Oxygen toxicity

What is oxygen toxicity?

Oxygen is a vital element that we need to breathe. But too much oxygen can be harmful. Our body is adapted to a certain oxygen pressure in the air, which is about 0.21 bar. If we breathe in more oxygen than normal, the oxygen pressure in our blood rises. This can lead to an overproduction of free radicals that attack and oxidize our cells.

There are two types of oxygen toxicity,depending onwhich part of the body is affected:

• Central oxygen toxicity: this affects the central nervous system (CNS), i.e. the brain and spinal cord. It can lead to seizures, loss of consciousness, personality changes and brain damage.
• Pulmonary oxygen toxicity: This affects the lungs and respiratory tract. It can lead to inflammation of the alveoli, pulmonary edema, impaired lung function and chronic lung disease.

How does oxygen toxicity occur?

Oxygen toxicity is caused by overexposure to elevated oxygen pressure. This can occur in various ways:

• During ventilation with pure oxygen or a high percentage of oxygen. This may be necessary for patients with severe respiratory distress or premature babies.
• With hyperbaric oxygenation (HBO). This is a form of therapy in which patients are treated with pure oxygen in a pressurized chamber. It is used for certain illnesses such as carbon monoxide poisoning or wound healing disorders.
• When diving with compressed air or enriched air mixtures (Nitrox). The oxygen pressure increases with depth. The deeper you dive, the higher the oxygen pressure.

The probability and severity of oxygen toxicity depend on several factors:

• The level of oxygen pressure
• The duration of exposure
• The individual sensitivity
• The physical activity
• The ambient temperature

What symptoms does oxygen toxicity cause?

The symptoms of oxygen toxicity can vary depending on the type and severity. Some symptoms may serve as warning signs, while others may appear suddenly and without warning.

The symptoms of central oxygen toxicity are:

• Tunnel vision
• ringing in the ears
• nausea
• dizziness
• vomiting
• Personality changes
• agitation
• anxiety
• confusion
• seizures
• Loss of consciousness

The symptoms of pulmonary oxygen toxicity are

• Cough
• shortness of breath
• Chest pain
• Bloody sputum
• fever

Long-term exposure to elevated oxygen pressure can also damage the eyes and lead to retinal damage.

How can oxygen toxicity be avoided or treated?

The best way to avoid oxygen toxicity is to keep the oxygen pressure as low as possible. This means inhaling only as much oxygen as you need and limiting the duration of exposure.

When ventilating with oxygen, the oxygen pressure in the blood should be checked regularly. The oxygen level should be adjusted so that it is sufficient but not too high. Ventilation should be stopped as soon as possible once the patient has recovered.

In the case of hyperbaric oxygenation, treatment should be carried out according to a set protocol. The pressure chamber should be operated with pauses and air breathing. Treatment should only be continued for as long as necessary.

When diving with compressed air or nitrox, the maximum diving depth and diving time should be observed. You should follow the tables or computers that show the permissible oxygen pressure and CNS load. You should also take sufficient breaks on the surface and not overexert yourself.

If you notice symptoms of oxygen toxicity, you should act immediately. During ventilation or HBO, reduce the amount of oxygen or stop the treatment. When diving, surface slowly and stop if necessary. You should also consult a doctor to rule out possible complications.