Mohave Rattle Snake Envenomation Workup
- Author: Sean P Bush, MD, FACEP; Chief Editor: Rick Kulkarni, MD more...
Laboratory Studies
Rhabdomyolysis may occur from severe snake envenomations but is best described after canebrake (Crotalus horridus atricaudatus) and Mohave (C scutulatus) rattlesnake envenomations.[7, 8, 11] Rhabdomyolysis may lead to myoglobinuric renal failure and subsequent electrolyte abnormalities, such as hyper- or hypokalemia or hypocalcemia.
- Creatine kinase (CK)
- Electrolytes
- Blood urea nitrogen (BUN) and creatinine
- Calcium
- Phosphorus
- Urinalysis
Mohave toxin has less effect on coagulation than other rattlesnake venoms. However, coagulopathies may occur. (See Snake Envenomations, Rattle for suggested laboratory tests.)
For respiratory difficulty, consider arterial blood gas (ABG) measurements.
Obtain laboratory and other diagnostic data on a case-by-case basis. Factors to consider may include severity of envenomation, physician preference, and cost.
Imaging Studies
- Radiographic findings may reveal teeth or fangs retained in the wound.
Other Tests
Obtain an electrocardiogram (ECG), if indicated. Although cardiac enzymes may rise with severe rhabdomyolysis, current literature suggests that this does not reflect cardiac injury.
Skin testing
Skin testing is not necessary before administering Crotaline Fab antivenom (CroFab) therapy.
Intracutaneous injection of 0.02-0.03 mL of a 1:10 dilution of horse serum or antivenom is recommended in the Antivenin Crotalidae Polyvalent package insert.
- A positive test result is manifested by the development of a wheal within 5-30 minutes. However, skin testing is unreliable. False-positive and false-negative results may occur.
- Using antivenom (further diluted to 1:100) rather than the horse serum control that is supplied may increase the sensitivity and specificity of the test.
- Skin testing may be considered variably useful in predicting immediate hypersensitivity in cases of moderate envenomation when it is uncertain if the need for antivenom outweighs the risk of anaphylaxis.
- Skin testing may sensitize individuals at risk for future exposures to antivenom, or it may precipitate anaphylaxis.
- If antivenom is clearly indicated, begin administration as described below, without waiting to perform a skin test.
Procedures
- Central venous or interosseous access may need to be obtained. However, avoid placing a central line in a noncompressible site (eg, subclavian) because of the risk of bleeding from venom-induced coagulopathy.
- Fasciotomy probably is not indicated in Mohave (venom A) envenomation. If severe swelling is noted, suspect envenomation by a snake other than a venom A Mohave rattlesnake and treat accordingly (see Snake Envenomations, Rattle).
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Bush SP, Green SM, Laack TA, Hayes WK, Cardwell MD, Tanen DA. Pressure immobilization delays mortality and increases intracompartmental pressure after artificial intramuscular rattlesnake envenomation in a porcine model. Ann Emerg Med. Dec 2004;44(6):599-604. [Medline].
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Bush SP, Green SM, Moynihan JA, Hayes WK, Cardwell MD. Crotalidae polyvalent immune Fab (ovine) antivenom is efficacious for envenomations by Southern Pacific rattlesnakes (Crotalus helleri). Ann Emerg Med. Dec 2002;40(6):619-24. [Medline].
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