A) MANAGEMENT OF MILD TO MODERATE ENVENOMATION
1) Treatment of mild to moderate toxicity begins with symptomatic and supportive care. Wounds should be cleaned and irrigated, and a tetanus toxoid booster should be given if needed. A limb with mild swelling should be kept in a position of comfort and reevaluated for any progression of swelling or signs and symptoms of developing necrosis. Elevate the affected limb. Antivenom may be warranted if clinical or laboratory markers worsen. Monitor neurologic and respiratory function frequently. Early signs of a neurotoxic envenomation include diplopia, ptosis, and ophthalmoplegia. Oxygen is indicated for anoxia and respiratory support, to be given as needed. Obtain baseline laboratory studies, IV access and begin fluids, vital signs, and cardiac monitoring. Antivenoms play a major role in treatment. Administer pain medication, tetanus prophylaxis, and antibiotics as necessary. EYE EXPOSURE: Treatment for patients with venom ophthalmia due to spitting elapids (more common in the continent of Africa) should receive immediate copious irrigation with water or saline, a single application of local anesthetic eye drops may facilitate opening tightly closed eyelids. Treatment with 0.1% epinephrine or 10% phenylephrine eye drops may rapidly relieve pain. Patients should receive fluorescein staining and a slit lamp exam. Patients without corneal erosions may be treated with antibiotic eye ointment, patching, and follow-up. Patients with corneal erosions should be treated with an antibiotic eye drops/ointment, a mydriatic agent, patching, and follow-up for daily slit lamp examinations until healed. Steroids are contraindicated, and antivenom either topically or systemically is not indicated unless there is a separate systemic envenomation.
B) MANAGEMENT OF SEVERE ENVENOMATION
1) Patients with severe local signs or symptoms or symptoms of progressive neurotoxicity (includes bulbar palsy that can result in dysphagia, slurred speech, choking, absence of gag reflex, or respiratory muscle paralysis) should receive antivenom (see antidote section). Patients with progressive neurotoxicity often require intubation and mechanical ventilation in addition to antivenom therapy. Patients with neurotoxic symptoms may benefit from treatment with an acetylcholinesterase; a test dose of edrophonium or neostigmine should be given. Patients who respond favorably may be treated with continued dosing of neostigmine with atropine. Patients who develop severe local toxicity with necrotic tissue may require debridement to decrease the risk of infection causing worsening functional status. Compartment syndrome is uncommon, and symptoms may be improved by treatment with antivenom.
C) DECONTAMINATION
1) PREHOSPITAL: Immobilize the affected limb and transport the patient to a medical facility. Pressure immobilization (lymphatic compression dressing) may be considered for envenomation from highly neurotoxic snakes and in patients with severe systemic signs of envenomation. Use an elastic, stretchy, crepe bandage (10 cm wide and at least 4.5 meters) or any long strip of material. Bound the bandage firmly around the entire bitten limb; start distally around the fingers or toes and move proximally to include a rigid splint. The bandage should be wrapped similar to a sprained ankle in which the wrap is snug, but does NOT occlude the peripheral pulses and a finger can be easily slipped between the layers. Arterial tourniquets should be avoided, and pressure immobilization should not be performed for envenomations by species that produce local tissue necrosis (eg, unlikely with snakes of this region, may occur in spitting cobras, N nigricollis of Africa), unless life-threatening systemic toxicity is also present.
2) HOSPITAL: Caution should be used when removing a compression dressing or tourniquet as patients may experience rapid progression or symptoms along with increased venom circulation. Antivenom should be available (and administered if there is evidence of significant envenomation) before a compression dressing is removed.
D) WOUND CARE
1) Local wound care and tetanus prophylaxis should be provided for all bites. The introduction of bacteria may occur at the time of the bite. Treatment should consist of cleaning the wound with an antiseptic followed by a booster dose of tetanus toxoid as appropriate. Antibiotic therapy should be initiated only if signs of infection are present. Antibiotics covering Staphylococcus aureus and Enterobacteriaceae bacteria can be useful in the presence of major swelling that is unresponsive to antivenom or suspicion of a secondary infection. Monitor the wound frequently.
E) AIRWAY MANAGEMENT
1) Early intubation and mechanical ventilation is recommended if a patient develops progressive neurotoxicity with signs of respiratory difficulty (eg, weakness, paralysis).
F) ANTIDOTE
1) Treat patients with severe or progressive symptoms with antivenom. If the snake species is positively identified, administer a species specific antivenom when available. Regional polyspecific antivenoms are appropriate when the snake species cannot be reliably identified or a species-specific antivenom is not available. Information on exotic antivenoms and their location, cross-indexed by snake species, can be obtained from your local poison control center. Indications for antivenom include neurotoxicity, spontaneous bleeding, coagulopathy, hypotension, shock arrhythmias, local envenomation by a species know to cause severe necrosis (eg, unlikely with snakes of this region, can occur with spitting cobras, N nigricollis of Africa), and extensive and rapidly progressive swelling. Antivenom should be given as soon as systemic toxicity or severe local effects are present, although it may still be of benefit late in the course of symptoms. Antivenom administration often does not prevent progression of neurotoxic effects or reverse already-established effects, however, it may decrease the time course of paralysis and recovery.
G) ENHANCED ELIMINATION
1) There is no role for hemodialysis or other methods of enhanced elimination in these patients.
H) PATIENT DISPOSITION
1) HOME CRITERIA: There is no role for home management of a suspected venomous snake bite.
2) OBSERVATION CRITERIA: Patients with a Middle East elapid bite should be sent to a medical facility and closely observed for the development of symptoms.
3) ADMISSION CRITERIA: Patients with evidence of progressive local toxicity should be admitted for antivenom treatment and close monitoring. Patients with systemic toxicity including neurotoxicity should be admitted to an ICU at a location with available antivenom.
4) CONSULT CRITERIA: Contact your local poison control center, a medical toxicologist or toxinologist for any patient with a suspected Middle East elapid bite. Patients with an ocular venom exposure should be evaluated by an ophthalmologist.
5) TRANSFER CRITERIA: All patients should be taken to the nearest hospital or clinic that stocks antivenom. If in a non-native geographic area the antivenom is not immediately available or routinely stocked, it will have to be obtained from the nearest zoo source, which may be at a distance and require some time. Thus, the patient should be taken to the nearest hospital capable of managing the patient's existing medical condition. If not already done, splint bitten extremity or area prior to transport. Turn patient on their side to prevent aspiration of vomitus.
I) PITFALLS
1) Failure to recognize local tissue injury progression, failure to recognize neurotoxic progression early, failure to treat early respiratory distress with acetylcholinesterase inhibitors and/or intubation, failure to administer antivenom early. The onset of neurotoxic signs and symptoms of elapid envenomation may be delayed. Deaths have been reported within 6 to 16 hours after envenomation by cobras.
J) DIFFERENTIAL DIAGNOSIS
1) The differential diagnosis includes envenomation by other elapid species (especially African elapids), botulism, Guillain Barre syndrome (Miller Fisher variant), or tetrodotoxin poisoning.