Rattlesnake Envenomation Treatment & Management

Updated: Jun 25, 2015
  • Author: Sean P Bush, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
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Treatment

Prehospital Care

Do nothing to injure the patient or impede travel to the ED.

Give general support of airway, breathing and circulation per advanced cardiac life support (ACLS) protocol with oxygen, monitors, 2 large bore intravenous lines, and fluid challenge. Minimize activity (if possible), remove jewelry or tight-fitting clothes in anticipation of swelling, and transport the patient to the ED as quickly and as safely as possible. Use a pen to mark and time the border of advancing edema often enough to gauge progression.

In some studies, no benefit was demonstrated when a negative pressure venom extraction device (eg, The Extractor from Sawyer Products) was evaluated; additional injury can result. [15, 16] Incision across fang marks is not recommended. Mouth suction is contraindicated. See the image below.

A recent study suggests that the Extractor (Sawyer A recent study suggests that the Extractor (Sawyer Products) does not reduce swelling after rattlesnake envenomation and may be associated with skin necrosis beneath the suction cup. Photo by Sean Bush, MD.

Lymphatic constriction bands and pressure immobilization techniques may inhibit the spread of venom, but whether they improve outcome is not clear. [17, 18] Limiting venom spread actually may be deleterious for pit viper envenomation if it increases local necrosis or compartment pressure. Tourniquets are not recommended.

Maintain the extremity in a neutral position.

First aid techniques that lack therapeutic value or are potentially more harmful than the snakebite include electric shock, alcohol, stimulants, aspirin, placing ice on the wound, and various folk and herbal remedies. Cost and risk of acute adverse reactions generally preclude field use of antivenom.

Attempts to capture or kill the snake cannot be recommended because of the risk of additional injury. If uncertainty exists about whether a particular snake is venomous, consider taking photographs of the snake from a safe distance of at least 6 feet away using a digital or Polaroid camera.

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Emergency Department Care

Adequate hydration with intravenous fluids is indicated. Patients with hypotension should be resuscitated first with two isotonic sodium chloride solution challenges (eg, 20 mL/kg). Treat persistent shock with colloids, followed by pressors as indicated.

Administer antivenom for signs of envenomation progression or imminent risk of an acute complication of envenomation (see Complications). Crotalidae polyvalent immune FAB ovine (CroFab) is a safe option [19, 20] and it is indicated even if the envenomation is minimal or mild. [21, 22] An equine Crotalidae immune FAB antivenin was approved in the United States in 2015. An antivenin should be given as a preventative measure if any signs of envenomation exist. Do not wait for the envenomation to get worse—permanent injury could result.

It is emphasized that grading envenomations is a dynamic process and additional antivenom should be given as indicated by a worsening clinical course. When considering the use of antivenom, the risk of adverse reaction to antivenom must be weighed against the benefits of reducing venom toxicity. [23] Alternatives (eg, a different type of antivenom, if available) should be considered as well.

Nonenvenomation, ie, dry bite (probably occurs in < 10% of rattlesnake bites, although estimates as high as 50% exist), is characterized by the following:

  • Local effects - Puncture wounds only
  • Systemic effects - None
  • Coagulation abnormalities - No laboratory evidence of coagulation abnormalities and no clinical evidence of abnormal bleeding or clotting

Minimal or mild envenomation is characterized by the following:

  • Local effects - Swelling, pain, tenderness, and/or ecchymosis confined to the immediate bite area
  • Systemic effects - None
  • Coagulation abnormalities - No laboratory evidence of coagulation abnormalities and no clinical evidence of abnormal bleeding or clotting

Moderate envenomation is characterized by the following:

  • Local effects - Swelling, pain, tenderness, and/or ecchymosis extending beyond the immediate bite area but involving less than the entire part
  • Systemic effects - Present but not life threatening; may include nausea, vomiting, oral paresthesias or unusual tastes, fasciculations (myokymia), mild hypotension (systolic blood pressure < 90 mm Hg), mild tachycardia (heart rate < 150 bpm), and tachypnea
  • Coagulation abnormalities - Laboratory evidence of coagulation abnormalities may be present, but no clinical evidence of abnormal bleeding or clotting exists; rattlesnake venom-induced coagulopathies commonly include thrombocytopenia, decreased fibrinogen, and/or elevated PT

Severe envenomation is characterized by the following:

  • Local effects - Swelling, pain, tenderness, and/or ecchymosis extending beyond the entire extremity or threatening the airway
  • Systemic effects - May include severe hypotension or shock, severe tachycardia or tachypnea, respiratory insufficiency, and/or severe altered mental status
  • Coagulation abnormalities - Markedly abnormal with serious bleeding or severe threat of bleeding
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Consultations

The American Association of Poison Control Centers may assist in the management of envenomations.

For assistance regarding use of CroFab for a patient bitten by a snake, contact the CroFab hotline at 1-87-SERPDRUG (1-877-377-3784).

Consider consulting a surgeon (eg, general, orthopedic, hand) if compartment syndrome is suspected.

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