Oxygen toxicity
The supplementation of oxygen can lead to oxygen toxicity, also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning. There are two main types of oxygen toxicity: central nervous system (CNS) toxicity, and pulmonary and ocular toxicity.Temporary exposure to high partial pressures of oxygen at greater than atmospheric pressure can lead to central nervous system toxicity (CNS). An early but serious sign of CNS oxygen toxicity is a grand-mal seizure, also known as a generalized tonic-clonic seizure. This type of seizure consists of a loss of consciousness and violent muscle contractions. Signs and symptoms of oxygen toxicity are usually prevalent, but there are no standard warning signs that a seizure is about to ensue. The convulsion caused by oxygen toxicity does not lead to hypoxia, a side effect common to most seizures, because the body has an excess amount of oxygen when the convulsion begins. The seizures can lead to drowning, however, if the convulsion is suffered by a diver still in the water.Prolonged exposure to higher oxygen levels at atmospheric pressure can lead to pulmonary and ocular toxicity. Symptoms of oxygen toxicity may include disorientation, respiratory problems, myopia, or accelerated development of cataracts. Prolonged exposure to higher than normal partial pressures of oxygen can result in oxidative damage to cell membranes. Signs of pulmonary (lung) oxygen toxicity begin with slight irritation in the trachea. A mild cough usually ensues, followed by greater irritation and a worse cough until breathing becomes quite painful and the cough becomes uncontrollable.
The highest risk of hyperoxia is in hyperbaric oxygen therapy, where it is a high probability side effect of the treatment for more serious conditions, and is considered an acceptable risk as it can be managed effectively without apparent long term effects. Diagnosis
Treatment
Oxygen supplementation is used to treat tissue hypoxia and to relieve arterial hypoxemia. High concentrations of oxygen are often given to patients with chronic obstructive pulmonary disease (COPD) or acute lung injury (ALI). Supplementing oxygen is known to cause tissue damage, with toxicity increasing with the increase of oxygen concentrations and exposure pressures. Unfortunately, the supplementation of oxygen is necessary if an individual is not able to obtain sufficient oxygen through respiration and perfusion. To decrease the chances of hyperoxia, the therapist should use the lowest concentration of oxygen required by an individual. At this time, there are no known alternatives to oxygen supplementation. See also
Hypoxia – Medical condition caused by lack of oxygen in the tissues
Hypoxemia – Abnormally low level of oxygen in the blood
Oxygen toxicity – Toxic effects of breathing in oxygen at high concentrations
Hyperbaric medicine – Medical treatment at raised ambient pressure


== References ==