What is the workup for a rattlesnake (Crotalinae) bite?

From the Guidelines

The workup for a rattlesnake bite requires immediate medical attention at the nearest emergency department, with a focus on stabilizing the patient and managing potential complications. The initial assessment should include evaluation of airway, breathing, and circulation, followed by removal of constrictive items like jewelry or tight clothing from the affected limb 1.

Key Recommendations

• The affected extremity should be immobilized at heart level, and the patient should avoid physical exertion, as recommended by the 2024 American Heart Association and American Red Cross guidelines for first aid 1.
• Laboratory tests, including complete blood count, coagulation studies, comprehensive metabolic panel, creatine kinase, and urinalysis, should be performed to assess for rhabdomyolysis and renal function.
• Serial measurements of the affected limb's circumference should be taken to monitor swelling progression.
• Antivenom (CroFab or Anavip) is the definitive treatment for moderate to severe envenomation, administered intravenously based on clinical severity rather than snake size or patient characteristics.
• Wound care includes cleansing and tetanus prophylaxis if needed, and pain management with acetaminophen or opioids may be necessary, but NSAIDs should be avoided due to potential bleeding complications 1.

Avoiding Harmful Interventions

• The use of suction, ice, electric shock, tourniquets, and pressure immobilization bandaging is not recommended, as these interventions have been shown to be ineffective or potentially harmful in the treatment of snakebites 1.
• Patients require close monitoring for at least 24 hours, with repeat laboratory testing at 6-hour intervals to assess for coagulopathy, and a comprehensive approach to address both the systemic effects of venom and prevent complications like compartment syndrome and tissue necrosis.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Rattlesnake Bite Workup

The workup for a rattlesnake (Crotalinae) bite involves several key considerations:

• Aggressive treatment with antivenin (Crotalidae) polyvalent, with an average of 15 to 20 vials required 2
• Management of hypersensitivity to horse serum, hematologic abnormalities, symptoms of envenomation, care of the bite site, and care of patients with severe symptoms 2
• First-aid therapy limited to splinting the extremity and transporting the victim to a medical facility, with definitive therapy involving administration of antivenin intravenously in adequate initial doses and repeating every two hours until the venom is completely neutralized 3

Comprehensive Work-up

A comprehensive work-up for rattlesnake bite victims includes:

• Looking for possible hematologic, neurologic, renal, and cardiovascular abnormalities 4
• Local wound care, systemic antivenom administration, tetanus prophylaxis, antibiotics in the presence of infection, and surgical treatment if needed, which may include debridement, fasciotomy, and rarely amputation 4
• Observation for a minimum of 8 hours, with any evidence of envenomation mandating a minimum of 24 hours of in-hospital observation 4

Antivenom Administration

Antivenom administration is a critical component of rattlesnake bite treatment:

• The most commonly used antivenom in the U.S. is CroFab, which has a much lower incidence of acute or delayed allergic reactions compared to older antivenoms 4
• Antivenom is indicated with any grade of envenomation, due to its improved risk-benefit ratio 4
• Allergic reactions to antivenom can occur, and physicians should be alert to their occurrence, particularly in patients receiving multiple treatments with antivenom 5, 6