Venomous Snakebites
FIELD MANAGEMENT
- Get the victim to definitive care as soon as possible.
- Splint a bitten extremity and keep it at heart level to lessen bleeding and discomfort.
- Avoid incisions into the bite wound, cooling, consultation with traditional healers, tourniquets, and electric shock because these measures are ineffective and may increase local tissue damage.
- If the offending snake is reliably identified and known to be primarily neurotoxic, pressure immobilization (wrapping of the entire limb in a bandage at a pressure of 40-70 mmHg for upper limbs or 55-70 mmHg for lower limbs) may be used. The victim must be carried to medical care, because walking will disperse venom from the bite site regardless of its anatomic location.
HOSPITAL MANAGEMENT
- Monitor vital signs, cardiac rhythm, urine output, and O2 saturation closely. Watch for evidence of cranial nerve dysfunction (e.g., ptosis), which may precede difficulty swallowing or respiratory insufficiency.
- Note the level of swelling and the circumference of the affected limb every 15 min until swelling has stabilized.
- Treat shock initially with isotonic saline (20-40 mL/kg IV); if hypotension persists, try 5% albumin (10-20 mL/kg IV) and vasopressors.
- Begin the search for appropriate, specific antivenom early in all cases of known venomous snakebite. In the United States, round-the-clock assistance is available from regional poison control centers.
- Any evidence of systemic envenomation (systemic symptoms or signs, laboratory abnormalities) and significant, progressive local findings (e.g., swelling that crosses a joint, involves more than half of the bitten limb, or is rapidly spreading; extensive blistering or bruising; severe pain) are indications for antivenom administration.
- Treating physicians should seek advice from snakebite experts regarding indications for and dosing of antivenom. The duration of antivenom administration depends on the offending snake species, but multiple doses are not effective in reversing bite responses that have already been established (e.g., renal failure, established paralysis, necrosis).
- Worldwide, antivenom quality varies. Rates of anaphylactoid reaction can exceed 50%, prompting some authorities to recommend pretreatment with low-dose SC epinephrine (0.25 mg of 1:1000 aqueous solution). Prophylactic use of antihistamines and glucocorticoids is not beneficial. CroFab, an antivenom used in the United States against North American pit viper species, poses a low risk of allergy elicitation.
- A trial of acetylcholinesterase inhibitors should be undertaken for pts with objective evidence of neurologic dysfunction because this treatment may cause neurologic improvement in pts bitten by snakes with postsynaptic neurotoxins.
- Elevate the bitten extremity above heart level once antivenom administration has been initiated.
- Update tetanus immunization.
- Observe pts for muscle-compartment syndrome.
- Observe pts with signs of envenomation in the hospital for at least 24 h. Pts with “dry” bites should be watched for at least 8 h because symptoms are commonly delayed.
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