Snake bite is a very common occupational accident seen amongst farmers and outdoor workers. Snake bite is usually higher during the rainy season. According to statistics, more than 5 million people per year are bitten by snakes. Snake poisoning is an acute medical emergency as it is fatal is not treated timely. Snake bite is very common in rural areas. In India, 4 types of venomous snake bite cause fatality.
Snake bites can be classified into 2 types – Venomous snake bites and non-venomous snake bites. Venomous snake bite is 3 types Neurotoxic, Hemotoxic and Myotoxic. Cobra and Krait are neurotoxic as they cause damage to the nervous system. Russell’s viper and saw-scaled viper are hemotoxic as they destroy blood.
2. COBRA / KRAIT BITE ( NEUROTOXIC )
Along with snake bite history and clinical signs and symptoms are observed. A bedside test is known as 20 WBCT (20-minute whole blood clotting test ). Here, 2-3 and fresh whole blood are taken from the patient and kept in a clean and dry glass vessel for 20 minutes at room temperature. After 20 minutes that glass vessel is tilted gently. If the blood is liquid, then it is proved that the patient has incoagulable blood suggestive of hemotoxic snake bite. For snake bite screening tests like CBC, urea, creatinine, coagulation profile, electrolyte is done. ABG ( Arterial Blood Gas ) analysis or pulmonary function test may be done if indicated.
Snake envenoming treatments are 2 types – Supportive treatment and Specific treatment.
SUPPORTIVE TREATMENT – The First step of supportive management is airway, breathing and circulation maintenance. After that treatment of vomiting, respiratory paralysis, renal failure, and snake shock are managed carefully. For respiratory failure respiratory support like ventilation is given. In the case of renal failure, dialysis is done. Management of shock must be done accordingly. Blood pressure, pulse, BUN, urine output should be monitored carefully during the treatment. Local pain and swelling in managed by paracetamol only. Aspirin or other NSAIDs group of drugs are avoided usually due to increased risk of coagulopathy.
SPECIFIC TREATMENT – Most specific and important treatment of snake venom poisoning is a specific anti-venom. Anti Snake Venom ( ASV ) is available in India in polyvalent form. Monovalent ASV is not available in India. Polyvalent ASV is effective against four common species in India – Russel’s viper, Common Cobra, Common Krait and Saw Scaled Viper. Antivenom is produced by hyperimmunized horses to produce antibodies against snake venom. The recommended dose of ASV is 10 vial of ASV initially. Not skin test for hypersensitivity is the required dose of anti-snake venom is the same for children and adults because snake injects the same amount of venom during the bite. 10 viral ASV is reconstituted with isotonic saline and given as slow intravenous injection over one hour, Injection hydrocortisone 100mg i.v., or injection adrenaline 0.25 ml S/C may be given as prophylactic to prevent ASV reaction.
Neurotoxic snake bite like Cobra, krait needs extra atropine. Atropine injection 0.6mg given intravenously by neostigmine 2mg intramuscular injection.