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Epidemiology 7,000–8,000 people are bitten by poisonous snakes/year in the US; about 5 die
When snake bite, esp. from a venomous snake, is confirmed or strongly suggested, the patient's airway, breathing, and circulation should be assessed, and he should be transported immediately to a medical facility equipped and staffed to handle snake bites. In the hospital, the patient is attached to a cardiac monitor, an automatic noninvasive blood pressure monitoring machine, and a pulse oximeter. If necessary, oxygen administered at 4 L/min via nasal cannula, and an intravenous infusion of Ringer's lactate or normal saline should be started. Pulses below the wound and capillary refill time in the wounded limb are assessed and compared to the unaffected limb. The circumference of the affected limb should be measured at the bite and at equal distances above and below it, to monitor the spread of edema and inflammation. Lung sounds are auscultated for clarity, and the patient is asked about medical history, allergies, and history of previous snakebite. Snakebite symptoms can range from mild swelling, pain, and erythema to hypotension, shock, and a disseminated intravascular coagulation-like syndrome. In all cases the affected limb should be placed in a neutral, resting position.
If the patient has actually received venom from the snake bite (only about 50% of patients have), the appropriate antivenin should be administered intravenously, appropriately diluted. If the required antivenin is prepared from horse serum, the patient should be tested for sensitivity before administering the antivenin. The antivenin should be infused slowly, over about an hour in most cases, and the patient monitored for adverse reactions for at least another hour. Resuscitation equipment for treating anaphylaxis should be readily available throughout the infusion. Children require a higher dosage of antivenin than do adults. A blood sample should be drawn from the patient for complete blood count, coagulation profile, BUN, creatinine, creatine kinase, and blood type and cross-match. A urine specimen should be obtained to test for myoglobinuria.
The wound should be cleaned with cool soap and water. Analgesics and other prescribed treatments (antibiotics, methylprednisolone, antihistamines) should be administered, as well as tetanus prophylaxis if indicated.
Snake antivenin information is available from the nearest Poison Control Center. The patient should be observed for potential complications such as compartment syndrome, coagulopathy, rhabdomyolysis, renal failure, and wound infection. Prior to discharge, the signs and symptoms of delayed adverse reactions to antivenin should be explained to the patient, and he or she should be advised to immediately report fever, malaise, joint pain, rash, or unusual body bruising.
The patient should be transported immediately to a medical facility equipped and staffed to handle snake bites. In the hospital, an intravenous infusion of Ringer's lactate or normal saline should be started.
A polyvalent antivenin serum for bites by pit vipers is prepared by Wyeth Lab. Inc. Antivenin for coral snake bite is also available from Wyeth. The use of antibodies to treat pit viper bites is being used experimentally.