Apnea.nl - Loss of Counciousness: Hyperventilation

By Rik Rösken

Hyperventilation is the condition that a human breaths more than he or she actually needs. Medically spoken, hyperventilation is the moment when the oxygen content of the blood rises above normal, with a decreased carbon-dioxide content.

The major effect of hyperventilation is the decreased concentration of carbon-dioxide in the blood and tissues. Carbon-dioxide is a gas that strongly influence our breathing pattern and signals during a breath-hold. Too much will cause the diver gasping for air, even when it is plentiful around him. A lack of carbon-dioxide can cause a tingling dizziness, disorientation and a strongly delayed breathing reflex, even after the diver has lost counciousness, due a lack of oxygen.

Hyperventilation was discovered in the seventies to increase dive time. The increase is only seemingly. By use of quick fast breaths the lungs and blood are pursed of carbon-dioxide. Due the lower levels of this gas, it will take considerable more time before we get symptoms that would let us return to the surface and breath again. The oxygen use however, will be un changed, and the diver becomes more sustible for loss of counciousness.

It is not surprising that the use of this technique in the seventies caused many cases of loss of counciousness during their dive with spearfishers and other underwater enthiausaists. This with, or without ascent black-out.

Thanks to the work of Jaques Mayol have we learned that yoga breathing can induce a better performance with a lesser risk on loss of counciousnesss. The slow breathing pattern certain plays a role to avoid the loss of counsciousness, but isn't the miracle bullet completely.

It is important to understand that hyperventilation can also occur with slow controlled breaths. The only condition is that the ventilation is more then the individual requires to sustain his or her metabolism. Breath-hold divers with slow breathing patterns showed still with scientific research a change of their carbon-dioxide and oxygen levels. A better breathing technique doesn't exclude hyperventilation as a cause.

Other possibilities, especially with inexperienced divers, is that the symptoms are not recognisable, and the diver is that far in the dive that he or she is not able to respond correctly. Training can supress signals, as both improper technique. A buddy is not only needed for safety during a dive, but also to observe during the peparation.

This is an important reason to aquire coaching and training on breathing techniques when persuing breath-hold diving. Due the ever apperent risk on loss of counciousness with breath-hold diving, it is important to have always a qualified diver at your side and to take safety precautions.