Oxygen is an indispensable element for maintaining life on Earth. Its optimum content in inhaled air for humans is 20-21%. Oxygen mixtures with an increased content of it are used to maintain the function of breathing when immersed in water, in the presence of rarefied air and outer space. In medicine, oxygen therapy is used to treat a number of diseases.
For any living organism, both a defect and an excess of oxygen are dangerous. What is hyperoxia, under what conditions does the disease develop and how dangerous is it for humans?
What is hyperoxia
Hyperoxy is a complex of pathological reactions that develops in the body with excess oxygen intake. The disease occurs when improper use of respiratory mixtures when immersed in depth (oxygen poisoning in diving), in aviation and astronautics, in the treatment of oxygen (hyperbaric oxygenation).
Factors aggravating the course of the disease:
- overheating or subcooling;
- physical activity;
- individual sensitivity;
- the content of harmful gases in the respiratory mixture, including carbon dioxide;
- accumulation of carbon dioxide in the body.
Oxygen poisoning, possibly due to the use of regenerative breathing apparatus, from improper use of the pressure chamber during decompression.
With a slight supersaturation of tissues with oxygen, oxygen intoxication can develop, which is accompanied by:
- opacity of consciousness;
- shroud before the eyes;
- noise in the ears.
There is a similar condition in the hyperventilation of the lungs (forced deep breaths and exhalations), or an unusual increase in the oxygen content in the atmospheric air - for example, among urban residents when leaving the city. In athletes, a similar situation can occur with high physical exertion simultaneously with deep breathing.
Signs of hyperoxia
When excessive amounts of oxygen enter the blood, normal compensatory reactions develop at first:
- slowing of breathing;
- narrowing of the vessels of the brain and lungs;
- decreased heart rate;
- a decrease in the volume of circulating blood.
Later, pathological processes appear, which are manifested in the violation of gas transport by blood and oxidation of cell membranes.
Normally, the blood from the lungs transport oxygen, back from the tissues - carbon dioxide. Overabundance of oxygen leads to its binding to hemoglobin, and to remove carbon dioxide free hemoglobin is not enough. Therefore, tissues are poisoned with carbon dioxide. It is shown by the following signs:
- redness of the face;
- loss of consciousness.
The second pathological mechanism of oxygen poisoning is associated with the destruction of cell membranes. Normally, oxygen is oxidized in the tissues completely, and with its excess there are many under-oxidized products - free radicals, which begin to interact primarily with the lipids of cell membranes. A cascade process starts, which can continue even after the oxygen level in the tissues is normalized.
Symptoms of Oxygen Poisoning
The intoxication with oxygen appears instantly, that is the latent period is absent. Overabundance of oxygen in the body leads to the appearance of the following symptoms:
convulsions may be the only sign - a consequence of rapid poisoning of the central nervous system with a high oxygen content;
- The first symptoms of poisoning are most often numbness of the fingers or tingling in them, twitching of the muscles of the face, trembling of the lips;
- periodic nausea and vomiting;
- impaired vision, right up to blindness;
- anxiety, anxiety, irritability, confusion;
- noise in the ears, sometimes pulsating, or resembling the sound of a bell;
- dizziness, impaired coordination of movements.
Symptoms of the disease depend on its shape.
Forms of oxygen poisoning
Depending on the prevalence of these or other symptoms in the poisoning with oxygen, three forms of the disease course are distinguished.
- The pulmonary form. In this form, the respiratory tract and the lungs are mostly affected. Characterized by edema and irritation of the mucous membrane, coughing, burning behind the sternum. With the increase in symptoms, hemorrhages develop in the internal organs, the brain and spinal cord, atelectasis (collapse) of the lungs. It is possible for prolonged breathing with a mixture with a low partial pressure of oxygen of 1.3-1.6 bar (for example, descent to a depth of 18 meters). The rate of reaction is proportional to the partial pressure and the time of inhalation of the mixture. Thus, at a partial oxygen pressure of 1 bar, hyperoxia in man occurs after 6 hours, and at 2.5 bar after 3 hours. If the causes are eliminated, the symptoms disappear after 2-4 hours, finally the organism is restored in 2-4 days.
Convulsive form. Hearing and visual impairment, irritability, tingling and twitching of the muscles develop. With the growth of hyperoxia, there are frequent convulsive seizures like epileptic seizures. Under water, the risk of drowning is high. The convulsive form is typical for poisoning with pure oxygen or mixtures with a partial pressure of 2-3 bar. When eliminating the causes of hyperoxia, a sleep occurs after seizures, which can last several hours. After a fit, there are no adverse effects.
- Vascular form. It develops at a partial pressure of over three bar. Characterized by a sharp drop in blood pressure, numerous hemorrhages in the skin and mucous membranes, stopping cardiac activity.
At a partial pressure of 5 bar, hyperoxia develops rapidly, there is instantaneous loss of consciousness and death occurs.
In diving practice, you can face pulmonary and convulsive forms of hyperoxia, as well as their mixed course.
The first aid is to eliminate excess oxygen:
- reduce the depth of descent and get to a stop;
- In case of unconsciousness, bring the victim to the senses (experienced divers use for this purpose a strong stream of oxygen, the flow of which reflexively catches the breath);
- in the chamber switch to breathing oxygen-depleted mixture or air;
- with cramps guard against damage, but do not fix;
- to carry out decompression at convulsions it is impossible;
- during the day, bed rest in a warm, darkened room with good ventilation.
In severe cases, oxygen poisoning may require medical intervention.
Treatment is determined by a physician based on the nature of hyperoxia.
- When pulmonary form impose venous tourniquets on the limbs, drain the foam from the lungs, treat acidosis, apply diuretics.
- For the removal of seizures, intravenously, "Aminazine", "Seduxen" or "Dimedrol".
- If there are appropriate indications, - prescribe funds for restoring cardiac activity, stimulating breathing and anesthetizing.
In order to prevent pneumonia, an antibiotic may be prescribed.
Prevention of hyperoxia is to comply with the rules for the use of oxygen mixtures and the use of breathing apparatus:
- Do not exceed the permissible depth of immersion;
- Do not exceed the permissible residence time at depth;
- when using mixtures with different oxygen content, strictly observe the marking of cylinders and the order of their use;
- observe the time spent in the decompression chamber;
- When performing decompression with pure oxygen, the respiration time should not exceed 3-3.5 hours;
- regularly check the technical integrity of the regenerative apparatus.
Let's sum up. Hyperoxia is a pathological reaction that develops with an excess of oxygen in the body. The disease develops when breathing with pure oxygen or its mixtures. In practice, divers, pilots and astronauts often suffer from the manifestation of hyperoxia symptoms. Also, possibly, the development of the disease in patients undergoing treatment in the pressure chamber.
Signs of oxygen poisoning - dizziness, blurred vision, tingling in the fingers and toes, trembling lips. In the future, convulsions or violations in the respiratory system develop. With the timely elimination of excess oxygen, the symptoms take place within a few hours, and completely the body recovers in a few days. In severe cases, the victim needs medical care.