Facts & Figures

Hypoxic Blackout and Hyperventilation

Learn more about the dangers of Hypoxic Blackout and Hyperventilation

Hypoxic BlackoutHypoxic Blackout is the severe reduction of oxygen to the body. Hypoxic Blackout dramatically affects brain function, leading to unconsciousness, be followed by brain damage then death.

When someone holds their breath, the Carbon Dioxide (CO2) levels in their bloodstream rise and oxygen levels decrease. This causes the urge to take breathe in new oxygen and expel CO2. If this doesn’t happen, Hypoxic Blackout occurs.

Hypoxic Blackout incidents have been recorded in m any aquatic activities including free diving, underwater hockey, swimming training and scuba diving.

Hyperventilation occurs when a person takes quick, deep breaths to reduce the CO2 in the blood. This action does not increase oxygen levels. With low CO2 and low oxygen levels, the body has little breathing stimulus, which may lead to unconsciousness.

Royal Life Saving does not recommend hyperventilation or underwater breath holding activities.

Click here to download a print friendly version of the Hypoxic Blackout Fact Sheet

Breath-holding Blackout

Royal Life Saving has recently supported a campaign by the Divers Alert Network (DAN) to raise awareness of the risk of breath-hold blackout in breath-hold diving and surface snorkelling. The breath-holding blackout campaign was created to reinforce the message that breath-holding blackout remains responsible for on-going deaths in both the experienced and inexperienced and needs to be taken seriously.

Click here to download a poster highlighting strategies for the prevention of breath-holding blackout