding behaviors; these are intentional hyperventilation, static apnea, and hypoxic training.
Other terms generally associated with freediving blackout include:
Freediving blackout
Freediving blackout, breath-hold blackout, or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, 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 provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.
Divers and swimmers who black out or grey out underwater during a dive will usually drown unless rescued and resuscitated within a short time. Freediving blackout has a high fatality rate, and mostly involves males younger than 40 years, but is generally avoidable. Risk cannot be quantified, but is clearly increased by any level of hyperventilation.
Freediving blackout can occur on any dive profile: at constant depth, on an ascent from depth, or at the surface following ascent from depth and may be described by a number of terms depending on the dive profile and depth at which consciousness is lost. Blackout during a shallow dive differs from blackout during ascent from a deep dive in that blackout during ascent is precipitated by depressurisation on ascent from depth while blackout in consistently shallow water is a consequence of hypocapnia following hyperventilation.
Different types of freediving blackout have become known under a variety of names; these include:
In this article constant pressure blackout and shallow water blackout refers to blackouts in shallow water following hyperventilation and ascent blackout and deep water blackout refers to blackout on ascent from depth. Some free divers consider blackout on ascent to be a special condition or subset of shallow water blackout but the primary underlying mechanisms differ. This confusion is exacerbated by the fact that in the case of blackout on ascent, hyperventilation induced hypocapnia also may be a contributory factor even if depressurisation on ascent is the actual precipitator.
Some scuba diving curricula may apply the terms shallow-water blackout and deep-water blackout differently; deep-water blackout being applied to the final stage of nitrogen narcosis while shallow water blackout may be applied to a blackout from a deep free dive. Nitrogen narcosis does not normally apply to freediving as free-divers start and finish the dive with only a single lungful of air and it has long been assumed that free divers are not exposed to the necessary pressure for long enough to absorb sufficient nitrogen. Where these terms are used in this manner there is usually little or no discussion of the phenomenon of blackouts not involving depressurisation and the cause may be variously attributed to either depressurisation or hypocapnia or both. This problem may stem from the origin of the term latent hypoxia in the context of a string of fatal, shallow water accidents with early military, closed-circuit rebreather apparatus prior to the development of effective oxygen partial pressure measurement. In the very different context of dynamic apnea sports careful consideration of terms is needed to avoid potentially dangerous confusion between two phenomena that actually have different characteristics, mechanisms and prevention measures. The application of the term shallow water blackout to deep dives and its subsequent association with extreme sports has tended to mislead many practitioners of static apnea and dynamic apnea distance diving into thinking that it does not apply to them even though isobaric shallow water blackout kills swimmers every year, often in shallow swimming pools.[citation needed]
The CDC has identified a consistent set of voluntary behaviors associated with unintentional drowning, known as dangerous underwater breath-holding behaviors; these are intentional hyperventilation, static apnea, and hypoxic training.
Other terms generally associated with freediving blackout include: