Intensive Care of Acute Poisoning - A. V. Hovenko 2010

Main types of acute poisoning and their treatment
Poisoning by animal venoms and toxins
Snakebites

The following representatives of vipers (Viperidae) are common in Ukraine: the common adder (Viperidae berus) and the steppe viper (Viperidae ursini). The venom of these snakes is produced and stored in specialized alveolar-tubular glands. During a bite, the venom is expelled through the grooves of the venom fangs. Snake fangs are mobile: in a closed Mouth they lie in a horizontal position, whereas when the mouth opens and during a strike, they pivot into a vertical position.

Snake venom consists of a complex of substances (Enzymes, tissue respiration inhibitors, Proteins, Peptides, NUCLEOTIDES, pigments, inorganic salts, anticoagulants).

Based on the MECHANISM OF ACTION of toxins and the symptoms of intoxication, snake envenomation can be divided into the following groups:

1) with a predominant effect on The Nervous system and myocardium (sea snakes, elapids, cobras);

2) with a predominant effect on Blood vessel walls and erythrocytes (vipers, rattlesnakes);

3) venoms containing neurotoxins and hemorrhagic or hypercoagulable enzymes.

Clinical manifestations of envenomation depend on the following factors:

- the dose of toxins;

- the concentration of toxins in the venom introduced into the body;

- the Location OF THE bite (bites to the HEAD, neck, or a blood vessel are the most dangerous);

- the specific body Tissues into which the venom was injected.

Viper Venom. A bite from a viperid snake causes localized pain, a burning sensation, hyperemia, Hemorrhage, and hemorrhagic edema at the site of the bite. In severe cases of envenomation, multiple hemorrhages and blisters spread across the victim's body (lymphangitis), accompanied by Swelling and tenderness of the Lymph Nodes near the bite site (lymphadenitis), and potential venous thrombosis. This results in edema of the affected limb and hemorrhagic infiltration of its tissues. The puncture wound bleeds and may develop ulcers and necrosis.

After some time, the victim develops shortness of breath, headache, nausea, vomiting, weakness, perspiration, a drop in blood pressure, and potential convulsions.

A discrepancy between BODY Temperature AND pulse is observed: with a mild fever (37.2-37.8 °С), the pulse accelerates to 120 beats per minute or more.

During the first 30-90 minutes, blood clotting sharply increases, fibrin is deposited in the capillaries, and multiple microthrombi occur. This is followed by a phase of hypocoagulation and bleeding (epistaxis, gastrointestinal bleeding, Hematuria).

Clinical Manifestations of Cobra Bites. Venoms of the Elapidae family and sea snakes (cobras, coral snakes) block neuromuscular and interneuronal synapses, and suppress the Cerebral Cortex AND subcortical centers. Following a cobra bite, local changes are mild; however, neuromuscular disorders rapidly develop, resembling an ascending paralysis. Symptoms include hypersalivation, generalized weakness, sensory disturbances, an elevated body temperature of 38-39 °С, respiratory depression, extrasystole, and atrioventricular block. Shock and pulmonary edema may also occur.

First Aid Measures.

1) reassure the victim;

2) wipe the bite area with a damp cloth to remove venom from the Skin surface;

3) restrict limb movement by immobilizing the limb and keeping it elevated;

4) transport the victim to the hospital as quickly as possible;

5) under no circumstances apply a tourniquet;

6) under no circumstances use traditional interventions: incisions, cauterization, excision, or oral suction of the venom.

Complications arising from The Use of tourniquets, pressure bandages, and other occlusion Methods:

1. Ischemia and Gangrene of the limb.

2. Injury to superficial nerves, particularly the lateral popliteal nerve.

3. Increased fibrinolytic activity in the compressed limb.

4. Blood stasis, edema, and increased bleeding in the compressed limb.

5. Shock upon release of a tight tourniquet.

6. Enhancement of the local effect of venom or toxin.

7. Cooling of the limb. It should be noted that the use of limb cooling currently varies widely across recommendations from different authors (some authors report significant complications associated with the use of ice).

Therapeutic measures performed during The transport of the casualty to a medical facility:

1. Monitoring of cardiac function (measurement of blood pressure and pulse rate).

2. Monitoring of the Respiratory system (determination of respiratory rate); administration of oxygen inhalation if necessary. If symptoms of severe respiratory failure develop, transfer the casualty to controlled mechanical ventilation.

3. Measurement of Limb circumference at the level of edema and 10 cm proximal to it.

4. Venipuncture.

5. Infusion therapy with crystalloid solutions.

6. To relieve anxiety in the casualty: moral support; drug therapy (sibazon 0.005 g orally or 2 ml of a 0.5% solution intramuscularly).

7. To relieve pain: analgesics.

8. In the event of vomiting: position the casualty on their side, lower the head of the bed, and administer antiemetics (metoclopramide 2 ml intramuscularly).

