Diagnosis of acute poisoning

Clinical diagnostics of acute poisoning is the most accessible method used both at the pre-hospital stage and in hospital, consists of identifying symptoms characteristic of the impact of a toxic substance on the body according to the principle of its selective toxicity. By affecting the toxicity receptor, a substance or group of substances with the same or similar mechanism of action cause a response of the body in the form of certain symptoms characteristic of one or another type of affected receptors.

Most chemicals encountered in everyday life as toxic agents, when entering the body, cause rapid development and clinical manifestation of the main characteristic symptoms of poisoning. For example, a comatose state develops quickly in case of poisoning with sleeping pills and neuroleptics, ethyl alcohol, muscarine- and nicotine-like symptoms in case of poisoning with anticholinesterase poisons, disturbances in the rhythm and conduction of the heart in case of poisoning with substances with cardiotropic action, blood damage (hemolysis, methemoglobinemia) in case of ingestion of "blood" poisons. It can be difficult to identify a specific effect in case of poisoning with substances with hepato- and nephrotoxic action. It is impossible to determine hepato- and nephropathy during a routine examination, without laboratory data, as well as without signs of jaundice, uremia, edema and other symptoms in the patient, since they appear no earlier than 3-4 days after ingestion of the poison. A similar situation occurs with methanol poisoning, in which toxic eye damage appears no earlier than 2-3 days after poisoning, when the pathological process becomes irreversible. Later - after several days (up to 7-10) - toxic damage to the peripheral nervous system (polyneuropathy, polyneuritis) appears with poisoning with metal compounds, organophosphorus compounds.

In such cases, clinical diagnosis is made based on the totality of anamnesis data (if any), and also taking into account non-specific, but pathognomonic symptoms for many poisonings. One of the most frequently observed in poisoning is the syndrome of gastrointestinal tract damage in the form of gastroenteritis, a chemical burn of the digestive tract. Vomiting and diarrhea are considered characteristic signs of poisoning with salts of heavy metals, dichloroethane, some alcohol substitutes, organophosphorus compounds, and plant-based poisons. In case of poisoning with methanol, ethylene glycol, and chlorinated hydrocarbons, the symptom complex described in the literature as toxic encephalopathy is of diagnostic value, which includes somatovegetative manifestations (facial hyperemia, scleral injection, hypertension, tachycardia) and disturbances of consciousness (inadequate behavior, disorientation, agitation, and sometimes seizures).

In cases where it is impossible to accurately determine the name of the substance that caused acute poisoning, the diagnosis is made based on the leading pathological syndrome(s) that have developed in the patient. For example, "poisoning with an anticholinesterase poison or an organophosphorus substance", "cauterizing poison", etc. The widely used diagnosis of "poisoning with an unknown poison" should be considered incorrect, since there is no independent nosological form of "unknown poison". It is more correct to use the term according to ICD-10 - "unspecified substance".

Chemical-toxicological diagnostics is considered the most reliable method of poisoning diagnostics, since it is not always possible to determine a specific substance based on the clinical picture, especially in the case of the use of several toxic substances or against the background of alcohol intoxication. There is a special chromatographic system for rapid, reliable, sufficiently sensitive and reproducible laboratory identification of toxic substances in the most accessible biological environments of the body (blood, urine).

Clinical and biochemical laboratory diagnostics of acute poisoning, although not specific, can be a valuable addition, allowing to identify changes characteristic of certain types of poisoning, in particular, determination of acid-base balance in case of poisoning with such alcohol surrogates as methanol, ethylene glycol, higher alcohols, blood damage (anemia, leukopenia, neutropenia, etc.) in case of poisoning with poisons of the aromatic hydrocarbon group, increased activity of liver enzymes, CPK, LDH, concentration of bilirubin, urea and creatinine, blood test for toxicity (pool of medium molecules) in case of damage with poisons of hepato- and nephrotropic action.

Functional or instrumental diagnostics of acute poisoning complements the clinical picture and laboratory data of chemical-toxicological research. Unlike the latter, it is non-specific and is aimed at identifying some important syndrome, without indicating the specific substance that caused the poisoning.

Esophagogastroduodenoscopy is most often used in clinical practice to detect chemical burns of the digestive tract. Esophagogastroduodenoscopy allows us to determine the nature of the lesion, the degree of severity, the extent, and the presence of esophageal-gastric bleeding. The observed picture is described as catarrhal, erosive or fibrinous-erosive, necrotic lesion of the mucous membrane of the digestive tract.

ECG allows to identify a specific disturbance of the rhythm and conduction of the heart, the so-called primary cardiotoxic effect, pathognomonic for poisoning with organophosphorus compounds and barium compounds.

In cases of poisoning with hepatotropic and nephrotropic toxins, radioisotope hepatorenografy is used, which allows identifying disorders of the secretory and excretory functions of these organs, as well as ultrasound of the liver and kidneys.

Bronchoscopy is used for early detection of toxic damage to the respiratory tract (toxic tracheobronchitis, OT) in cases of poisoning with chlorine vapors, ammonia and other gases with an irritating, cauterizing effect.

EEG and CT of the brain are widely used for differential diagnosis of comatose states.

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