Organophosphorus compounds: application, principle of action and features. Poisoning with organophosphorus compounds, first aid

Organophosphorus compounds belong to the category of pesticides that are destined for the destruction of weeds, insects and rodents.

These insecticides are widely used not only in the agricultural sector, but also in everyday life. Many varieties of OPC have a high toxicity and are capable of causing serious poisoning both when they enter the body, and in contact with the mucous membranes of the nasopharynx and the eyes, and even with intact skin.

Poisoning statistics for WCF

Acute intoxication with organophosphorus compounds is in fact the first place among other exogenous poisonings, not only in severity, but also in frequency. The lethality of such poisonings is almost 20%, and the frequency - about 15% of all cases of intoxication. It is of interest that alcohol is a kind of antidote for poisoning by organophosphorus compounds. The victims who were in a state of strong alcohol intoxication at the time of insecticide poisoning, the disease is much easier (seizures and paresis of the respiratory muscles are absent). However, hemodynamic disorders can be more pronounced.

Possible causes of insecticide poisoning

Poisoning with organophosphorus compounds can be associated with occupational activity and can occur as a result of non-compliance with the rules for handling toxic substances. The negligence of one or more people can turn into not only serious poisonings for themselves, but also lead to mass intoxication.

In addition , poisoning with organophosphorus compounds can be of a household nature. Causes of accidents can be different, for example:

• The absence of signs on the container with poisonous liquid stored at home (a person can take poison inside by mistake, or intentionally for the purpose of intoxication);
• Storage of insecticides in places accessible to children (children by nature are very curious, and even if a container with pesticide is signed, a small child can still drink dangerous liquid and get acute poisoning);
• Non-compliance with safety regulations (neglect of protective equipment when using toxic substances in the household, such as a respirator, gloves, goggles, protective clothing).

When organophosphorus compounds in large doses fall into the human body, they can cause damage to various parts of the central nervous system, which leads to neuritis, paralysis and other serious consequences, even to death.

Classification of organophosphorus compounds according to the degree of toxicity

• The most toxic - insecticides based on thiophos, metaphos, mercapto-phos, octamethyl;
• Highly toxic - preparations based on methylmercaptophosphate, phosphamide, dichlorophosphate;
• Medium-toxic - chlorophos, carbofos, methylnitrophos and insecticides based on them, as well as saiphos, cyanophos, tribufos;
• Low-toxic - demufos, bromophos, temefos.

Symptoms of poisoning the WCF

By severity, poisoning is divided into 3 stages. The clinic for poisoning with organophosphorus compounds is as follows:

With mild intoxication (stage I):

• Psychomotor agitation and a sense of fear;
• labored breathing;
• Dilated pupils (miosis);
• Spastic pain in the abdomen;
• Increased salivation and vomiting;
• Severe headaches;
• High blood pressure;
• Excessive sweating;
• Raucous breath.

When the form is moderate (stage II):

• Psychomotor agitation may persist or be gradually replaced by inhibition, and sometimes - and a coma;
• Pronounced miosis, pupils to light cease to react;
• Maximum symptoms of hyperhidrosis are manifested (salivation (salivation), sweating, bronchorea (sputum excretion from the bronchi) is maximized);
• Fibrillar twitching of the eyelids, muscles of the chest, legs, and sometimes all muscles;
• The periodic appearance of a common hypertone of the muscles of the body, tonic convulsions;
• Sharply increases the tone of the chest;
• Blood pressure reaches the maximum values (250/160);
• Involuntary defecation and urination, accompanied by painful tenesmus (false urges).

Severe form of poisoning (stage III):

• The patient falls into a deep coma;
• All reflexes are weakened or completely absent;
• Severe hypoxia;
• Sharply pronounced miosis;
• Preservation of symptoms of hyperhidrosis;
• A change in muscle hypertonicity, myofibrillation, and tonic convulsions with paralytic musculature relaxation;
• Breathing is strongly inhibited, the depth and frequency of respiratory movements are irregular, paralysis of the respiratory center is possible;
• The heart rate decreases to critical values (40-20 per min.);
• Tachycardia increases (more than 120 beats per minute);
• Blood pressure continues to fall;
• Develops toxic encephalopathy with edema and numerous diapedemic hemorrhages of predominantly mixed type caused by paralysis of the respiratory muscles and depression of the respiratory center;
• Skin covers turn pale, cyanosis appears (the skin and mucous membranes acquire a cyanotic color).

Consequences of poisoning with phosphorus-containing insecticides

When organophosphorus compounds enter the body, first aid provided in a timely and correct manner is one of the fundamental factors determining the further course of the disease. The diagnosis of FOS intoxication is relatively easy to make according to the characteristic clinical picture, but whether the outcome will be favorable or the victim will die depends largely on the subsequent actions of the physicians.

Because of the high toxicity, organophosphorus compounds, when ingested, cause irreparable harm to virtually all vital organs and systems. In this regard, even with a favorable outcome, the functions of some organs can not be completely restored.

Among the complications, which are usually accompanied by severe intoxication with organophosphorous substances, include pneumonia, rhythm and conduction of the heart, acute intoxication psychoses, etc.

Course of the disease

During the first few days after the poisoning the patient is in a serious condition due to cardiovascular collapse. Then there comes a gradual compensation and his well-being improves. However, after 2-3 weeks, the development of severe toxic polyneuropathy is not ruled out. In some cases, a number of cranial nerves may be involved in the process.

The course of such late polyneuropathies is rather protracted, sometimes accompanied by persistent motor disorders. Restoration of the functions of the peripheral nervous system is bad. There may also be a return of acute disorders, such as cholinergic crises. This is explained by the fact that the deposited organophosphorus compound is "thrown out" from various tissues into the circulatory system.

Treatment

When serious poisoning with organophosphorus compounds occurs, first aid should include aggressive cleansing of the digestive tract by washing the stomach with a probe, forced diuresis, etc., maintaining breathing and applying specific antidotes. Next, a set of resuscitation measures, including pharmacotherapy, is used to maintain and restore damaged body functions, including measures to restore cardiac activity, treatment of homeostatic disorders and exotoxic shock.

Restoration of respiratory function

Organophosphorus compounds that enter the body in large quantities usually cause respiratory distress, the causes of which are excessive oropharyngeal secretion, bronchospasm and paralysis of the respiratory musculature. In this regard, the first thing that doctors are trying to do is to restore airway patency and provide adequate ventilation. In the presence of abundant emetic masses and oropharyngeal discharge, aspiration is used (taking liquids with the help of vacuum). In acute poisoning FOS reanimation measures include intubation of the trachea, artificial ventilation.

Antidote therapy

The use of antidotes (antidotes) is an important part of emergency pharmacotherapy for acute poisoning. Preparations of this group affect the kinetics of a toxic substance in the body, ensure its absorption or elimination, reduce the effect of toxins on receptors, prevent dangerous metabolism and eliminate dangerous disorders of vital body functions caused by poisoning.

Antidote for poisoning with organophosphorus compounds is taken together with other specialized medicinal products. Pharmacotherapy is carried out in parallel with general resuscitation and detoxification therapeutic measures.

It should be remembered that if there is no possibility of urgent resuscitation, then the life of the victim can save only the antidote of organophosphorus compounds, and the earlier it is introduced, the more likely the victim will be to a favorable outcome of the disease.

Classification of antidotes

Antidotes are divided into four groups:

• Symptomatic (pharmacological);
• Biochemical (toxicokinetic);
• Chemical (toxicotropic);
• Antitoxic immunopreparations.

With the appearance of the first symptoms of poisoning by organophosphorus compounds, even at the stage of pre-hospitalization of the victim, antidotes of symptomatic and toxicotropic groups are used, since they have clear indications for use. Drugs of toxicokinetic action require strict adherence to the instructions, because ambulance doctors can not always accurately determine the indications for their use. Antitoxic immunopreparations are used in the conditions of a medical institution.

Specific therapy for acute poisoning with organophosphorus compounds

The complex of measures includes the use of anticholinergics (medications such as atropine) in combination with cholinesterase reagents. In the first hour after hospitalization of the patient intensive atropinization is carried out. Atropine in large doses is administered intravenously to stop the existing symptoms of hyperhidrosis. There should also be signs of a slight overdose of the drug, expressed by dry skin and moderate tachycardia.

To maintain this condition, atropine is administered repeatedly, but in smaller doses. Supportive atropinization creates a persistent blockade of the m-cholinergic systems of the injured organism against the action of the acetylcholine preparation for the time necessary for the destruction and elimination of the toxin.

Modern cholinesterase reactivators are capable of effectively activating oppressed cholinesterase and neutralizing various phosphorus-containing compounds. When carrying out specific therapy, the cholinesterase activity is constantly monitored.