Oxygen toxicity

The Paul Bert effect or Neuro Toxic effect is a reversible poisoning of the central nervous system during breathing of breathing gas mixtures with high oxygen partial pressure, for example, when diving using pure oxygen or oxygen-enriched air ( Nitrox). He is a part of the form Sauerstofftoxikose. Was named the effect after the French physician Paul Bert. The occurrence of the effect depends on both the partial pressure of oxygen as well as the contact time. Damage to the lungs due to the longer exposure of an increased partial pressure of oxygen is referred to as Smith - Lorrain effect ( " Pulmonary " effect).

Occurrence and impact

When using normal air with a share of 21% oxygen which is necessary for the occurrence of poisoning combination of oxygen partial pressure and exposure time is not reached; this can only occur when using pure oxygen, nitrox or other oxygen -enriched breathing gases.

For oxygen partial pressures above 1.6 bar occurs within a relatively short time to a poisoning of the central nervous system, resulting in seizures, which can best be compared to those of epilepsy. This can lead to the loss of water under the mouthpiece of the regulator and thus the danger of drowning. The risk of an occurrence is individually different. Unfavourable conditions such as strong physical stress, cold, hypoglycemia, and hypercarbia favor the occurrence of toxic effects. About Water - as in a pressure chamber - the sound pressure symptoms after normalization from without after-effects.

The seizures usually begin with twitching around the mouth and eyelids, previously to faster pulse, nausea, dizziness, headache, restlessness, ringing in the ears and tube Watch occur as the first signals. But you can also quite abruptly appear. Breathing problems, which manifest themselves in a quick, shallow breathing, anxiety associated with feelings of suffocation and then make the transition until it comes very quickly to toxic convulsions of the whole body, and loss of consciousness.

To avoid CNS toxicity Recreational divers should always observe the maximum depth for a particular oxygen mixture.

Literature and sources

• Roche Medical Dictionary, 5th Edition; Elsevier GmbH Urban & Fischer Verlag; Munich / Jena 2003; ISBN 3-437-15072-3; Online version keyword: Sauerstofftoxikose
• Pschyrembel Clinical Dictionary - CD- ROM Version 259th edition; Walter de Gruyter Verlag; Berlin / New York 2002; ISBN 3-11-016523-6