9. In the event of anaphylactic shock — adrenaline.

10. For allergic manifestations — H1-blockers.

Therapeutic measures performed at the hospital stage of medical care:

1. Examination of the casualty.

2. Determination of blood pressure, pulse rate, and pulse oximetry.

3. Monitoring of the respiratory system.

4. Measurement of limb circumference at the level of edema and 10 cm proximal to it, and comparison of these data with previous measurements.

5. Clinical and Laboratory examination: complete blood count, urinalysis, hematocrit, coagulogram, blood electrolytes, bilirubin, urea, total protein, and surgical consultation. Additional tests and consultations as necessary.

6. Continuation of infusion therapy initiated at the pre-hospital stage, with the administration of colloids and plasma alkalinization.

7. In case of agitation — administration of sedatives (sibazon, etc.).

8. Administration of analgesics in case of severe pain.

9. Administration of a specific antidote - antitoxin (see App. 8).

10. Administration of tetanus antitoxin or toxoid (According to the instructions).

11. Administration of anticoagulants in the absence of bleeding (doses equivalent to 300-500 IU/kg of body weight per day of heparin are administered intravenously every three hours under Blood Coagulation monitoring). If bleeding occurs after heparin administration, an antidote is used: protamine sulfate - 1 mg per 100 IU of heparin.

12. Broad-spectrum Antibiotics.

13. Symptomatic therapy.

14. Hemodialysis in the presence of signs of ACUTE RENAL FAILURE.

Victims with mild poisoning should be monitored by a physician for 6-8 hours, while those with moderate or severe poisoning require at least 24 hours of observation.

Antitoxin therapy should not be administered in all cases of poisoning because:

- all existing antitoxins can cause severe serum reactions;

- antitoxins have a specific range of specific or nonspecific neutralizing activity. Therefore, if a poison outside this range enters the body, administration of the antitoxin will be ineffective;

- antitoxins are always expensive and have a limited shelf life.

Indications for antitoxin administration.

I. Systemic intoxication.

1. Hemostatic disorders: spontaneous systemic bleeding (e.g., from the Gums, Nose), coagulopathy (failure of blood to clot, elevated fibrinogen degradation products, thrombocytopenia).

2. Cardiovascular disorders: shock, hypotension, arrhythmia, Heart Failure, pulmonary edema.

3. Neurotoxicity.

4. Generalized acute Skeletal Muscle necrosis.

5. Impaired consciousness (regardless of the cause).

II. Severe local intoxication.

1. Edema involving more than half of the bitten limb.

2. Presence of large blisters or hemorrhages on the limb.

3. High risk of necrosis associated with bites to the fingers.

Contraindications to antitoxin administration

There are no absolute contraindications to antitoxin administration in patients with life-threatening intoxication. In individuals with a history of allergies (asthma, hay fever, vernal Conjunctivitis, food and drug allergies) and documented hypersensitivity to sera, the risk of severe adverse reactions is very high. These reactions can sometimes be prevented or mitigated by prior subcutaneous administration of epinephrine and intravenous administration of corticosteroids and antihistamines. Rapid desensitization is not performed.

Procedure for Antitoxin Administration

Administering a monospecific antitoxin is optimal. In cases of unknown snake species envenomation, a polyvalent antitoxin is used. Many authors recommend the Besredka method for antitoxin administration. However, in recent years, the intravenous route has been recommended to prevent allergic reactions. The antitoxin is administered at a dose of 5 mL per minute as an intravenous push or via an infusion over 30–60 minutes in isotonic sodium chloride solution. A pressure bandage is applied over the venipuncture site.

Systemic Reactions to Antitoxin

1. Neurotoxicity: develops slowly.

2. Cardiovascular complications (hypotension, bradycardia): develop within 10–20 minutes.

3. Cessation of spontaneous systemic bleeding: occurs within 15–30 minutes.

4. Restoration of blood clotting: occurs within 1–6 hours.

5. If severe cardiovascular or neurotoxic syndromes persist for more than 30 minutes, or if blood fails to clot for more than 6 hours, the antitoxin administration is repeated at the same dose.

Allergic Reactions to Antitoxin

1. Early reactions — develop 10–15 minutes after THE START OF intravenous administration. Symptoms include coughing, palpitations, pruritus, flushing, nausea, vomiting, and headache. In more than 5% of patients, early symptoms are followed by signs of severe anaphylaxis: hypotension, bronchiolospasm, and angioedema. Management: a) adrenaline intravenously, 0.5–1 mL of a 0.1% solution (1:1000); b) antihistamines and corticosteroids.

2. Pyrogenic reactions — may develop 1–2 hours after the initiation of antitoxin therapy. Symptoms include chills, tremors, a sharp spike in body temperature, vomiting, and diarrhea. Management: physical cooling methods and administration of antipyretics (paracetamol 5 mg/kg of body weight intramuscularly or orally).

3. Late reactions — develop as serum sickness, typically appearing about 7 days after administration. Management: antihistamines are used for relatively mild reactions; corticosteroids are additionally prescribed in severe cases.