Anti-Snake Venom Treatment Protocol
Activate emergency medical services immediately and transport the patient to a hospital for antivenom administration, as antivenom is the definitive treatment for snake envenomation and is only available in hospital settings. 1
Immediate Field Management (Pre-Hospital)
Essential Actions
- Call 911 or activate EMS immediately for any person bitten by a venomous or possibly venomous snake 1
- Remove all rings, watches, and constricting jewelry from the bitten extremity before swelling develops, as progressive edema can cause ischemic injury to digits 2, 3
- Immobilize the bitten extremity completely and keep it at or below heart level to minimize venom absorption through the lymphatic system 2, 3
- Minimize all physical exertion by the victim during transport, as walking or activity accelerates systemic venom absorption 1, 2
Geographic-Specific Pressure Immobilization
The approach to pressure immobilization depends critically on snake type and geographic location:
- For North American pit viper bites (rattlesnakes, copperheads, cottonmouths): Do NOT use pressure immobilization bandaging, as it may worsen local tissue injury by trapping cytotoxic venom at the bite site 2, 3
- For neurotoxic snakes (coral snakes, sea snakes, exotic species): Apply pressure immobilization with 40-70 mm Hg in the upper extremity or 55-70 mm Hg in the lower extremity around the entire length of the bitten limb 2, 4
This distinction is critical because >95% of North American envenomations involve cytotoxic pit viper venom, where pressure immobilization causes harm rather than benefit 1, 3
Contraindicated First Aid Measures (Potentially Harmful)
Avoid all of the following interventions, as they are ineffective and potentially harmful:
- Do NOT apply ice or cold therapy - causes additional tissue injury without removing venom 1, 4
- Do NOT use suction devices (with or without incision) - removes negligible venom and may aggravate injury 1, 2
- Do NOT apply tourniquets - worsens local tissue injury without preventing systemic envenomation 1, 2
- Do NOT use electric shock therapy - completely ineffective and potentially harmful 1, 2
Hospital-Based Definitive Treatment
Antivenom Administration Indications
Antivenom should be administered as soon as there is evidence of envenoming, which includes: 5
- Progressive local injury (worsening swelling, ecchymosis)
- Venom-induced consumption coagulopathy
- Sudden collapse or hypotension
- Myotoxicity (elevated creatine kinase)
- Neurotoxicity (muscle weakness, ptosis, respiratory distress)
- Thrombotic microangiopathy
- Renal impairment
Monitoring and Admission
- Admit ALL suspected snakebite patients for at least 12-48 hours with continuous monitoring, as neurotoxicity onset can be delayed up to 13 hours despite minimal local findings 2, 3, 5
- Perform serial blood testing: activated partial thromboplastin time, international normalized ratio, and creatine kinase levels 5
- Conduct serial neurological examinations for all patients 5
Antivenom Dosing
- One vial of the relevant antivenom is sufficient to bind all circulating venom 5
- Antivenom therapy is most effective when given within four hours of the snakebite 6
- Test for hypersensitivity to antivenom before administration 6
- Be prepared to manage acute anaphylactic reactions (may develop within an hour) and delayed serum sickness (5-14 days post-administration) 7
Current U.S. Antivenom Options
For pit viper envenomation in the United States, CroFab (Fab antivenom) has demonstrated efficacy in prospective trials and produces fewer acute or delayed allergic reactions compared to older IgG antivenoms 8. However, Fab molecules have a shorter half-life and may require additional doses to prevent recurrence of venom effects 8.
Critical Clinical Pitfalls to Avoid
Most Dangerous Assumption
Never assume no envenomation based on absence of immediate pain or swelling - this is the most critical pitfall, as neurotoxic bites (coral snakes, sea snakes) cause life-threatening systemic toxicity despite minimal local findings 2, 3, 4
Other Key Pitfalls
- Do not delay transport to attempt ineffective field interventions, as time to antivenom is the most important prognostic factor 2, 3
- Do not apply pressure immobilization techniques developed for neurotoxic snakes to North American pit viper bites, as this worsens cytotoxic tissue damage 2, 3
- Do not withhold antivenom based solely on laboratory abnormalities without clinical bleeding - the presence of bleeding diathesis along with raised clotting time should guide ASV use 9
Venom Type Recognition for Treatment Planning
Hemotoxic/Cytotoxic Venom (Pit Vipers)
- Causes progressive local tissue necrosis, coagulopathy, and thrombocytopenia 2
- Presents with immediate pain, swelling, and redness at bite site within 30 minutes 3
- Pressure immobilization is contraindicated 2