 |  |  |  |  |  |  |
BLACKOUT
It happens when the brain lack enough oxygen! The brain dyes after 5 minute of lack of circulation and per se
lack of oxygen, what we called brain death.
In free diving blackout usually and most frequently happens when ascent in shallow water after deep or
exhaustive dives.usualy ascent must be slow to decrease the rapid expansion of lungs witch mean the rapid
decreasing of partial pressure of oxygen in the alveoli.
Free divers have an enemy, the HYPERVENTILATION.
Hyperventilation is a “primitive” way of respiration, some divers do to increase time of breathholding.the danger
of hyperventilation is not only blackout is also cardiac arrhythmias -sensual tachycardia and ventricular which
can also lead to fainting and blackout- due to ph alkalization of plasma.usualy hyperventilation decrease the
CO2 level and it never increase the O2 saturation in the plasma and hemoglobine.diminishing plasma CO2
level leads to increase breathold time -CO2 is one stimulator of the respiratory nervous center in the bulba
with O2 level,ph,thoracic cost vertebral mechanical receptor- giving a false sensation of well being to the diver
per se the diver continue in the depth using pressurized O2 in alveoli , and in the ascent this consummated O2
decreases as soon as the diver go up rapidly which leads to decreasing of O2 level, to hypoxic ,we must know
at this time usually we do not have cardiovascular problems ,cardiac arrest or hypotension, only the level of O2
is decreased at cellular level. If the PaO2 is < 50mmhg we usually have a short amnesia. If < 40mm we have
judgment perturbation and <30mm lost of consciousness.
It happens when the brain lack enough oxygen! The brain dyes after 5 minute of lack of circulation and per se
lack of oxygen, what we called brain death.
In free diving blackout usually and most frequently happens when ascent in shallow water after deep or
exhaustive dives.usualy ascent must be slow to decrease the rapid expansion of lungs witch mean the rapid
decreasing of partial pressure of oxygen in the alveoli.
Free divers have an enemy, the HYPERVENTILATION.
Hyperventilation is a “primitive” way of respiration, some divers do to increase time of breathholding.the danger
of hyperventilation is not only blackout is also cardiac arrhythmias -sensual tachycardia and ventricular which
can also lead to fainting and blackout- due to ph alkalization of plasma.usualy hyperventilation decrease the
CO2 level and it never increase the O2 saturation in the plasma and hemoglobine.diminishing plasma CO2
level leads to increase breathold time -CO2 is one stimulator of the respiratory nervous center in the bulba
with O2 level,ph,thoracic cost vertebral mechanical receptor- giving a false sensation of well being to the diver
per se the diver continue in the depth using pressurized O2 in alveoli , and in the ascent this consummated O2
decreases as soon as the diver go up rapidly which leads to decreasing of O2 level, to hypoxic ,we must know
at this time usually we do not have cardiovascular problems ,cardiac arrest or hypotension, only the level of O2
is decreased at cellular level. If the PaO2 is < 50mmhg we usually have a short amnesia. If < 40mm we have
judgment perturbation and <30mm lost of consciousness.
